3003 lines
96 KiB
C
3003 lines
96 KiB
C
/*-------------------------------------------------------------------------
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*
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* prepjointree.c
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* Planner preprocessing for subqueries and join tree manipulation.
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*
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* NOTE: the intended sequence for invoking these operations is
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* pull_up_sublinks
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* inline_set_returning_functions
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* pull_up_subqueries
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* flatten_simple_union_all
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* do expression preprocessing (including flattening JOIN alias vars)
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* reduce_outer_joins
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*
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*
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* Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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*
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* IDENTIFICATION
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* src/backend/optimizer/prep/prepjointree.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "catalog/pg_type.h"
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#include "nodes/makefuncs.h"
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#include "nodes/nodeFuncs.h"
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#include "optimizer/clauses.h"
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#include "optimizer/placeholder.h"
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#include "optimizer/prep.h"
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#include "optimizer/subselect.h"
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#include "optimizer/tlist.h"
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#include "parser/parse_relation.h"
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#include "parser/parsetree.h"
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#include "rewrite/rewriteManip.h"
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typedef struct pullup_replace_vars_context
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{
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PlannerInfo *root;
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List *targetlist; /* tlist of subquery being pulled up */
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RangeTblEntry *target_rte; /* RTE of subquery */
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Relids relids; /* relids within subquery, as numbered after
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* pullup (set only if target_rte->lateral) */
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bool *outer_hasSubLinks; /* -> outer query's hasSubLinks */
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int varno; /* varno of subquery */
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bool need_phvs; /* do we need PlaceHolderVars? */
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bool wrap_non_vars; /* do we need 'em on *all* non-Vars? */
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Node **rv_cache; /* cache for results with PHVs */
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} pullup_replace_vars_context;
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typedef struct reduce_outer_joins_state
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{
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Relids relids; /* base relids within this subtree */
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bool contains_outer; /* does subtree contain outer join(s)? */
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List *sub_states; /* List of states for subtree components */
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} reduce_outer_joins_state;
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static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
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Relids *relids);
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static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
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Node **jtlink1, Relids available_rels1,
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Node **jtlink2, Relids available_rels2);
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static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
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JoinExpr *lowest_outer_join,
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JoinExpr *lowest_nulling_outer_join,
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AppendRelInfo *containing_appendrel,
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bool deletion_ok);
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static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode,
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RangeTblEntry *rte,
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JoinExpr *lowest_outer_join,
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JoinExpr *lowest_nulling_outer_join,
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AppendRelInfo *containing_appendrel,
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bool deletion_ok);
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static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode,
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RangeTblEntry *rte);
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static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
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int parentRTindex, Query *setOpQuery,
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int childRToffset);
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static void make_setop_translation_list(Query *query, Index newvarno,
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List **translated_vars);
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static bool is_simple_subquery(Query *subquery, RangeTblEntry *rte,
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JoinExpr *lowest_outer_join,
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bool deletion_ok);
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static Node *pull_up_simple_values(PlannerInfo *root, Node *jtnode,
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RangeTblEntry *rte);
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static bool is_simple_values(PlannerInfo *root, RangeTblEntry *rte,
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bool deletion_ok);
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static bool is_simple_union_all(Query *subquery);
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static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery,
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List *colTypes);
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static bool is_safe_append_member(Query *subquery);
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static bool jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted,
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Relids safe_upper_varnos);
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static void replace_vars_in_jointree(Node *jtnode,
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pullup_replace_vars_context *context,
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JoinExpr *lowest_nulling_outer_join);
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static Node *pullup_replace_vars(Node *expr,
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pullup_replace_vars_context *context);
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static Node *pullup_replace_vars_callback(Var *var,
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replace_rte_variables_context *context);
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static Query *pullup_replace_vars_subquery(Query *query,
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pullup_replace_vars_context *context);
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static Node *pull_up_subqueries_cleanup(Node *jtnode);
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static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode);
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static void reduce_outer_joins_pass2(Node *jtnode,
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reduce_outer_joins_state *state,
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PlannerInfo *root,
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Relids nonnullable_rels,
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List *nonnullable_vars,
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List *forced_null_vars);
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static void substitute_multiple_relids(Node *node,
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int varno, Relids subrelids);
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static void fix_append_rel_relids(List *append_rel_list, int varno,
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Relids subrelids);
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static Node *find_jointree_node_for_rel(Node *jtnode, int relid);
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/*
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* pull_up_sublinks
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* Attempt to pull up ANY and EXISTS SubLinks to be treated as
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* semijoins or anti-semijoins.
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*
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* A clause "foo op ANY (sub-SELECT)" can be processed by pulling the
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* sub-SELECT up to become a rangetable entry and treating the implied
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* comparisons as quals of a semijoin. However, this optimization *only*
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* works at the top level of WHERE or a JOIN/ON clause, because we cannot
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* distinguish whether the ANY ought to return FALSE or NULL in cases
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* involving NULL inputs. Also, in an outer join's ON clause we can only
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* do this if the sublink is degenerate (ie, references only the nullable
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* side of the join). In that case it is legal to push the semijoin
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* down into the nullable side of the join. If the sublink references any
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* nonnullable-side variables then it would have to be evaluated as part
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* of the outer join, which makes things way too complicated.
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*
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* Under similar conditions, EXISTS and NOT EXISTS clauses can be handled
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* by pulling up the sub-SELECT and creating a semijoin or anti-semijoin.
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*
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* This routine searches for such clauses and does the necessary parsetree
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* transformations if any are found.
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*
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* This routine has to run before preprocess_expression(), so the quals
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* clauses are not yet reduced to implicit-AND format, and are not guaranteed
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* to be AND/OR-flat either. That means we need to recursively search through
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* explicit AND clauses. We stop as soon as we hit a non-AND item.
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*/
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void
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pull_up_sublinks(PlannerInfo *root)
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{
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Node *jtnode;
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Relids relids;
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/* Begin recursion through the jointree */
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jtnode = pull_up_sublinks_jointree_recurse(root,
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(Node *) root->parse->jointree,
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&relids);
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/*
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* root->parse->jointree must always be a FromExpr, so insert a dummy one
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* if we got a bare RangeTblRef or JoinExpr out of the recursion.
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*/
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if (IsA(jtnode, FromExpr))
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root->parse->jointree = (FromExpr *) jtnode;
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else
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root->parse->jointree = makeFromExpr(list_make1(jtnode), NULL);
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}
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/*
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* Recurse through jointree nodes for pull_up_sublinks()
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*
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* In addition to returning the possibly-modified jointree node, we return
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* a relids set of the contained rels into *relids.
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*/
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static Node *
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pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
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Relids *relids)
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{
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if (jtnode == NULL)
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{
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*relids = NULL;
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}
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else if (IsA(jtnode, RangeTblRef))
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{
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int varno = ((RangeTblRef *) jtnode)->rtindex;
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*relids = bms_make_singleton(varno);
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/* jtnode is returned unmodified */
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}
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else if (IsA(jtnode, FromExpr))
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{
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FromExpr *f = (FromExpr *) jtnode;
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List *newfromlist = NIL;
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Relids frelids = NULL;
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FromExpr *newf;
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Node *jtlink;
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ListCell *l;
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/* First, recurse to process children and collect their relids */
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foreach(l, f->fromlist)
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{
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Node *newchild;
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Relids childrelids;
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newchild = pull_up_sublinks_jointree_recurse(root,
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lfirst(l),
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&childrelids);
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newfromlist = lappend(newfromlist, newchild);
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frelids = bms_join(frelids, childrelids);
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}
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/* Build the replacement FromExpr; no quals yet */
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newf = makeFromExpr(newfromlist, NULL);
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/* Set up a link representing the rebuilt jointree */
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jtlink = (Node *) newf;
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/* Now process qual --- all children are available for use */
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newf->quals = pull_up_sublinks_qual_recurse(root, f->quals,
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&jtlink, frelids,
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NULL, NULL);
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/*
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* Note that the result will be either newf, or a stack of JoinExprs
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* with newf at the base. We rely on subsequent optimization steps to
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* flatten this and rearrange the joins as needed.
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*
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* Although we could include the pulled-up subqueries in the returned
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* relids, there's no need since upper quals couldn't refer to their
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* outputs anyway.
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*/
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*relids = frelids;
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jtnode = jtlink;
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}
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else if (IsA(jtnode, JoinExpr))
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{
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JoinExpr *j;
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Relids leftrelids;
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Relids rightrelids;
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Node *jtlink;
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/*
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* Make a modifiable copy of join node, but don't bother copying its
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* subnodes (yet).
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*/
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j = (JoinExpr *) palloc(sizeof(JoinExpr));
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memcpy(j, jtnode, sizeof(JoinExpr));
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jtlink = (Node *) j;
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/* Recurse to process children and collect their relids */
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j->larg = pull_up_sublinks_jointree_recurse(root, j->larg,
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&leftrelids);
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j->rarg = pull_up_sublinks_jointree_recurse(root, j->rarg,
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&rightrelids);
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/*
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* Now process qual, showing appropriate child relids as available,
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* and attach any pulled-up jointree items at the right place. In the
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* inner-join case we put new JoinExprs above the existing one (much
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* as for a FromExpr-style join). In outer-join cases the new
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* JoinExprs must go into the nullable side of the outer join. The
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* point of the available_rels machinations is to ensure that we only
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* pull up quals for which that's okay.
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*
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* We don't expect to see any pre-existing JOIN_SEMI or JOIN_ANTI
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* nodes here.
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*/
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switch (j->jointype)
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{
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case JOIN_INNER:
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j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
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&jtlink,
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bms_union(leftrelids,
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rightrelids),
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NULL, NULL);
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break;
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case JOIN_LEFT:
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j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
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&j->rarg,
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rightrelids,
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NULL, NULL);
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break;
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case JOIN_FULL:
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/* can't do anything with full-join quals */
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break;
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case JOIN_RIGHT:
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j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
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&j->larg,
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leftrelids,
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NULL, NULL);
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break;
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default:
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elog(ERROR, "unrecognized join type: %d",
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(int) j->jointype);
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break;
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}
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/*
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* Although we could include the pulled-up subqueries in the returned
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* relids, there's no need since upper quals couldn't refer to their
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* outputs anyway. But we *do* need to include the join's own rtindex
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* because we haven't yet collapsed join alias variables, so upper
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* levels would mistakenly think they couldn't use references to this
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* join.
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*/
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*relids = bms_join(leftrelids, rightrelids);
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if (j->rtindex)
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*relids = bms_add_member(*relids, j->rtindex);
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jtnode = jtlink;
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}
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else
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elog(ERROR, "unrecognized node type: %d",
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(int) nodeTag(jtnode));
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return jtnode;
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}
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/*
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* Recurse through top-level qual nodes for pull_up_sublinks()
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*
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* jtlink1 points to the link in the jointree where any new JoinExprs should
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* be inserted if they reference available_rels1 (i.e., available_rels1
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* denotes the relations present underneath jtlink1). Optionally, jtlink2 can
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* point to a second link where new JoinExprs should be inserted if they
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* reference available_rels2 (pass NULL for both those arguments if not used).
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* Note that SubLinks referencing both sets of variables cannot be optimized.
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* If we find multiple pull-up-able SubLinks, they'll get stacked onto jtlink1
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* and/or jtlink2 in the order we encounter them. We rely on subsequent
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* optimization to rearrange the stack if appropriate.
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*
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* Returns the replacement qual node, or NULL if the qual should be removed.
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*/
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static Node *
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pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
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Node **jtlink1, Relids available_rels1,
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Node **jtlink2, Relids available_rels2)
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{
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if (node == NULL)
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return NULL;
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if (IsA(node, SubLink))
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{
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SubLink *sublink = (SubLink *) node;
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JoinExpr *j;
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Relids child_rels;
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/* Is it a convertible ANY or EXISTS clause? */
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if (sublink->subLinkType == ANY_SUBLINK)
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{
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if ((j = convert_ANY_sublink_to_join(root, sublink,
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available_rels1)) != NULL)
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{
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/* Yes; insert the new join node into the join tree */
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j->larg = *jtlink1;
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*jtlink1 = (Node *) j;
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/* Recursively process pulled-up jointree nodes */
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j->rarg = pull_up_sublinks_jointree_recurse(root,
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j->rarg,
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&child_rels);
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/*
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* Now recursively process the pulled-up quals. Any inserted
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* joins can get stacked onto either j->larg or j->rarg,
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* depending on which rels they reference.
