Re: Insight into indexes? (or inverting then externally) - Mailing list pgsql-general

What's the performance like?  I have a similar table (about 3 million
names, and I get great (sub second) performance when searching on a name
doing a select distinct name where name like 'smith john%'.

Have you run an EXPLAIN on the query you are doing?  Is it even using
your indexes?

-Pete

Oleg Bartunov wrote:

>Joshua,
>
>what kind of queries do you need ? Do you need to perform full text search ?
>
>    Oleg
>On Wed, 5 Jun 2002, Joshua b. Jore wrote:
>
>>So far as I can tell indexes in PostgreSQL are fairly opaque things. The
>>planner may or may not decide to use them, exactly what they contain is
>>largely unknown (unless I want to read the source), how PostgreSQL uses
>>them and in which cases a btree index is better than a hash index.
>>
>>Foo. If I've managed to just skip over a manual section please whack me
>>with a 2x4. If I haven't then any links would be appreciated. I'm
>>considering how best to provide a fast index on a 2.5 million row table
>>(all the voters in Minnesota). Since I can't see what PostgreSQL is doing
>>with the indexes I have to wonder if I can eke out some more performance
>>by just indexing the record's id numbers (a usually numeric char(10) -
>>blame the MN Secretary of State for the "mostly" part) in PostgreSQL and
>>then sticking an inverted index into say... BerkeleyDB.
>>
>>Records might look like where it's obvious that the ids store nicely..
>>
>>lname.db
>>'Jore' => '12345678901234567890'
>>
>>So before I jump down this rabbit hole is there anything I can do to
>>PostgreSQL to see what is in the indexes and if there is any way to tweak
>>them? And when is a hash index preferrable to a btree index? Or that other
>>index type that I don't remember the name of.
>>
>>Joshua b. Jore ; http://www.greentechnologist.org ; 1121 1233 1311 200
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>>
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>
>    Regards,
>        Oleg
>_____________________________________________________________
>Oleg Bartunov, sci.researcher, hostmaster of AstroNet,
>Sternberg Astronomical Institute, Moscow University (Russia)
>Internet: oleg@sai.msu.su, http://www.sai.msu.su/~megera/
>phone: +007(095)939-16-83, +007(095)939-23-83
>
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