On Wed, Jun 22, 2016 at 4:11 AM, Amit Langote <langote_amit...@lab.ntt.co.jp> wrote: >> In an outer join we have to differentiate between a row being null (because >> there was no joining row on nullable side) and a non-null row with all >> column values being null. If we cast the whole-row expression to a text >> e.g. r.*::text and test the resultant value for nullness, it gives us what >> we want. A null row casted to text is null and a row with all null values >> casted to text is not null. > > You are right. There may be non-null rows with all columns null which are > handled wrongly (as Rushabh reports) and the hack I proposed is not right > for. Especially if from non-nullable side as in the reported case, NULL > test for such a whole-row-var would produce the wrong result. Casting to > text as your patch does produces the correct behavior.
I agree, but I think we'd better cast to pg_catalog.text instead, just to be safe. Committed that way. -- 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
