Re: Incorrect index being used

On Fri, Oct 11, 2013 at 9:32 AM, Jesse Long <jpl(at)unknown(dot)za(dot)net> wrote:

> explain select * from archive_document_index where node_id = 29 and value
> = 'BSH70002152';
> QUERY PLAN
> ------------------------------**------------------------------**
> ------------------------------**------------------------------**--
> Index Scan using archive_document_index_node_**id_value_idx on
> archive_document_index (cost=0.57..36.13 rows=14 width=33)
> Index Cond: ((node_id = 29) AND ((value)::text = 'BSH70002152'::text))
> (2 rows)
>

I believe that this is what Tom is suggesting:

SELECT *
FROM ARCHIVE_DOCUMENT AS ad
WHERE ad.NODE_ID = 29
AND ad.ARCHIVE_DATE >= '2013-07-08 18:28:00'
AND EXISTS (SELECT *
FROM ARCHIVE_DOCUMENT_INDEX AS adi
WHERE adi.ARCHIVE_ID = ad.ID
AND adi.NODE_ID = ad.NODE_ID
AND (adi.VALUE = 'BSH70002152' OR adi.VALUE = 'TC212592')
)
ORDER BY ad.ARCHIVE_DATE DESC
LIMIT 10;

Forgive my changing of the aliases. I found names like r0 difficult to
interpret easily.

This is a much simpler query since it only requires one subselect, and I
believe Tom is suggesting that this query may be able to make use of the
index or at least find some more efficient plan. How does this perform?