| From: | Kevin Grittner <kgrittn(at)ymail(dot)com> |
|---|---|
| To: | "Jonathan S(dot) Katz" <jonathan(dot)katz(at)excoventures(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: IS NOT DISTINCT FROM + Indexing |
| Date: | 2014-07-23 17:33:50 |
| Message-ID: | 1406136830.49529.YahooMailNeo@web122302.mail.ne1.yahoo.com |
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| Lists: | pgsql-hackers |
Jonathan S. Katz <jonathan(dot)katz(at)excoventures(dot)com> wrote:
> before embarking on something laborious (as even just indexing
> is nontrivial), I think it would be good to figure out how people
> are using IS [NOT] DISTINCT FROM and if there is interest in
> having it be indexable, let alone used in a JOIN optimization.
> It could become a handy tool to simplify the SQL in queries that
> are returning a lot of NULL / NOT NULL data mixed together.
To prevent subtle inconsistencies, I think we would need to limit
support to data types with a btree opclass which uses "=" as the
equality operator on indexes using that opclass (either by default
or explicitly). That limitation would still allow a lot of useful
cases.
--
Kevin Grittner
EDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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