1477 lines
49 KiB
C
1477 lines
49 KiB
C
/*-------------------------------------------------------------------------
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*
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* initsplan.c
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* Target list, qualification, joininfo initialization routines
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*
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* Portions Copyright (c) 1996-2009, 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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* $PostgreSQL: pgsql/src/backend/optimizer/plan/initsplan.c,v 1.153 2009/05/07 20:13:09 tgl Exp $
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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_operator.h"
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#include "catalog/pg_type.h"
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#include "optimizer/clauses.h"
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#include "optimizer/cost.h"
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#include "optimizer/joininfo.h"
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#include "optimizer/pathnode.h"
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#include "optimizer/paths.h"
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#include "optimizer/placeholder.h"
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#include "optimizer/planmain.h"
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#include "optimizer/prep.h"
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#include "optimizer/restrictinfo.h"
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#include "optimizer/var.h"
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#include "parser/parse_expr.h"
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#include "parser/parse_oper.h"
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#include "utils/builtins.h"
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#include "utils/lsyscache.h"
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#include "utils/syscache.h"
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/* These parameters are set by GUC */
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int from_collapse_limit;
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int join_collapse_limit;
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static List *deconstruct_recurse(PlannerInfo *root, Node *jtnode,
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bool below_outer_join,
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Relids *qualscope, Relids *inner_join_rels);
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static SpecialJoinInfo *make_outerjoininfo(PlannerInfo *root,
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Relids left_rels, Relids right_rels,
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Relids inner_join_rels,
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JoinType jointype, List *clause);
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static void distribute_qual_to_rels(PlannerInfo *root, Node *clause,
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bool is_deduced,
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bool below_outer_join,
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JoinType jointype,
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Relids qualscope,
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Relids ojscope,
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Relids outerjoin_nonnullable);
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static bool check_outerjoin_delay(PlannerInfo *root, Relids *relids_p,
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Relids *nullable_relids_p, bool is_pushed_down);
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static bool check_redundant_nullability_qual(PlannerInfo *root, Node *clause);
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static void check_mergejoinable(RestrictInfo *restrictinfo);
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static void check_hashjoinable(RestrictInfo *restrictinfo);
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/*****************************************************************************
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*
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* JOIN TREES
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*
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*****************************************************************************/
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/*
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* add_base_rels_to_query
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*
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* Scan the query's jointree and create baserel RelOptInfos for all
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* the base relations (ie, table, subquery, and function RTEs)
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* appearing in the jointree.
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*
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* The initial invocation must pass root->parse->jointree as the value of
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* jtnode. Internally, the function recurses through the jointree.
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*
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* At the end of this process, there should be one baserel RelOptInfo for
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* every non-join RTE that is used in the query. Therefore, this routine
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* is the only place that should call build_simple_rel with reloptkind
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* RELOPT_BASEREL. (Note: build_simple_rel recurses internally to build
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* "other rel" RelOptInfos for the members of any appendrels we find here.)
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*/
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void
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add_base_rels_to_query(PlannerInfo *root, Node *jtnode)
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{
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if (jtnode == NULL)
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return;
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if (IsA(jtnode, RangeTblRef))
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{
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int varno = ((RangeTblRef *) jtnode)->rtindex;
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(void) build_simple_rel(root, varno, RELOPT_BASEREL);
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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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ListCell *l;
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foreach(l, f->fromlist)
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add_base_rels_to_query(root, lfirst(l));
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}
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else if (IsA(jtnode, JoinExpr))
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{
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JoinExpr *j = (JoinExpr *) jtnode;
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add_base_rels_to_query(root, j->larg);
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add_base_rels_to_query(root, j->rarg);
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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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}
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/*****************************************************************************
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*
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* TARGET LISTS
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*
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*****************************************************************************/
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/*
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* build_base_rel_tlists
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* Add targetlist entries for each var needed in the query's final tlist
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* to the appropriate base relations.
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*
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* We mark such vars as needed by "relation 0" to ensure that they will
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* propagate up through all join plan steps.
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*/
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void
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build_base_rel_tlists(PlannerInfo *root, List *final_tlist)
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{
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List *tlist_vars = pull_var_clause((Node *) final_tlist,
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PVC_INCLUDE_PLACEHOLDERS);
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if (tlist_vars != NIL)
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{
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add_vars_to_targetlist(root, tlist_vars, bms_make_singleton(0));
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list_free(tlist_vars);
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}
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}
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/*
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* add_vars_to_targetlist
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* For each variable appearing in the list, add it to the owning
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* relation's targetlist if not already present, and mark the variable
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* as being needed for the indicated join (or for final output if
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* where_needed includes "relation 0").
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*
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* The list may also contain PlaceHolderVars. These don't necessarily
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* have a single owning relation; we keep their attr_needed info in
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* root->placeholder_list instead.
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*/
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void
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add_vars_to_targetlist(PlannerInfo *root, List *vars, Relids where_needed)
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{
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ListCell *temp;
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Assert(!bms_is_empty(where_needed));
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foreach(temp, vars)
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{
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Node *node = (Node *) lfirst(temp);
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if (IsA(node, Var))
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{
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Var *var = (Var *) node;
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RelOptInfo *rel = find_base_rel(root, var->varno);
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int attno = var->varattno;
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Assert(attno >= rel->min_attr && attno <= rel->max_attr);
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attno -= rel->min_attr;
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if (rel->attr_needed[attno] == NULL)
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{
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/* Variable not yet requested, so add to reltargetlist */
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/* XXX is copyObject necessary here? */
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rel->reltargetlist = lappend(rel->reltargetlist,
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copyObject(var));
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}
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rel->attr_needed[attno] = bms_add_members(rel->attr_needed[attno],
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where_needed);
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}
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else if (IsA(node, PlaceHolderVar))
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{
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PlaceHolderVar *phv = (PlaceHolderVar *) node;
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PlaceHolderInfo *phinfo = find_placeholder_info(root, phv);
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phinfo->ph_needed = bms_add_members(phinfo->ph_needed,
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where_needed);
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}
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else
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elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
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}
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}
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/*****************************************************************************
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*
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* JOIN TREE PROCESSING
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*
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*****************************************************************************/
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/*
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* deconstruct_jointree
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* Recursively scan the query's join tree for WHERE and JOIN/ON qual
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* clauses, and add these to the appropriate restrictinfo and joininfo
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* lists belonging to base RelOptInfos. Also, add SpecialJoinInfo nodes
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* to root->join_info_list for any outer joins appearing in the query tree.
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* Return a "joinlist" data structure showing the join order decisions
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* that need to be made by make_one_rel().
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*
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* The "joinlist" result is a list of items that are either RangeTblRef
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* jointree nodes or sub-joinlists. All the items at the same level of
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* joinlist must be joined in an order to be determined by make_one_rel()
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* (note that legal orders may be constrained by SpecialJoinInfo nodes).
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* A sub-joinlist represents a subproblem to be planned separately. Currently
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* sub-joinlists arise only from FULL OUTER JOIN or when collapsing of
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* subproblems is stopped by join_collapse_limit or from_collapse_limit.
