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types of unspecified parameters when submitted via extended query protocol. This worked in 8.2 but I had broken it during plancache changes. DECLARE CURSOR is now treated almost exactly like a plain SELECT through parse analysis, rewrite, and planning; only just before sending to the executor do we divert it away to ProcessUtility. This requires a special-case check in a number of places, but practically all of them were already special-casing SELECT INTO, so it's not too ugly. (Maybe it would be a good idea to merge the two by treating IntoClause as a form of utility statement? Not going to worry about that now, though.) That approach doesn't work for EXPLAIN, however, so for that I punted and used a klugy solution of running parse analysis an extra time if under extended query protocol.
1796 lines
51 KiB
C
1796 lines
51 KiB
C
/*-------------------------------------------------------------------------
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*
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* parse_clause.c
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* handle clauses in parser
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*
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* Portions Copyright (c) 1996-2007, 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/parser/parse_clause.c,v 1.165 2007/04/27 22:05:48 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 "access/heapam.h"
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#include "catalog/heap.h"
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#include "catalog/pg_type.h"
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#include "commands/defrem.h"
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#include "nodes/makefuncs.h"
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#include "optimizer/clauses.h"
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#include "optimizer/tlist.h"
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#include "optimizer/var.h"
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#include "parser/analyze.h"
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#include "parser/parsetree.h"
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#include "parser/parse_clause.h"
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#include "parser/parse_coerce.h"
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#include "parser/parse_expr.h"
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#include "parser/parse_oper.h"
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#include "parser/parse_relation.h"
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#include "parser/parse_target.h"
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#include "rewrite/rewriteManip.h"
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#include "utils/guc.h"
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#include "utils/lsyscache.h"
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#define ORDER_CLAUSE 0
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#define GROUP_CLAUSE 1
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#define DISTINCT_ON_CLAUSE 2
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static char *clauseText[] = {"ORDER BY", "GROUP BY", "DISTINCT ON"};
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static void extractRemainingColumns(List *common_colnames,
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List *src_colnames, List *src_colvars,
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List **res_colnames, List **res_colvars);
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static Node *transformJoinUsingClause(ParseState *pstate,
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List *leftVars, List *rightVars);
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static Node *transformJoinOnClause(ParseState *pstate, JoinExpr *j,
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RangeTblEntry *l_rte,
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RangeTblEntry *r_rte,
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List *relnamespace,
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Relids containedRels);
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static RangeTblEntry *transformTableEntry(ParseState *pstate, RangeVar *r);
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static RangeTblEntry *transformRangeSubselect(ParseState *pstate,
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RangeSubselect *r);
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static RangeTblEntry *transformRangeFunction(ParseState *pstate,
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RangeFunction *r);
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static Node *transformFromClauseItem(ParseState *pstate, Node *n,
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RangeTblEntry **top_rte, int *top_rti,
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List **relnamespace,
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Relids *containedRels);
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static Node *buildMergedJoinVar(ParseState *pstate, JoinType jointype,
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Var *l_colvar, Var *r_colvar);
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static TargetEntry *findTargetlistEntry(ParseState *pstate, Node *node,
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List **tlist, int clause);
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/*
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* transformFromClause -
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* Process the FROM clause and add items to the query's range table,
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* joinlist, and namespaces.
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*
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* Note: we assume that pstate's p_rtable, p_joinlist, p_relnamespace, and
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* p_varnamespace lists were initialized to NIL when the pstate was created.
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* We will add onto any entries already present --- this is needed for rule
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* processing, as well as for UPDATE and DELETE.
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*
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* The range table may grow still further when we transform the expressions
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* in the query's quals and target list. (This is possible because in
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* POSTQUEL, we allowed references to relations not specified in the
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* from-clause. PostgreSQL keeps this extension to standard SQL.)
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*/
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void
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transformFromClause(ParseState *pstate, List *frmList)
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{
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ListCell *fl;
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/*
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* The grammar will have produced a list of RangeVars, RangeSubselects,
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* RangeFunctions, and/or JoinExprs. Transform each one (possibly adding
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* entries to the rtable), check for duplicate refnames, and then add it
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* to the joinlist and namespaces.
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*/
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foreach(fl, frmList)
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{
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Node *n = lfirst(fl);
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RangeTblEntry *rte;
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int rtindex;
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List *relnamespace;
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Relids containedRels;
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n = transformFromClauseItem(pstate, n,
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&rte,
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&rtindex,
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&relnamespace,
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&containedRels);
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checkNameSpaceConflicts(pstate, pstate->p_relnamespace, relnamespace);
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pstate->p_joinlist = lappend(pstate->p_joinlist, n);
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pstate->p_relnamespace = list_concat(pstate->p_relnamespace,
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relnamespace);
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pstate->p_varnamespace = lappend(pstate->p_varnamespace, rte);
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bms_free(containedRels);
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}
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}
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/*
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* setTargetTable
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* Add the target relation of INSERT/UPDATE/DELETE to the range table,
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* and make the special links to it in the ParseState.
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*
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* We also open the target relation and acquire a write lock on it.
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* This must be done before processing the FROM list, in case the target
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* is also mentioned as a source relation --- we want to be sure to grab
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* the write lock before any read lock.
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*
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* If alsoSource is true, add the target to the query's joinlist and
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* namespace. For INSERT, we don't want the target to be joined to;
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* it's a destination of tuples, not a source. For UPDATE/DELETE,
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* we do need to scan or join the target. (NOTE: we do not bother
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* to check for namespace conflict; we assume that the namespace was
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* initially empty in these cases.)
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*
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* Finally, we mark the relation as requiring the permissions specified
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* by requiredPerms.
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*
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* Returns the rangetable index of the target relation.
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*/
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int
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setTargetTable(ParseState *pstate, RangeVar *relation,
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bool inh, bool alsoSource, AclMode requiredPerms)
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{
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RangeTblEntry *rte;
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int rtindex;
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/* Close old target; this could only happen for multi-action rules */
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if (pstate->p_target_relation != NULL)
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heap_close(pstate->p_target_relation, NoLock);
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/*
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* Open target rel and grab suitable lock (which we will hold till end of
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* transaction).
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*
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* analyze.c will eventually do the corresponding heap_close(), but *not*
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* release the lock.
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*/
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pstate->p_target_relation = heap_openrv(relation, RowExclusiveLock);
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/*
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* Now build an RTE.
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*/
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rte = addRangeTableEntryForRelation(pstate, pstate->p_target_relation,
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relation->alias, inh, false);
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pstate->p_target_rangetblentry = rte;
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/* assume new rte is at end */
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rtindex = list_length(pstate->p_rtable);
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Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
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/*
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* Override addRangeTableEntry's default ACL_SELECT permissions check, and
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* instead mark target table as requiring exactly the specified
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* permissions.
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*
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* If we find an explicit reference to the rel later during parse
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* analysis, we will add the ACL_SELECT bit back again; see
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* scanRTEForColumn (for simple field references), ExpandColumnRefStar
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* (for foo.*) and ExpandAllTables (for *).
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*/
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rte->requiredPerms = requiredPerms;
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/*
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* If UPDATE/DELETE, add table to joinlist and namespaces.
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*/
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if (alsoSource)
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addRTEtoQuery(pstate, rte, true, true, true);
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return rtindex;
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}
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/*
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* Simplify InhOption (yes/no/default) into boolean yes/no.
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*
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* The reason we do things this way is that we don't want to examine the
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* SQL_inheritance option flag until parse_analyze is run. Otherwise,
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* we'd do the wrong thing with query strings that intermix SET commands
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* with queries.
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*/
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bool
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interpretInhOption(InhOption inhOpt)
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{
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switch (inhOpt)
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{
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case INH_NO:
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return false;
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case INH_YES:
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return true;
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case INH_DEFAULT:
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return SQL_inheritance;
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}
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elog(ERROR, "bogus InhOption value: %d", inhOpt);
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return false; /* keep compiler quiet */
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}
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/*
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* Given a relation-options list (of DefElems), return true iff the specified
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* table/result set should be created with OIDs. This needs to be done after
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* parsing the query string because the return value can depend upon the
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* default_with_oids GUC var.