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*/
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j->quals = pull_up_sublinks_qual_recurse(root,
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j->quals,
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&j->larg,
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available_rels1,
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&j->rarg,
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child_rels);
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/* Return NULL representing constant TRUE */
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return NULL;
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}
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if (available_rels2 != NULL &&
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(j = convert_ANY_sublink_to_join(root, sublink,
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available_rels2)) != NULL)
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{
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/* Yes; insert the new join node into the join tree */
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j->larg = *jtlink2;
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*jtlink2 = (Node *) j;
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/* Recursively process pulled-up jointree nodes */
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j->rarg = pull_up_sublinks_jointree_recurse(root,
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j->rarg,
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&child_rels);
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/*
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* Now recursively process the pulled-up quals. Any inserted
|
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* joins can get stacked onto either j->larg or j->rarg,
|
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* depending on which rels they reference.
|
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*/
|
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j->quals = pull_up_sublinks_qual_recurse(root,
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j->quals,
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&j->larg,
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available_rels2,
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&j->rarg,
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child_rels);
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/* Return NULL representing constant TRUE */
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return NULL;
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}
|
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}
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else if (sublink->subLinkType == EXISTS_SUBLINK)
|
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{
|
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if ((j = convert_EXISTS_sublink_to_join(root, sublink, false,
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available_rels1)) != NULL)
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{
|
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/* Yes; insert the new join node into the join tree */
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j->larg = *jtlink1;
|
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*jtlink1 = (Node *) j;
|
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/* Recursively process pulled-up jointree nodes */
|
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j->rarg = pull_up_sublinks_jointree_recurse(root,
|
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j->rarg,
|
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&child_rels);
|
|
|
|
/*
|
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* Now recursively process the pulled-up quals. Any inserted
|
|
* joins can get stacked onto either j->larg or j->rarg,
|
|
* depending on which rels they reference.
|
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*/
|
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j->quals = pull_up_sublinks_qual_recurse(root,
|
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j->quals,
|
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&j->larg,
|
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available_rels1,
|
|
&j->rarg,
|
|
child_rels);
|
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/* Return NULL representing constant TRUE */
|
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return NULL;
|
|
}
|
|
if (available_rels2 != NULL &&
|
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(j = convert_EXISTS_sublink_to_join(root, sublink, false,
|
|
available_rels2)) != NULL)
|
|
{
|
|
/* Yes; insert the new join node into the join tree */
|
|
j->larg = *jtlink2;
|
|
*jtlink2 = (Node *) j;
|
|
/* Recursively process pulled-up jointree nodes */
|
|
j->rarg = pull_up_sublinks_jointree_recurse(root,
|
|
j->rarg,
|
|
&child_rels);
|
|
|
|
/*
|
|
* Now recursively process the pulled-up quals. Any inserted
|
|
* joins can get stacked onto either j->larg or j->rarg,
|
|
* depending on which rels they reference.
|
|
*/
|
|
j->quals = pull_up_sublinks_qual_recurse(root,
|
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j->quals,
|
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&j->larg,
|
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available_rels2,
|
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&j->rarg,
|
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child_rels);
|
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/* Return NULL representing constant TRUE */
|
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return NULL;
|
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}
|
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}
|
|
/* Else return it unmodified */
|
|
return node;
|
|
}
|
|
if (not_clause(node))
|
|
{
|
|
/* If the immediate argument of NOT is EXISTS, try to convert */
|
|
SubLink *sublink = (SubLink *) get_notclausearg((Expr *) node);
|
|
JoinExpr *j;
|
|
Relids child_rels;
|
|
|
|
if (sublink && IsA(sublink, SubLink))
|
|
{
|
|
if (sublink->subLinkType == EXISTS_SUBLINK)
|
|
{
|
|
if ((j = convert_EXISTS_sublink_to_join(root, sublink, true,
|
|
available_rels1)) != NULL)
|
|
{
|
|
/* Yes; insert the new join node into the join tree */
|
|
j->larg = *jtlink1;
|
|
*jtlink1 = (Node *) j;
|
|
/* Recursively process pulled-up jointree nodes */
|
|
j->rarg = pull_up_sublinks_jointree_recurse(root,
|
|
j->rarg,
|
|
&child_rels);
|
|
|
|
/*
|
|
* Now recursively process the pulled-up quals. Because
|
|
* we are underneath a NOT, we can't pull up sublinks that
|
|
* reference the left-hand stuff, but it's still okay to
|
|
* pull up sublinks referencing j->rarg.
|
|
*/
|
|
j->quals = pull_up_sublinks_qual_recurse(root,
|
|
j->quals,
|
|
&j->rarg,
|
|
child_rels,
|
|
NULL, NULL);
|
|
/* Return NULL representing constant TRUE */
|
|
return NULL;
|
|
}
|
|
if (available_rels2 != NULL &&
|
|
(j = convert_EXISTS_sublink_to_join(root, sublink, true,
|
|
available_rels2)) != NULL)
|
|
{
|
|
/* Yes; insert the new join node into the join tree */
|
|
j->larg = *jtlink2;
|
|
*jtlink2 = (Node *) j;
|
|
/* Recursively process pulled-up jointree nodes */
|
|
j->rarg = pull_up_sublinks_jointree_recurse(root,
|
|
j->rarg,
|
|
&child_rels);
|
|
|
|
/*
|
|
* Now recursively process the pulled-up quals. Because
|
|
* we are underneath a NOT, we can't pull up sublinks that
|
|
* reference the left-hand stuff, but it's still okay to
|
|
* pull up sublinks referencing j->rarg.
|
|
*/
|
|
j->quals = pull_up_sublinks_qual_recurse(root,
|
|
j->quals,
|
|
&j->rarg,
|
|
child_rels,
|
|
NULL, NULL);
|
|
/* Return NULL representing constant TRUE */
|
|
return NULL;
|
|
}
|
|
}
|
|
}
|
|
/* Else return it unmodified */
|
|
return node;
|
|
}
|
|
if (and_clause(node))
|
|
{
|
|
/* Recurse into AND clause */
|
|
List *newclauses = NIL;
|
|
ListCell *l;
|
|
|
|
foreach(l, ((BoolExpr *) node)->args)
|
|
{
|
|
Node *oldclause = (Node *) lfirst(l);
|
|
Node *newclause;
|
|
|
|
newclause = pull_up_sublinks_qual_recurse(root,
|
|
oldclause,
|
|
jtlink1,
|
|
available_rels1,
|
|
jtlink2,
|
|
available_rels2);
|
|
if (newclause)
|
|
newclauses = lappend(newclauses, newclause);
|
|
}
|
|
/* We might have got back fewer clauses than we started with */
|
|
if (newclauses == NIL)
|
|
return NULL;
|
|
else if (list_length(newclauses) == 1)
|
|
return (Node *) linitial(newclauses);
|
|
else
|
|
return (Node *) make_andclause(newclauses);
|
|
}
|
|
/* Stop if not an AND */
|
|
return node;
|
|
}
|
|
|
|
/*
|
|
* inline_set_returning_functions
|
|
* Attempt to "inline" set-returning functions in the FROM clause.
|
|
*
|
|
* If an RTE_FUNCTION rtable entry invokes a set-returning function that
|
|
* contains just a simple SELECT, we can convert the rtable entry to an
|
|
* RTE_SUBQUERY entry exposing the SELECT directly. This is especially
|
|
* useful if the subquery can then be "pulled up" for further optimization,
|
|
* but we do it even if not, to reduce executor overhead.
|
|
*
|
|
* This has to be done before we have started to do any optimization of
|
|
* subqueries, else any such steps wouldn't get applied to subqueries
|
|
* obtained via inlining. However, we do it after pull_up_sublinks
|
|
* so that we can inline any functions used in SubLink subselects.
|
|
*
|
|
* Like most of the planner, this feels free to scribble on its input data
|
|
* structure.
|
|
*/
|
|
void
|
|
inline_set_returning_functions(PlannerInfo *root)
|
|
{
|
|
ListCell *rt;
|
|
|
|
foreach(rt, root->parse->rtable)
|
|
{
|
|
RangeTblEntry *rte = (RangeTblEntry *) lfirst(rt);
|
|
|
|
if (rte->rtekind == RTE_FUNCTION)
|
|
{
|
|
Query *funcquery;
|
|
|
|
/* Check safety of expansion, and expand if possible */
|
|
funcquery = inline_set_returning_function(root, rte);
|
|
if (funcquery)
|
|
{
|
|
/* Successful expansion, replace the rtable entry */
|
|
rte->rtekind = RTE_SUBQUERY;
|
|
rte->subquery = funcquery;
|
|
rte->functions = NIL;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* pull_up_subqueries
|
|
* Look for subqueries in the rangetable that can be pulled up into
|
|
* the parent query. If the subquery has no special features like
|
|
* grouping/aggregation then we can merge it into the parent's jointree.
|
|
* Also, subqueries that are simple UNION ALL structures can be
|
|
* converted into "append relations".
|
|
*/
|
|
void
|
|
pull_up_subqueries(PlannerInfo *root)
|
|
{
|
|
/* Top level of jointree must always be a FromExpr */
|
|
Assert(IsA(root->parse->jointree, FromExpr));
|
|
/* Reset flag saying we need a deletion cleanup pass */
|
|
root->hasDeletedRTEs = false;
|
|
/* Recursion starts with no containing join nor appendrel */
|
|
root->parse->jointree = (FromExpr *)
|
|
pull_up_subqueries_recurse(root, (Node *) root->parse->jointree,
|
|
NULL, NULL, NULL, false);
|
|
/* Apply cleanup phase if necessary */
|
|
if (root->hasDeletedRTEs)
|
|
root->parse->jointree = (FromExpr *)
|
|
pull_up_subqueries_cleanup((Node *) root->parse->jointree);
|
|
Assert(IsA(root->parse->jointree, FromExpr));
|
|
}
|
|
|
|
/*
|
|
* pull_up_subqueries_recurse
|
|
* Recursive guts of pull_up_subqueries.
|
|
*
|
|
* This recursively processes the jointree and returns a modified jointree.
|
|
* Or, if it's valid to drop the current node from the jointree completely,
|
|
* it returns NULL.
|
|
*
|
|
* If this jointree node is within either side of an outer join, then
|
|
* lowest_outer_join references the lowest such JoinExpr node; otherwise
|
|
* it is NULL. We use this to constrain the effects of LATERAL subqueries.
|
|
*
|
|
* If this jointree node is within the nullable side of an outer join, then
|
|
* lowest_nulling_outer_join references the lowest such JoinExpr node;
|
|
* otherwise it is NULL. This forces use of the PlaceHolderVar mechanism for
|
|
* references to non-nullable targetlist items, but only for references above
|
|
* that join.
|
|
*
|
|
* If we are looking at a member subquery of an append relation,
|
|
* containing_appendrel describes that relation; else it is NULL.
|
|
* This forces use of the PlaceHolderVar mechanism for all non-Var targetlist
|
|
* items, and puts some additional restrictions on what can be pulled up.
|
|
*
|
|
* deletion_ok is TRUE if the caller can cope with us returning NULL for a
|
|
* deletable leaf node (for example, a VALUES RTE that could be pulled up).
|
|
* If it's FALSE, we'll avoid pullup in such cases.
|
|
*
|
|
* A tricky aspect of this code is that if we pull up a subquery we have
|
|
* to replace Vars that reference the subquery's outputs throughout the
|
|
* parent query, including quals attached to jointree nodes above the one
|
|
* we are currently processing! We handle this by being careful not to
|
|
* change the jointree structure while recursing: no nodes other than leaf
|
|
* RangeTblRef entries and entirely-empty FromExprs will be replaced or
|
|
* deleted. Also, we can't turn pullup_replace_vars loose on the whole
|
|
* jointree, because it'll return a mutated copy of the tree; we have to
|
|
* invoke it just on the quals, instead. This behavior is what makes it
|
|
* reasonable to pass lowest_outer_join and lowest_nulling_outer_join as
|
|
* pointers rather than some more-indirect way of identifying the lowest
|
|
* OJs. Likewise, we don't replace append_rel_list members but only their
|
|
* substructure, so the containing_appendrel reference is safe to use.
|
|
*
|
|
* Because of the rule that no jointree nodes with substructure can be
|
|
* replaced, we cannot fully handle the case of deleting nodes from the tree:
|
|
* when we delete one child of a JoinExpr, we need to replace the JoinExpr
|
|
* with a FromExpr, and that can't happen here. Instead, we set the
|
|
* root->hasDeletedRTEs flag, which tells pull_up_subqueries() that an
|
|
* additional pass over the tree is needed to clean up.
|
|
*/
|
|
static Node *
|
|
pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
|
|
JoinExpr *lowest_outer_join,
|
|
JoinExpr *lowest_nulling_outer_join,
|
|
AppendRelInfo *containing_appendrel,
|
|
bool deletion_ok)
|
|
{
|
|
Assert(jtnode != NULL);
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
RangeTblEntry *rte = rt_fetch(varno, root->parse->rtable);
|
|
|
|
/*
|
|
* Is this a subquery RTE, and if so, is the subquery simple enough to
|
|
* pull up?
|
|
*
|
|
* If we are looking at an append-relation member, we can't pull it up
|
|
* unless is_safe_append_member says so.
|
|
*/
|
|
if (rte->rtekind == RTE_SUBQUERY &&
|
|
is_simple_subquery(rte->subquery, rte,
|
|
lowest_outer_join, deletion_ok) &&
|
|
(containing_appendrel == NULL ||
|
|
is_safe_append_member(rte->subquery)))
|
|
return pull_up_simple_subquery(root, jtnode, rte,
|
|
lowest_outer_join,
|
|
lowest_nulling_outer_join,
|
|
containing_appendrel,
|
|
deletion_ok);
|
|
|
|
/*
|
|
* Alternatively, is it a simple UNION ALL subquery? If so, flatten
|
|
* into an "append relation".
|
|
*
|
|
* It's safe to do this regardless of whether this query is itself an
|
|
* appendrel member. (If you're thinking we should try to flatten the
|
|
* two levels of appendrel together, you're right; but we handle that
|
|
* in set_append_rel_pathlist, not here.)
|
|
*/
|
|
if (rte->rtekind == RTE_SUBQUERY &&
|
|
is_simple_union_all(rte->subquery))
|
|
return pull_up_simple_union_all(root, jtnode, rte);
|
|
|
|
/*
|
|
* Or perhaps it's a simple VALUES RTE?
|
|
*
|
|
* We don't allow VALUES pullup below an outer join nor into an
|
|
* appendrel (such cases are impossible anyway at the moment).
|
|
*/
|
|
if (rte->rtekind == RTE_VALUES &&
|
|
lowest_outer_join == NULL &&
|
|
containing_appendrel == NULL &&
|
|
is_simple_values(root, rte, deletion_ok))
|
|
return pull_up_simple_values(root, jtnode, rte);
|
|
|
|
/* Otherwise, do nothing at this node. */
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
bool have_undeleted_child = false;
|
|
ListCell *l;
|
|
|
|
Assert(containing_appendrel == NULL);
|
|
|
|
/*
|
|
* If the FromExpr has quals, it's not deletable even if its parent
|
|
* would allow deletion.
|
|
*/
|
|
if (f->quals)
|
|
deletion_ok = false;
|
|
|
|
foreach(l, f->fromlist)
|
|
{
|
|
/*
|
|
* In a non-deletable FromExpr, we can allow deletion of child
|
|
* nodes so long as at least one child remains; so it's okay
|
|
* either if any previous child survives, or if there's more to
|
|
* come. If all children are deletable in themselves, we'll force
|
|
* the last one to remain unflattened.
|
|
*
|
|
* As a separate matter, we can allow deletion of all children of
|
|
* the top-level FromExpr in a query, since that's a special case
|
|
* anyway.