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*
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* NOTE: when dealing with inner joins, it is appropriate to let a qual clause
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* be evaluated at the lowest level where all the variables it mentions are
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* available. However, we cannot push a qual down into the nullable side(s)
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* of an outer join since the qual might eliminate matching rows and cause a
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* NULL row to be incorrectly emitted by the join. Therefore, we artificially
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* OR the minimum-relids of such an outer join into the required_relids of
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* clauses appearing above it. This forces those clauses to be delayed until
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* application of the outer join (or maybe even higher in the join tree).
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*/
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List *
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deconstruct_jointree(PlannerInfo *root)
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{
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Relids qualscope;
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Relids inner_join_rels;
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/* Start recursion at top of jointree */
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Assert(root->parse->jointree != NULL &&
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IsA(root->parse->jointree, FromExpr));
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return deconstruct_recurse(root, (Node *) root->parse->jointree, false,
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&qualscope, &inner_join_rels);
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}
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/*
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* deconstruct_recurse
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* One recursion level of deconstruct_jointree processing.
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*
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* Inputs:
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* jtnode is the jointree node to examine
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* below_outer_join is TRUE if this node is within the nullable side of a
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* higher-level outer join
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* Outputs:
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* *qualscope gets the set of base Relids syntactically included in this
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* jointree node (do not modify or free this, as it may also be pointed
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* to by RestrictInfo and SpecialJoinInfo nodes)
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* *inner_join_rels gets the set of base Relids syntactically included in
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* inner joins appearing at or below this jointree node (do not modify
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* or free this, either)
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* Return value is the appropriate joinlist for this jointree node
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*
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* In addition, entries will be added to root->join_info_list for outer joins.
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*/
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static List *
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deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join,
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Relids *qualscope, Relids *inner_join_rels)
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{
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List *joinlist;
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if (jtnode == NULL)
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{
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*qualscope = NULL;
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*inner_join_rels = NULL;
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return NIL;
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}
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if (IsA(jtnode, RangeTblRef))
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{
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int varno = ((RangeTblRef *) jtnode)->rtindex;
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/* No quals to deal with, just return correct result */
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*qualscope = bms_make_singleton(varno);
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/* A single baserel does not create an inner join */
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*inner_join_rels = NULL;
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joinlist = list_make1(jtnode);
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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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int remaining;
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ListCell *l;
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/*
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* First, recurse to handle child joins. We collapse subproblems into
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* a single joinlist whenever the resulting joinlist wouldn't exceed
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* from_collapse_limit members. Also, always collapse one-element
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* subproblems, since that won't lengthen the joinlist anyway.
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*/
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*qualscope = NULL;
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*inner_join_rels = NULL;
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joinlist = NIL;
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remaining = list_length(f->fromlist);
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foreach(l, f->fromlist)
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{
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Relids sub_qualscope;
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List *sub_joinlist;
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int sub_members;
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sub_joinlist = deconstruct_recurse(root, lfirst(l),
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below_outer_join,
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&sub_qualscope,
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inner_join_rels);
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*qualscope = bms_add_members(*qualscope, sub_qualscope);
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sub_members = list_length(sub_joinlist);
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remaining--;
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if (sub_members <= 1 ||
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list_length(joinlist) + sub_members + remaining <= from_collapse_limit)
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joinlist = list_concat(joinlist, sub_joinlist);
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else
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joinlist = lappend(joinlist, sub_joinlist);
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}
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/*
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* A FROM with more than one list element is an inner join subsuming
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* all below it, so we should report inner_join_rels = qualscope. If
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* there was exactly one element, we should (and already did) report
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* whatever its inner_join_rels were. If there were no elements (is
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* that possible?) the initialization before the loop fixed it.
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*/
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if (list_length(f->fromlist) > 1)
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*inner_join_rels = *qualscope;
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/*
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* Now process the top-level quals.
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*/
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foreach(l, (List *) f->quals)
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{
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Node *qual = (Node *) lfirst(l);
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distribute_qual_to_rels(root, qual,
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false, below_outer_join, JOIN_INNER,
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*qualscope, NULL, NULL);
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}
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}
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else if (IsA(jtnode, JoinExpr))
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{
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JoinExpr *j = (JoinExpr *) jtnode;
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Relids leftids,
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rightids,
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left_inners,
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right_inners,
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nonnullable_rels,
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ojscope;
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List *leftjoinlist,
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*rightjoinlist;
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SpecialJoinInfo *sjinfo;
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ListCell *l;
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/*
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* Order of operations here is subtle and critical. First we recurse
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* to handle sub-JOINs. Their join quals will be placed without
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* regard for whether this level is an outer join, which is correct.
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* Then we place our own join quals, which are restricted by lower
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* outer joins in any case, and are forced to this level if this is an
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* outer join and they mention the outer side. Finally, if this is an
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* outer join, we create a join_info_list entry for the join. This
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* will prevent quals above us in the join tree that use those rels
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* from being pushed down below this level. (It's okay for upper
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* quals to be pushed down to the outer side, however.)
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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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leftjoinlist = deconstruct_recurse(root, j->larg,
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below_outer_join,
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&leftids, &left_inners);
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rightjoinlist = deconstruct_recurse(root, j->rarg,
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below_outer_join,
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&rightids, &right_inners);
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*qualscope = bms_union(leftids, rightids);
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*inner_join_rels = *qualscope;
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/* Inner join adds no restrictions for quals */
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nonnullable_rels = NULL;
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break;
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case JOIN_LEFT:
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case JOIN_ANTI:
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leftjoinlist = deconstruct_recurse(root, j->larg,
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below_outer_join,
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&leftids, &left_inners);
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rightjoinlist = deconstruct_recurse(root, j->rarg,
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true,
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&rightids, &right_inners);
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*qualscope = bms_union(leftids, rightids);
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*inner_join_rels = bms_union(left_inners, right_inners);
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nonnullable_rels = leftids;
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break;
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case JOIN_SEMI:
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leftjoinlist = deconstruct_recurse(root, j->larg,
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below_outer_join,
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&leftids, &left_inners);
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rightjoinlist = deconstruct_recurse(root, j->rarg,
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below_outer_join,
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&rightids, &right_inners);
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*qualscope = bms_union(leftids, rightids);
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*inner_join_rels = bms_union(left_inners, right_inners);
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/* Semi join adds no restrictions for quals */
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nonnullable_rels = NULL;
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break;
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case JOIN_FULL:
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leftjoinlist = deconstruct_recurse(root, j->larg,
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true,
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&leftids, &left_inners);
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rightjoinlist = deconstruct_recurse(root, j->rarg,
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true,
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&rightids, &right_inners);
|
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*qualscope = bms_union(leftids, rightids);
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*inner_join_rels = bms_union(left_inners, right_inners);
|
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/* each side is both outer and inner */
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nonnullable_rels = *qualscope;
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break;
|
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default:
|
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/* JOIN_RIGHT was eliminated during reduce_outer_joins() */
|
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elog(ERROR, "unrecognized join type: %d",
|
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(int) j->jointype);
|
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nonnullable_rels = NULL; /* keep compiler quiet */
|
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leftjoinlist = rightjoinlist = NIL;
|
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break;
|
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}
|
|
|
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/*
|
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* For an OJ, form the SpecialJoinInfo now, because we need the OJ's
|
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* semantic scope (ojscope) to pass to distribute_qual_to_rels. But
|
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* we mustn't add it to join_info_list just yet, because we don't want
|
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* distribute_qual_to_rels to think it is an outer join below us.