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*/
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bool
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interpretOidsOption(List *defList)
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{
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ListCell *cell;
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/* Scan list to see if OIDS was included */
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foreach(cell, defList)
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{
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DefElem *def = (DefElem *) lfirst(cell);
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if (pg_strcasecmp(def->defname, "oids") == 0)
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return defGetBoolean(def);
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}
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/* OIDS option was not specified, so use default. */
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return default_with_oids;
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}
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/*
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* Extract all not-in-common columns from column lists of a source table
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*/
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static void
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extractRemainingColumns(List *common_colnames,
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List *src_colnames, List *src_colvars,
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List **res_colnames, List **res_colvars)
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{
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List *new_colnames = NIL;
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List *new_colvars = NIL;
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ListCell *lnames,
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*lvars;
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Assert(list_length(src_colnames) == list_length(src_colvars));
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forboth(lnames, src_colnames, lvars, src_colvars)
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{
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char *colname = strVal(lfirst(lnames));
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bool match = false;
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ListCell *cnames;
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foreach(cnames, common_colnames)
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{
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char *ccolname = strVal(lfirst(cnames));
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if (strcmp(colname, ccolname) == 0)
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{
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match = true;
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break;
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}
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}
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if (!match)
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{
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new_colnames = lappend(new_colnames, lfirst(lnames));
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new_colvars = lappend(new_colvars, lfirst(lvars));
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}
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}
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*res_colnames = new_colnames;
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*res_colvars = new_colvars;
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}
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/* transformJoinUsingClause()
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* Build a complete ON clause from a partially-transformed USING list.
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* We are given lists of nodes representing left and right match columns.
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* Result is a transformed qualification expression.
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*/
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static Node *
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transformJoinUsingClause(ParseState *pstate, List *leftVars, List *rightVars)
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{
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Node *result = NULL;
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ListCell *lvars,
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*rvars;
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/*
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* We cheat a little bit here by building an untransformed operator tree
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* whose leaves are the already-transformed Vars. This is OK because
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* transformExpr() won't complain about already-transformed subnodes.
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*/
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forboth(lvars, leftVars, rvars, rightVars)
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{
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Node *lvar = (Node *) lfirst(lvars);
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Node *rvar = (Node *) lfirst(rvars);
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A_Expr *e;
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e = makeSimpleA_Expr(AEXPR_OP, "=",
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copyObject(lvar), copyObject(rvar),
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-1);
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if (result == NULL)
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result = (Node *) e;
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else
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{
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A_Expr *a;
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a = makeA_Expr(AEXPR_AND, NIL, result, (Node *) e, -1);
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result = (Node *) a;
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}
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}
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/*
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* Since the references are already Vars, and are certainly from the input
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* relations, we don't have to go through the same pushups that
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* transformJoinOnClause() does. Just invoke transformExpr() to fix up
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* the operators, and we're done.
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*/
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result = transformExpr(pstate, result);
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result = coerce_to_boolean(pstate, result, "JOIN/USING");
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return result;
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}
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/* transformJoinOnClause()
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* Transform the qual conditions for JOIN/ON.
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* Result is a transformed qualification expression.
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*/
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static Node *
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transformJoinOnClause(ParseState *pstate, JoinExpr *j,
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RangeTblEntry *l_rte,
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RangeTblEntry *r_rte,
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List *relnamespace,
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Relids containedRels)
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{
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Node *result;
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List *save_relnamespace;
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List *save_varnamespace;
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Relids clause_varnos;
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int varno;
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/*
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* This is a tad tricky, for two reasons. First, the namespace that the
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* join expression should see is just the two subtrees of the JOIN plus
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* any outer references from upper pstate levels. So, temporarily set
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* this pstate's namespace accordingly. (We need not check for refname
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* conflicts, because transformFromClauseItem() already did.) NOTE: this
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* code is OK only because the ON clause can't legally alter the namespace
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* by causing implicit relation refs to be added.
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*/
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save_relnamespace = pstate->p_relnamespace;
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save_varnamespace = pstate->p_varnamespace;
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pstate->p_relnamespace = relnamespace;
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pstate->p_varnamespace = list_make2(l_rte, r_rte);
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result = transformWhereClause(pstate, j->quals, "JOIN/ON");
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pstate->p_relnamespace = save_relnamespace;
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pstate->p_varnamespace = save_varnamespace;
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/*
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* Second, we need to check that the ON condition doesn't refer to any
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* rels outside the input subtrees of the JOIN. It could do that despite
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* our hack on the namespace if it uses fully-qualified names. So, grovel
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* through the transformed clause and make sure there are no bogus
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* references. (Outer references are OK, and are ignored here.)
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*/
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clause_varnos = pull_varnos(result);
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clause_varnos = bms_del_members(clause_varnos, containedRels);
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if ((varno = bms_first_member(clause_varnos)) >= 0)
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{
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
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errmsg("JOIN/ON clause refers to \"%s\", which is not part of JOIN",
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rt_fetch(varno, pstate->p_rtable)->eref->aliasname)));
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}
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bms_free(clause_varnos);
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return result;
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}
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/*
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* transformTableEntry --- transform a RangeVar (simple relation reference)
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*/
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static RangeTblEntry *
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transformTableEntry(ParseState *pstate, RangeVar *r)
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{
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RangeTblEntry *rte;
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/*
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* mark this entry to indicate it comes from the FROM clause. In SQL, the
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* target list can only refer to range variables specified in the from
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* clause but we follow the more powerful POSTQUEL semantics and
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* automatically generate the range variable if not specified. However
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* there are times we need to know whether the entries are legitimate.
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*/
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rte = addRangeTableEntry(pstate, r, r->alias,
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interpretInhOption(r->inhOpt), true);
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return rte;
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}
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/*
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* transformRangeSubselect --- transform a sub-SELECT appearing in FROM
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*/
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static RangeTblEntry *
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transformRangeSubselect(ParseState *pstate, RangeSubselect *r)
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{
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List *parsetrees;
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Query *query;
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RangeTblEntry *rte;
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/*
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* We require user to supply an alias for a subselect, per SQL92. To relax
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* this, we'd have to be prepared to gin up a unique alias for an
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* unlabeled subselect.
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*/
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if (r->alias == NULL)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("subquery in FROM must have an alias")));
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/*
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* Analyze and transform the subquery.
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*/
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parsetrees = parse_sub_analyze(r->subquery, pstate);
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/*
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* Check that we got something reasonable. Most of these conditions are
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* probably impossible given restrictions of the grammar, but check 'em
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* anyway.
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*/
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if (list_length(parsetrees) != 1)
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elog(ERROR, "unexpected parse analysis result for subquery in FROM");
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query = (Query *) linitial(parsetrees);
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if (query == NULL || !IsA(query, Query))
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elog(ERROR, "unexpected parse analysis result for subquery in FROM");
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if (query->commandType != CMD_SELECT ||
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query->utilityStmt != NULL)
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elog(ERROR, "expected SELECT query from subquery in FROM");
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if (query->intoClause != NULL)
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ereport(ERROR,
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(errcode(ERRCODE_SYNTAX_ERROR),
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errmsg("subquery in FROM cannot have SELECT INTO")));
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/*
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* The subquery cannot make use of any variables from FROM items created
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* earlier in the current query. Per SQL92, the scope of a FROM item does
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* not include other FROM items. Formerly we hacked the namespace so that
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* the other variables weren't even visible, but it seems more useful to
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* leave them visible and give a specific error message.
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*
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* XXX this will need further work to support SQL99's LATERAL() feature,
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* wherein such references would indeed be legal.
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*
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* We can skip groveling through the subquery if there's not anything
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* visible in the current query. Also note that outer references are OK.
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*/
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if (pstate->p_relnamespace || pstate->p_varnamespace)
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{
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if (contain_vars_of_level((Node *) query, 1))
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
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errmsg("subquery in FROM cannot refer to other relations of same query level")));
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}
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/*
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* OK, build an RTE for the subquery.
