From 140c989238685df6e2961977a1d966d7835d46b7 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 5 Apr 2008 01:58:42 +0000 Subject: [PATCH] Defend against JOINs having more than 32K columns altogether. We cannot currently support this because we must be able to build Vars referencing join columns, and varattno is only 16 bits wide. Perhaps this should be improved in future, but considering that it never came up before, I'm not sure the problem is worth much effort. Per bug #4070 from Marcello Ceschia. The problem seems largely academic in 8.0 and 7.4, because they have (different) O(N^2) performance issues with such wide joins, but back-patch all the way anyway. --- src/backend/parser/parse_relation.c | 10 ++++++++++ src/include/access/attnum.h | 1 + 2 files changed, 11 insertions(+) diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c index 90b0627a32..5b552096f4 100644 --- a/src/backend/parser/parse_relation.c +++ b/src/backend/parser/parse_relation.c @@ -935,6 +935,16 @@ addRangeTableEntryForJoin(ParseState *pstate, Alias *eref; int numaliases; + /* + * Fail if join has too many columns --- we must be able to reference + * any of the columns with an AttrNumber. + */ + if (list_length(aliasvars) > MaxAttrNumber) + ereport(ERROR, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("joins can have at most %d columns", + MaxAttrNumber))); + rte->rtekind = RTE_JOIN; rte->relid = InvalidOid; rte->subquery = NULL; diff --git a/src/include/access/attnum.h b/src/include/access/attnum.h index 5de97fc04a..4cd97c060e 100644 --- a/src/include/access/attnum.h +++ b/src/include/access/attnum.h @@ -21,6 +21,7 @@ typedef int16 AttrNumber; #define InvalidAttrNumber 0 +#define MaxAttrNumber 32767 /* ---------------- * support macros -- 2.39.5