RE: Questions about btree_gin vs btree_gist for low cardinalitycolumns - Mailing list pgsql-general

From Steven Winfield
Subject RE: Questions about btree_gin vs btree_gist for low cardinalitycolumns
Date
Msg-id E9FA92C2921F31408041863B74EE4C2001BD706B65@ccpmaildag02.cantab.local
Whole thread Raw
In response to Re: Questions about btree_gin vs btree_gist for low cardinality columns  (Morris de Oryx <morrisdeoryx@gmail.com>)
List pgsql-general
> In the case of a single column with a small set of distinct values over a large set of rows, how would a Bloom filter
bepreferable to, say, a GIN index on an integer value? 
 

I don't think it would - it's probably better suited to the multi-column case you described previously.

> I have to say, this is actually a good reminder in my case. We've got a lot of small-distinct-values-big-rows
columns.For example, "server_id", "company_id", "facility_id", and so on. Only a handful of parent keys with many
millionsof related rows. Perhaps it would be conceivable to use a Bloom index to do quick lookups on combinations of
suchvalues within the same table. I haven't tried Bloom indexes in Postgres, this might be worth some experimenting.
 

Yes, this is more like the use case I was thinking of.

Steve.

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