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*/
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rte = addRangeTableEntryForSubquery(pstate, query, r->alias, true);
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return rte;
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}
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/*
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* transformRangeFunction --- transform a function call appearing in FROM
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*/
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static RangeTblEntry *
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transformRangeFunction(ParseState *pstate, RangeFunction *r)
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{
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Node *funcexpr;
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char *funcname;
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RangeTblEntry *rte;
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/*
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* Get function name for possible use as alias. We use the same
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* transformation rules as for a SELECT output expression. For a FuncCall
|
|
* node, the result will be the function name, but it is possible for the
|
|
* grammar to hand back other node types.
|
|
*/
|
|
funcname = FigureColname(r->funccallnode);
|
|
|
|
/*
|
|
* Transform the raw expression.
|
|
*/
|
|
funcexpr = transformExpr(pstate, r->funccallnode);
|
|
|
|
/*
|
|
* The function parameters cannot make use of any variables from other
|
|
* FROM items. (Compare to transformRangeSubselect(); the coding is
|
|
* different though because we didn't parse as a sub-select with its own
|
|
* level of namespace.)
|
|
*
|
|
* XXX this will need further work to support SQL99's LATERAL() feature,
|
|
* wherein such references would indeed be legal.
|
|
*/
|
|
if (pstate->p_relnamespace || pstate->p_varnamespace)
|
|
{
|
|
if (contain_vars_of_level(funcexpr, 0))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
|
|
errmsg("function expression in FROM cannot refer to other relations of same query level")));
|
|
}
|
|
|
|
/*
|
|
* Disallow aggregate functions in the expression. (No reason to postpone
|
|
* this check until parseCheckAggregates.)
|
|
*/
|
|
if (pstate->p_hasAggs)
|
|
{
|
|
if (checkExprHasAggs(funcexpr))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_GROUPING_ERROR),
|
|
errmsg("cannot use aggregate function in function expression in FROM")));
|
|
}
|
|
|
|
/*
|
|
* OK, build an RTE for the function.
|
|
*/
|
|
rte = addRangeTableEntryForFunction(pstate, funcname, funcexpr,
|
|
r, true);
|
|
|
|
/*
|
|
* If a coldeflist was supplied, ensure it defines a legal set of names
|
|
* (no duplicates) and datatypes (no pseudo-types, for instance).
|
|
* addRangeTableEntryForFunction looked up the type names but didn't check
|
|
* them further than that.
|
|
*/
|
|
if (r->coldeflist)
|
|
{
|
|
TupleDesc tupdesc;
|
|
|
|
tupdesc = BuildDescFromLists(rte->eref->colnames,
|
|
rte->funccoltypes,
|
|
rte->funccoltypmods);
|
|
CheckAttributeNamesTypes(tupdesc, RELKIND_COMPOSITE_TYPE);
|
|
}
|
|
|
|
return rte;
|
|
}
|
|
|
|
|
|
/*
|
|
* transformFromClauseItem -
|
|
* Transform a FROM-clause item, adding any required entries to the
|
|
* range table list being built in the ParseState, and return the
|
|
* transformed item ready to include in the joinlist and namespaces.
|
|
* This routine can recurse to handle SQL92 JOIN expressions.
|
|
*
|
|
* The function return value is the node to add to the jointree (a
|
|
* RangeTblRef or JoinExpr). Additional output parameters are:
|
|
*
|
|
* *top_rte: receives the RTE corresponding to the jointree item.
|
|
* (We could extract this from the function return node, but it saves cycles
|
|
* to pass it back separately.)
|
|
*
|
|
* *top_rti: receives the rangetable index of top_rte. (Ditto.)
|
|
*
|
|
* *relnamespace: receives a List of the RTEs exposed as relation names
|
|
* by this item.
|
|
*
|
|
* *containedRels: receives a bitmap set of the rangetable indexes
|
|
* of all the base and join relations represented in this jointree item.
|
|
* This is needed for checking JOIN/ON conditions in higher levels.
|
|
*
|
|
* We do not need to pass back an explicit varnamespace value, because
|
|
* in all cases the varnamespace contribution is exactly top_rte.
|
|
*/
|
|
static Node *
|
|
transformFromClauseItem(ParseState *pstate, Node *n,
|
|
RangeTblEntry **top_rte, int *top_rti,
|
|
List **relnamespace,
|
|
Relids *containedRels)
|
|
{
|
|
if (IsA(n, RangeVar))
|
|
{
|
|
/* Plain relation reference */
|
|
RangeTblRef *rtr;
|
|
RangeTblEntry *rte;
|
|
int rtindex;
|
|
|
|
rte = transformTableEntry(pstate, (RangeVar *) n);
|
|
/* assume new rte is at end */
|
|
rtindex = list_length(pstate->p_rtable);
|
|
Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
|
|
*top_rte = rte;
|
|
*top_rti = rtindex;
|
|
*relnamespace = list_make1(rte);
|
|
*containedRels = bms_make_singleton(rtindex);
|
|
rtr = makeNode(RangeTblRef);
|
|
rtr->rtindex = rtindex;
|
|
return (Node *) rtr;
|
|
}
|
|
else if (IsA(n, RangeSubselect))
|
|
{
|
|
/* sub-SELECT is like a plain relation */
|
|
RangeTblRef *rtr;
|
|
RangeTblEntry *rte;
|
|
int rtindex;
|
|
|
|
rte = transformRangeSubselect(pstate, (RangeSubselect *) n);
|
|
/* assume new rte is at end */
|
|
rtindex = list_length(pstate->p_rtable);
|
|
Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
|
|
*top_rte = rte;
|
|
*top_rti = rtindex;
|
|
*relnamespace = list_make1(rte);
|
|
*containedRels = bms_make_singleton(rtindex);
|
|
rtr = makeNode(RangeTblRef);
|
|
rtr->rtindex = rtindex;
|
|
return (Node *) rtr;
|
|
}
|
|
else if (IsA(n, RangeFunction))
|
|
{
|
|
/* function is like a plain relation */
|
|
RangeTblRef *rtr;
|
|
RangeTblEntry *rte;
|
|
int rtindex;
|
|
|
|
rte = transformRangeFunction(pstate, (RangeFunction *) n);
|
|
/* assume new rte is at end */
|
|
rtindex = list_length(pstate->p_rtable);
|
|
Assert(rte == rt_fetch(rtindex, pstate->p_rtable));
|
|
*top_rte = rte;
|
|
*top_rti = rtindex;
|
|
*relnamespace = list_make1(rte);
|
|
*containedRels = bms_make_singleton(rtindex);
|
|
rtr = makeNode(RangeTblRef);
|
|
rtr->rtindex = rtindex;
|
|
return (Node *) rtr;
|
|
}
|
|
else if (IsA(n, JoinExpr))
|
|
{
|
|
/* A newfangled join expression */
|
|
JoinExpr *j = (JoinExpr *) n;
|
|
RangeTblEntry *l_rte;
|
|
RangeTblEntry *r_rte;
|
|
int l_rtindex;
|
|
int r_rtindex;
|
|
Relids l_containedRels,
|
|
r_containedRels,
|
|
my_containedRels;
|
|
List *l_relnamespace,
|
|
*r_relnamespace,
|
|
*my_relnamespace,
|
|
*l_colnames,
|
|
*r_colnames,
|
|
*res_colnames,
|
|
*l_colvars,
|
|
*r_colvars,
|
|
*res_colvars;
|
|
RangeTblEntry *rte;
|
|
|
|
/*
|
|
* Recursively process the left and right subtrees
|
|
*/
|
|
j->larg = transformFromClauseItem(pstate, j->larg,
|
|
&l_rte,
|
|
&l_rtindex,
|
|
&l_relnamespace,
|
|
&l_containedRels);
|
|
j->rarg = transformFromClauseItem(pstate, j->rarg,
|
|
&r_rte,
|
|
&r_rtindex,
|
|
&r_relnamespace,
|
|
&r_containedRels);
|
|
|
|
/*
|
|
* Check for conflicting refnames in left and right subtrees. Must do
|
|
* this because higher levels will assume I hand back a self-
|
|
* consistent namespace subtree.