|
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*
|
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* Semijoins are a bit of a hybrid: we build a SpecialJoinInfo,
|
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* but we want ojscope = NULL for distribute_qual_to_rels.
|
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*/
|
|
if (j->jointype != JOIN_INNER)
|
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{
|
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sjinfo = make_outerjoininfo(root,
|
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leftids, rightids,
|
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*inner_join_rels,
|
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j->jointype,
|
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(List *) j->quals);
|
|
if (j->jointype == JOIN_SEMI)
|
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ojscope = NULL;
|
|
else
|
|
ojscope = bms_union(sjinfo->min_lefthand,
|
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sjinfo->min_righthand);
|
|
}
|
|
else
|
|
{
|
|
sjinfo = NULL;
|
|
ojscope = NULL;
|
|
}
|
|
|
|
/* Process the qual clauses */
|
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foreach(l, (List *) j->quals)
|
|
{
|
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Node *qual = (Node *) lfirst(l);
|
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|
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distribute_qual_to_rels(root, qual,
|
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false, below_outer_join, j->jointype,
|
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*qualscope,
|
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ojscope, nonnullable_rels);
|
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}
|
|
|
|
/* Now we can add the SpecialJoinInfo to join_info_list */
|
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if (sjinfo)
|
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root->join_info_list = lappend(root->join_info_list, sjinfo);
|
|
|
|
/*
|
|
* Finally, compute the output joinlist. We fold subproblems together
|
|
* except at a FULL JOIN or where join_collapse_limit would be
|
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* exceeded.
|
|
*/
|
|
if (j->jointype == JOIN_FULL)
|
|
{
|
|
/* force the join order exactly at this node */
|
|
joinlist = list_make1(list_make2(leftjoinlist, rightjoinlist));
|
|
}
|
|
else if (list_length(leftjoinlist) + list_length(rightjoinlist) <=
|
|
join_collapse_limit)
|
|
{
|
|
/* OK to combine subproblems */
|
|
joinlist = list_concat(leftjoinlist, rightjoinlist);
|
|
}
|
|
else
|
|
{
|
|
/* can't combine, but needn't force join order above here */
|
|
Node *leftpart,
|
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*rightpart;
|
|
|
|
/* avoid creating useless 1-element sublists */
|
|
if (list_length(leftjoinlist) == 1)
|
|
leftpart = (Node *) linitial(leftjoinlist);
|
|
else
|
|
leftpart = (Node *) leftjoinlist;
|
|
if (list_length(rightjoinlist) == 1)
|
|
rightpart = (Node *) linitial(rightjoinlist);
|
|
else
|
|
rightpart = (Node *) rightjoinlist;
|
|
joinlist = list_make2(leftpart, rightpart);
|
|
}
|
|
}
|
|
else
|
|
{
|
|
elog(ERROR, "unrecognized node type: %d",
|
|
(int) nodeTag(jtnode));
|
|
joinlist = NIL; /* keep compiler quiet */
|
|
}
|
|
return joinlist;
|
|
}
|
|
|
|
/*
|
|
* make_outerjoininfo
|
|
* Build a SpecialJoinInfo for the current outer join
|
|
*
|
|
* Inputs:
|
|
* left_rels: the base Relids syntactically on outer side of join
|
|
* right_rels: the base Relids syntactically on inner side of join
|
|
* inner_join_rels: base Relids participating in inner joins below this one
|
|
* jointype: what it says (must always be LEFT, FULL, SEMI, or ANTI)
|
|
* clause: the outer join's join condition (in implicit-AND format)
|
|
*
|
|
* The node should eventually be appended to root->join_info_list, but we
|
|
* do not do that here.
|
|
*
|
|
* Note: we assume that this function is invoked bottom-up, so that
|
|
* root->join_info_list already contains entries for all outer joins that are
|
|
* syntactically below this one.
|
|
*/
|
|
static SpecialJoinInfo *
|
|
make_outerjoininfo(PlannerInfo *root,
|
|
Relids left_rels, Relids right_rels,
|
|
Relids inner_join_rels,
|
|
JoinType jointype, List *clause)
|
|
{
|
|
SpecialJoinInfo *sjinfo = makeNode(SpecialJoinInfo);
|
|
Relids clause_relids;
|
|
Relids strict_relids;
|
|
Relids min_lefthand;
|
|
Relids min_righthand;
|
|
ListCell *l;
|
|
|
|
/*
|
|
* We should not see RIGHT JOIN here because left/right were switched
|
|
* earlier
|
|
*/
|
|
Assert(jointype != JOIN_INNER);
|
|
Assert(jointype != JOIN_RIGHT);
|
|
|
|
/*
|
|
* Presently the executor cannot support FOR UPDATE/SHARE marking of rels
|
|
* appearing on the nullable side of an outer join. (It's somewhat unclear
|
|
* what that would mean, anyway: what should we mark when a result row is
|
|
* generated from no element of the nullable relation?) So, complain if
|
|
* any nullable rel is FOR UPDATE/SHARE.
|
|
*
|
|
* You might be wondering why this test isn't made far upstream in the
|
|
* parser. It's because the parser hasn't got enough info --- consider
|
|
* FOR UPDATE applied to a view. Only after rewriting and flattening do
|
|
* we know whether the view contains an outer join.
|
|
*/
|
|
foreach(l, root->parse->rowMarks)
|
|
{
|
|
RowMarkClause *rc = (RowMarkClause *) lfirst(l);
|
|
|
|
if (bms_is_member(rc->rti, right_rels) ||
|
|
(jointype == JOIN_FULL && bms_is_member(rc->rti, left_rels)))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
errmsg("SELECT FOR UPDATE/SHARE cannot be applied to the nullable side of an outer join")));
|
|
}
|
|
|
|
sjinfo->syn_lefthand = left_rels;
|
|
sjinfo->syn_righthand = right_rels;
|
|
sjinfo->jointype = jointype;
|
|
/* this always starts out false */
|
|
sjinfo->delay_upper_joins = false;
|
|
sjinfo->join_quals = clause;
|
|
|
|
/* If it's a full join, no need to be very smart */
|
|
if (jointype == JOIN_FULL)
|
|
{
|
|
sjinfo->min_lefthand = bms_copy(left_rels);
|
|
sjinfo->min_righthand = bms_copy(right_rels);
|
|
sjinfo->lhs_strict = false; /* don't care about this */
|
|
return sjinfo;
|
|
}
|
|
|
|
/*
|
|
* Retrieve all relids mentioned within the join clause.
|
|
*/
|
|
clause_relids = pull_varnos((Node *) clause);
|
|
|
|
/*
|
|
* For which relids is the clause strict, ie, it cannot succeed if the
|
|
* rel's columns are all NULL?
|
|
*/
|
|
strict_relids = find_nonnullable_rels((Node *) clause);
|
|
|
|
/* Remember whether the clause is strict for any LHS relations */
|
|
sjinfo->lhs_strict = bms_overlap(strict_relids, left_rels);
|
|
|
|
/*
|
|
* Required LHS always includes the LHS rels mentioned in the clause. We
|
|
* may have to add more rels based on lower outer joins; see below.
|
|
*/
|
|
min_lefthand = bms_intersect(clause_relids, left_rels);
|
|
|
|
/*
|
|
* Similarly for required RHS. But here, we must also include any lower
|
|
* inner joins, to ensure we don't try to commute with any of them.
