Thread: Determine if an index is a B-tree, GIST, or something else?
Is there any way to determine, by querying pg_index and other pg_* tables, whether an index was created as `USING something`? I've already got a big query joining pg_class, pg_index, etc. to pull out various attributes about the indexes in my database, and I'd like to include whether it's a GIST index, a B-Tree, or whatever was in the USING clause when the index was created.
I see that I can join with the pg_opclass table, but that has 100+ rows, and I'm not sure how to tell what is a B-Tree and what isn't. Any advice?
Thanks,
Paul
--
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Pulchritudo splendor veritatis.
I see that I can join with the pg_opclass table, but that has 100+ rows, and I'm not sure how to tell what is a B-Tree and what isn't. Any advice?
Thanks,
Paul
--
_________________________________
Pulchritudo splendor veritatis.
On Jan 17, 2013, at 10:03 AM, Paul Jungwirth wrote: > Is there any way to determine, by querying pg_index and other pg_* tables, whether an index was created as `USING something`?I've already got a big query joining pg_class, pg_index, etc. to pull out various attributes about the indexesin my database, and I'd like to include whether it's a GIST index, a B-Tree, or whatever was in the USING clause whenthe index was created. > > I see that I can join with the pg_opclass table, but that has 100+ rows, and I'm not sure how to tell what is a B-Treeand what isn't. Any advice? pg_indexes (not pg_index) seems to have the data you're looking for, unless I misunderstood the question.
Hi, On Thu, 2013-01-17 at 10:03 -0800, Paul Jungwirth wrote: > Is there any way to determine, by querying pg_index and other pg_* tables, > whether an index was created as `USING something`? I've already got a big > query joining pg_class, pg_index, etc. to pull out various attributes about > the indexes in my database, and I'd like to include whether it's a GIST > index, a B-Tree, or whatever was in the USING clause when the index was > created. You can either look at pg_indexes, or use pg_get_indexdef(oid) function, where oid is index's oid. Regards, -- Devrim GÜNDÜZ Principal Systems Engineer @ EnterpriseDB: http://www.enterprisedb.com PostgreSQL Danışmanı/Consultant, Red Hat Certified Engineer Community: devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr http://www.gunduz.org Twitter: http://twitter.com/devrimgunduz
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> pg_indexes (not pg_index) seems to have the data you're looking for, unless I misunderstood the question.
That is a lovely table, but I want to get each attribute individually, without having to parse the CREATE INDEX .... statement.It looks like I was almost there with pg_opclass. This will tell me what kind of index is required for each operator:
select opcnamespace, opcname, amname from pg_opclass o, pg_am a where o.opcmethod = a.oid;
Thanks,
Paul
Paul Jungwirth <pj@illuminatedcomputing.com> writes:
> So in principle I can just join pg_index, pg_opclass, and pg_am to get my
> answer. It's actually a little more complicated because pg_index.indclass
> is not an oid, but an oidvector, with one entry for each column in the
> index. But unless I'm mistaken, every column in given index must use the
> same index method. For instance in a 2-column index you can't say `USING
> (btree, gist)`. So I can join with `pg_index.indclass[0] = pg_opclass.oid`.
> Can anyone confirm for me that for any index, every pg_opclass it uses will
> have the same pg_am?
pg_opclass seems the hard way --- just use pg_class.relam, which is the
OID of the index's AM. (And yes, all the opclasses had better match
that.)
regards, tom lane
> pg_opclass seems the hard way --- just use pg_class.relam, which is
> the OID of the index's AM.
Ah, that works like a charm. Thanks!
Paul> the OID of the index's AM.
Ah, that works like a charm. Thanks!
Hi, On Thu, 2013-01-17 at 10:03 -0800, Paul Jungwirth wrote: > Is there any way to determine, by querying pg_index and other pg_* tables, > whether an index was created as `USING something`? I've already got a big > query joining pg_class, pg_index, etc. to pull out various attributes about > the indexes in my database, and I'd like to include whether it's a GIST > index, a B-Tree, or whatever was in the USING clause when the index was > created. You can either look at pg_indexes, or use pg_get_indexdef(oid) function, where oid is index's oid. Regards, -- Devrim GÜNDÜZ Principal Systems Engineer @ EnterpriseDB: http://www.enterprisedb.com PostgreSQL Danışmanı/Consultant, Red Hat Certified Engineer Community: devrim~PostgreSQL.org, devrim.gunduz~linux.org.tr http://www.gunduz.org Twitter: http://twitter.com/devrimgunduz