|
|
*/
|
|
checkNameSpaceConflicts(pstate, l_relnamespace, r_relnamespace);
|
|
|
|
/*
|
|
* Generate combined relation membership info for possible use by
|
|
* transformJoinOnClause below.
|
|
*/
|
|
my_relnamespace = list_concat(l_relnamespace, r_relnamespace);
|
|
my_containedRels = bms_join(l_containedRels, r_containedRels);
|
|
|
|
pfree(r_relnamespace); /* free unneeded list header */
|
|
|
|
/*
|
|
* Extract column name and var lists from both subtrees
|
|
*
|
|
* Note: expandRTE returns new lists, safe for me to modify
|
|
*/
|
|
expandRTE(l_rte, l_rtindex, 0, false,
|
|
&l_colnames, &l_colvars);
|
|
expandRTE(r_rte, r_rtindex, 0, false,
|
|
&r_colnames, &r_colvars);
|
|
|
|
/*
|
|
* Natural join does not explicitly specify columns; must generate
|
|
* columns to join. Need to run through the list of columns from each
|
|
* table or join result and match up the column names. Use the first
|
|
* table, and check every column in the second table for a match.
|
|
* (We'll check that the matches were unique later on.) The result of
|
|
* this step is a list of column names just like an explicitly-written
|
|
* USING list.
|
|
*/
|
|
if (j->isNatural)
|
|
{
|
|
List *rlist = NIL;
|
|
ListCell *lx,
|
|
*rx;
|
|
|
|
Assert(j->using == NIL); /* shouldn't have USING() too */
|
|
|
|
foreach(lx, l_colnames)
|
|
{
|
|
char *l_colname = strVal(lfirst(lx));
|
|
Value *m_name = NULL;
|
|
|
|
foreach(rx, r_colnames)
|
|
{
|
|
char *r_colname = strVal(lfirst(rx));
|
|
|
|
if (strcmp(l_colname, r_colname) == 0)
|
|
{
|
|
m_name = makeString(l_colname);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* matched a right column? then keep as join column... */
|
|
if (m_name != NULL)
|
|
rlist = lappend(rlist, m_name);
|
|
}
|
|
|
|
j->using = rlist;
|
|
}
|
|
|
|
/*
|
|
* Now transform the join qualifications, if any.
|
|
*/
|
|
res_colnames = NIL;
|
|
res_colvars = NIL;
|
|
|
|
if (j->using)
|
|
{
|
|
/*
|
|
* JOIN/USING (or NATURAL JOIN, as transformed above). Transform
|
|
* the list into an explicit ON-condition, and generate a list of
|
|
* merged result columns.
|
|
*/
|
|
List *ucols = j->using;
|
|
List *l_usingvars = NIL;
|
|
List *r_usingvars = NIL;
|
|
ListCell *ucol;
|
|
|
|
Assert(j->quals == NULL); /* shouldn't have ON() too */
|
|
|
|
foreach(ucol, ucols)
|
|
{
|
|
char *u_colname = strVal(lfirst(ucol));
|
|
ListCell *col;
|
|
int ndx;
|
|
int l_index = -1;
|
|
int r_index = -1;
|
|
Var *l_colvar,
|
|
*r_colvar;
|
|
|
|
/* Check for USING(foo,foo) */
|
|
foreach(col, res_colnames)
|
|
{
|
|
char *res_colname = strVal(lfirst(col));
|
|
|
|
if (strcmp(res_colname, u_colname) == 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_DUPLICATE_COLUMN),
|
|
errmsg("column name \"%s\" appears more than once in USING clause",
|
|
u_colname)));
|
|
}
|
|
|
|
/* Find it in left input */
|
|
ndx = 0;
|
|
foreach(col, l_colnames)
|
|
{
|
|
char *l_colname = strVal(lfirst(col));
|
|
|
|
if (strcmp(l_colname, u_colname) == 0)
|
|
{
|
|
if (l_index >= 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
|
|
errmsg("common column name \"%s\" appears more than once in left table",
|
|
u_colname)));
|
|
l_index = ndx;
|
|
}
|
|
ndx++;
|
|
}
|
|
if (l_index < 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_UNDEFINED_COLUMN),
|
|
errmsg("column \"%s\" specified in USING clause does not exist in left table",
|
|
u_colname)));
|
|
|
|
/* Find it in right input */
|
|
ndx = 0;
|
|
foreach(col, r_colnames)
|
|
{
|
|
char *r_colname = strVal(lfirst(col));
|
|
|
|
if (strcmp(r_colname, u_colname) == 0)
|
|
{
|
|
if (r_index >= 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
|
|
errmsg("common column name \"%s\" appears more than once in right table",
|
|
u_colname)));
|
|
r_index = ndx;
|
|
}
|
|
ndx++;
|
|
}
|
|
if (r_index < 0)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_UNDEFINED_COLUMN),
|
|
errmsg("column \"%s\" specified in USING clause does not exist in right table",
|
|
u_colname)));
|
|
|
|
l_colvar = list_nth(l_colvars, l_index);
|
|
l_usingvars = lappend(l_usingvars, l_colvar);
|
|
r_colvar = list_nth(r_colvars, r_index);
|
|
r_usingvars = lappend(r_usingvars, r_colvar);
|
|
|
|
res_colnames = lappend(res_colnames, lfirst(ucol));
|
|
res_colvars = lappend(res_colvars,
|
|
buildMergedJoinVar(pstate,
|
|
j->jointype,
|
|
l_colvar,
|
|
r_colvar));
|
|
}
|
|
|
|
j->quals = transformJoinUsingClause(pstate,
|
|
l_usingvars,
|
|
r_usingvars);
|
|
}
|
|
else if (j->quals)
|
|
{
|
|
/* User-written ON-condition; transform it */
|
|
j->quals = transformJoinOnClause(pstate, j,
|
|
l_rte, r_rte,
|
|
my_relnamespace,
|
|
my_containedRels);
|
|
}
|
|
else
|
|
{
|
|
/* CROSS JOIN: no quals */
|
|
}
|
|
|
|
/* Add remaining columns from each side to the output columns */
|
|
extractRemainingColumns(res_colnames,
|
|
l_colnames, l_colvars,
|
|
&l_colnames, &l_colvars);
|
|
extractRemainingColumns(res_colnames,
|
|
r_colnames, r_colvars,
|
|
&r_colnames, &r_colvars);
|
|
res_colnames = list_concat(res_colnames, l_colnames);
|
|
res_colvars = list_concat(res_colvars, l_colvars);
|
|
res_colnames = list_concat(res_colnames, r_colnames);
|
|
res_colvars = list_concat(res_colvars, r_colvars);
|
|
|
|
/*
|
|
* Check alias (AS clause), if any.
|
|
*/
|
|
if (j->alias)
|
|
{
|
|
if (j->alias->colnames != NIL)
|
|
{
|
|
if (list_length(j->alias->colnames) > list_length(res_colnames))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
errmsg("column alias list for \"%s\" has too many entries",
|
|
j->alias->aliasname)));
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Now build an RTE for the result of the join
|
|
*/
|
|
rte = addRangeTableEntryForJoin(pstate,
|
|
res_colnames,
|
|
j->jointype,
|
|
res_colvars,
|
|
j->alias,
|
|
true);
|
|
|
|
/* assume new rte is at end */
|
|
j->rtindex = list_length(pstate->p_rtable);
|
|
Assert(rte == rt_fetch(j->rtindex, pstate->p_rtable));
|
|
|
|
*top_rte = rte;
|
|
*top_rti = j->rtindex;
|
|
|
|
/*
|
|
* Prepare returned namespace list. If the JOIN has an alias then it
|
|
* hides the contained RTEs as far as the relnamespace goes;
|
|
* otherwise, put the contained RTEs and *not* the JOIN into
|
|
* relnamespace.