|
|
*/
|
|
min_righthand = bms_int_members(bms_union(clause_relids, inner_join_rels),
|
|
right_rels);
|
|
|
|
foreach(l, root->join_info_list)
|
|
{
|
|
SpecialJoinInfo *otherinfo = (SpecialJoinInfo *) lfirst(l);
|
|
|
|
/* ignore full joins --- other mechanisms preserve their ordering */
|
|
if (otherinfo->jointype == JOIN_FULL)
|
|
continue;
|
|
|
|
/*
|
|
* For a lower OJ in our LHS, if our join condition uses the lower
|
|
* join's RHS and is not strict for that rel, we must preserve the
|
|
* ordering of the two OJs, so add lower OJ's full syntactic relset to
|
|
* min_lefthand. (We must use its full syntactic relset, not just its
|
|
* min_lefthand + min_righthand. This is because there might be other
|
|
* OJs below this one that this one can commute with, but we cannot
|
|
* commute with them if we don't with this one.) Also, if the
|
|
* current join is an antijoin, we must preserve ordering regardless
|
|
* of strictness.
|
|
*
|
|
* Note: I believe we have to insist on being strict for at least one
|
|
* rel in the lower OJ's min_righthand, not its whole syn_righthand.
|
|
*/
|
|
if (bms_overlap(left_rels, otherinfo->syn_righthand))
|
|
{
|
|
if (bms_overlap(clause_relids, otherinfo->syn_righthand) &&
|
|
(jointype == JOIN_ANTI ||
|
|
!bms_overlap(strict_relids, otherinfo->min_righthand)))
|
|
{
|
|
min_lefthand = bms_add_members(min_lefthand,
|
|
otherinfo->syn_lefthand);
|
|
min_lefthand = bms_add_members(min_lefthand,
|
|
otherinfo->syn_righthand);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* For a lower OJ in our RHS, if our join condition does not use the
|
|
* lower join's RHS and the lower OJ's join condition is strict, we
|
|
* can interchange the ordering of the two OJs; otherwise we must add
|
|
* lower OJ's full syntactic relset to min_righthand. Here, we must
|
|
* preserve ordering anyway if either the current join is a semijoin,
|
|
* or the lower OJ is an antijoin.
|
|
*
|
|
* Here, we have to consider that "our join condition" includes any
|
|
* clauses that syntactically appeared above the lower OJ and below
|
|
* ours; those are equivalent to degenerate clauses in our OJ and must
|
|
* be treated as such. Such clauses obviously can't reference our
|
|
* LHS, and they must be non-strict for the lower OJ's RHS (else
|
|
* reduce_outer_joins would have reduced the lower OJ to a plain
|
|
* join). Hence the other ways in which we handle clauses within our
|
|
* join condition are not affected by them. The net effect is
|
|
* therefore sufficiently represented by the delay_upper_joins flag
|
|
* saved for us by check_outerjoin_delay.
|
|
*/
|
|
if (bms_overlap(right_rels, otherinfo->syn_righthand))
|
|
{
|
|
if (bms_overlap(clause_relids, otherinfo->syn_righthand) ||
|
|
jointype == JOIN_SEMI ||
|
|
otherinfo->jointype == JOIN_ANTI ||
|
|
!otherinfo->lhs_strict || otherinfo->delay_upper_joins)
|
|
{
|
|
min_righthand = bms_add_members(min_righthand,
|
|
otherinfo->syn_lefthand);
|
|
min_righthand = bms_add_members(min_righthand,
|
|
otherinfo->syn_righthand);
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* If we found nothing to put in min_lefthand, punt and make it the full
|
|
* LHS, to avoid having an empty min_lefthand which will confuse later
|
|
* processing. (We don't try to be smart about such cases, just correct.)
|
|
* Likewise for min_righthand.
|
|
*/
|
|
if (bms_is_empty(min_lefthand))
|
|
min_lefthand = bms_copy(left_rels);
|
|
if (bms_is_empty(min_righthand))
|
|
min_righthand = bms_copy(right_rels);
|
|
|
|
/* Now they'd better be nonempty */
|
|
Assert(!bms_is_empty(min_lefthand));
|
|
Assert(!bms_is_empty(min_righthand));
|
|
/* Shouldn't overlap either */
|
|
Assert(!bms_overlap(min_lefthand, min_righthand));
|
|
|
|
sjinfo->min_lefthand = min_lefthand;
|
|
sjinfo->min_righthand = min_righthand;
|
|
|
|
return sjinfo;
|
|
}
|
|
|
|
|
|
/*****************************************************************************
|
|
*
|
|
* QUALIFICATIONS
|
|
*
|
|
*****************************************************************************/
|
|
|
|
/*
|
|
* distribute_qual_to_rels
|
|
* Add clause information to either the baserestrictinfo or joininfo list
|
|
* (depending on whether the clause is a join) of each base relation
|
|
* mentioned in the clause. A RestrictInfo node is created and added to
|
|
* the appropriate list for each rel. Alternatively, if the clause uses a
|
|
* mergejoinable operator and is not delayed by outer-join rules, enter
|
|
* the left- and right-side expressions into the query's list of
|
|
* EquivalenceClasses.
|
|
*
|
|
* 'clause': the qual clause to be distributed
|
|
* 'is_deduced': TRUE if the qual came from implied-equality deduction
|
|
* 'below_outer_join': TRUE if the qual is from a JOIN/ON that is below the
|
|
* nullable side of a higher-level outer join
|
|
* 'jointype': type of join the qual is from (JOIN_INNER for a WHERE clause)
|
|
* 'qualscope': set of baserels the qual's syntactic scope covers
|
|
* 'ojscope': NULL if not an outer-join qual, else the minimum set of baserels
|
|
* needed to form this join
|
|
* 'outerjoin_nonnullable': NULL if not an outer-join qual, else the set of
|
|
* baserels appearing on the outer (nonnullable) side of the join
|
|
* (for FULL JOIN this includes both sides of the join, and must in fact
|
|
* equal qualscope)
|
|
*
|
|
* 'qualscope' identifies what level of JOIN the qual came from syntactically.
|
|
* 'ojscope' is needed if we decide to force the qual up to the outer-join
|
|
* level, which will be ojscope not necessarily qualscope.
|
|
*
|
|
* At the time this is called, root->join_info_list must contain entries for
|
|
* all and only those special joins that are syntactically below this qual.
|
|
*/
|
|
static void
|
|
distribute_qual_to_rels(PlannerInfo *root, Node *clause,
|
|
bool is_deduced,
|
|
bool below_outer_join,
|
|
JoinType jointype,
|
|
Relids qualscope,
|
|
Relids ojscope,
|
|
Relids outerjoin_nonnullable)
|
|
{
|
|
Relids relids;
|
|
bool is_pushed_down;
|
|
bool outerjoin_delayed;
|
|
bool pseudoconstant = false;
|
|
bool maybe_equivalence;
|
|
bool maybe_outer_join;
|
|
Relids nullable_relids;
|
|
RestrictInfo *restrictinfo;
|
|
|
|
/*
|
|
* Retrieve all relids mentioned within the clause.
|
|
*/
|
|
relids = pull_varnos(clause);
|
|
|
|
/*
|
|
* Cross-check: clause should contain no relids not within its scope.