|
|
*/
|
|
bool sub_deletion_ok = (deletion_ok ||
|
|
have_undeleted_child ||
|
|
lnext(l) != NULL ||
|
|
f == root->parse->jointree);
|
|
|
|
lfirst(l) = pull_up_subqueries_recurse(root, lfirst(l),
|
|
lowest_outer_join,
|
|
lowest_nulling_outer_join,
|
|
NULL,
|
|
sub_deletion_ok);
|
|
if (lfirst(l) != NULL)
|
|
have_undeleted_child = true;
|
|
}
|
|
|
|
if (deletion_ok && !have_undeleted_child)
|
|
{
|
|
/* OK to delete this FromExpr entirely */
|
|
root->hasDeletedRTEs = true; /* probably is set already */
|
|
return NULL;
|
|
}
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
Assert(containing_appendrel == NULL);
|
|
/* Recurse, being careful to tell myself when inside outer join */
|
|
switch (j->jointype)
|
|
{
|
|
case JOIN_INNER:
|
|
|
|
/*
|
|
* INNER JOIN can allow deletion of either child node, but not
|
|
* both. So right child gets permission to delete only if
|
|
* left child didn't get removed.
|
|
*/
|
|
j->larg = pull_up_subqueries_recurse(root, j->larg,
|
|
lowest_outer_join,
|
|
lowest_nulling_outer_join,
|
|
NULL,
|
|
true);
|
|
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
|
|
lowest_outer_join,
|
|
lowest_nulling_outer_join,
|
|
NULL,
|
|
j->larg != NULL);
|
|
break;
|
|
case JOIN_LEFT:
|
|
case JOIN_SEMI:
|
|
case JOIN_ANTI:
|
|
j->larg = pull_up_subqueries_recurse(root, j->larg,
|
|
j,
|
|
lowest_nulling_outer_join,
|
|
NULL,
|
|
false);
|
|
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
|
|
j,
|
|
j,
|
|
NULL,
|
|
false);
|
|
break;
|
|
case JOIN_FULL:
|
|
j->larg = pull_up_subqueries_recurse(root, j->larg,
|
|
j,
|
|
j,
|
|
NULL,
|
|
false);
|
|
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
|
|
j,
|
|
j,
|
|
NULL,
|
|
false);
|
|
break;
|
|
case JOIN_RIGHT:
|
|
j->larg = pull_up_subqueries_recurse(root, j->larg,
|
|
j,
|
|
j,
|
|
NULL,
|
|
false);
|
|
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
|
|
j,
|
|
lowest_nulling_outer_join,
|
|
NULL,
|
|
false);
|
|
break;
|
|
default:
|
|
elog(ERROR, "unrecognized join type: %d",
|
|
(int) j->jointype);
|
|
break;
|
|
}
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return jtnode;
|
|
}
|
|
|
|
/*
|
|
* pull_up_simple_subquery
|
|
* Attempt to pull up a single simple subquery.
|
|
*
|
|
* jtnode is a RangeTblRef that has been tentatively identified as a simple
|
|
* subquery by pull_up_subqueries. We return the replacement jointree node,
|
|
* or NULL if the subquery can be deleted entirely, or jtnode itself if we
|
|
* determine that the subquery can't be pulled up after all.
|
|
*
|
|
* rte is the RangeTblEntry referenced by jtnode. Remaining parameters are
|
|
* as for pull_up_subqueries_recurse.
|
|
*/
|
|
static Node *
|
|
pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
|
|
JoinExpr *lowest_outer_join,
|
|
JoinExpr *lowest_nulling_outer_join,
|
|
AppendRelInfo *containing_appendrel,
|
|
bool deletion_ok)
|
|
{
|
|
Query *parse = root->parse;
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
Query *subquery;
|
|
PlannerInfo *subroot;
|
|
int rtoffset;
|
|
pullup_replace_vars_context rvcontext;
|
|
ListCell *lc;
|
|
|
|
/*
|
|
* Need a modifiable copy of the subquery to hack on. Even if we didn't
|
|
* sometimes choose not to pull up below, we must do this to avoid
|
|
* problems if the same subquery is referenced from multiple jointree
|
|
* items (which can't happen normally, but might after rule rewriting).
|
|
*/
|
|
subquery = copyObject(rte->subquery);
|
|
|
|
/*
|
|
* Create a PlannerInfo data structure for this subquery.
|
|
*
|
|
* NOTE: the next few steps should match the first processing in
|
|
* subquery_planner(). Can we refactor to avoid code duplication, or
|
|
* would that just make things uglier?
|
|
*/
|
|
subroot = makeNode(PlannerInfo);
|
|
subroot->parse = subquery;
|
|
subroot->glob = root->glob;
|
|
subroot->query_level = root->query_level;
|
|
subroot->parent_root = root->parent_root;
|
|
subroot->plan_params = NIL;
|
|
subroot->planner_cxt = CurrentMemoryContext;
|
|
subroot->init_plans = NIL;
|
|
subroot->cte_plan_ids = NIL;
|
|
subroot->multiexpr_params = NIL;
|
|
subroot->eq_classes = NIL;
|
|
subroot->append_rel_list = NIL;
|
|
subroot->rowMarks = NIL;
|
|
subroot->hasRecursion = false;
|
|
subroot->wt_param_id = -1;
|
|
subroot->non_recursive_plan = NULL;
|
|
|
|
/* No CTEs to worry about */
|
|
Assert(subquery->cteList == NIL);
|
|
|
|
/*
|
|
* Pull up any SubLinks within the subquery's quals, so that we don't
|
|
* leave unoptimized SubLinks behind.
|
|
*/
|
|
if (subquery->hasSubLinks)
|
|
pull_up_sublinks(subroot);
|
|
|
|
/*
|
|
* Similarly, inline any set-returning functions in its rangetable.
|
|
*/
|
|
inline_set_returning_functions(subroot);
|
|
|
|
/*
|
|
* Recursively pull up the subquery's subqueries, so that
|
|
* pull_up_subqueries' processing is complete for its jointree and
|
|
* rangetable.
|
|
*
|
|
* Note: it's okay that the subquery's recursion starts with NULL for
|
|
* containing-join info, even if we are within an outer join in the upper
|
|
* query; the lower query starts with a clean slate for outer-join
|
|
* semantics. Likewise, we needn't pass down appendrel state.
|
|
*/
|
|
pull_up_subqueries(subroot);
|
|
|
|
/*
|
|
* Now we must recheck whether the subquery is still simple enough to pull
|
|
* up. If not, abandon processing it.
|
|
*
|
|
* We don't really need to recheck all the conditions involved, but it's
|
|
* easier just to keep this "if" looking the same as the one in
|
|
* pull_up_subqueries_recurse.
|
|
*/
|
|
if (is_simple_subquery(subquery, rte,
|
|
lowest_outer_join, deletion_ok) &&
|
|
(containing_appendrel == NULL || is_safe_append_member(subquery)))
|
|
{
|
|
/* good to go */
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Give up, return unmodified RangeTblRef.
|
|
*
|
|
* Note: The work we just did will be redone when the subquery gets
|
|
* planned on its own. Perhaps we could avoid that by storing the
|
|
* modified subquery back into the rangetable, but I'm not gonna risk
|
|
* it now.
|
|
*/
|
|
return jtnode;
|
|
}
|
|
|
|
/*
|
|
* We must flatten any join alias Vars in the subquery's targetlist,
|
|
* because pulling up the subquery's subqueries might have changed their
|
|
* expansions into arbitrary expressions, which could affect
|
|
* pullup_replace_vars' decisions about whether PlaceHolderVar wrappers
|
|
* are needed for tlist entries. (Likely it'd be better to do
|
|
* flatten_join_alias_vars on the whole query tree at some earlier stage,
|
|
* maybe even in the rewriter; but for now let's just fix this case here.)
|
|
*/
|
|
subquery->targetList = (List *)
|
|
flatten_join_alias_vars(subroot, (Node *) subquery->targetList);
|
|
|
|
/*
|
|
* Adjust level-0 varnos in subquery so that we can append its rangetable
|
|
* to upper query's. We have to fix the subquery's append_rel_list as
|
|
* well.
|
|
*/
|
|
rtoffset = list_length(parse->rtable);
|
|
OffsetVarNodes((Node *) subquery, rtoffset, 0);
|
|
OffsetVarNodes((Node *) subroot->append_rel_list, rtoffset, 0);
|
|
|
|
/*
|
|
* Upper-level vars in subquery are now one level closer to their parent
|
|
* than before.
|
|
*/
|
|
IncrementVarSublevelsUp((Node *) subquery, -1, 1);
|
|
IncrementVarSublevelsUp((Node *) subroot->append_rel_list, -1, 1);
|
|
|
|
/*
|
|
* The subquery's targetlist items are now in the appropriate form to
|
|
* insert into the top query, but if we are under an outer join then
|
|
* non-nullable items and lateral references may have to be turned into
|
|
* PlaceHolderVars. If we are dealing with an appendrel member then
|
|
* anything that's not a simple Var has to be turned into a
|
|
* PlaceHolderVar. Set up required context data for pullup_replace_vars.
|
|
*/
|
|
rvcontext.root = root;
|
|
rvcontext.targetlist = subquery->targetList;
|
|
rvcontext.target_rte = rte;
|
|
if (rte->lateral)
|
|
rvcontext.relids = get_relids_in_jointree((Node *) subquery->jointree,
|
|
true);
|
|
else /* won't need relids */
|
|
rvcontext.relids = NULL;
|
|
rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
|
|
rvcontext.varno = varno;
|
|
rvcontext.need_phvs = (lowest_nulling_outer_join != NULL ||
|
|
containing_appendrel != NULL);
|
|
rvcontext.wrap_non_vars = (containing_appendrel != NULL);
|
|
/* initialize cache array with indexes 0 .. length(tlist) */
|
|
rvcontext.rv_cache = palloc0((list_length(subquery->targetList) + 1) *
|
|
sizeof(Node *));
|
|
|
|
/*
|
|
* Replace all of the top query's references to the subquery's outputs
|
|
* with copies of the adjusted subtlist items, being careful not to
|
|
* replace any of the jointree structure. (This'd be a lot cleaner if we
|
|
* could use query_tree_mutator.) We have to use PHVs in the targetList,
|
|
* returningList, and havingQual, since those are certainly above any
|
|
* outer join. replace_vars_in_jointree tracks its location in the
|
|
* jointree and uses PHVs or not appropriately.
|
|
*/
|
|
parse->targetList = (List *)
|
|
pullup_replace_vars((Node *) parse->targetList, &rvcontext);
|
|
parse->returningList = (List *)
|
|
pullup_replace_vars((Node *) parse->returningList, &rvcontext);
|
|
if (parse->onConflict)
|
|
parse->onConflict->onConflictSet = (List *)
|
|
pullup_replace_vars((Node *) parse->onConflict->onConflictSet, &rvcontext);
|
|
replace_vars_in_jointree((Node *) parse->jointree, &rvcontext,
|
|
lowest_nulling_outer_join);
|
|
Assert(parse->setOperations == NULL);
|
|
parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);
|
|
|
|
/*
|
|
* Replace references in the translated_vars lists of appendrels. When
|
|
* pulling up an appendrel member, we do not need PHVs in the list of the
|
|
* parent appendrel --- there isn't any outer join between. Elsewhere, use
|
|
* PHVs for safety. (This analysis could be made tighter but it seems
|
|
* unlikely to be worth much trouble.)
|
|
*/
|
|
foreach(lc, root->append_rel_list)
|
|
{
|
|
AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(lc);
|
|
bool save_need_phvs = rvcontext.need_phvs;
|
|
|
|
if (appinfo == containing_appendrel)
|
|
rvcontext.need_phvs = false;
|
|
appinfo->translated_vars = (List *)
|
|
pullup_replace_vars((Node *) appinfo->translated_vars, &rvcontext);
|
|
rvcontext.need_phvs = save_need_phvs;
|
|
}
|
|
|
|
/*
|
|
* Replace references in the joinaliasvars lists of join RTEs.
|
|
*
|
|
* You might think that we could avoid using PHVs for alias vars of joins
|
|
* below lowest_nulling_outer_join, but that doesn't work because the
|
|
* alias vars could be referenced above that join; we need the PHVs to be
|
|
* present in such references after the alias vars get flattened. (It
|
|
* might be worth trying to be smarter here, someday.)
|
|
*/
|
|
foreach(lc, parse->rtable)
|
|
{
|
|
RangeTblEntry *otherrte = (RangeTblEntry *) lfirst(lc);
|
|
|
|
if (otherrte->rtekind == RTE_JOIN)
|
|
otherrte->joinaliasvars = (List *)
|
|
pullup_replace_vars((Node *) otherrte->joinaliasvars,
|
|
&rvcontext);
|
|
}
|
|
|
|
/*
|
|
* If the subquery had a LATERAL marker, propagate that to any of its
|
|
* child RTEs that could possibly now contain lateral cross-references.
|
|
* The children might or might not contain any actual lateral
|
|
* cross-references, but we have to mark the pulled-up child RTEs so that
|
|
* later planner stages will check for such.
|
|
*/
|
|
if (rte->lateral)
|
|
{
|
|
foreach(lc, subquery->rtable)
|
|
{
|
|
RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(lc);
|
|
|
|
switch (child_rte->rtekind)
|
|
{
|
|
case RTE_RELATION:
|
|
if (child_rte->tablesample)
|
|
child_rte->lateral = true;
|
|
break;
|
|
case RTE_SUBQUERY:
|
|
case RTE_FUNCTION:
|
|
case RTE_VALUES:
|
|
child_rte->lateral = true;
|
|
break;
|
|
case RTE_JOIN:
|
|
case RTE_CTE:
|
|
/* these can't contain any lateral references */
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now append the adjusted rtable entries to upper query. (We hold off
|
|
* until after fixing the upper rtable entries; no point in running that
|
|
* code on the subquery ones too.)
|
|
*/
|
|
parse->rtable = list_concat(parse->rtable, subquery->rtable);
|
|
|
|
/*
|
|
* Pull up any FOR UPDATE/SHARE markers, too. (OffsetVarNodes already
|
|
* adjusted the marker rtindexes, so just concat the lists.)
|
|
*/
|
|
parse->rowMarks = list_concat(parse->rowMarks, subquery->rowMarks);
|
|
|
|
/*
|
|
* We also have to fix the relid sets of any PlaceHolderVar nodes in the
|
|
* parent query. (This could perhaps be done by pullup_replace_vars(),
|
|
* but it seems cleaner to use two passes.) Note in particular that any
|
|
* PlaceHolderVar nodes just created by pullup_replace_vars() will be
|
|
* adjusted, so having created them with the subquery's varno is correct.
|
|
*
|
|
* Likewise, relids appearing in AppendRelInfo nodes have to be fixed. We
|
|
* already checked that this won't require introducing multiple subrelids
|
|
* into the single-slot AppendRelInfo structs.