|
|
*/
|
|
if (j->alias)
|
|
{
|
|
*relnamespace = list_make1(rte);
|
|
list_free(my_relnamespace);
|
|
}
|
|
else
|
|
*relnamespace = my_relnamespace;
|
|
|
|
/*
|
|
* Include join RTE in returned containedRels set
|
|
*/
|
|
*containedRels = bms_add_member(my_containedRels, j->rtindex);
|
|
|
|
return (Node *) j;
|
|
}
|
|
else
|
|
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(n));
|
|
return NULL; /* can't get here, keep compiler quiet */
|
|
}
|
|
|
|
/*
|
|
* buildMergedJoinVar -
|
|
* generate a suitable replacement expression for a merged join column
|
|
*/
|
|
static Node *
|
|
buildMergedJoinVar(ParseState *pstate, JoinType jointype,
|
|
Var *l_colvar, Var *r_colvar)
|
|
{
|
|
Oid outcoltype;
|
|
int32 outcoltypmod;
|
|
Node *l_node,
|
|
*r_node,
|
|
*res_node;
|
|
|
|
/*
|
|
* Choose output type if input types are dissimilar.
|
|
*/
|
|
outcoltype = l_colvar->vartype;
|
|
outcoltypmod = l_colvar->vartypmod;
|
|
if (outcoltype != r_colvar->vartype)
|
|
{
|
|
outcoltype = select_common_type(list_make2_oid(l_colvar->vartype,
|
|
r_colvar->vartype),
|
|
"JOIN/USING");
|
|
outcoltypmod = -1; /* ie, unknown */
|
|
}
|
|
else if (outcoltypmod != r_colvar->vartypmod)
|
|
{
|
|
/* same type, but not same typmod */
|
|
outcoltypmod = -1; /* ie, unknown */
|
|
}
|
|
|
|
/*
|
|
* Insert coercion functions if needed. Note that a difference in typmod
|
|
* can only happen if input has typmod but outcoltypmod is -1. In that
|
|
* case we insert a RelabelType to clearly mark that result's typmod is
|
|
* not same as input. We never need coerce_type_typmod.
|
|
*/
|
|
if (l_colvar->vartype != outcoltype)
|
|
l_node = coerce_type(pstate, (Node *) l_colvar, l_colvar->vartype,
|
|
outcoltype, outcoltypmod,
|
|
COERCION_IMPLICIT, COERCE_IMPLICIT_CAST);
|
|
else if (l_colvar->vartypmod != outcoltypmod)
|
|
l_node = (Node *) makeRelabelType((Expr *) l_colvar,
|
|
outcoltype, outcoltypmod,
|
|
COERCE_IMPLICIT_CAST);
|
|
else
|
|
l_node = (Node *) l_colvar;
|
|
|
|
if (r_colvar->vartype != outcoltype)
|
|
r_node = coerce_type(pstate, (Node *) r_colvar, r_colvar->vartype,
|
|
outcoltype, outcoltypmod,
|
|
COERCION_IMPLICIT, COERCE_IMPLICIT_CAST);
|
|
else if (r_colvar->vartypmod != outcoltypmod)
|
|
r_node = (Node *) makeRelabelType((Expr *) r_colvar,
|
|
outcoltype, outcoltypmod,
|
|
COERCE_IMPLICIT_CAST);
|
|
else
|
|
r_node = (Node *) r_colvar;
|
|
|
|
/*
|
|
* Choose what to emit
|
|
*/
|
|
switch (jointype)
|
|
{
|
|
case JOIN_INNER:
|
|
|
|
/*
|
|
* We can use either var; prefer non-coerced one if available.
|
|
*/
|
|
if (IsA(l_node, Var))
|
|
res_node = l_node;
|
|
else if (IsA(r_node, Var))
|
|
res_node = r_node;
|
|
else
|
|
res_node = l_node;
|
|
break;
|
|
case JOIN_LEFT:
|
|
/* Always use left var */
|
|
res_node = l_node;
|
|
break;
|
|
case JOIN_RIGHT:
|
|
/* Always use right var */
|
|
res_node = r_node;
|
|
break;
|
|
case JOIN_FULL:
|
|
{
|
|
/*
|
|
* Here we must build a COALESCE expression to ensure that the
|
|
* join output is non-null if either input is.
|
|
*/
|
|
CoalesceExpr *c = makeNode(CoalesceExpr);
|
|
|
|
c->coalescetype = outcoltype;
|
|
c->args = list_make2(l_node, r_node);
|
|
res_node = (Node *) c;
|
|
break;
|
|
}
|
|
default:
|
|
elog(ERROR, "unrecognized join type: %d", (int) jointype);
|
|
res_node = NULL; /* keep compiler quiet */
|
|
break;
|
|
}
|
|
|
|
return res_node;
|
|
}
|
|
|
|
|
|
/*
|
|
* transformWhereClause -
|
|
* Transform the qualification and make sure it is of type boolean.
|
|
* Used for WHERE and allied clauses.
|
|
*
|
|
* constructName does not affect the semantics, but is used in error messages
|
|
*/
|
|
Node *
|
|
transformWhereClause(ParseState *pstate, Node *clause,
|
|
const char *constructName)
|
|
{
|
|
Node *qual;
|
|
|
|
if (clause == NULL)
|
|
return NULL;
|
|
|
|
qual = transformExpr(pstate, clause);
|
|
|
|
qual = coerce_to_boolean(pstate, qual, constructName);
|
|
|
|
return qual;
|
|
}
|
|
|
|
|
|
/*
|
|
* transformLimitClause -
|
|
* Transform the expression and make sure it is of type bigint.
|
|
* Used for LIMIT and allied clauses.
|
|
*
|
|
* Note: as of Postgres 8.2, LIMIT expressions are expected to yield int8,
|
|
* rather than int4 as before.
|
|
*
|
|
* constructName does not affect the semantics, but is used in error messages
|
|
*/
|
|
Node *
|
|
transformLimitClause(ParseState *pstate, Node *clause,
|
|
const char *constructName)
|
|
{
|
|
Node *qual;
|
|
|
|
if (clause == NULL)
|
|
return NULL;
|
|
|
|
qual = transformExpr(pstate, clause);
|
|
|
|
qual = coerce_to_specific_type(pstate, qual, INT8OID, constructName);
|
|
|
|
/*
|
|
* LIMIT can't refer to any vars or aggregates of the current query; we
|
|
* don't allow subselects either (though that case would at least be
|
|
* sensible)
|
|
*/
|
|
if (contain_vars_of_level(qual, 0))
|
|
{
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
|
|
/* translator: %s is name of a SQL construct, eg LIMIT */
|
|
errmsg("argument of %s must not contain variables",
|
|
constructName)));
|
|
}
|
|
if (checkExprHasAggs(qual))
|
|
{
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_GROUPING_ERROR),
|
|
/* translator: %s is name of a SQL construct, eg LIMIT */
|
|
errmsg("argument of %s must not contain aggregates",
|
|
constructName)));
|
|
}
|
|
if (contain_subplans(qual))
|
|
{
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
|
|
/* translator: %s is name of a SQL construct, eg LIMIT */
|
|
errmsg("argument of %s must not contain subqueries",
|
|
constructName)));
|
|
}
|
|
|
|
return qual;
|
|
}
|
|
|
|
|
|
/*
|
|
* findTargetlistEntry -
|
|
* Returns the targetlist entry matching the given (untransformed) node.
|
|
* If no matching entry exists, one is created and appended to the target
|
|
* list as a "resjunk" node.
|
|
*
|
|
* node the ORDER BY, GROUP BY, or DISTINCT ON expression to be matched
|
|
* tlist the target list (passed by reference so we can append to it)
|
|
* clause identifies clause type being processed
|
|
*/
|
|
static TargetEntry *
|
|
findTargetlistEntry(ParseState *pstate, Node *node, List **tlist, int clause)
|
|
{
|
|
TargetEntry *target_result = NULL;
|
|
ListCell *tl;
|
|
Node *expr;
|
|
|
|
/*----------
|
|
* Handle two special cases as mandated by the SQL92 spec:
|
|
*
|
|
* 1. Bare ColumnName (no qualifier or subscripts)
|
|
* For a bare identifier, we search for a matching column name
|
|
* in the existing target list. Multiple matches are an error
|
|
* unless they refer to identical values; for example,
|
|
* we allow SELECT a, a FROM table ORDER BY a
|
|
* but not SELECT a AS b, b FROM table ORDER BY b
|
|
* If no match is found, we fall through and treat the identifier
|
|
* as an expression.