|
|
* Otherwise the parser messed up.
|
|
*/
|
|
if (!bms_is_subset(relids, qualscope))
|
|
elog(ERROR, "JOIN qualification cannot refer to other relations");
|
|
if (ojscope && !bms_is_subset(relids, ojscope))
|
|
elog(ERROR, "JOIN qualification cannot refer to other relations");
|
|
|
|
/*
|
|
* If the clause is variable-free, our normal heuristic for pushing it
|
|
* down to just the mentioned rels doesn't work, because there are none.
|
|
*
|
|
* If the clause is an outer-join clause, we must force it to the OJ's
|
|
* semantic level to preserve semantics.
|
|
*
|
|
* Otherwise, when the clause contains volatile functions, we force it to
|
|
* be evaluated at its original syntactic level. This preserves the
|
|
* expected semantics.
|
|
*
|
|
* When the clause contains no volatile functions either, it is actually a
|
|
* pseudoconstant clause that will not change value during any one
|
|
* execution of the plan, and hence can be used as a one-time qual in a
|
|
* gating Result plan node. We put such a clause into the regular
|
|
* RestrictInfo lists for the moment, but eventually createplan.c will
|
|
* pull it out and make a gating Result node immediately above whatever
|
|
* plan node the pseudoconstant clause is assigned to. It's usually best
|
|
* to put a gating node as high in the plan tree as possible. If we are
|
|
* not below an outer join, we can actually push the pseudoconstant qual
|
|
* all the way to the top of the tree. If we are below an outer join, we
|
|
* leave the qual at its original syntactic level (we could push it up to
|
|
* just below the outer join, but that seems more complex than it's
|
|
* worth).
|
|
*/
|
|
if (bms_is_empty(relids))
|
|
{
|
|
if (ojscope)
|
|
{
|
|
/* clause is attached to outer join, eval it there */
|
|
relids = bms_copy(ojscope);
|
|
/* mustn't use as gating qual, so don't mark pseudoconstant */
|
|
}
|
|
else
|
|
{
|
|
/* eval at original syntactic level */
|
|
relids = bms_copy(qualscope);
|
|
if (!contain_volatile_functions(clause))
|
|
{
|
|
/* mark as gating qual */
|
|
pseudoconstant = true;
|
|
/* tell createplan.c to check for gating quals */
|
|
root->hasPseudoConstantQuals = true;
|
|
/* if not below outer join, push it to top of tree */
|
|
if (!below_outer_join)
|
|
{
|
|
relids =
|
|
get_relids_in_jointree((Node *) root->parse->jointree,
|
|
false);
|
|
qualscope = bms_copy(relids);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*----------
|
|
* Check to see if clause application must be delayed by outer-join
|
|
* considerations.
|
|
*
|
|
* A word about is_pushed_down: we mark the qual as "pushed down" if
|
|
* it is (potentially) applicable at a level different from its original
|
|
* syntactic level. This flag is used to distinguish OUTER JOIN ON quals
|
|
* from other quals pushed down to the same joinrel. The rules are:
|
|
* WHERE quals and INNER JOIN quals: is_pushed_down = true.
|
|
* Non-degenerate OUTER JOIN quals: is_pushed_down = false.
|
|
* Degenerate OUTER JOIN quals: is_pushed_down = true.
|
|
* A "degenerate" OUTER JOIN qual is one that doesn't mention the
|
|
* non-nullable side, and hence can be pushed down into the nullable side
|
|
* without changing the join result. It is correct to treat it as a
|
|
* regular filter condition at the level where it is evaluated.
|
|
*
|
|
* Note: it is not immediately obvious that a simple boolean is enough
|
|
* for this: if for some reason we were to attach a degenerate qual to
|
|
* its original join level, it would need to be treated as an outer join
|
|
* qual there. However, this cannot happen, because all the rels the
|
|
* clause mentions must be in the outer join's min_righthand, therefore
|
|
* the join it needs must be formed before the outer join; and we always
|
|
* attach quals to the lowest level where they can be evaluated. But
|
|
* if we were ever to re-introduce a mechanism for delaying evaluation
|
|
* of "expensive" quals, this area would need work.
|
|
*----------
|
|
*/
|
|
if (is_deduced)
|
|
{
|
|
/*
|
|
* If the qual came from implied-equality deduction, it should not be
|
|
* outerjoin-delayed, else deducer blew it. But we can't check this
|
|
* because the join_info_list may now contain OJs above where the qual
|
|
* belongs.
|
|
*/
|
|
Assert(!ojscope);
|
|
is_pushed_down = true;
|
|
outerjoin_delayed = false;
|
|
nullable_relids = NULL;
|
|
/* Don't feed it back for more deductions */
|
|
maybe_equivalence = false;
|
|
maybe_outer_join = false;
|
|
}
|
|
else if (bms_overlap(relids, outerjoin_nonnullable))
|
|
{
|
|
/*
|
|
* The qual is attached to an outer join and mentions (some of the)
|
|
* rels on the nonnullable side, so it's not degenerate.
|
|
*
|
|
* We can't use such a clause to deduce equivalence (the left and
|
|
* right sides might be unequal above the join because one of them has
|
|
* gone to NULL) ... but we might be able to use it for more limited
|
|
* deductions, if it is mergejoinable. So consider adding it to the
|
|
* lists of set-aside outer-join clauses.
|
|
*/
|
|
is_pushed_down = false;
|
|
maybe_equivalence = false;
|
|
maybe_outer_join = true;
|
|
|
|
/* Check to see if must be delayed by lower outer join */
|
|
outerjoin_delayed = check_outerjoin_delay(root,
|
|
&relids,
|
|
&nullable_relids,
|
|
false);
|
|
|
|
/*
|
|
* Now force the qual to be evaluated exactly at the level of joining
|
|
* corresponding to the outer join. We cannot let it get pushed down
|
|
* into the nonnullable side, since then we'd produce no output rows,
|
|
* rather than the intended single null-extended row, for any
|
|
* nonnullable-side rows failing the qual.
|
|
*
|
|
* (Do this step after calling check_outerjoin_delay, because that
|
|
* trashes relids.)
|
|
*/
|
|
Assert(ojscope);
|
|
relids = ojscope;
|
|
Assert(!pseudoconstant);
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Normal qual clause or degenerate outer-join clause. Either way, we
|
|
* can mark it as pushed-down.
|
|
*/
|
|
is_pushed_down = true;
|
|
|
|
/* Check to see if must be delayed by lower outer join */
|
|
outerjoin_delayed = check_outerjoin_delay(root,
|
|
&relids,
|
|
&nullable_relids,
|
|
true);
|
|
|
|
if (outerjoin_delayed)
|
|
{
|
|
/* Should still be a subset of current scope ... */
|
|
Assert(bms_is_subset(relids, qualscope));
|
|
|
|
/*
|
|
* Because application of the qual will be delayed by outer join,
|
|
* we mustn't assume its vars are equal everywhere.
|
|
*/
|
|
maybe_equivalence = false;
|
|
|
|
/*
|
|
* It's possible that this is an IS NULL clause that's redundant
|
|
* with a lower antijoin; if so we can just discard it. We need
|
|
* not test in any of the other cases, because this will only
|
|
* be possible for pushed-down, delayed clauses.