|
|
*/
|
|
if (parse->hasSubLinks || root->glob->lastPHId != 0 ||
|
|
root->append_rel_list)
|
|
{
|
|
Relids subrelids;
|
|
|
|
subrelids = get_relids_in_jointree((Node *) subquery->jointree, false);
|
|
substitute_multiple_relids((Node *) parse, varno, subrelids);
|
|
fix_append_rel_relids(root->append_rel_list, varno, subrelids);
|
|
}
|
|
|
|
/*
|
|
* And now add subquery's AppendRelInfos to our list.
|
|
*/
|
|
root->append_rel_list = list_concat(root->append_rel_list,
|
|
subroot->append_rel_list);
|
|
|
|
/*
|
|
* We don't have to do the equivalent bookkeeping for outer-join or
|
|
* LATERAL info, because that hasn't been set up yet. placeholder_list
|
|
* likewise.
|
|
*/
|
|
Assert(root->join_info_list == NIL);
|
|
Assert(subroot->join_info_list == NIL);
|
|
Assert(root->lateral_info_list == NIL);
|
|
Assert(subroot->lateral_info_list == NIL);
|
|
Assert(root->placeholder_list == NIL);
|
|
Assert(subroot->placeholder_list == NIL);
|
|
|
|
/*
|
|
* Miscellaneous housekeeping.
|
|
*
|
|
* Although replace_rte_variables() faithfully updated parse->hasSubLinks
|
|
* if it copied any SubLinks out of the subquery's targetlist, we still
|
|
* could have SubLinks added to the query in the expressions of FUNCTION
|
|
* and VALUES RTEs copied up from the subquery. So it's necessary to copy
|
|
* subquery->hasSubLinks anyway. Perhaps this can be improved someday.
|
|
*/
|
|
parse->hasSubLinks |= subquery->hasSubLinks;
|
|
|
|
/*
|
|
* subquery won't be pulled up if it hasAggs or hasWindowFuncs, so no work
|
|
* needed on those flags
|
|
*/
|
|
|
|
/*
|
|
* Return the adjusted subquery jointree to replace the RangeTblRef entry
|
|
* in parent's jointree; or, if we're flattening a subquery with empty
|
|
* FROM list, return NULL to signal deletion of the subquery from the
|
|
* parent jointree (and set hasDeletedRTEs to ensure cleanup later).
|
|
*/
|
|
if (subquery->jointree->fromlist == NIL)
|
|
{
|
|
Assert(deletion_ok);
|
|
Assert(subquery->jointree->quals == NULL);
|
|
root->hasDeletedRTEs = true;
|
|
return NULL;
|
|
}
|
|
|
|
return (Node *) subquery->jointree;
|
|
}
|
|
|
|
/*
|
|
* pull_up_simple_union_all
|
|
* Pull up a single simple UNION ALL subquery.
|
|
*
|
|
* jtnode is a RangeTblRef that has been identified as a simple UNION ALL
|
|
* subquery by pull_up_subqueries. We pull up the leaf subqueries and
|
|
* build an "append relation" for the union set. The result value is just
|
|
* jtnode, since we don't actually need to change the query jointree.
|
|
*/
|
|
static Node *
|
|
pull_up_simple_union_all(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
|
|
{
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
Query *subquery = rte->subquery;
|
|
int rtoffset = list_length(root->parse->rtable);
|
|
List *rtable;
|
|
|
|
/*
|
|
* Make a modifiable copy of the subquery's rtable, so we can adjust
|
|
* upper-level Vars in it. There are no such Vars in the setOperations
|
|
* tree proper, so fixing the rtable should be sufficient.
|
|
*/
|
|
rtable = copyObject(subquery->rtable);
|
|
|
|
/*
|
|
* Upper-level vars in subquery are now one level closer to their parent
|
|
* than before. We don't have to worry about offsetting varnos, though,
|
|
* because the UNION leaf queries can't cross-reference each other.
|
|
*/
|
|
IncrementVarSublevelsUp_rtable(rtable, -1, 1);
|
|
|
|
/*
|
|
* If the UNION ALL subquery had a LATERAL marker, propagate that to all
|
|
* its children. The individual children might or might not contain any
|
|
* actual lateral cross-references, but we have to mark the pulled-up
|
|
* child RTEs so that later planner stages will check for such.
|
|
*/
|
|
if (rte->lateral)
|
|
{
|
|
ListCell *rt;
|
|
|
|
foreach(rt, rtable)
|
|
{
|
|
RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(rt);
|
|
|
|
Assert(child_rte->rtekind == RTE_SUBQUERY);
|
|
child_rte->lateral = true;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Append child RTEs to parent rtable.
|
|
*/
|
|
root->parse->rtable = list_concat(root->parse->rtable, rtable);
|
|
|
|
/*
|
|
* Recursively scan the subquery's setOperations tree and add
|
|
* AppendRelInfo nodes for leaf subqueries to the parent's
|
|
* append_rel_list. Also apply pull_up_subqueries to the leaf subqueries.
|
|
*/
|
|
Assert(subquery->setOperations);
|
|
pull_up_union_leaf_queries(subquery->setOperations, root, varno, subquery,
|
|
rtoffset);
|
|
|
|
/*
|
|
* Mark the parent as an append relation.
|
|
*/
|
|
rte->inh = true;
|
|
|
|
return jtnode;
|
|
}
|
|
|
|
/*
|
|
* pull_up_union_leaf_queries -- recursive guts of pull_up_simple_union_all
|
|
*
|
|
* Build an AppendRelInfo for each leaf query in the setop tree, and then
|
|
* apply pull_up_subqueries to the leaf query.
|
|
*
|
|
* Note that setOpQuery is the Query containing the setOp node, whose tlist
|
|
* contains references to all the setop output columns. When called from
|
|
* pull_up_simple_union_all, this is *not* the same as root->parse, which is
|
|
* the parent Query we are pulling up into.
|
|
*
|
|
* parentRTindex is the appendrel parent's index in root->parse->rtable.
|
|
*
|
|
* The child RTEs have already been copied to the parent. childRToffset
|
|
* tells us where in the parent's range table they were copied. When called
|
|
* from flatten_simple_union_all, childRToffset is 0 since the child RTEs
|
|
* were already in root->parse->rtable and no RT index adjustment is needed.
|
|
*/
|
|
static void
|
|
pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
|
|
Query *setOpQuery, int childRToffset)
|
|
{
|
|
if (IsA(setOp, RangeTblRef))
|
|
{
|
|
RangeTblRef *rtr = (RangeTblRef *) setOp;
|
|
int childRTindex;
|
|
AppendRelInfo *appinfo;
|
|
|
|
/*
|
|
* Calculate the index in the parent's range table
|
|
*/
|
|
childRTindex = childRToffset + rtr->rtindex;
|
|
|
|
/*
|
|
* Build a suitable AppendRelInfo, and attach to parent's list.
|
|
*/
|
|
appinfo = makeNode(AppendRelInfo);
|
|
appinfo->parent_relid = parentRTindex;
|
|
appinfo->child_relid = childRTindex;
|
|
appinfo->parent_reltype = InvalidOid;
|
|
appinfo->child_reltype = InvalidOid;
|
|
make_setop_translation_list(setOpQuery, childRTindex,
|
|
&appinfo->translated_vars);
|
|
appinfo->parent_reloid = InvalidOid;
|
|
root->append_rel_list = lappend(root->append_rel_list, appinfo);
|
|
|
|
/*
|
|
* Recursively apply pull_up_subqueries to the new child RTE. (We
|
|
* must build the AppendRelInfo first, because this will modify it.)
|
|
* Note that we can pass NULL for containing-join info even if we're
|
|
* actually under an outer join, because the child's expressions
|
|
* aren't going to propagate up to the join. Also, we ignore the
|
|
* possibility that pull_up_subqueries_recurse() returns a different
|
|
* jointree node than what we pass it; if it does, the important thing
|
|
* is that it replaced the child relid in the AppendRelInfo node.
|
|
*/
|
|
rtr = makeNode(RangeTblRef);
|
|
rtr->rtindex = childRTindex;
|
|
(void) pull_up_subqueries_recurse(root, (Node *) rtr,
|
|
NULL, NULL, appinfo, false);
|
|
}
|
|
else if (IsA(setOp, SetOperationStmt))
|
|
{
|
|
SetOperationStmt *op = (SetOperationStmt *) setOp;
|
|
|
|
/* Recurse to reach leaf queries */
|
|
pull_up_union_leaf_queries(op->larg, root, parentRTindex, setOpQuery,
|
|
childRToffset);
|
|
pull_up_union_leaf_queries(op->rarg, root, parentRTindex, setOpQuery,
|
|
childRToffset);
|
|
}
|
|
else
|
|
{
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(setOp));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* make_setop_translation_list
|
|
* Build the list of translations from parent Vars to child Vars for
|
|
* a UNION ALL member. (At this point it's just a simple list of
|
|
* referencing Vars, but if we succeed in pulling up the member
|
|
* subquery, the Vars will get replaced by pulled-up expressions.)
|
|
*/
|
|
static void
|
|
make_setop_translation_list(Query *query, Index newvarno,
|
|
List **translated_vars)
|
|
{
|
|
List *vars = NIL;
|
|
ListCell *l;
|
|
|
|
foreach(l, query->targetList)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(l);
|
|
|
|
if (tle->resjunk)
|
|
continue;
|
|
|
|
vars = lappend(vars, makeVarFromTargetEntry(newvarno, tle));
|
|
}
|
|
|
|
*translated_vars = vars;
|
|
}
|
|
|
|
/*
|
|
* is_simple_subquery
|
|
* Check a subquery in the range table to see if it's simple enough
|
|
* to pull up into the parent query.
|
|
*
|
|
* rte is the RTE_SUBQUERY RangeTblEntry that contained the subquery.
|
|
* (Note subquery is not necessarily equal to rte->subquery; it could be a
|
|
* processed copy of that.)
|
|
* lowest_outer_join is the lowest outer join above the subquery, or NULL.
|
|
* deletion_ok is TRUE if it'd be okay to delete the subquery entirely.
|
|
*/
|
|
static bool
|
|
is_simple_subquery(Query *subquery, RangeTblEntry *rte,
|
|
JoinExpr *lowest_outer_join,
|
|
bool deletion_ok)
|
|
{
|
|
/*
|
|
* Let's just make sure it's a valid subselect ...
|
|
*/
|
|
if (!IsA(subquery, Query) ||
|
|
subquery->commandType != CMD_SELECT ||
|
|
subquery->utilityStmt != NULL)
|
|
elog(ERROR, "subquery is bogus");
|
|
|
|
/*
|
|
* Can't currently pull up a query with setops (unless it's simple UNION
|
|
* ALL, which is handled by a different code path). Maybe after querytree
|
|
* redesign...
|
|
*/
|
|
if (subquery->setOperations)
|
|
return false;
|
|
|
|
/*
|
|
* Can't pull up a subquery involving grouping, aggregation, sorting,
|
|
* limiting, or WITH. (XXX WITH could possibly be allowed later)
|
|
*
|
|
* We also don't pull up a subquery that has explicit FOR UPDATE/SHARE
|
|
* clauses, because pullup would cause the locking to occur semantically
|
|
* higher than it should. Implicit FOR UPDATE/SHARE is okay because in
|
|
* that case the locking was originally declared in the upper query
|
|
* anyway.
|
|
*/
|
|
if (subquery->hasAggs ||
|
|
subquery->hasWindowFuncs ||
|
|
subquery->groupClause ||
|
|
subquery->groupingSets ||
|
|
subquery->havingQual ||
|
|
subquery->sortClause ||
|
|
subquery->distinctClause ||
|
|
subquery->limitOffset ||
|
|
subquery->limitCount ||
|
|
subquery->hasForUpdate ||
|
|
subquery->cteList)
|
|
return false;
|
|
|
|
/*
|
|
* Don't pull up if the RTE represents a security-barrier view; we
|
|
* couldn't prevent information leakage once the RTE's Vars are scattered
|
|
* about in the upper query.
|
|
*/
|
|
if (rte->security_barrier)
|
|
return false;
|
|
|
|
/*
|
|
* Don't pull up a subquery with an empty jointree, unless it has no quals
|
|
* and deletion_ok is TRUE. query_planner() will correctly generate a
|
|
* Result plan for a jointree that's totally empty, but we can't cope with
|
|
* an empty FromExpr appearing lower down in a jointree: we identify join
|
|
* rels via baserelid sets, so we couldn't distinguish a join containing
|
|
* such a FromExpr from one without it. This would for example break the
|
|
* PlaceHolderVar mechanism, since we'd have no way to identify where to
|
|
* evaluate a PHV coming out of the subquery. We can only handle such
|
|
* cases if the place where the subquery is linked is a FromExpr or inner
|
|
* JOIN that would still be nonempty after removal of the subquery, so
|
|
* that it's still identifiable via its contained baserelids. Safe
|
|
* contexts are signaled by deletion_ok. But even in a safe context, we
|
|
* must keep the subquery if it has any quals, because it's unclear where
|
|
* to put them in the upper query. (Note that deletion of a subquery is
|
|
* also dependent on the check below that its targetlist contains no
|
|
* set-returning functions. Deletion from a FROM list or inner JOIN is
|
|
* okay only if the subquery must return exactly one row.)
|
|
*/
|
|
if (subquery->jointree->fromlist == NIL &&
|
|
(subquery->jointree->quals || !deletion_ok))
|
|
return false;
|
|
|
|
/*
|
|
* If the subquery is LATERAL, check for pullup restrictions from that.
|
|
*/
|
|
if (rte->lateral)
|
|
{
|
|
bool restricted;
|
|
Relids safe_upper_varnos;
|
|
|
|
/*
|
|
* The subquery's WHERE and JOIN/ON quals mustn't contain any lateral
|
|
* references to rels outside a higher outer join (including the case
|
|
* where the outer join is within the subquery itself). In such a
|
|
* case, pulling up would result in a situation where we need to
|
|
* postpone quals from below an outer join to above it, which is
|
|
* probably completely wrong and in any case is a complication that
|
|
* doesn't seem worth addressing at the moment.