|
|
* For GROUP BY, it is incorrect to match the grouping item against
|
|
* targetlist entries: according to SQL92, an identifier in GROUP BY
|
|
* is a reference to a column name exposed by FROM, not to a target
|
|
* list column. However, many implementations (including pre-7.0
|
|
* PostgreSQL) accept this anyway. So for GROUP BY, we look first
|
|
* to see if the identifier matches any FROM column name, and only
|
|
* try for a targetlist name if it doesn't. This ensures that we
|
|
* adhere to the spec in the case where the name could be both.
|
|
* DISTINCT ON isn't in the standard, so we can do what we like there;
|
|
* we choose to make it work like ORDER BY, on the rather flimsy
|
|
* grounds that ordinary DISTINCT works on targetlist entries.
|
|
*
|
|
* 2. IntegerConstant
|
|
* This means to use the n'th item in the existing target list.
|
|
* Note that it would make no sense to order/group/distinct by an
|
|
* actual constant, so this does not create a conflict with our
|
|
* extension to order/group by an expression.
|
|
* GROUP BY column-number is not allowed by SQL92, but since
|
|
* the standard has no other behavior defined for this syntax,
|
|
* we may as well accept this common extension.
|
|
*
|
|
* Note that pre-existing resjunk targets must not be used in either case,
|
|
* since the user didn't write them in his SELECT list.
|
|
*
|
|
* If neither special case applies, fall through to treat the item as
|
|
* an expression.
|
|
*----------
|
|
*/
|
|
if (IsA(node, ColumnRef) &&
|
|
list_length(((ColumnRef *) node)->fields) == 1)
|
|
{
|
|
char *name = strVal(linitial(((ColumnRef *) node)->fields));
|
|
int location = ((ColumnRef *) node)->location;
|
|
|
|
if (clause == GROUP_CLAUSE)
|
|
{
|
|
/*
|
|
* In GROUP BY, we must prefer a match against a FROM-clause
|
|
* column to one against the targetlist. Look to see if there is
|
|
* a matching column. If so, fall through to let transformExpr()
|
|
* do the rest. NOTE: if name could refer ambiguously to more
|
|
* than one column name exposed by FROM, colNameToVar will
|
|
* ereport(ERROR). That's just what we want here.
|
|
*
|
|
* Small tweak for 7.4.3: ignore matches in upper query levels.
|
|
* This effectively changes the search order for bare names to (1)
|
|
* local FROM variables, (2) local targetlist aliases, (3) outer
|
|
* FROM variables, whereas before it was (1) (3) (2). SQL92 and
|
|
* SQL99 do not allow GROUPing BY an outer reference, so this
|
|
* breaks no cases that are legal per spec, and it seems a more
|
|
* self-consistent behavior.
|
|
*/
|
|
if (colNameToVar(pstate, name, true, location) != NULL)
|
|
name = NULL;
|
|
}
|
|
|
|
if (name != NULL)
|
|
{
|
|
foreach(tl, *tlist)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(tl);
|
|
|
|
if (!tle->resjunk &&
|
|
strcmp(tle->resname, name) == 0)
|
|
{
|
|
if (target_result != NULL)
|
|
{
|
|
if (!equal(target_result->expr, tle->expr))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_AMBIGUOUS_COLUMN),
|
|
|
|
/*------
|
|
translator: first %s is name of a SQL construct, eg ORDER BY */
|
|
errmsg("%s \"%s\" is ambiguous",
|
|
clauseText[clause], name),
|
|
parser_errposition(pstate, location)));
|
|
}
|
|
else
|
|
target_result = tle;
|
|
/* Stay in loop to check for ambiguity */
|
|
}
|
|
}
|
|
if (target_result != NULL)
|
|
return target_result; /* return the first match */
|
|
}
|
|
}
|
|
if (IsA(node, A_Const))
|
|
{
|
|
Value *val = &((A_Const *) node)->val;
|
|
int targetlist_pos = 0;
|
|
int target_pos;
|
|
|
|
if (!IsA(val, Integer))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_SYNTAX_ERROR),
|
|
/* translator: %s is name of a SQL construct, eg ORDER BY */
|
|
errmsg("non-integer constant in %s",
|
|
clauseText[clause])));
|
|
target_pos = intVal(val);
|
|
foreach(tl, *tlist)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(tl);
|
|
|
|
if (!tle->resjunk)
|
|
{
|
|
if (++targetlist_pos == target_pos)
|
|
return tle; /* return the unique match */
|
|
}
|
|
}
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
|
|
/* translator: %s is name of a SQL construct, eg ORDER BY */
|
|
errmsg("%s position %d is not in select list",
|
|
clauseText[clause], target_pos)));
|
|
}
|
|
|
|
/*
|
|
* Otherwise, we have an expression (this is a Postgres extension not
|
|
* found in SQL92). Convert the untransformed node to a transformed
|
|
* expression, and search for a match in the tlist. NOTE: it doesn't
|
|
* really matter whether there is more than one match. Also, we are
|
|
* willing to match a resjunk target here, though the above cases must
|
|
* ignore resjunk targets.
|
|
*/
|
|
expr = transformExpr(pstate, node);
|
|
|
|
foreach(tl, *tlist)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(tl);
|
|
|
|
if (equal(expr, tle->expr))
|
|
return tle;
|
|
}
|
|
|
|
/*
|
|
* If no matches, construct a new target entry which is appended to the
|
|
* end of the target list. This target is given resjunk = TRUE so that it
|
|
* will not be projected into the final tuple.
|
|
*/
|
|
target_result = transformTargetEntry(pstate, node, expr, NULL, true);
|
|
|
|
*tlist = lappend(*tlist, target_result);
|
|
|
|
return target_result;
|
|
}
|
|
|
|
static GroupClause *
|
|
make_group_clause(TargetEntry *tle, List *targetlist,
|
|
Oid sortop, bool nulls_first)
|
|
{
|
|
GroupClause *result;
|
|
|
|
result = makeNode(GroupClause);
|
|
result->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
|
|
result->sortop = sortop;
|
|
result->nulls_first = nulls_first;
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* transformGroupClause -
|
|
* transform a GROUP BY clause
|
|
*
|
|
* GROUP BY items will be added to the targetlist (as resjunk columns)
|
|
* if not already present, so the targetlist must be passed by reference.
|
|
*
|
|
* The order of the elements of the grouping clause does not affect
|
|
* the semantics of the query. However, the optimizer is not currently
|
|
* smart enough to reorder the grouping clause, so we try to do some
|
|
* primitive reordering here.
|
|
*/
|
|
List *
|
|
transformGroupClause(ParseState *pstate, List *grouplist,
|
|
List **targetlist, List *sortClause)
|
|
{
|
|
List *result = NIL;
|
|
List *tle_list = NIL;
|
|
ListCell *l;
|
|
|
|
/* Preprocess the grouping clause, lookup TLEs */
|
|
foreach(l, grouplist)
|
|
{
|
|
TargetEntry *tle;
|
|
Oid restype;
|
|
|
|
tle = findTargetlistEntry(pstate, lfirst(l),
|
|
targetlist, GROUP_CLAUSE);
|
|
|
|
/* if tlist item is an UNKNOWN literal, change it to TEXT */
|
|
restype = exprType((Node *) tle->expr);
|
|
|
|
if (restype == UNKNOWNOID)
|
|
tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
|
|
restype, TEXTOID, -1,
|
|
COERCION_IMPLICIT,
|
|
COERCE_IMPLICIT_CAST);
|
|
|
|
tle_list = lappend(tle_list, tle);
|
|
}
|
|
|
|
/*
|
|
* Now iterate through the ORDER BY clause. If we find a grouping element
|
|
* that matches the ORDER BY element, append the grouping element to the
|
|
* result set immediately. Otherwise, stop iterating. The effect of this
|
|
* is to look for a prefix of the ORDER BY list in the grouping clauses,
|
|
* and to move that prefix to the front of the GROUP BY.
