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Extend CTE patch to support recursive UNION (ie, without ALL). The

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implementation uses an in-memory hash table, so it will poop out for very
large recursive results ... but the performance characteristics of a
sort-based implementation would be pretty unpleasant too.
This commit is contained in:
Tom Lane
2008-10-07 19:27:04 +00:00
parent 059349be0c
commit 0d115dde82
13 changed files with 345 additions and 74 deletions
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10
src/backend/parser/parse_cte.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/parser/parse_cte.c,v 2.2 2008/10/05 22:50:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/parser/parse_cte.c,v 2.3 2008/10/07 19:27:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -601,11 +601,11 @@ checkWellFormedRecursion(CteState *cstate)
if (!cte->cterecursive)
continue;
/* Must have top-level UNION ALL */
if (stmt->op != SETOP_UNION || !stmt->all)
/* Must have top-level UNION */
if (stmt->op != SETOP_UNION)
ereport(ERROR,
(errcode(ERRCODE_INVALID_RECURSION),
errmsg("recursive query \"%s\" does not have the form non-recursive-term UNION ALL recursive-term",
errmsg("recursive query \"%s\" does not have the form non-recursive-term UNION [ALL] recursive-term",
cte->ctename),
parser_errposition(cstate->pstate, cte->location)));
@ -628,7 +628,7 @@ checkWellFormedRecursion(CteState *cstate)
elog(ERROR, "missing recursive reference");
/*
* Disallow ORDER BY and similar decoration atop the UNION ALL.
* Disallow ORDER BY and similar decoration atop the UNION.
* These don't make sense because it's impossible to figure out what
* they mean when we have only part of the recursive query's results.
* (If we did allow them, we'd have to check for recursive references