Re: Updated RUM-index and support for bigint as part of index

[Oleg Bartunov <obartunov@xxxxxxxxx>]

On Tue, Aug 2, 2016 at 9:08 PM, Andreas Joseph Krogh <andreas@xxxxxxxxxx> wrote:

Hi.

 

I see the RUM-index is updated, which is great!

 

I wonder, to be able to sort by timestamp one has to create the index like this:

 

CREATE INDEX rumidx ON origo_email_delivery USING rum (fts_all rum_tsvector_timestamp_ops, received_timestamp) 
    WITH (attach = 'received_timestamp', TO = 'fts_all', order_by_attach = TRUE );

Then, to be able to use the index for sorting by the "received_timestamp"-column one has to issue a query like this:

EXPLAIN ANALYZE SELECT
                    del.entity_id,
                    del.subject,
                    del.received_timestamp,
                    fts_all <=> to_tsquery('simple', 'andreas&kr') AS rank
                FROM origo_email_delivery del
                WHERE del.fts_all @@ to_tsquery('simple', 'andreas&kr')
                ORDER BY '2000-01-01' :: TIMESTAMP <=> del.received_timestamp
                LIMIT 10;

                                                                    QUERY PLAN                                                                    
--------------------------------------------------------------------------------------------------------------------------------------------------
 Limit  (cost=14.40..26.47 rows=10 width=89) (actual time=10.908..10.952 rows=10 loops=1)
   ->  Index Scan using rumidx on origo_email_delivery del  (cost=14.40..3221.22 rows=2657 width=89) (actual time=10.906..10.947 rows=10 loops=1)
         Index Cond: (fts_all @@ '''andreas'' & ''kr'''::tsquery)
         Order By: (received_timestamp <=> '2000-01-01 00:00:00'::timestamp without time zone)
 Planning time: 0.491 ms
 Execution time: 11.010 ms
(6 rows)

 

The ORDER BY part seems strange; It seems one has to find a value "lower than any other value" to use as a kind of base, why is this necessary? It also seems that in order to be able to sort DESC one has to provide a timestamp value "higher than any other value", is this correct?

have you considered <=| and |=> operators ? <=> in ORDER BY works like KNN.

 

 

It would be great if the docs explained this.

 

I really miss the opportunity to include a BIGINT as part of the index, so that the WHERE-clause could be like this:

 

WHERE del.fts_all @@ to_tsquery('simple', 'andreas&kr') AND del.folder_id IN (1,2,3)

 

Having this would be perfect for my use-case searching in email in folders, sorted by received_date, and having it use ONE index.

 

Will this be supported?

 

Thanks.

 

--

Andreas Joseph Krogh

CTO / Partner - Visena AS

Mobile: +47 909 56 963

andreas@xxxxxxxxxx

www.visena.com