From c9eeef2a15c02ff7dd2bf3251dbee925b050fc0f Mon Sep 17 00:00:00 2001 From: Tomas Vondra Date: Mon, 20 Sep 2021 00:34:57 +0200 Subject: [PATCH] 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 78917844dee..afe6744e237 100644 --- a/src/backend/commands/statscmds.c +++ b/src/backend/commands/statscmds.c @@ -288,9 +288,24 @@ 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. *