|
|
*/
|
|
if (lowest_outer_join != NULL)
|
|
{
|
|
restricted = true;
|
|
safe_upper_varnos = get_relids_in_jointree((Node *) lowest_outer_join,
|
|
true);
|
|
}
|
|
else
|
|
{
|
|
restricted = false;
|
|
safe_upper_varnos = NULL; /* doesn't matter */
|
|
}
|
|
|
|
if (jointree_contains_lateral_outer_refs((Node *) subquery->jointree,
|
|
restricted, safe_upper_varnos))
|
|
return false;
|
|
|
|
/*
|
|
* If there's an outer join above the LATERAL subquery, also disallow
|
|
* pullup if the subquery's targetlist has any references to rels
|
|
* outside the outer join, since these might get pulled into quals
|
|
* above the subquery (but in or below the outer join) and then lead
|
|
* to qual-postponement issues similar to the case checked for above.
|
|
* (We wouldn't need to prevent pullup if no such references appear in
|
|
* outer-query quals, but we don't have enough info here to check
|
|
* that. Also, maybe this restriction could be removed if we forced
|
|
* such refs to be wrapped in PlaceHolderVars, even when they're below
|
|
* the nearest outer join? But it's a pretty hokey usage, so not
|
|
* clear this is worth sweating over.)
|
|
*/
|
|
if (lowest_outer_join != NULL)
|
|
{
|
|
Relids lvarnos = pull_varnos_of_level((Node *) subquery->targetList, 1);
|
|
|
|
if (!bms_is_subset(lvarnos, safe_upper_varnos))
|
|
return false;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Don't pull up a subquery that has any set-returning functions in its
|
|
* targetlist. Otherwise we might well wind up inserting set-returning
|
|
* functions into places where they mustn't go, such as quals of higher
|
|
* queries. This also ensures deletion of an empty jointree is valid.
|
|
*/
|
|
if (expression_returns_set((Node *) subquery->targetList))
|
|
return false;
|
|
|
|
/*
|
|
* Don't pull up a subquery that has any volatile functions in its
|
|
* targetlist. Otherwise we might introduce multiple evaluations of these
|
|
* functions, if they get copied to multiple places in the upper query,
|
|
* leading to surprising results. (Note: the PlaceHolderVar mechanism
|
|
* doesn't quite guarantee single evaluation; else we could pull up anyway
|
|
* and just wrap such items in PlaceHolderVars ...)
|
|
*/
|
|
if (contain_volatile_functions((Node *) subquery->targetList))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* pull_up_simple_values
|
|
* Pull up a single simple VALUES RTE.
|
|
*
|
|
* jtnode is a RangeTblRef that has been identified as a simple VALUES RTE
|
|
* by pull_up_subqueries. We always return NULL indicating that the RTE
|
|
* can be deleted entirely (all failure cases should have been detected by
|
|
* is_simple_values()).
|
|
*
|
|
* rte is the RangeTblEntry referenced by jtnode. Because of the limited
|
|
* possible usage of VALUES RTEs, we do not need the remaining parameters
|
|
* of pull_up_subqueries_recurse.
|
|
*/
|
|
static Node *
|
|
pull_up_simple_values(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
|
|
{
|
|
Query *parse = root->parse;
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
List *values_list;
|
|
List *tlist;
|
|
AttrNumber attrno;
|
|
pullup_replace_vars_context rvcontext;
|
|
ListCell *lc;
|
|
|
|
Assert(rte->rtekind == RTE_VALUES);
|
|
Assert(list_length(rte->values_lists) == 1);
|
|
|
|
/*
|
|
* Need a modifiable copy of the VALUES list to hack on, just in case it's
|
|
* multiply referenced.
|
|
*/
|
|
values_list = (List *) copyObject(linitial(rte->values_lists));
|
|
|
|
/*
|
|
* The VALUES RTE can't contain any Vars of level zero, let alone any that
|
|
* are join aliases, so no need to flatten join alias Vars.
|
|
*/
|
|
Assert(!contain_vars_of_level((Node *) values_list, 0));
|
|
|
|
/*
|
|
* Set up required context data for pullup_replace_vars. In particular,
|
|
* we have to make the VALUES list look like a subquery targetlist.
|
|
*/
|
|
tlist = NIL;
|
|
attrno = 1;
|
|
foreach(lc, values_list)
|
|
{
|
|
tlist = lappend(tlist,
|
|
makeTargetEntry((Expr *) lfirst(lc),
|
|
attrno,
|
|
NULL,
|
|
false));
|
|
attrno++;
|
|
}
|
|
rvcontext.root = root;
|
|
rvcontext.targetlist = tlist;
|
|
rvcontext.target_rte = rte;
|
|
rvcontext.relids = NULL;
|
|
rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
|
|
rvcontext.varno = varno;
|
|
rvcontext.need_phvs = false;
|
|
rvcontext.wrap_non_vars = false;
|
|
/* initialize cache array with indexes 0 .. length(tlist) */
|
|
rvcontext.rv_cache = palloc0((list_length(tlist) + 1) *
|
|
sizeof(Node *));
|
|
|
|
/*
|
|
* Replace all of the top query's references to the RTE's outputs with
|
|
* copies of the adjusted VALUES expressions, being careful not to replace
|
|
* any of the jointree structure. (This'd be a lot cleaner if we could use
|
|
* query_tree_mutator.) Much of this should be no-ops in the dummy Query
|
|
* that surrounds a VALUES RTE, but it's not enough code to be worth
|
|
* removing.
|
|
*/
|
|
parse->targetList = (List *)
|
|
pullup_replace_vars((Node *) parse->targetList, &rvcontext);
|
|
parse->returningList = (List *)
|
|
pullup_replace_vars((Node *) parse->returningList, &rvcontext);
|
|
if (parse->onConflict)
|
|
parse->onConflict->onConflictSet = (List *)
|
|
pullup_replace_vars((Node *) parse->onConflict->onConflictSet, &rvcontext);
|
|
replace_vars_in_jointree((Node *) parse->jointree, &rvcontext, NULL);
|
|
Assert(parse->setOperations == NULL);
|
|
parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);
|
|
|
|
/*
|
|
* There should be no appendrels to fix, nor any join alias Vars, nor any
|
|
* outer joins and hence no PlaceHolderVars.
|
|
*/
|
|
Assert(root->append_rel_list == NIL);
|
|
Assert(list_length(parse->rtable) == 1);
|
|
Assert(root->join_info_list == NIL);
|
|
Assert(root->lateral_info_list == NIL);
|
|
Assert(root->placeholder_list == NIL);
|
|
|
|
/*
|
|
* Return NULL to signal deletion of the VALUES RTE from the parent
|
|
* jointree (and set hasDeletedRTEs to ensure cleanup later).
|
|
*/
|
|
root->hasDeletedRTEs = true;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* is_simple_values
|
|
* Check a VALUES RTE in the range table to see if it's simple enough
|
|
* to pull up into the parent query.
|
|
*
|
|
* rte is the RTE_VALUES RangeTblEntry to check.
|
|
* deletion_ok is TRUE if it'd be okay to delete the VALUES RTE entirely.
|
|
*/
|
|
static bool
|
|
is_simple_values(PlannerInfo *root, RangeTblEntry *rte, bool deletion_ok)
|
|
{
|
|
Assert(rte->rtekind == RTE_VALUES);
|
|
|
|
/*
|
|
* We can only pull up a VALUES RTE if deletion_ok is TRUE. It's
|
|
* basically the same case as a sub-select with empty FROM list; see
|
|
* comments in is_simple_subquery().
|
|
*/
|
|
if (!deletion_ok)
|
|
return false;
|
|
|
|
/*
|
|
* Also, there must be exactly one VALUES list, else it's not semantically
|
|
* correct to delete the VALUES RTE.
|
|
*/
|
|
if (list_length(rte->values_lists) != 1)
|
|
return false;
|
|
|
|
/*
|
|
* Because VALUES can't appear under an outer join (or at least, we won't
|
|
* try to pull it up if it does), we need not worry about LATERAL.
|
|
*/
|
|
|
|
/*
|
|
* Don't pull up a VALUES that contains any set-returning or volatile
|
|
* functions. Again, the considerations here are basically identical to
|
|
* restrictions on a subquery's targetlist.
|
|
*/
|
|
if (expression_returns_set((Node *) rte->values_lists) ||
|
|
contain_volatile_functions((Node *) rte->values_lists))
|
|
return false;
|
|
|
|
/*
|
|
* Do not pull up a VALUES that's not the only RTE in its parent query.
|
|
* This is actually the only case that the parser will generate at the
|
|
* moment, and assuming this is true greatly simplifies
|
|
* pull_up_simple_values().
|
|
*/
|
|
if (list_length(root->parse->rtable) != 1 ||
|
|
rte != (RangeTblEntry *) linitial(root->parse->rtable))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* is_simple_union_all
|
|
* Check a subquery to see if it's a simple UNION ALL.
|
|
*
|
|
* We require all the setops to be UNION ALL (no mixing) and there can't be
|
|
* any datatype coercions involved, ie, all the leaf queries must emit the
|
|
* same datatypes.
|
|
*/
|
|
static bool
|
|
is_simple_union_all(Query *subquery)
|
|
{
|
|
SetOperationStmt *topop;
|
|
|
|
/* Let's just make sure it's a valid subselect ... */
|
|
if (!IsA(subquery, Query) ||
|
|
subquery->commandType != CMD_SELECT ||
|
|
subquery->utilityStmt != NULL)
|
|
elog(ERROR, "subquery is bogus");
|
|
|
|
/* Is it a set-operation query at all? */
|
|
topop = (SetOperationStmt *) subquery->setOperations;
|
|
if (!topop)
|
|
return false;
|
|
Assert(IsA(topop, SetOperationStmt));
|
|
|
|
/* Can't handle ORDER BY, LIMIT/OFFSET, locking, or WITH */
|
|
if (subquery->sortClause ||
|
|
subquery->limitOffset ||
|
|
subquery->limitCount ||
|
|
subquery->rowMarks ||
|
|
subquery->cteList)
|
|
return false;
|
|
|
|
/* Recursively check the tree of set operations */
|
|
return is_simple_union_all_recurse((Node *) topop, subquery,
|
|
topop->colTypes);
|
|
}
|
|
|
|
static bool
|
|
is_simple_union_all_recurse(Node *setOp, Query *setOpQuery, List *colTypes)
|
|
{
|
|
if (IsA(setOp, RangeTblRef))
|
|
{
|
|
RangeTblRef *rtr = (RangeTblRef *) setOp;
|
|
RangeTblEntry *rte = rt_fetch(rtr->rtindex, setOpQuery->rtable);
|
|
Query *subquery = rte->subquery;
|
|
|
|
Assert(subquery != NULL);
|
|
|
|
/* Leaf nodes are OK if they match the toplevel column types */
|
|
/* We don't have to compare typmods or collations here */
|
|
return tlist_same_datatypes(subquery->targetList, colTypes, true);
|
|
}
|
|
else if (IsA(setOp, SetOperationStmt))
|
|
{
|
|
SetOperationStmt *op = (SetOperationStmt *) setOp;
|
|
|
|
/* Must be UNION ALL */
|
|
if (op->op != SETOP_UNION || !op->all)
|
|
return false;
|
|
|
|
/* Recurse to check inputs */
|
|
return is_simple_union_all_recurse(op->larg, setOpQuery, colTypes) &&
|
|
is_simple_union_all_recurse(op->rarg, setOpQuery, colTypes);
|
|
}
|
|
else
|
|
{
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(setOp));
|
|
return false; /* keep compiler quiet */
|
|
}
|
|
}
|
|
|
|
/*
|
|
* is_safe_append_member
|
|
* Check a subquery that is a leaf of a UNION ALL appendrel to see if it's
|
|
* safe to pull up.
|
|
*/
|
|
static bool
|
|
is_safe_append_member(Query *subquery)
|
|
{
|
|
FromExpr *jtnode;
|
|
|
|
/*
|
|
* It's only safe to pull up the child if its jointree contains exactly
|
|
* one RTE, else the AppendRelInfo data structure breaks. The one base RTE
|
|
* could be buried in several levels of FromExpr, however.
|
|
*
|
|
* Also, the child can't have any WHERE quals because there's no place to
|
|
* put them in an appendrel. (This is a bit annoying...) If we didn't
|
|
* need to check this, we'd just test whether get_relids_in_jointree()
|
|
* yields a singleton set, to be more consistent with the coding of
|
|
* fix_append_rel_relids().
|
|
*/
|
|
jtnode = subquery->jointree;
|
|
while (IsA(jtnode, FromExpr))
|
|
{
|
|
if (jtnode->quals != NULL)
|
|
return false;
|
|
if (list_length(jtnode->fromlist) != 1)
|
|
return false;
|
|
jtnode = linitial(jtnode->fromlist);
|
|
}
|
|
if (!IsA(jtnode, RangeTblRef))
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
/*
|
|
* jointree_contains_lateral_outer_refs
|
|
* Check for disallowed lateral references in a jointree's quals
|
|
*
|
|
* If restricted is false, all level-1 Vars are allowed (but we still must
|
|
* search the jointree, since it might contain outer joins below which there
|
|
* will be restrictions). If restricted is true, return TRUE when any qual
|
|
* in the jointree contains level-1 Vars coming from outside the rels listed
|
|
* in safe_upper_varnos.
|
|
*/
|
|
static bool
|
|
jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted,
|
|
Relids safe_upper_varnos)
|
|
{
|
|
if (jtnode == NULL)
|
|
return false;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
return false;
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
ListCell *l;
|
|
|
|
/* First, recurse to check child joins */
|
|
foreach(l, f->fromlist)
|
|
{
|
|
if (jointree_contains_lateral_outer_refs(lfirst(l),
|
|
restricted,
|
|
safe_upper_varnos))
|
|
return true;
|
|
}
|
|
|
|
/* Then check the top-level quals */
|
|
if (restricted &&
|
|
!bms_is_subset(pull_varnos_of_level(f->quals, 1),
|
|
safe_upper_varnos))
|
|
return true;
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
/*
|
|
* If this is an outer join, we mustn't allow any upper lateral
|
|
* references in or below it.
|
|
*/
|
|
if (j->jointype != JOIN_INNER)
|
|
{
|
|
restricted = true;
|
|
safe_upper_varnos = NULL;
|
|
}
|
|
|
|
/* Check the child joins */
|
|
if (jointree_contains_lateral_outer_refs(j->larg,
|
|
restricted,
|
|
safe_upper_varnos))
|
|
return true;
|
|
if (jointree_contains_lateral_outer_refs(j->rarg,
|
|
restricted,
|
|
safe_upper_varnos))
|
|
return true;
|
|
|
|
/* Check the JOIN's qual clauses */
|
|
if (restricted &&
|
|
!bms_is_subset(pull_varnos_of_level(j->quals, 1),
|
|
safe_upper_varnos))
|
|
return true;
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* Helper routine for pull_up_subqueries: do pullup_replace_vars on every
|
|
* expression in the jointree, without changing the jointree structure itself.
