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Commitceb5db6

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Defend against JOINs having more than 32K columns altogether. We cannot
currently support this because we must be able to build Vars referencingjoin columns, and varattno is only 16 bits wide. Perhaps this should beimproved in future, but considering that it never came up before, I'm notsure the problem is worth much effort. Per bug #4070 from MarcelloCeschia.The problem seems largely academic in 8.0 and 7.4, because they have(different) O(N^2) performance issues with such wide joins, butback-patch all the way anyway.
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2 files changed

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-2
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2 files changed

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‎src/backend/parser/parse_relation.c

Lines changed: 11 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.130 2008/01/01 19:45:51 momjian Exp $
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* $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.131 2008/04/05 01:58:20 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -1025,6 +1025,16 @@ addRangeTableEntryForJoin(ParseState *pstate,
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Alias*eref;
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intnumaliases;
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/*
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* Fail if join has too many columns --- we must be able to reference
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* any of the columns with an AttrNumber.
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*/
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if (list_length(aliasvars)>MaxAttrNumber)
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ereport(ERROR,
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(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
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errmsg("joins can have at most %d columns",
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MaxAttrNumber)));
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rte->rtekind=RTE_JOIN;
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rte->relid=InvalidOid;
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rte->subquery=NULL;

‎src/include/access/attnum.h

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
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* Portions Copyright (c) 1996-2008, 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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* $PostgreSQL: pgsql/src/include/access/attnum.h,v 1.24 2008/01/01 19:45:56 momjian Exp $
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* $PostgreSQL: pgsql/src/include/access/attnum.h,v 1.25 2008/04/05 01:58:20 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
@@ -21,6 +21,7 @@
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typedefint16AttrNumber;
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#defineInvalidAttrNumber0
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#defineMaxAttrNumber32767
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/* ----------------
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*support macros

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