|
|
*/
|
|
foreach(l, sortClause)
|
|
{
|
|
SortClause *sc = (SortClause *) lfirst(l);
|
|
ListCell *prev = NULL;
|
|
ListCell *tl;
|
|
bool found = false;
|
|
|
|
foreach(tl, tle_list)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(tl);
|
|
|
|
if (sc->tleSortGroupRef == tle->ressortgroupref)
|
|
{
|
|
GroupClause *gc;
|
|
|
|
tle_list = list_delete_cell(tle_list, tl, prev);
|
|
|
|
/* Use the sort clause's sorting information */
|
|
gc = make_group_clause(tle, *targetlist,
|
|
sc->sortop, sc->nulls_first);
|
|
result = lappend(result, gc);
|
|
found = true;
|
|
break;
|
|
}
|
|
|
|
prev = tl;
|
|
}
|
|
|
|
/* As soon as we've failed to match an ORDER BY element, stop */
|
|
if (!found)
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Now add any remaining elements of the GROUP BY list in the order we
|
|
* received them.
|
|
*
|
|
* XXX: are there any additional criteria to consider when ordering
|
|
* grouping clauses?
|
|
*/
|
|
foreach(l, tle_list)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(l);
|
|
GroupClause *gc;
|
|
Oid sort_op;
|
|
|
|
/*
|
|
* Avoid making duplicate grouplist entries. Note that we don't
|
|
* enforce a particular sortop here. Along with the copying of sort
|
|
* information above, this means that if you write something like
|
|
* "GROUP BY foo ORDER BY foo USING <<<", the GROUP BY operation
|
|
* silently takes on the equality semantics implied by the ORDER BY.
|
|
*/
|
|
if (targetIsInSortList(tle, InvalidOid, result))
|
|
continue;
|
|
|
|
sort_op = ordering_oper_opid(exprType((Node *) tle->expr));
|
|
gc = make_group_clause(tle, *targetlist, sort_op, false);
|
|
result = lappend(result, gc);
|
|
}
|
|
|
|
list_free(tle_list);
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* transformSortClause -
|
|
* transform an ORDER BY clause
|
|
*
|
|
* ORDER BY items will be added to the targetlist (as resjunk columns)
|
|
* if not already present, so the targetlist must be passed by reference.
|
|
*/
|
|
List *
|
|
transformSortClause(ParseState *pstate,
|
|
List *orderlist,
|
|
List **targetlist,
|
|
bool resolveUnknown)
|
|
{
|
|
List *sortlist = NIL;
|
|
ListCell *olitem;
|
|
|
|
foreach(olitem, orderlist)
|
|
{
|
|
SortBy *sortby = lfirst(olitem);
|
|
TargetEntry *tle;
|
|
|
|
tle = findTargetlistEntry(pstate, sortby->node,
|
|
targetlist, ORDER_CLAUSE);
|
|
|
|
sortlist = addTargetToSortList(pstate, tle,
|
|
sortlist, *targetlist,
|
|
sortby->sortby_dir,
|
|
sortby->sortby_nulls,
|
|
sortby->useOp,
|
|
resolveUnknown);
|
|
}
|
|
|
|
return sortlist;
|
|
}
|
|
|
|
/*
|
|
* transformDistinctClause -
|
|
* transform a DISTINCT or DISTINCT ON clause
|
|
*
|
|
* Since we may need to add items to the query's sortClause list, that list
|
|
* is passed by reference. Likewise for the targetlist.
|
|
*/
|
|
List *
|
|
transformDistinctClause(ParseState *pstate, List *distinctlist,
|
|
List **targetlist, List **sortClause)
|
|
{
|
|
List *result = NIL;
|
|
ListCell *slitem;
|
|
ListCell *dlitem;
|
|
|
|
/* No work if there was no DISTINCT clause */
|
|
if (distinctlist == NIL)
|
|
return NIL;
|
|
|
|
if (linitial(distinctlist) == NULL)
|
|
{
|
|
/* We had SELECT DISTINCT */
|
|
|
|
/*
|
|
* All non-resjunk elements from target list that are not already in
|
|
* the sort list should be added to it. (We don't really care what
|
|
* order the DISTINCT fields are checked in, so we can leave the
|
|
* user's ORDER BY spec alone, and just add additional sort keys to it
|
|
* to ensure that all targetlist items get sorted.)
|
|
*/
|
|
*sortClause = addAllTargetsToSortList(pstate,
|
|
*sortClause,
|
|
*targetlist,
|
|
true);
|
|
|
|
/*
|
|
* Now, DISTINCT list consists of all non-resjunk sortlist items.
|
|
* Actually, all the sortlist items had better be non-resjunk!
|
|
* Otherwise, user wrote SELECT DISTINCT with an ORDER BY item that
|
|
* does not appear anywhere in the SELECT targetlist, and we can't
|
|
* implement that with only one sorting pass...
|
|
*/
|
|
foreach(slitem, *sortClause)
|
|
{
|
|
SortClause *scl = (SortClause *) lfirst(slitem);
|
|
TargetEntry *tle = get_sortgroupclause_tle(scl, *targetlist);
|
|
|
|
if (tle->resjunk)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
|
|
errmsg("for SELECT DISTINCT, ORDER BY expressions must appear in select list")));
|
|
else
|
|
result = lappend(result, copyObject(scl));
|
|
}
|
|
}
|
|
else
|
|
{
|
|
/* We had SELECT DISTINCT ON (expr, ...) */
|
|
|
|
/*
|
|
* If the user writes both DISTINCT ON and ORDER BY, then the two
|
|
* expression lists must match (until one or the other runs out).
|
|
* Otherwise the ORDER BY requires a different sort order than the
|
|
* DISTINCT does, and we can't implement that with only one sort pass
|
|
* (and if we do two passes, the results will be rather
|
|
* unpredictable). However, it's OK to have more DISTINCT ON
|
|
* expressions than ORDER BY expressions; we can just add the extra
|
|
* DISTINCT values to the sort list, much as we did above for ordinary
|
|
* DISTINCT fields.
|
|
*
|
|
* Actually, it'd be OK for the common prefixes of the two lists to
|
|
* match in any order, but implementing that check seems like more
|
|
* trouble than it's worth.
|
|
*/
|
|
ListCell *nextsortlist = list_head(*sortClause);
|
|
|
|
foreach(dlitem, distinctlist)
|
|
{
|
|
TargetEntry *tle;
|
|
|
|
tle = findTargetlistEntry(pstate, lfirst(dlitem),
|
|
targetlist, DISTINCT_ON_CLAUSE);
|
|
|
|
if (nextsortlist != NULL)
|
|
{
|
|
SortClause *scl = (SortClause *) lfirst(nextsortlist);
|
|
|
|
if (tle->ressortgroupref != scl->tleSortGroupRef)
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_INVALID_COLUMN_REFERENCE),
|
|
errmsg("SELECT DISTINCT ON expressions must match initial ORDER BY expressions")));
|
|
result = lappend(result, copyObject(scl));
|
|
nextsortlist = lnext(nextsortlist);
|
|
}
|
|
else
|
|
{
|
|
*sortClause = addTargetToSortList(pstate, tle,
|
|
*sortClause, *targetlist,
|
|
SORTBY_DEFAULT,
|
|
SORTBY_NULLS_DEFAULT,
|
|
NIL, true);
|
|
|
|
/*
|
|
* Probably, the tle should always have been added at the end
|
|
* of the sort list ... but search to be safe.
|
|
*/
|
|
foreach(slitem, *sortClause)
|
|
{
|
|
SortClause *scl = (SortClause *) lfirst(slitem);
|
|
|
|
if (tle->ressortgroupref == scl->tleSortGroupRef)
|
|
{
|
|
result = lappend(result, copyObject(scl));
|
|
break;
|
|
}
|
|
}
|
|
if (slitem == NULL) /* should not happen */
|
|
elog(ERROR, "failed to add DISTINCT ON clause to target list");
|
|
}
|
|
}
|
|
}
|
|
|
|
return result;
|
|
}
|
|
|
|
/*
|
|
* addAllTargetsToSortList
|
|
* Make sure all non-resjunk targets in the targetlist are in the
|
|
* ORDER BY list, adding the not-yet-sorted ones to the end of the list.
