Re: Index Usage and Running Times by FullTextSearch with prefix matching

Tom Lane-2 wrote
> rawi <

> only4com@

> > writes:
>> And querying: FTS with prefix matching:
> 
>> SELECT count(a)
>> FROM t1
>> WHERE a_tsvector @@ to_tsquery('aaa:* & b:* & c:* & d:*')
> 
>> (RESULT: count: 619)
>> Total query runtime: 21266 ms.
> 
> FWIW, I get fairly decent performance for cases like this in HEAD
> (at least with a GIN index; GIST seems much less able to do well with
> short prefixes).  What PG version are you testing?

Last tests with PG 9.2:

Whereas the "whole words" full text search stays at ~350ms for 900,000
records I tryed the number of records, which are becoming to make one
suffer, querying for prefixes:

RECORDS        RUNTIME (ms)
10,000        13
100,000        81
200,000        172
400,000        7,284
900,000        20,888

Regards, Rawi




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