|
|
*/
|
|
if (check_redundant_nullability_qual(root, clause))
|
|
return;
|
|
}
|
|
else
|
|
{
|
|
/*
|
|
* Qual is not delayed by any lower outer-join restriction, so we
|
|
* can consider feeding it to the equivalence machinery. However,
|
|
* if it's itself within an outer-join clause, treat it as though
|
|
* it appeared below that outer join (note that we can only get
|
|
* here when the clause references only nullable-side rels).
|
|
*/
|
|
maybe_equivalence = true;
|
|
if (outerjoin_nonnullable != NULL)
|
|
below_outer_join = true;
|
|
}
|
|
|
|
/*
|
|
* Since it doesn't mention the LHS, it's certainly not useful as a
|
|
* set-aside OJ clause, even if it's in an OJ.
|
|
*/
|
|
maybe_outer_join = false;
|
|
}
|
|
|
|
/*
|
|
* Build the RestrictInfo node itself.
|
|
*/
|
|
restrictinfo = make_restrictinfo((Expr *) clause,
|
|
is_pushed_down,
|
|
outerjoin_delayed,
|
|
pseudoconstant,
|
|
relids,
|
|
nullable_relids);
|
|
|
|
/*
|
|
* If it's a join clause (either naturally, or because delayed by
|
|
* outer-join rules), add vars used in the clause to targetlists of their
|
|
* relations, so that they will be emitted by the plan nodes that scan
|
|
* those relations (else they won't be available at the join node!).
|
|
*
|
|
* Note: if the clause gets absorbed into an EquivalenceClass then this
|
|
* may be unnecessary, but for now we have to do it to cover the case
|
|
* where the EC becomes ec_broken and we end up reinserting the original
|
|
* clauses into the plan.
|
|
*/
|
|
if (bms_membership(relids) == BMS_MULTIPLE)
|
|
{
|
|
List *vars = pull_var_clause(clause, PVC_INCLUDE_PLACEHOLDERS);
|
|
|
|
add_vars_to_targetlist(root, vars, relids);
|
|
list_free(vars);
|
|
}
|
|
|
|
/*
|
|
* We check "mergejoinability" of every clause, not only join clauses,
|
|
* because we want to know about equivalences between vars of the same
|
|
* relation, or between vars and consts.
|
|
*/
|
|
check_mergejoinable(restrictinfo);
|
|
|
|
/*
|
|
* If it is a true equivalence clause, send it to the EquivalenceClass
|
|
* machinery. We do *not* attach it directly to any restriction or join
|
|
* lists. The EC code will propagate it to the appropriate places later.
|
|
*
|
|
* If the clause has a mergejoinable operator and is not
|
|
* outerjoin-delayed, yet isn't an equivalence because it is an outer-join
|
|
* clause, the EC code may yet be able to do something with it. We add it
|
|
* to appropriate lists for further consideration later. Specifically:
|
|
*
|
|
* If it is a left or right outer-join qualification that relates the two
|
|
* sides of the outer join (no funny business like leftvar1 = leftvar2 +
|
|
* rightvar), we add it to root->left_join_clauses or
|
|
* root->right_join_clauses according to which side the nonnullable
|
|
* variable appears on.
|
|
*
|
|
* If it is a full outer-join qualification, we add it to
|
|
* root->full_join_clauses. (Ideally we'd discard cases that aren't
|
|
* leftvar = rightvar, as we do for left/right joins, but this routine
|
|
* doesn't have the info needed to do that; and the current usage of the
|
|
* full_join_clauses list doesn't require that, so it's not currently
|
|
* worth complicating this routine's API to make it possible.)
|
|
*
|
|
* If none of the above hold, pass it off to
|
|
* distribute_restrictinfo_to_rels().
|
|
*/
|
|
if (restrictinfo->mergeopfamilies)
|
|
{
|
|
if (maybe_equivalence)
|
|
{
|
|
if (process_equivalence(root, restrictinfo, below_outer_join))
|
|
return;
|
|
/* EC rejected it, so pass to distribute_restrictinfo_to_rels */
|
|
}
|
|
else if (maybe_outer_join && restrictinfo->can_join)
|
|
{
|
|
if (bms_is_subset(restrictinfo->left_relids,
|
|
outerjoin_nonnullable) &&
|
|
!bms_overlap(restrictinfo->right_relids,
|
|
outerjoin_nonnullable))
|
|
{
|
|
/* we have outervar = innervar */
|
|
root->left_join_clauses = lappend(root->left_join_clauses,
|
|
restrictinfo);
|
|
return;
|
|
}
|
|
if (bms_is_subset(restrictinfo->right_relids,
|
|
outerjoin_nonnullable) &&
|
|
!bms_overlap(restrictinfo->left_relids,
|
|
outerjoin_nonnullable))
|
|
{
|
|
/* we have innervar = outervar */
|
|
root->right_join_clauses = lappend(root->right_join_clauses,
|
|
restrictinfo);
|
|
return;
|
|
}
|
|
if (jointype == JOIN_FULL)
|
|
{
|
|
/* FULL JOIN (above tests cannot match in this case) */
|
|
root->full_join_clauses = lappend(root->full_join_clauses,
|
|
restrictinfo);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* No EC special case applies, so push it into the clause lists */
|
|
distribute_restrictinfo_to_rels(root, restrictinfo);
|
|
}
|
|
|
|
/*
|
|
* check_outerjoin_delay
|
|
* Detect whether a qual referencing the given relids must be delayed
|
|
* in application due to the presence of a lower outer join, and/or
|
|
* may force extra delay of higher-level outer joins.
|
|
*
|
|
* If the qual must be delayed, add relids to *relids_p to reflect the lowest
|
|
* safe level for evaluating the qual, and return TRUE. Any extra delay for
|
|
* higher-level joins is reflected by setting delay_upper_joins to TRUE in
|
|
* SpecialJoinInfo structs. We also compute nullable_relids, the set of
|
|
* referenced relids that are nullable by lower outer joins (note that this
|
|
* can be nonempty even for a non-delayed qual).
|
|
*
|
|
* For an is_pushed_down qual, we can evaluate the qual as soon as (1) we have
|
|
* all the rels it mentions, and (2) we are at or above any outer joins that
|
|
* can null any of these rels and are below the syntactic location of the
|
|
* given qual. We must enforce (2) because pushing down such a clause below
|
|
* the OJ might cause the OJ to emit null-extended rows that should not have
|
|
* been formed, or that should have been rejected by the clause. (This is
|
|
* only an issue for non-strict quals, since if we can prove a qual mentioning
|
|
* only nullable rels is strict, we'd have reduced the outer join to an inner
|
|
* join in reduce_outer_joins().)
|
|
*
|
|
* To enforce (2), scan the join_info_list and merge the required-relid sets of
|
|
* any such OJs into the clause's own reference list. At the time we are
|
|
* called, the join_info_list contains only outer joins below this qual. We
|
|
* have to repeat the scan until no new relids get added; this ensures that
|
|
* the qual is suitably delayed regardless of the order in which OJs get
|
|
* executed. As an example, if we have one OJ with LHS=A, RHS=B, and one with
|
|
* LHS=B, RHS=C, it is implied that these can be done in either order; if the
|
|
* B/C join is done first then the join to A can null C, so a qual actually
|
|
* mentioning only C cannot be applied below the join to A.
