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UNION work for UNION ALL and other union stuff.

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This commit is contained in:
Bruce Momjian
1997-12-27 06:41:41 +00:00
parent 2730c4a45c
commit 4ce24c8aa9
8 changed files with 178 additions and 84 deletions
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69
src/backend/parser/analyze.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.56 1997/12/24 06:06:18 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/parser/analyze.c,v 1.57 1997/12/27 06:41:26 momjian Exp $
*
*-------------------------------------------------------------------------
*/
@ -839,16 +839,75 @@ transformSelectStmt(ParseState *pstate, RetrieveStmt *stmt)
if (pstate->p_numAgg > 0)
finalizeAggregates(pstate, qry);
qry->unionall = stmt->unionall; /* in child, so unionClause may be false */
if (stmt->unionClause)
{
List *ulist = NIL;
QueryTreeList *qlist;
int i;
int i, last_union = -1;
bool union_all_found = false, union_found = false;
qlist = parse_analyze(stmt->unionClause);
/*
* Do we need to split up our unions because we have UNION
* and UNION ALL?
*/
for (i=0; i < qlist->len; i++)
ulist = lappend(ulist, qlist->qtrees[i]);
qry->unionClause = ulist;
{
if (qlist->qtrees[i]->unionall)
union_all_found = true;
else
{
union_found = true;
last_union = i;
}
}
/* A trailing UNION negates the affect of earlier UNION ALLs */
if (!union_all_found ||
!union_found ||
/* last entry is a UNION */
!qlist->qtrees[qlist->len-1]->unionall)
{
for (i=0; i < qlist->len; i++)
ulist = lappend(ulist, qlist->qtrees[i]);
qry->unionClause = ulist;
}
else
{
List *union_list = NIL;
Query *hold_qry;
/*
* We have mixed unions and non-unions, so we concentrate on
* the last UNION in the list.
*/
for (i=0; i <= last_union; i++)
{
qlist->qtrees[i]->unionall = false; /*make queries consistent*/
union_list = lappend(union_list, qlist->qtrees[i]);
}
/*
* Make the first UNION ALL after the last UNION our new
* top query
*/
hold_qry = qry;
qry = qlist->qtrees[last_union + 1];
qry->unionClause = lcons(hold_qry, NIL); /* UNION queries */
hold_qry->unionall = true; /* UNION ALL this into other queries */
hold_qry->unionClause = union_list;
/*
* The first UNION ALL after the last UNION is our anchor,
* we skip it.
*/
for (i=last_union + 2; i < qlist->len; i++)
/* all queries are UNION ALL */
qry->unionClause = lappend(qry->unionClause, qlist->qtrees[i]);
}
}
else
qry->unionClause = NULL;