|
|
* Ugly, but there's no other way...
|
|
*
|
|
* If we are at or below lowest_nulling_outer_join, we can suppress use of
|
|
* PlaceHolderVars wrapped around the replacement expressions.
|
|
*/
|
|
static void
|
|
replace_vars_in_jointree(Node *jtnode,
|
|
pullup_replace_vars_context *context,
|
|
JoinExpr *lowest_nulling_outer_join)
|
|
{
|
|
if (jtnode == NULL)
|
|
return;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
/*
|
|
* If the RangeTblRef refers to a LATERAL subquery (that isn't the
|
|
* same subquery we're pulling up), it might contain references to the
|
|
* target subquery, which we must replace. We drive this from the
|
|
* jointree scan, rather than a scan of the rtable, for a couple of
|
|
* reasons: we can avoid processing no-longer-referenced RTEs, and we
|
|
* can use the appropriate setting of need_phvs depending on whether
|
|
* the RTE is above possibly-nulling outer joins or not.
|
|
*/
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
|
|
if (varno != context->varno) /* ignore target subquery itself */
|
|
{
|
|
RangeTblEntry *rte = rt_fetch(varno, context->root->parse->rtable);
|
|
|
|
Assert(rte != context->target_rte);
|
|
if (rte->lateral)
|
|
{
|
|
switch (rte->rtekind)
|
|
{
|
|
case RTE_RELATION:
|
|
/* shouldn't be marked LATERAL unless tablesample */
|
|
Assert(rte->tablesample);
|
|
rte->tablesample = (TableSampleClause *)
|
|
pullup_replace_vars((Node *) rte->tablesample,
|
|
context);
|
|
break;
|
|
case RTE_SUBQUERY:
|
|
rte->subquery =
|
|
pullup_replace_vars_subquery(rte->subquery,
|
|
context);
|
|
break;
|
|
case RTE_FUNCTION:
|
|
rte->functions = (List *)
|
|
pullup_replace_vars((Node *) rte->functions,
|
|
context);
|
|
break;
|
|
case RTE_VALUES:
|
|
rte->values_lists = (List *)
|
|
pullup_replace_vars((Node *) rte->values_lists,
|
|
context);
|
|
break;
|
|
case RTE_JOIN:
|
|
case RTE_CTE:
|
|
/* these shouldn't be marked LATERAL */
|
|
Assert(false);
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
ListCell *l;
|
|
|
|
foreach(l, f->fromlist)
|
|
replace_vars_in_jointree(lfirst(l), context,
|
|
lowest_nulling_outer_join);
|
|
f->quals = pullup_replace_vars(f->quals, context);
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
bool save_need_phvs = context->need_phvs;
|
|
|
|
if (j == lowest_nulling_outer_join)
|
|
{
|
|
/* no more PHVs in or below this join */
|
|
context->need_phvs = false;
|
|
lowest_nulling_outer_join = NULL;
|
|
}
|
|
replace_vars_in_jointree(j->larg, context, lowest_nulling_outer_join);
|
|
replace_vars_in_jointree(j->rarg, context, lowest_nulling_outer_join);
|
|
j->quals = pullup_replace_vars(j->quals, context);
|
|
|
|
/*
|
|
* We don't bother to update the colvars list, since it won't be used
|
|
* again ...
|
|
*/
|
|
context->need_phvs = save_need_phvs;
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
}
|
|
|
|
/*
|
|
* Apply pullup variable replacement throughout an expression tree
|
|
*
|
|
* Returns a modified copy of the tree, so this can't be used where we
|
|
* need to do in-place replacement.
|
|
*/
|
|
static Node *
|
|
pullup_replace_vars(Node *expr, pullup_replace_vars_context *context)
|
|
{
|
|
return replace_rte_variables(expr,
|
|
context->varno, 0,
|
|
pullup_replace_vars_callback,
|
|
(void *) context,
|
|
context->outer_hasSubLinks);
|
|
}
|
|
|
|
static Node *
|
|
pullup_replace_vars_callback(Var *var,
|
|
replace_rte_variables_context *context)
|
|
{
|
|
pullup_replace_vars_context *rcon = (pullup_replace_vars_context *) context->callback_arg;
|
|
int varattno = var->varattno;
|
|
Node *newnode;
|
|
|
|
/*
|
|
* If PlaceHolderVars are needed, we cache the modified expressions in
|
|
* rcon->rv_cache[]. This is not in hopes of any material speed gain
|
|
* within this function, but to avoid generating identical PHVs with
|
|
* different IDs. That would result in duplicate evaluations at runtime,
|
|
* and possibly prevent optimizations that rely on recognizing different
|
|
* references to the same subquery output as being equal(). So it's worth
|
|
* a bit of extra effort to avoid it.
|
|
*/
|
|
if (rcon->need_phvs &&
|
|
varattno >= InvalidAttrNumber &&
|
|
varattno <= list_length(rcon->targetlist) &&
|
|
rcon->rv_cache[varattno] != NULL)
|
|
{
|
|
/* Just copy the entry and fall through to adjust its varlevelsup */
|
|
newnode = copyObject(rcon->rv_cache[varattno]);
|
|
}
|
|
else if (varattno == InvalidAttrNumber)
|
|
{
|
|
/* Must expand whole-tuple reference into RowExpr */
|
|
RowExpr *rowexpr;
|
|
List *colnames;
|
|
List *fields;
|
|
bool save_need_phvs = rcon->need_phvs;
|
|
int save_sublevelsup = context->sublevels_up;
|
|
|
|
/*
|
|
* If generating an expansion for a var of a named rowtype (ie, this
|
|
* is a plain relation RTE), then we must include dummy items for
|
|
* dropped columns. If the var is RECORD (ie, this is a JOIN), then
|
|
* omit dropped columns. Either way, attach column names to the
|
|
* RowExpr for use of ruleutils.c.
|
|
*
|
|
* In order to be able to cache the results, we always generate the
|
|
* expansion with varlevelsup = 0, and then adjust if needed.
|
|
*/
|
|
expandRTE(rcon->target_rte,
|
|
var->varno, 0 /* not varlevelsup */ , var->location,
|
|
(var->vartype != RECORDOID),
|
|
&colnames, &fields);
|
|
/* Adjust the generated per-field Vars, but don't insert PHVs */
|
|
rcon->need_phvs = false;
|
|
context->sublevels_up = 0; /* to match the expandRTE output */
|
|
fields = (List *) replace_rte_variables_mutator((Node *) fields,
|
|
context);
|
|
rcon->need_phvs = save_need_phvs;
|
|
context->sublevels_up = save_sublevelsup;
|
|
|
|
rowexpr = makeNode(RowExpr);
|
|
rowexpr->args = fields;
|
|
rowexpr->row_typeid = var->vartype;
|
|
rowexpr->row_format = COERCE_IMPLICIT_CAST;
|
|
rowexpr->colnames = colnames;
|
|
rowexpr->location = var->location;
|
|
newnode = (Node *) rowexpr;
|
|
|
|
/*
|
|
* Insert PlaceHolderVar if needed. Notice that we are wrapping one
|
|
* PlaceHolderVar around the whole RowExpr, rather than putting one
|
|
* around each element of the row. This is because we need the
|
|
* expression to yield NULL, not ROW(NULL,NULL,...) when it is forced
|
|
* to null by an outer join.
|
|
*/
|
|
if (rcon->need_phvs)
|
|
{
|
|
/* RowExpr is certainly not strict, so always need PHV */
|
|
newnode = (Node *)
|
|
make_placeholder_expr(rcon->root,
|
|
(Expr *) newnode,
|
|
bms_make_singleton(rcon->varno));
|
|
/* cache it with the PHV, and with varlevelsup still zero */
|
|
rcon->rv_cache[InvalidAttrNumber] = copyObject(newnode);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* Normal case referencing one targetlist element */
|
|
TargetEntry *tle = get_tle_by_resno(rcon->targetlist, varattno);
|
|
|
|
if (tle == NULL) /* shouldn't happen */
|
|
elog(ERROR, "could not find attribute %d in subquery targetlist",
|
|
varattno);
|
|
|
|
/* Make a copy of the tlist item to return */
|
|
newnode = copyObject(tle->expr);
|
|
|
|
/* Insert PlaceHolderVar if needed */
|
|
if (rcon->need_phvs)
|
|
{
|
|
bool wrap;
|
|
|
|
if (newnode && IsA(newnode, Var) &&
|
|
((Var *) newnode)->varlevelsup == 0)
|
|
{
|
|
/*
|
|
* Simple Vars always escape being wrapped, unless they are
|
|
* lateral references to something outside the subquery being
|
|
* pulled up. (Even then, we could omit the PlaceHolderVar if
|
|
* the referenced rel is under the same lowest outer join, but
|
|
* it doesn't seem worth the trouble to check that.)
|
|
*/
|
|
if (rcon->target_rte->lateral &&
|
|
!bms_is_member(((Var *) newnode)->varno, rcon->relids))
|
|
wrap = true;
|
|
else
|
|
wrap = false;
|
|
}
|
|
else if (newnode && IsA(newnode, PlaceHolderVar) &&
|
|
((PlaceHolderVar *) newnode)->phlevelsup == 0)
|
|
{
|
|
/* No need to wrap a PlaceHolderVar with another one, either */
|
|
wrap = false;
|
|
}
|
|
else if (rcon->wrap_non_vars)
|
|
{
|
|
/* Wrap all non-Vars in a PlaceHolderVar */
|
|
wrap = true;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* If it contains a Var of the subquery being pulled up, and
|
|
* does not contain any non-strict constructs, then it's
|
|
* certainly nullable so we don't need to insert a
|
|
* PlaceHolderVar.
|
|
*
|
|
* This analysis could be tighter: in particular, a non-strict
|
|
* construct hidden within a lower-level PlaceHolderVar is not
|
|
* reason to add another PHV. But for now it doesn't seem
|
|
* worth the code to be more exact.
|
|
*
|
|
* Note: in future maybe we should insert a PlaceHolderVar
|
|
* anyway, if the tlist item is expensive to evaluate?
|
|
*
|
|
* For a LATERAL subquery, we have to check the actual var
|
|
* membership of the node, but if it's non-lateral then any
|
|
* level-zero var must belong to the subquery.
|
|
*/
|
|
if ((rcon->target_rte->lateral ?
|
|
bms_overlap(pull_varnos((Node *) newnode), rcon->relids) :
|
|
contain_vars_of_level((Node *) newnode, 0)) &&
|
|
!contain_nonstrict_functions((Node *) newnode))
|
|
{
|
|
/* No wrap needed */
|
|
wrap = false;
|
|
}
|
|
else
|
|
{
|
|
/* Else wrap it in a PlaceHolderVar */
|
|
wrap = true;
|
|
}
|
|
}
|
|
|
|
if (wrap)
|
|
newnode = (Node *)
|
|
make_placeholder_expr(rcon->root,
|
|
(Expr *) newnode,
|
|
bms_make_singleton(rcon->varno));
|
|
|
|
/*
|
|
* Cache it if possible (ie, if the attno is in range, which it
|
|
* probably always should be). We can cache the value even if we
|
|
* decided we didn't need a PHV, since this result will be
|
|
* suitable for any request that has need_phvs.
|
|
*/
|
|
if (varattno > InvalidAttrNumber &&
|
|
varattno <= list_length(rcon->targetlist))
|
|
rcon->rv_cache[varattno] = copyObject(newnode);
|
|
}
|
|
}
|
|
|
|
/* Must adjust varlevelsup if tlist item is from higher query */
|
|
if (var->varlevelsup > 0)
|
|
IncrementVarSublevelsUp(newnode, var->varlevelsup, 0);
|
|
|
|
return newnode;
|
|
}
|
|
|
|
/*
|
|
* Apply pullup variable replacement to a subquery
|
|
*
|
|
* This needs to be different from pullup_replace_vars() because
|
|
* replace_rte_variables will think that it shouldn't increment sublevels_up
|
|
* before entering the Query; so we need to call it with sublevels_up == 1.
|
|
*/
|
|
static Query *
|
|
pullup_replace_vars_subquery(Query *query,
|
|
pullup_replace_vars_context *context)
|
|
{
|
|
Assert(IsA(query, Query));
|
|
return (Query *) replace_rte_variables((Node *) query,
|
|
context->varno, 1,
|
|
pullup_replace_vars_callback,
|
|
(void *) context,
|
|
NULL);
|
|
}
|
|
|
|
/*
|
|
* pull_up_subqueries_cleanup
|
|
* Recursively fix up jointree after deletion of some subqueries.
|
|
*
|
|
* The jointree now contains some NULL subtrees, which we need to get rid of.
|
|
* In a FromExpr, just rebuild the child-node list with null entries deleted.
|
|
* In an inner JOIN, replace the JoinExpr node with a one-child FromExpr.
|
|
*/
|
|
static Node *
|
|
pull_up_subqueries_cleanup(Node *jtnode)
|
|
{
|
|
Assert(jtnode != NULL);
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
/* Nothing to do at leaf nodes. */
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
List *newfrom = NIL;
|
|
ListCell *l;
|
|
|
|
foreach(l, f->fromlist)
|
|
{
|
|
Node *child = (Node *) lfirst(l);
|
|
|
|
if (child == NULL)
|
|
continue;
|
|
child = pull_up_subqueries_cleanup(child);
|
|
newfrom = lappend(newfrom, child);
|
|
}
|
|
f->fromlist = newfrom;
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
if (j->larg)
|
|
j->larg = pull_up_subqueries_cleanup(j->larg);
|
|
if (j->rarg)
|
|
j->rarg = pull_up_subqueries_cleanup(j->rarg);
|
|
if (j->larg == NULL)
|
|
{
|
|
Assert(j->jointype == JOIN_INNER);
|
|
Assert(j->rarg != NULL);
|
|
return (Node *) makeFromExpr(list_make1(j->rarg), j->quals);
|
|
}
|
|
else if (j->rarg == NULL)
|
|
{
|
|
Assert(j->jointype == JOIN_INNER);
|
|
return (Node *) makeFromExpr(list_make1(j->larg), j->quals);
|
|
}
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return jtnode;
|
|
}
|
|
|
|
|
|
/*
|
|
* flatten_simple_union_all
|
|
* Try to optimize top-level UNION ALL structure into an appendrel
|
|
*
|
|
* If a query's setOperations tree consists entirely of simple UNION ALL
|
|
* operations, flatten it into an append relation, which we can process more
|
|
* intelligently than the general setops case. Otherwise, do nothing.