|
|
*
|
|
* For a non-pushed-down qual, this isn't going to determine where we place the
|
|
* qual, but we need to determine outerjoin_delayed and nullable_relids anyway
|
|
* for use later in the planning process.
|
|
*
|
|
* Lastly, a pushed-down qual that references the nullable side of any current
|
|
* join_info_list member and has to be evaluated above that OJ (because its
|
|
* required relids overlap the LHS too) causes that OJ's delay_upper_joins
|
|
* flag to be set TRUE. This will prevent any higher-level OJs from
|
|
* being interchanged with that OJ, which would result in not having any
|
|
* correct place to evaluate the qual. (The case we care about here is a
|
|
* sub-select WHERE clause within the RHS of some outer join. The WHERE
|
|
* clause must effectively be treated as a degenerate clause of that outer
|
|
* join's condition. Rather than trying to match such clauses with joins
|
|
* directly, we set delay_upper_joins here, and when the upper outer join
|
|
* is processed by make_outerjoininfo, it will refrain from allowing the
|
|
* two OJs to commute.)
|
|
*/
|
|
static bool
|
|
check_outerjoin_delay(PlannerInfo *root,
|
|
Relids *relids_p, /* in/out parameter */
|
|
Relids *nullable_relids_p, /* output parameter */
|
|
bool is_pushed_down)
|
|
{
|
|
Relids relids;
|
|
Relids nullable_relids;
|
|
bool outerjoin_delayed;
|
|
bool found_some;
|
|
|
|
/* fast path if no special joins */
|
|
if (root->join_info_list == NIL)
|
|
{
|
|
*nullable_relids_p = NULL;
|
|
return false;
|
|
}
|
|
|
|
/* must copy relids because we need the original value at the end */
|
|
relids = bms_copy(*relids_p);
|
|
nullable_relids = NULL;
|
|
outerjoin_delayed = false;
|
|
do
|
|
{
|
|
ListCell *l;
|
|
|
|
found_some = false;
|
|
foreach(l, root->join_info_list)
|
|
{
|
|
SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(l);
|
|
|
|
/* do we reference any nullable rels of this OJ? */
|
|
if (bms_overlap(relids, sjinfo->min_righthand) ||
|
|
(sjinfo->jointype == JOIN_FULL &&
|
|
bms_overlap(relids, sjinfo->min_lefthand)))
|
|
{
|
|
/* yes; have we included all its rels in relids? */
|
|
if (!bms_is_subset(sjinfo->min_lefthand, relids) ||
|
|
!bms_is_subset(sjinfo->min_righthand, relids))
|
|
{
|
|
/* no, so add them in */
|
|
relids = bms_add_members(relids, sjinfo->min_lefthand);
|
|
relids = bms_add_members(relids, sjinfo->min_righthand);
|
|
outerjoin_delayed = true;
|
|
/* we'll need another iteration */
|
|
found_some = true;
|
|
}
|
|
/* track all the nullable rels of relevant OJs */
|
|
nullable_relids = bms_add_members(nullable_relids,
|
|
sjinfo->min_righthand);
|
|
if (sjinfo->jointype == JOIN_FULL)
|
|
nullable_relids = bms_add_members(nullable_relids,
|
|
sjinfo->min_lefthand);
|
|
/* set delay_upper_joins if needed */
|
|
if (is_pushed_down && sjinfo->jointype != JOIN_FULL &&
|
|
bms_overlap(relids, sjinfo->min_lefthand))
|
|
sjinfo->delay_upper_joins = true;
|
|
}
|
|
}
|
|
} while (found_some);
|
|
|
|
/* identify just the actually-referenced nullable rels */
|
|
nullable_relids = bms_int_members(nullable_relids, *relids_p);
|
|
|
|
/* replace *relids_p, and return nullable_relids */
|
|
bms_free(*relids_p);
|
|
*relids_p = relids;
|
|
*nullable_relids_p = nullable_relids;
|
|
return outerjoin_delayed;
|
|
}
|
|
|
|
/*
|
|
* check_redundant_nullability_qual
|
|
* Check to see if the qual is an IS NULL qual that is redundant with
|
|
* a lower JOIN_ANTI join.
|
|
*
|
|
* We want to suppress redundant IS NULL quals, not so much to save cycles
|
|
* as to avoid generating bogus selectivity estimates for them. So if
|
|
* redundancy is detected here, distribute_qual_to_rels() just throws away
|
|
* the qual.
|
|
*/
|
|
static bool
|
|
check_redundant_nullability_qual(PlannerInfo *root, Node *clause)
|
|
{
|
|
Var *forced_null_var;
|
|
Index forced_null_rel;
|
|
ListCell *lc;
|
|
|
|
/* Check for IS NULL, and identify the Var forced to NULL */
|
|
forced_null_var = find_forced_null_var(clause);
|
|
if (forced_null_var == NULL)
|
|
return false;
|
|
forced_null_rel = forced_null_var->varno;
|
|
|
|
/*
|
|
* If the Var comes from the nullable side of a lower antijoin, the
|
|
* IS NULL condition is necessarily true.
|
|
*/
|
|
foreach(lc, root->join_info_list)
|
|
{
|
|
SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc);
|
|
|
|
if (sjinfo->jointype == JOIN_ANTI &&
|
|
bms_is_member(forced_null_rel, sjinfo->syn_righthand))
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/*
|
|
* distribute_restrictinfo_to_rels
|
|
* Push a completed RestrictInfo into the proper restriction or join
|
|
* clause list(s).
|
|
*
|
|
* This is the last step of distribute_qual_to_rels() for ordinary qual
|
|
* clauses. Clauses that are interesting for equivalence-class processing
|
|
* are diverted to the EC machinery, but may ultimately get fed back here.
|
|
*/
|
|
void
|
|
distribute_restrictinfo_to_rels(PlannerInfo *root,
|
|
RestrictInfo *restrictinfo)
|
|
{
|
|
Relids relids = restrictinfo->required_relids;
|
|
RelOptInfo *rel;
|
|
|
|
switch (bms_membership(relids))
|
|
{
|
|
case BMS_SINGLETON:
|
|
|
|
/*
|
|
* There is only one relation participating in the clause, so it
|
|
* is a restriction clause for that relation.
|
|
*/
|
|
rel = find_base_rel(root, bms_singleton_member(relids));
|
|
|
|
/* Add clause to rel's restriction list */
|
|
rel->baserestrictinfo = lappend(rel->baserestrictinfo,
|
|
restrictinfo);
|
|
break;
|
|
case BMS_MULTIPLE:
|
|
|
|
/*
|
|
* The clause is a join clause, since there is more than one rel
|
|
* in its relid set.
|
|
*/
|
|
|
|
/*
|
|
* Check for hashjoinable operators. (We don't bother setting the
|
|
* hashjoin info if we're not going to need it.)
|
|
*/
|
|
if (enable_hashjoin)
|
|
check_hashjoinable(restrictinfo);
|
|
|
|
/*
|
|
* Add clause to the join lists of all the relevant relations.
|
|
*/
|
|
add_join_clause_to_rels(root, restrictinfo, relids);
|
|
break;
|
|
default:
|
|
|
|
/*
|
|
* clause references no rels, and therefore we have no place to
|
|
* attach it. Shouldn't get here if callers are working properly.
