Re: Searching GIN-index (FTS) and sort by timestamp-column - Mailing list pgsql-performance
På onsdag 16. mars 2016 kl. 14:53:04, skrev Andreas Joseph Krogh <andreas@visena.com>:
På onsdag 16. mars 2016 kl. 14:37:27, skrev Tom Lane <tgl@sss.pgh.pa.us>:Andreas Joseph Krogh <andreas@visena.com> writes:
> 1. Why isnt' folder_id part of the index-cond?
Because a GIN index is useless for sorting.
> 2. Is there a way to make it use the (same) index to sort by
> received_timestamp?
No.
> 3. Using a GIN-index, is there a way to use the index at all for sorting?
No.
> 4. It doesn't seem like ts_rank uses the index for sorting either.
Same reason.
regards, tom laneSo it's basically impossible to use FTS/GIN with sorting on large datasets?Are there any plans to improve this situation?Thanks.
This paper talks about ORDER BY optimizations for FTS (starting at slide 6 and 7):
http://www.sai.msu.su/~megera/postgres/talks/Next%20generation%20of%20GIN.pdf
This indicates some work is being done in this area.
Oleg, if you're listening, do you guys have any exiting news regarding this?
-- 
Andreas Joseph Krogh
CTO / Partner - Visena AS
Mobile: +47 909 56 963
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