|
|
*
|
|
* In most cases, this can succeed only for a top-level query, because for a
|
|
* subquery in FROM, the parent query's invocation of pull_up_subqueries would
|
|
* already have flattened the UNION via pull_up_simple_union_all. But there
|
|
* are a few cases we can support here but not in that code path, for example
|
|
* when the subquery also contains ORDER BY.
|
|
*/
|
|
void
|
|
flatten_simple_union_all(PlannerInfo *root)
|
|
{
|
|
Query *parse = root->parse;
|
|
SetOperationStmt *topop;
|
|
Node *leftmostjtnode;
|
|
int leftmostRTI;
|
|
RangeTblEntry *leftmostRTE;
|
|
int childRTI;
|
|
RangeTblEntry *childRTE;
|
|
RangeTblRef *rtr;
|
|
|
|
/* Shouldn't be called unless query has setops */
|
|
topop = (SetOperationStmt *) parse->setOperations;
|
|
Assert(topop && IsA(topop, SetOperationStmt));
|
|
|
|
/* Can't optimize away a recursive UNION */
|
|
if (root->hasRecursion)
|
|
return;
|
|
|
|
/*
|
|
* Recursively check the tree of set operations. If not all UNION ALL
|
|
* with identical column types, punt.
|
|
*/
|
|
if (!is_simple_union_all_recurse((Node *) topop, parse, topop->colTypes))
|
|
return;
|
|
|
|
/*
|
|
* Locate the leftmost leaf query in the setops tree. The upper query's
|
|
* Vars all refer to this RTE (see transformSetOperationStmt).
|
|
*/
|
|
leftmostjtnode = topop->larg;
|
|
while (leftmostjtnode && IsA(leftmostjtnode, SetOperationStmt))
|
|
leftmostjtnode = ((SetOperationStmt *) leftmostjtnode)->larg;
|
|
Assert(leftmostjtnode && IsA(leftmostjtnode, RangeTblRef));
|
|
leftmostRTI = ((RangeTblRef *) leftmostjtnode)->rtindex;
|
|
leftmostRTE = rt_fetch(leftmostRTI, parse->rtable);
|
|
Assert(leftmostRTE->rtekind == RTE_SUBQUERY);
|
|
|
|
/*
|
|
* Make a copy of the leftmost RTE and add it to the rtable. This copy
|
|
* will represent the leftmost leaf query in its capacity as a member of
|
|
* the appendrel. The original will represent the appendrel as a whole.
|
|
* (We must do things this way because the upper query's Vars have to be
|
|
* seen as referring to the whole appendrel.)
|
|
*/
|
|
childRTE = copyObject(leftmostRTE);
|
|
parse->rtable = lappend(parse->rtable, childRTE);
|
|
childRTI = list_length(parse->rtable);
|
|
|
|
/* Modify the setops tree to reference the child copy */
|
|
((RangeTblRef *) leftmostjtnode)->rtindex = childRTI;
|
|
|
|
/* Modify the formerly-leftmost RTE to mark it as an appendrel parent */
|
|
leftmostRTE->inh = true;
|
|
|
|
/*
|
|
* Form a RangeTblRef for the appendrel, and insert it into FROM. The top
|
|
* Query of a setops tree should have had an empty FromClause initially.
|
|
*/
|
|
rtr = makeNode(RangeTblRef);
|
|
rtr->rtindex = leftmostRTI;
|
|
Assert(parse->jointree->fromlist == NIL);
|
|
parse->jointree->fromlist = list_make1(rtr);
|
|
|
|
/*
|
|
* Now pretend the query has no setops. We must do this before trying to
|
|
* do subquery pullup, because of Assert in pull_up_simple_subquery.
|
|
*/
|
|
parse->setOperations = NULL;
|
|
|
|
/*
|
|
* Build AppendRelInfo information, and apply pull_up_subqueries to the
|
|
* leaf queries of the UNION ALL. (We must do that now because they
|
|
* weren't previously referenced by the jointree, and so were missed by
|
|
* the main invocation of pull_up_subqueries.)
|
|
*/
|
|
pull_up_union_leaf_queries((Node *) topop, root, leftmostRTI, parse, 0);
|
|
}
|
|
|
|
|
|
/*
|
|
* reduce_outer_joins
|
|
* Attempt to reduce outer joins to plain inner joins.
|
|
*
|
|
* The idea here is that given a query like
|
|
* SELECT ... FROM a LEFT JOIN b ON (...) WHERE b.y = 42;
|
|
* we can reduce the LEFT JOIN to a plain JOIN if the "=" operator in WHERE
|
|
* is strict. The strict operator will always return NULL, causing the outer
|
|
* WHERE to fail, on any row where the LEFT JOIN filled in NULLs for b's
|
|
* columns. Therefore, there's no need for the join to produce null-extended
|
|
* rows in the first place --- which makes it a plain join not an outer join.
|
|
* (This scenario may not be very likely in a query written out by hand, but
|
|
* it's reasonably likely when pushing quals down into complex views.)
|
|
*
|
|
* More generally, an outer join can be reduced in strength if there is a
|
|
* strict qual above it in the qual tree that constrains a Var from the
|
|
* nullable side of the join to be non-null. (For FULL joins this applies
|
|
* to each side separately.)
|
|
*
|
|
* Another transformation we apply here is to recognize cases like
|
|
* SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL;
|
|
* If the join clause is strict for b.y, then only null-extended rows could
|
|
* pass the upper WHERE, and we can conclude that what the query is really
|
|
* specifying is an anti-semijoin. We change the join type from JOIN_LEFT
|
|
* to JOIN_ANTI. The IS NULL clause then becomes redundant, and must be
|
|
* removed to prevent bogus selectivity calculations, but we leave it to
|
|
* distribute_qual_to_rels to get rid of such clauses.
|
|
*
|
|
* Also, we get rid of JOIN_RIGHT cases by flipping them around to become
|
|
* JOIN_LEFT. This saves some code here and in some later planner routines,
|
|
* but the main reason to do it is to not need to invent a JOIN_REVERSE_ANTI
|
|
* join type.
|
|
*
|
|
* To ease recognition of strict qual clauses, we require this routine to be
|
|
* run after expression preprocessing (i.e., qual canonicalization and JOIN
|
|
* alias-var expansion).
|
|
*/
|
|
void
|
|
reduce_outer_joins(PlannerInfo *root)
|
|
{
|
|
reduce_outer_joins_state *state;
|
|
|
|
/*
|
|
* To avoid doing strictness checks on more quals than necessary, we want
|
|
* to stop descending the jointree as soon as there are no outer joins
|
|
* below our current point. This consideration forces a two-pass process.
|
|
* The first pass gathers information about which base rels appear below
|
|
* each side of each join clause, and about whether there are outer
|
|
* join(s) below each side of each join clause. The second pass examines
|
|
* qual clauses and changes join types as it descends the tree.
|
|
*/
|
|
state = reduce_outer_joins_pass1((Node *) root->parse->jointree);
|
|
|
|
/* planner.c shouldn't have called me if no outer joins */
|
|
if (state == NULL || !state->contains_outer)
|
|
elog(ERROR, "so where are the outer joins?");
|
|
|
|
reduce_outer_joins_pass2((Node *) root->parse->jointree,
|
|
state, root, NULL, NIL, NIL);
|
|
}
|
|
|
|
/*
|
|
* reduce_outer_joins_pass1 - phase 1 data collection
|
|
*
|
|
* Returns a state node describing the given jointree node.
|
|
*/
|
|
static reduce_outer_joins_state *
|
|
reduce_outer_joins_pass1(Node *jtnode)
|
|
{
|
|
reduce_outer_joins_state *result;
|
|
|
|
result = (reduce_outer_joins_state *)
|
|
palloc(sizeof(reduce_outer_joins_state));
|
|
result->relids = NULL;
|
|
result->contains_outer = false;
|
|
result->sub_states = NIL;
|
|
|
|
if (jtnode == NULL)
|
|
return result;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
|
|
result->relids = bms_make_singleton(varno);
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
ListCell *l;
|
|
|
|
foreach(l, f->fromlist)
|
|
{
|
|
reduce_outer_joins_state *sub_state;
|
|
|
|
sub_state = reduce_outer_joins_pass1(lfirst(l));
|
|
result->relids = bms_add_members(result->relids,
|
|
sub_state->relids);
|
|
result->contains_outer |= sub_state->contains_outer;
|
|
result->sub_states = lappend(result->sub_states, sub_state);
|
|
}
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
reduce_outer_joins_state *sub_state;
|
|
|
|
/* join's own RT index is not wanted in result->relids */
|
|
if (IS_OUTER_JOIN(j->jointype))
|
|
result->contains_outer = true;
|
|
|
|
sub_state = reduce_outer_joins_pass1(j->larg);
|
|
result->relids = bms_add_members(result->relids,
|
|
sub_state->relids);
|
|
result->contains_outer |= sub_state->contains_outer;
|
|
result->sub_states = lappend(result->sub_states, sub_state);
|
|
|
|
sub_state = reduce_outer_joins_pass1(j->rarg);
|
|
result->relids = bms_add_members(result->relids,
|
|
sub_state->relids);
|
|
result->contains_outer |= sub_state->contains_outer;
|
|
result->sub_states = lappend(result->sub_states, sub_state);
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* reduce_outer_joins_pass2 - phase 2 processing
|
|
*
|
|
* jtnode: current jointree node
|
|
* state: state data collected by phase 1 for this node
|
|
* root: toplevel planner state
|
|
* nonnullable_rels: set of base relids forced non-null by upper quals
|
|
* nonnullable_vars: list of Vars forced non-null by upper quals
|
|
* forced_null_vars: list of Vars forced null by upper quals
|
|
*/
|
|
static void
|
|
reduce_outer_joins_pass2(Node *jtnode,
|
|
reduce_outer_joins_state *state,
|
|
PlannerInfo *root,
|
|
Relids nonnullable_rels,
|
|
List *nonnullable_vars,
|
|
List *forced_null_vars)
|
|
{
|
|
/*
|
|
* pass 2 should never descend as far as an empty subnode or base rel,
|
|
* because it's only called on subtrees marked as contains_outer.
|
|
*/
|
|
if (jtnode == NULL)
|
|
elog(ERROR, "reached empty jointree");
|
|
if (IsA(jtnode, RangeTblRef))
|
|
elog(ERROR, "reached base rel");
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
ListCell *l;
|
|
ListCell *s;
|
|
Relids pass_nonnullable_rels;
|
|
List *pass_nonnullable_vars;
|
|
List *pass_forced_null_vars;
|
|
|
|
/* Scan quals to see if we can add any constraints */
|
|
pass_nonnullable_rels = find_nonnullable_rels(f->quals);
|
|
pass_nonnullable_rels = bms_add_members(pass_nonnullable_rels,
|
|
nonnullable_rels);
|
|
/* NB: we rely on list_concat to not damage its second argument */
|
|
pass_nonnullable_vars = find_nonnullable_vars(f->quals);
|
|
pass_nonnullable_vars = list_concat(pass_nonnullable_vars,
|
|
nonnullable_vars);
|
|
pass_forced_null_vars = find_forced_null_vars(f->quals);
|
|
pass_forced_null_vars = list_concat(pass_forced_null_vars,
|
|
forced_null_vars);
|
|
/* And recurse --- but only into interesting subtrees */
|
|
Assert(list_length(f->fromlist) == list_length(state->sub_states));
|
|
forboth(l, f->fromlist, s, state->sub_states)
|
|
{
|
|
reduce_outer_joins_state *sub_state = lfirst(s);
|
|
|
|
if (sub_state->contains_outer)
|
|
reduce_outer_joins_pass2(lfirst(l), sub_state, root,
|
|
pass_nonnullable_rels,
|
|
pass_nonnullable_vars,
|
|
pass_forced_null_vars);
|
|
}
|
|
bms_free(pass_nonnullable_rels);
|
|
/* can't so easily clean up var lists, unfortunately */
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
int rtindex = j->rtindex;
|
|
JoinType jointype = j->jointype;
|
|
reduce_outer_joins_state *left_state = linitial(state->sub_states);
|
|
reduce_outer_joins_state *right_state = lsecond(state->sub_states);
|
|
List *local_nonnullable_vars = NIL;
|
|
bool computed_local_nonnullable_vars = false;
|
|
|
|
/* Can we simplify this join? */
|
|
switch (jointype)
|
|
{
|
|
case JOIN_INNER:
|
|
break;
|
|
case JOIN_LEFT:
|
|
if (bms_overlap(nonnullable_rels, right_state->relids))
|
|
jointype = JOIN_INNER;
|
|
break;
|
|
case JOIN_RIGHT:
|
|
if (bms_overlap(nonnullable_rels, left_state->relids))
|
|
jointype = JOIN_INNER;
|
|
break;
|
|
case JOIN_FULL:
|
|
if (bms_overlap(nonnullable_rels, left_state->relids))
|
|
{
|
|
if (bms_overlap(nonnullable_rels, right_state->relids))
|
|
jointype = JOIN_INNER;
|
|
else
|
|
jointype = JOIN_LEFT;
|
|
}
|
|
else
|
|
{
|
|
if (bms_overlap(nonnullable_rels, right_state->relids))
|
|
jointype = JOIN_RIGHT;
|
|
}
|
|
break;
|
|
case JOIN_SEMI:
|
|
case JOIN_ANTI:
|
|
|
|
/*
|
|
* These could only have been introduced by pull_up_sublinks,
|
|
* so there's no way that upper quals could refer to their
|
|
* righthand sides, and no point in checking.
|
|
*/
|
|
break;
|
|
default:
|
|
elog(ERROR, "unrecognized join type: %d",
|
|
(int) jointype);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Convert JOIN_RIGHT to JOIN_LEFT. Note that in the case where we
|
|
* reduced JOIN_FULL to JOIN_RIGHT, this will mean the JoinExpr no
|
|
* longer matches the internal ordering of any CoalesceExpr's built to
|
|
* represent merged join variables. We don't care about that at
|
|
* present, but be wary of it ...
