postgres.git / summary / log / commit / refs

commit    66061077155d68463ec00604ba7d6f0ae69716e8
Author:   Tomas Vondra <tomas.vondra@postgresql.org>
Date:     Sun Sep 19 22:34:57 2021 +0000

    Disallow extended statistics on system columns
    
    Since introduction of extended statistics, we've disallowed references
    to system columns. So for example
    
        CREATE STATISTICS s ON ctid FROM t;
    
    would fail. But with extended statistics on expressions, it was possible
    to work around this limitation quite easily
    
        CREATE STATISTICS s ON (ctid::text) FROM t;
    
    This is an oversight in a4d75c86bf, fixed by adding a simple check.
    Backpatch to PostgreSQL 14, where support for extended statistics on
    expressions was introduced.
    
    Backpatch-through: 14
    Discussion: https://postgr.es/m/20210816013255.GS10479%40telsasoft.com


 src/backend/commands/statscmds.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/src/backend/commands/statscmds.c b/src/backend/commands/statscmds.c
index 651b85ccc91..c4b9bd29ec9 100644
--- a/src/backend/commands/statscmds.c
+++ b/src/backend/commands/statscmds.c
@@ -287,9 +287,24 @@ CreateStatistics(CreateStatsStmt *stmt)
 			Node	   *expr = selem->expr;
 			Oid			atttype;
 			TypeCacheEntry *type;
+			Bitmapset  *attnums = NULL;
+			int			k;
 
 			Assert(expr != NULL);
 
+			/* Disallow expressions referencing system attributes. */
+			pull_varattnos(expr, 1, &attnums);
+
+			k = -1;
+			while ((k = bms_next_member(attnums, k)) >= 0)
+			{
+				AttrNumber	attnum = k + FirstLowInvalidHeapAttributeNumber;
+				if (attnum <= 0)
+					ereport(ERROR,
+						(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+						 errmsg("statistics creation on system columns is not supported")));
+			}
+
 			/*
 			 * Disallow data types without a less-than operator.
 			 *


[parent: 2a9a34c3100d]