| From: | Andrew Gierth <andrew(at)tao11(dot)riddles(dot)org(dot)uk> |
|---|---|
| To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
| Cc: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Kevin Grittner <kgrittn(at)gmail(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, Peter Eisentraut <peter(dot)eisentraut(at)2ndquadrant(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, "pgsql-hackers\(at)postgresql(dot)org" <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: No longer possible to query catalogs for index capabilities? |
| Date: | 2016-08-10 14:52:16 |
| Message-ID: | 87a8gkr8fu.fsf@news-spur.riddles.org.uk |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
Updated patch. Changes:
- returns NULL rather than "cache lookup failed"
- added pg_index_column_has_property (incl. docs)
- added regression tests
Not changed / need consideration:
- this still has everything in amapi.c rather than creating any new
files. Also, the regression tests are in create_index.sql for lack
of any obviously better place.
The list of column properties is:
ordered - (same as "amcanorder" AM capability)
ordered_asc
ordered_desc
ordered_nulls_first
ordered_nulls_last
If "ordered" is true then exactly one of _asc/_desc and exactly one of
_nulls_first/_last will be true; if "ordered" is false then all the
others will be false too. The intended usage is something like
CASE WHEN pg_index_column_has_property(idx, attno, 'ordered_asc')
THEN 'ASC'
WHEN pg_index_column_has_property(idx, attno, 'ordered_desc')
THEN 'DESC'
ELSE '' -- or NULL
END
Comments?
--
Andrew (irc:RhodiumToad)
| Attachment | Content-Type | Size |
|---|---|---|
| amcap2.patch | text/x-patch | 21.9 KB |
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Heikki Linnakangas | 2016-08-10 15:09:25 | Re: Proposal for CSN based snapshots |
| Previous Message | Tom Lane | 2016-08-10 14:51:24 | Re: Proposal for CSN based snapshots |