|
|
*/
|
|
elog(ERROR, "cannot cope with variable-free clause");
|
|
break;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* process_implied_equality
|
|
* Create a restrictinfo item that says "item1 op item2", and push it
|
|
* into the appropriate lists. (In practice opno is always a btree
|
|
* equality operator.)
|
|
*
|
|
* "qualscope" is the nominal syntactic level to impute to the restrictinfo.
|
|
* This must contain at least all the rels used in the expressions, but it
|
|
* is used only to set the qual application level when both exprs are
|
|
* variable-free. Otherwise the qual is applied at the lowest join level
|
|
* that provides all its variables.
|
|
*
|
|
* "both_const" indicates whether both items are known pseudo-constant;
|
|
* in this case it is worth applying eval_const_expressions() in case we
|
|
* can produce constant TRUE or constant FALSE. (Otherwise it's not,
|
|
* because the expressions went through eval_const_expressions already.)
|
|
*
|
|
* This is currently used only when an EquivalenceClass is found to
|
|
* contain pseudoconstants. See path/pathkeys.c for more details.
|
|
*/
|
|
void
|
|
process_implied_equality(PlannerInfo *root,
|
|
Oid opno,
|
|
Expr *item1,
|
|
Expr *item2,
|
|
Relids qualscope,
|
|
bool below_outer_join,
|
|
bool both_const)
|
|
{
|
|
Expr *clause;
|
|
|
|
/*
|
|
* Build the new clause. Copy to ensure it shares no substructure with
|
|
* original (this is necessary in case there are subselects in there...)
|
|
*/
|
|
clause = make_opclause(opno,
|
|
BOOLOID, /* opresulttype */
|
|
false, /* opretset */
|
|
(Expr *) copyObject(item1),
|
|
(Expr *) copyObject(item2));
|
|
|
|
/* If both constant, try to reduce to a boolean constant. */
|
|
if (both_const)
|
|
{
|
|
clause = (Expr *) eval_const_expressions(root, (Node *) clause);
|
|
|
|
/* If we produced const TRUE, just drop the clause */
|
|
if (clause && IsA(clause, Const))
|
|
{
|
|
Const *cclause = (Const *) clause;
|
|
|
|
Assert(cclause->consttype == BOOLOID);
|
|
if (!cclause->constisnull && DatumGetBool(cclause->constvalue))
|
|
return;
|
|
}
|
|
}
|
|
|
|
/* Make a copy of qualscope to avoid problems if source EC changes */
|
|
qualscope = bms_copy(qualscope);
|
|
|
|
/*
|
|
* Push the new clause into all the appropriate restrictinfo lists.
|
|
*/
|
|
distribute_qual_to_rels(root, (Node *) clause,
|
|
true, below_outer_join, JOIN_INNER,
|
|
qualscope, NULL, NULL);
|
|
}
|
|
|
|
/*
|
|
* build_implied_join_equality --- build a RestrictInfo for a derived equality
|
|
*
|
|
* This overlaps the functionality of process_implied_equality(), but we
|
|
* must return the RestrictInfo, not push it into the joininfo tree.
|
|
*/
|
|
RestrictInfo *
|
|
build_implied_join_equality(Oid opno,
|
|
Expr *item1,
|
|
Expr *item2,
|
|
Relids qualscope)
|
|
{
|
|
RestrictInfo *restrictinfo;
|
|
Expr *clause;
|
|
|
|
/*
|
|
* Build the new clause. Copy to ensure it shares no substructure with
|
|
* original (this is necessary in case there are subselects in there...)
|
|
*/
|
|
clause = make_opclause(opno,
|
|
BOOLOID, /* opresulttype */
|
|
false, /* opretset */
|
|
(Expr *) copyObject(item1),
|
|
(Expr *) copyObject(item2));
|
|
|
|
/* Make a copy of qualscope to avoid problems if source EC changes */
|
|
qualscope = bms_copy(qualscope);
|
|
|
|
/*
|
|
* Build the RestrictInfo node itself.
|
|
*/
|
|
restrictinfo = make_restrictinfo(clause,
|
|
true, /* is_pushed_down */
|
|
false, /* outerjoin_delayed */
|
|
false, /* pseudoconstant */
|
|
qualscope, /* required_relids */
|
|
NULL); /* nullable_relids */
|
|
|
|
/* Set mergejoinability info always, and hashjoinability if enabled */
|
|
check_mergejoinable(restrictinfo);
|
|
if (enable_hashjoin)
|
|
check_hashjoinable(restrictinfo);
|
|
|
|
return restrictinfo;
|
|
}
|
|
|
|
|
|
/*****************************************************************************
|
|
*
|
|
* CHECKS FOR MERGEJOINABLE AND HASHJOINABLE CLAUSES
|
|
*
|
|
*****************************************************************************/
|
|
|
|
/*
|
|
* check_mergejoinable
|
|
* If the restrictinfo's clause is mergejoinable, set the mergejoin
|
|
* info fields in the restrictinfo.
|
|
*
|
|
* Currently, we support mergejoin for binary opclauses where
|
|
* the operator is a mergejoinable operator. The arguments can be
|
|
* anything --- as long as there are no volatile functions in them.
|
|
*/
|
|
static void
|
|
check_mergejoinable(RestrictInfo *restrictinfo)
|
|
{
|
|
Expr *clause = restrictinfo->clause;
|
|
Oid opno;
|
|
|
|
if (restrictinfo->pseudoconstant)
|
|
return;
|
|
if (!is_opclause(clause))
|
|
return;
|
|
if (list_length(((OpExpr *) clause)->args) != 2)
|
|
return;
|
|
|
|
opno = ((OpExpr *) clause)->opno;
|
|
|
|
if (op_mergejoinable(opno) &&
|
|
!contain_volatile_functions((Node *) clause))
|
|
restrictinfo->mergeopfamilies = get_mergejoin_opfamilies(opno);
|
|
|
|
/*
|
|
* Note: op_mergejoinable is just a hint; if we fail to find the operator
|
|
* in any btree opfamilies, mergeopfamilies remains NIL and so the clause
|
|
* is not treated as mergejoinable.
|
|
*/
|
|
}
|
|
|
|
/*
|
|
* check_hashjoinable
|
|
* If the restrictinfo's clause is hashjoinable, set the hashjoin
|
|
* info fields in the restrictinfo.
|
|
*
|
|
* Currently, we support hashjoin for binary opclauses where
|
|
* the operator is a hashjoinable operator. The arguments can be
|
|
* anything --- as long as there are no volatile functions in them.
|
|
*/
|
|
static void
|
|
check_hashjoinable(RestrictInfo *restrictinfo)
|
|
{
|
|
Expr *clause = restrictinfo->clause;
|
|
Oid opno;
|
|
|
|
if (restrictinfo->pseudoconstant)
|
|
return;
|
|
if (!is_opclause(clause))
|
|
return;
|
|
if (list_length(((OpExpr *) clause)->args) != 2)
|
|
return;
|
|
|
|
opno = ((OpExpr *) clause)->opno;
|
|
|
|
if (op_hashjoinable(opno) &&
|
|
!contain_volatile_functions((Node *) clause))
|
|
restrictinfo->hashjoinoperator = opno;
|
|
}
|