postgres.git / summary / log / commit / refs

commit    ceb5db69d4fbbd327a2ae2d589069008bbe57bb6
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Sat Apr 05 01:58:20 2008 +0000
First released in: 8.4.0, 7.4.20, 8.0.16, 8.1.12, 8.2.8, 8.3.2

    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 | 12 +++++++++++-
 src/include/access/attnum.h         |  3 ++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/src/backend/parser/parse_relation.c b/src/backend/parser/parse_relation.c
index 6d5fb189406..68855a70074 100644
--- a/src/backend/parser/parse_relation.c
+++ b/src/backend/parser/parse_relation.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.130 2008/01/01 19:45:51 momjian Exp $
+ *	  $PostgreSQL: pgsql/src/backend/parser/parse_relation.c,v 1.131 2008/04/05 01:58:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1025,6 +1025,16 @@ 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 c1ec4947ffe..033f2ee786d 100644
--- a/src/include/access/attnum.h
+++ b/src/include/access/attnum.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/access/attnum.h,v 1.24 2008/01/01 19:45:56 momjian Exp $
+ * $PostgreSQL: pgsql/src/include/access/attnum.h,v 1.25 2008/04/05 01:58:20 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -21,6 +21,7 @@
 typedef int16 AttrNumber;
 
 #define InvalidAttrNumber		0
+#define MaxAttrNumber			32767
 
 /* ----------------
  *		support macros


[parent: 2a1cf97c2293]