On Tue, Sep 24, 2013 at 7:14 AM, Stephen Frost <sfr...@snowman.net> wrote: >> Of course, you don't need citext, or any other data type with a loose >> notion of equality, to generate that sort of problem: > [...] >> rhaas=# set datestyle = 'german'; >> SET > > I'm talking about *planner differences* changing the results. If we've > got a ton of cases where a different plan means different output, then > we've got some serious problems. I'd argue that it's pretty darn clear > that datestyle is going to be a *slightly* different animal. My example > doesn't *require* changing any GUCs, it was just expedient for > illustration.
I'm completely confused, here. What's so special about planner differences? Obviously, there are tons of queries that can produce different results based on planner differences, but materialized views didn't create that problem and they aren't responsible for solving it. Also, even restricting ourselves to planner differences, there's no particular link between the behavior of the type's equality operator and whether or not the query always produces the same results. For example, let's consider good old text. rhaas=# create table tag_data (id integer, tag text, userid text, primary key (id, tag)); CREATE TABLE rhaas=# insert into tag_data values (1, 'foo', 'tom'), (1, 'bar', 'dick'), (2, 'baz', 'harry'); INSERT 0 3 rhaas=# select id, string_agg(tag||':'||userid, ', ') tags from tag_data group by 1; id | tags ----+------------------- 1 | foo:tom, bar:dick 2 | baz:harry (2 rows) rhaas=# set enable_seqscan=false; SET rhaas=# select id, string_agg(tag||':'||userid, ', ') tags from tag_data group by 1; id | tags ----+------------------- 1 | bar:dick, foo:tom 2 | baz:harry (2 rows) Now texteq() is just a glorified version of memcmp(), so what does this complaint possibly have to do with Kevin's patch, or even materialized views in general? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