|
|
* This is typically used to help implement SELECT DISTINCT.
|
|
*
|
|
* See addTargetToSortList for info about pstate and resolveUnknown inputs.
|
|
*
|
|
* Returns the updated ORDER BY list.
|
|
*/
|
|
List *
|
|
addAllTargetsToSortList(ParseState *pstate, List *sortlist,
|
|
List *targetlist, bool resolveUnknown)
|
|
{
|
|
ListCell *l;
|
|
|
|
foreach(l, targetlist)
|
|
{
|
|
TargetEntry *tle = (TargetEntry *) lfirst(l);
|
|
|
|
if (!tle->resjunk)
|
|
sortlist = addTargetToSortList(pstate, tle,
|
|
sortlist, targetlist,
|
|
SORTBY_DEFAULT,
|
|
SORTBY_NULLS_DEFAULT,
|
|
NIL, resolveUnknown);
|
|
}
|
|
return sortlist;
|
|
}
|
|
|
|
/*
|
|
* addTargetToSortList
|
|
* If the given targetlist entry isn't already in the ORDER BY list,
|
|
* add it to the end of the list, using the given sort ordering info.
|
|
*
|
|
* If resolveUnknown is TRUE, convert TLEs of type UNKNOWN to TEXT. If not,
|
|
* do nothing (which implies the search for a sort operator will fail).
|
|
* pstate should be provided if resolveUnknown is TRUE, but can be NULL
|
|
* otherwise.
|
|
*
|
|
* Returns the updated ORDER BY list.
|
|
*/
|
|
List *
|
|
addTargetToSortList(ParseState *pstate, TargetEntry *tle,
|
|
List *sortlist, List *targetlist,
|
|
SortByDir sortby_dir, SortByNulls sortby_nulls,
|
|
List *sortby_opname, bool resolveUnknown)
|
|
{
|
|
Oid restype = exprType((Node *) tle->expr);
|
|
Oid sortop;
|
|
Oid cmpfunc;
|
|
bool reverse;
|
|
|
|
/* if tlist item is an UNKNOWN literal, change it to TEXT */
|
|
if (restype == UNKNOWNOID && resolveUnknown)
|
|
{
|
|
tle->expr = (Expr *) coerce_type(pstate, (Node *) tle->expr,
|
|
restype, TEXTOID, -1,
|
|
COERCION_IMPLICIT,
|
|
COERCE_IMPLICIT_CAST);
|
|
restype = TEXTOID;
|
|
}
|
|
|
|
/* determine the sortop */
|
|
switch (sortby_dir)
|
|
{
|
|
case SORTBY_DEFAULT:
|
|
case SORTBY_ASC:
|
|
sortop = ordering_oper_opid(restype);
|
|
reverse = false;
|
|
break;
|
|
case SORTBY_DESC:
|
|
sortop = reverse_ordering_oper_opid(restype);
|
|
reverse = true;
|
|
break;
|
|
case SORTBY_USING:
|
|
Assert(sortby_opname != NIL);
|
|
sortop = compatible_oper_opid(sortby_opname,
|
|
restype,
|
|
restype,
|
|
false);
|
|
/*
|
|
* Verify it's a valid ordering operator, and determine
|
|
* whether to consider it like ASC or DESC.
|
|
*/
|
|
if (!get_compare_function_for_ordering_op(sortop,
|
|
&cmpfunc, &reverse))
|
|
ereport(ERROR,
|
|
(errcode(ERRCODE_WRONG_OBJECT_TYPE),
|
|
errmsg("operator %s is not a valid ordering operator",
|
|
strVal(llast(sortby_opname))),
|
|
errhint("Ordering operators must be \"<\" or \">\" members of btree operator families.")));
|
|
break;
|
|
default:
|
|
elog(ERROR, "unrecognized sortby_dir: %d", sortby_dir);
|
|
sortop = InvalidOid; /* keep compiler quiet */
|
|
reverse = false;
|
|
break;
|
|
}
|
|
|
|
/* avoid making duplicate sortlist entries */
|
|
if (!targetIsInSortList(tle, sortop, sortlist))
|
|
{
|
|
SortClause *sortcl = makeNode(SortClause);
|
|
|
|
sortcl->tleSortGroupRef = assignSortGroupRef(tle, targetlist);
|
|
|
|
sortcl->sortop = sortop;
|
|
|
|
switch (sortby_nulls)
|
|
{
|
|
case SORTBY_NULLS_DEFAULT:
|
|
/* NULLS FIRST is default for DESC; other way for ASC */
|
|
sortcl->nulls_first = reverse;
|
|
break;
|
|
case SORTBY_NULLS_FIRST:
|
|
sortcl->nulls_first = true;
|
|
break;
|
|
case SORTBY_NULLS_LAST:
|
|
sortcl->nulls_first = false;
|
|
break;
|
|
default:
|
|
elog(ERROR, "unrecognized sortby_nulls: %d", sortby_nulls);
|
|
break;
|
|
}
|
|
|
|
sortlist = lappend(sortlist, sortcl);
|
|
}
|
|
|
|
return sortlist;
|
|
}
|
|
|
|
/*
|
|
* assignSortGroupRef
|
|
* Assign the targetentry an unused ressortgroupref, if it doesn't
|
|
* already have one. Return the assigned or pre-existing refnumber.
|
|
*
|
|
* 'tlist' is the targetlist containing (or to contain) the given targetentry.
|
|
*/
|
|
Index
|
|
assignSortGroupRef(TargetEntry *tle, List *tlist)
|
|
{
|
|
Index maxRef;
|
|
ListCell *l;
|
|
|
|
if (tle->ressortgroupref) /* already has one? */
|
|
return tle->ressortgroupref;
|
|
|
|
/* easiest way to pick an unused refnumber: max used + 1 */
|
|
maxRef = 0;
|
|
foreach(l, tlist)
|
|
{
|
|
Index ref = ((TargetEntry *) lfirst(l))->ressortgroupref;
|
|
|
|
if (ref > maxRef)
|
|
maxRef = ref;
|
|
}
|
|
tle->ressortgroupref = maxRef + 1;
|
|
return tle->ressortgroupref;
|
|
}
|
|
|
|
/*
|
|
* targetIsInSortList
|
|
* Is the given target item already in the sortlist?
|
|
* If sortop is not InvalidOid, also test for a match to the sortop.
|
|
*
|
|
* It is not an oversight that this function ignores the nulls_first flag.
|
|
* We check sortop when determining if an ORDER BY item is redundant with
|
|
* earlier ORDER BY items, because it's conceivable that "ORDER BY
|
|
* foo USING <, foo USING <<<" is not redundant, if <<< distinguishes
|
|
* values that < considers equal. We need not check nulls_first
|
|
* however, because a lower-order column with the same sortop but
|
|
* opposite nulls direction is redundant. Also, we can consider
|
|
* ORDER BY foo ASC, foo DESC redundant, so check for a commutator match.
|
|
*
|
|
* Works for both SortClause and GroupClause lists. Note that the main
|
|
* reason we need this routine (and not just a quick test for nonzeroness
|
|
* of ressortgroupref) is that a TLE might be in only one of the lists.
|
|
*/
|
|
bool
|
|
targetIsInSortList(TargetEntry *tle, Oid sortop, List *sortList)
|
|
{
|
|
Index ref = tle->ressortgroupref;
|
|
ListCell *l;
|
|
|
|
/* no need to scan list if tle has no marker */
|
|
if (ref == 0)
|
|
return false;
|
|
|
|
foreach(l, sortList)
|
|
{
|
|
SortClause *scl = (SortClause *) lfirst(l);
|
|
|
|
if (scl->tleSortGroupRef == ref &&
|
|
(sortop == InvalidOid ||
|
|
sortop == scl->sortop ||
|
|
sortop == get_commutator(scl->sortop)))
|
|
return true;
|
|
}
|
|
return false;
|
|
}
|