From b5febc1d125cac37c626cb7c96936db6839ec733 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 1 Mar 2018 15:35:03 -0500 Subject: Fix IOS planning when only some index columns can return an attribute. Since 9.5, it's possible that some but not all columns of an index support returning the indexed value for index-only scans. If the same indexed column appears in index columns that behave both ways, check_index_only() supposed that it'd be OK to do an index-only scan testing that column; but that fails if we have to recheck the indexed condition on one of the columns that doesn't support this. In principle we could make this work by remapping the recheck expressions to pull the value from a column that does support returning the indexed value. But such cases are so weird and rare that, at least for now, it doesn't seem worth the trouble. Instead, just teach check_index_only that a value is returnable only if all the index columns containing it are returnable, rather than any of them. Per report from David Pereiro Lagares. Back-patch to 9.5 where the possibility of this situation appeared. Kyotaro Horiguchi Discussion: https://postgr.es/m/1516210494.1798.16.camel@nlpgo.com --- contrib/btree_gist/sql/inet.sql | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) (limited to 'contrib/btree_gist/sql') diff --git a/contrib/btree_gist/sql/inet.sql b/contrib/btree_gist/sql/inet.sql index 328846c0a38..08952f2c449 100644 --- a/contrib/btree_gist/sql/inet.sql +++ b/contrib/btree_gist/sql/inet.sql @@ -29,3 +29,21 @@ SELECT count(*) FROM inettmp WHERE a = '89.225.196.191'::inet; SELECT count(*) FROM inettmp WHERE a >= '89.225.196.191'::inet; SELECT count(*) FROM inettmp WHERE a > '89.225.196.191'::inet; + +VACUUM inettmp; + +-- gist_inet_ops lacks a fetch function, so this should not be index-only scan +EXPLAIN (COSTS OFF) +SELECT count(*) FROM inettmp WHERE a = '89.225.196.191'::inet; + +SELECT count(*) FROM inettmp WHERE a = '89.225.196.191'::inet; + +DROP INDEX inetidx; + +CREATE INDEX ON inettmp USING gist (a gist_inet_ops, a inet_ops); + +-- likewise here (checks for core planner bug) +EXPLAIN (COSTS OFF) +SELECT count(*) FROM inettmp WHERE a = '89.225.196.191'::inet; + +SELECT count(*) FROM inettmp WHERE a = '89.225.196.191'::inet; -- cgit v1.2.3