|
|
*/
|
|
if (jointype == JOIN_RIGHT)
|
|
{
|
|
Node *tmparg;
|
|
|
|
tmparg = j->larg;
|
|
j->larg = j->rarg;
|
|
j->rarg = tmparg;
|
|
jointype = JOIN_LEFT;
|
|
right_state = linitial(state->sub_states);
|
|
left_state = lsecond(state->sub_states);
|
|
}
|
|
|
|
/*
|
|
* See if we can reduce JOIN_LEFT to JOIN_ANTI. This is the case if
|
|
* the join's own quals are strict for any var that was forced null by
|
|
* higher qual levels. NOTE: there are other ways that we could
|
|
* detect an anti-join, in particular if we were to check whether Vars
|
|
* coming from the RHS must be non-null because of table constraints.
|
|
* That seems complicated and expensive though (in particular, one
|
|
* would have to be wary of lower outer joins). For the moment this
|
|
* seems sufficient.
|
|
*/
|
|
if (jointype == JOIN_LEFT)
|
|
{
|
|
List *overlap;
|
|
|
|
local_nonnullable_vars = find_nonnullable_vars(j->quals);
|
|
computed_local_nonnullable_vars = true;
|
|
|
|
/*
|
|
* It's not sufficient to check whether local_nonnullable_vars and
|
|
* forced_null_vars overlap: we need to know if the overlap
|
|
* includes any RHS variables.
|
|
*/
|
|
overlap = list_intersection(local_nonnullable_vars,
|
|
forced_null_vars);
|
|
if (overlap != NIL &&
|
|
bms_overlap(pull_varnos((Node *) overlap),
|
|
right_state->relids))
|
|
jointype = JOIN_ANTI;
|
|
}
|
|
|
|
/* Apply the jointype change, if any, to both jointree node and RTE */
|
|
if (rtindex && jointype != j->jointype)
|
|
{
|
|
RangeTblEntry *rte = rt_fetch(rtindex, root->parse->rtable);
|
|
|
|
Assert(rte->rtekind == RTE_JOIN);
|
|
Assert(rte->jointype == j->jointype);
|
|
rte->jointype = jointype;
|
|
}
|
|
j->jointype = jointype;
|
|
|
|
/* Only recurse if there's more to do below here */
|
|
if (left_state->contains_outer || right_state->contains_outer)
|
|
{
|
|
Relids local_nonnullable_rels;
|
|
List *local_forced_null_vars;
|
|
Relids pass_nonnullable_rels;
|
|
List *pass_nonnullable_vars;
|
|
List *pass_forced_null_vars;
|
|
|
|
/*
|
|
* If this join is (now) inner, we can add any constraints its
|
|
* quals provide to those we got from above. But if it is outer,
|
|
* we can pass down the local constraints only into the nullable
|
|
* side, because an outer join never eliminates any rows from its
|
|
* non-nullable side. Also, there is no point in passing upper
|
|
* constraints into the nullable side, since if there were any
|
|
* we'd have been able to reduce the join. (In the case of upper
|
|
* forced-null constraints, we *must not* pass them into the
|
|
* nullable side --- they either applied here, or not.) The upshot
|
|
* is that we pass either the local or the upper constraints,
|
|
* never both, to the children of an outer join.
|
|
*
|
|
* Note that a SEMI join works like an inner join here: it's okay
|
|
* to pass down both local and upper constraints. (There can't be
|
|
* any upper constraints affecting its inner side, but it's not
|
|
* worth having a separate code path to avoid passing them.)
|
|
*
|
|
* At a FULL join we just punt and pass nothing down --- is it
|
|
* possible to be smarter?
|
|
*/
|
|
if (jointype != JOIN_FULL)
|
|
{
|
|
local_nonnullable_rels = find_nonnullable_rels(j->quals);
|
|
if (!computed_local_nonnullable_vars)
|
|
local_nonnullable_vars = find_nonnullable_vars(j->quals);
|
|
local_forced_null_vars = find_forced_null_vars(j->quals);
|
|
if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
|
|
{
|
|
/* OK to merge upper and local constraints */
|
|
local_nonnullable_rels = bms_add_members(local_nonnullable_rels,
|
|
nonnullable_rels);
|
|
local_nonnullable_vars = list_concat(local_nonnullable_vars,
|
|
nonnullable_vars);
|
|
local_forced_null_vars = list_concat(local_forced_null_vars,
|
|
forced_null_vars);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* no use in calculating these */
|
|
local_nonnullable_rels = NULL;
|
|
local_forced_null_vars = NIL;
|
|
}
|
|
|
|
if (left_state->contains_outer)
|
|
{
|
|
if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
|
|
{
|
|
/* pass union of local and upper constraints */
|
|
pass_nonnullable_rels = local_nonnullable_rels;
|
|
pass_nonnullable_vars = local_nonnullable_vars;
|
|
pass_forced_null_vars = local_forced_null_vars;
|
|
}
|
|
else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */
|
|
{
|
|
/* can't pass local constraints to non-nullable side */
|
|
pass_nonnullable_rels = nonnullable_rels;
|
|
pass_nonnullable_vars = nonnullable_vars;
|
|
pass_forced_null_vars = forced_null_vars;
|
|
}
|
|
else
|
|
{
|
|
/* no constraints pass through JOIN_FULL */
|
|
pass_nonnullable_rels = NULL;
|
|
pass_nonnullable_vars = NIL;
|
|
pass_forced_null_vars = NIL;
|
|
}
|
|
reduce_outer_joins_pass2(j->larg, left_state, root,
|
|
pass_nonnullable_rels,
|
|
pass_nonnullable_vars,
|
|
pass_forced_null_vars);
|
|
}
|
|
|
|
if (right_state->contains_outer)
|
|
{
|
|
if (jointype != JOIN_FULL) /* ie, INNER/LEFT/SEMI/ANTI */
|
|
{
|
|
/* pass appropriate constraints, per comment above */
|
|
pass_nonnullable_rels = local_nonnullable_rels;
|
|
pass_nonnullable_vars = local_nonnullable_vars;
|
|
pass_forced_null_vars = local_forced_null_vars;
|
|
}
|
|
else
|
|
{
|
|
/* no constraints pass through JOIN_FULL */
|
|
pass_nonnullable_rels = NULL;
|
|
pass_nonnullable_vars = NIL;
|
|
pass_forced_null_vars = NIL;
|
|
}
|
|
reduce_outer_joins_pass2(j->rarg, right_state, root,
|
|
pass_nonnullable_rels,
|
|
pass_nonnullable_vars,
|
|
pass_forced_null_vars);
|
|
}
|
|
bms_free(local_nonnullable_rels);
|
|
}
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
}
|
|
|
|
/*
|
|
* substitute_multiple_relids - adjust node relid sets after pulling up
|
|
* a subquery
|
|
*
|
|
* Find any PlaceHolderVar nodes in the given tree that reference the
|
|
* pulled-up relid, and change them to reference the replacement relid(s).
|
|
*
|
|
* NOTE: although this has the form of a walker, we cheat and modify the
|
|
* nodes in-place. This should be OK since the tree was copied by
|
|
* pullup_replace_vars earlier. Avoid scribbling on the original values of
|
|
* the bitmapsets, though, because expression_tree_mutator doesn't copy those.
|
|
*/
|
|
|
|
typedef struct
|
|
{
|
|
int varno;
|
|
int sublevels_up;
|
|
Relids subrelids;
|
|
} substitute_multiple_relids_context;
|
|
|
|
static bool
|
|
substitute_multiple_relids_walker(Node *node,
|
|
substitute_multiple_relids_context *context)
|
|
{
|
|
if (node == NULL)
|
|
return false;
|
|
if (IsA(node, PlaceHolderVar))
|
|
{
|
|
PlaceHolderVar *phv = (PlaceHolderVar *) node;
|
|
|
|
if (phv->phlevelsup == context->sublevels_up &&
|
|
bms_is_member(context->varno, phv->phrels))
|
|
{
|
|
phv->phrels = bms_union(phv->phrels,
|
|
context->subrelids);
|
|
phv->phrels = bms_del_member(phv->phrels,
|
|
context->varno);
|
|
}
|
|
/* fall through to examine children */
|
|
}
|
|
if (IsA(node, Query))
|
|
{
|
|
/* Recurse into subselects */
|
|
bool result;
|
|
|
|
context->sublevels_up++;
|
|
result = query_tree_walker((Query *) node,
|
|
substitute_multiple_relids_walker,
|
|
(void *) context, 0);
|
|
context->sublevels_up--;
|
|
return result;
|
|
}
|
|
/* Shouldn't need to handle planner auxiliary nodes here */
|
|
Assert(!IsA(node, SpecialJoinInfo));
|
|
Assert(!IsA(node, LateralJoinInfo));
|
|
Assert(!IsA(node, AppendRelInfo));
|
|
Assert(!IsA(node, PlaceHolderInfo));
|
|
Assert(!IsA(node, MinMaxAggInfo));
|
|
|
|
return expression_tree_walker(node, substitute_multiple_relids_walker,
|
|
(void *) context);
|
|
}
|
|
|
|
static void
|
|
substitute_multiple_relids(Node *node, int varno, Relids subrelids)
|
|
{
|
|
substitute_multiple_relids_context context;
|
|
|
|
context.varno = varno;
|
|
context.sublevels_up = 0;
|
|
context.subrelids = subrelids;
|
|
|
|
/*
|
|
* Must be prepared to start with a Query or a bare expression tree.
|
|
*/
|
|
query_or_expression_tree_walker(node,
|
|
substitute_multiple_relids_walker,
|
|
(void *) &context,
|
|
0);
|
|
}
|
|
|
|
/*
|
|
* fix_append_rel_relids: update RT-index fields of AppendRelInfo nodes
|
|
*
|
|
* When we pull up a subquery, any AppendRelInfo references to the subquery's
|
|
* RT index have to be replaced by the substituted relid (and there had better
|
|
* be only one). We also need to apply substitute_multiple_relids to their
|
|
* translated_vars lists, since those might contain PlaceHolderVars.
|
|
*
|
|
* We assume we may modify the AppendRelInfo nodes in-place.
|
|
*/
|
|
static void
|
|
fix_append_rel_relids(List *append_rel_list, int varno, Relids subrelids)
|
|
{
|
|
ListCell *l;
|
|
int subvarno = -1;
|
|
|
|
/*
|
|
* We only want to extract the member relid once, but we mustn't fail
|
|
* immediately if there are multiple members; it could be that none of the
|
|
* AppendRelInfo nodes refer to it. So compute it on first use. Note that
|
|
* bms_singleton_member will complain if set is not singleton.
|
|
*/
|
|
foreach(l, append_rel_list)
|
|
{
|
|
AppendRelInfo *appinfo = (AppendRelInfo *) lfirst(l);
|
|
|
|
/* The parent_relid shouldn't ever be a pullup target */
|
|
Assert(appinfo->parent_relid != varno);
|
|
|
|
if (appinfo->child_relid == varno)
|
|
{
|
|
if (subvarno < 0)
|
|
subvarno = bms_singleton_member(subrelids);
|
|
appinfo->child_relid = subvarno;
|
|
}
|
|
|
|
/* Also finish fixups for its translated vars */
|
|
substitute_multiple_relids((Node *) appinfo->translated_vars,
|
|
varno, subrelids);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* get_relids_in_jointree: get set of RT indexes present in a jointree
|
|
*
|
|
* If include_joins is true, join RT indexes are included; if false,
|
|
* only base rels are included.
|
|
*/
|
|
Relids
|
|
get_relids_in_jointree(Node *jtnode, bool include_joins)
|
|
{
|
|
Relids result = NULL;
|
|
|
|
if (jtnode == NULL)
|
|
return result;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
|
|
result = bms_make_singleton(varno);
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
ListCell *l;
|
|
|
|
foreach(l, f->fromlist)
|
|
{
|
|
result = bms_join(result,
|
|
get_relids_in_jointree(lfirst(l),
|
|
include_joins));
|
|
}
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
result = get_relids_in_jointree(j->larg, include_joins);
|
|
result = bms_join(result,
|
|
get_relids_in_jointree(j->rarg, include_joins));
|
|
if (include_joins && j->rtindex)
|
|
result = bms_add_member(result, j->rtindex);
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* get_relids_for_join: get set of base RT indexes making up a join
|
|
*/
|
|
Relids
|
|
get_relids_for_join(PlannerInfo *root, int joinrelid)
|
|
{
|
|
Node *jtnode;
|
|
|
|
jtnode = find_jointree_node_for_rel((Node *) root->parse->jointree,
|
|
joinrelid);
|
|
if (!jtnode)
|
|
elog(ERROR, "could not find join node %d", joinrelid);
|
|
return get_relids_in_jointree(jtnode, false);
|
|
}
|
|
|
|
/*
|
|
* find_jointree_node_for_rel: locate jointree node for a base or join RT index
|
|
*
|
|
* Returns NULL if not found
|
|
*/
|
|
static Node *
|
|
find_jointree_node_for_rel(Node *jtnode, int relid)
|
|
{
|
|
if (jtnode == NULL)
|
|
return NULL;
|
|
if (IsA(jtnode, RangeTblRef))
|
|
{
|
|
int varno = ((RangeTblRef *) jtnode)->rtindex;
|
|
|
|
if (relid == varno)
|
|
return jtnode;
|
|
}
|
|
else if (IsA(jtnode, FromExpr))
|
|
{
|
|
FromExpr *f = (FromExpr *) jtnode;
|
|
ListCell *l;
|
|
|
|
foreach(l, f->fromlist)
|
|
{
|
|
jtnode = find_jointree_node_for_rel(lfirst(l), relid);
|
|
if (jtnode)
|
|
return jtnode;
|
|
}
|
|
}
|
|
else if (IsA(jtnode, JoinExpr))
|
|
{
|
|
JoinExpr *j = (JoinExpr *) jtnode;
|
|
|
|
if (relid == j->rtindex)
|
|
return jtnode;
|
|
jtnode = find_jointree_node_for_rel(j->larg, relid);
|
|
if (jtnode)
|
|
return jtnode;
|
|
jtnode = find_jointree_node_for_rel(j->rarg, relid);
|
|
if (jtnode)
|
|
return jtnode;
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
return NULL;
|
|
}
|