Re: Optimizing No matching record Queries

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Dean Gibson (DB Administrator) wrote:
The questions are:

1. Why in the planner scanning the entire idx_listing_entrydate, when I'd think it should be scanning the entire pk_listingstatus_listingstatusid ?

It's looking at the ORDER BY and sees that the query needs the 10 most recent, so tries searching by date. That's sensible where you are going to have a lot of matches for fklistingsourceid.

Which suggests that statistics for "fklistingsourceid" aren't high enough, like Greg suggested. If that doesn't help, the index on (fklistingsourceid,entrydate) that Stephen might well do so.

2. Why is "Index Scan using pk_listingstatus_listingstatusid on listingstatus listingsta1_ (cost=0.00..0.27 rows=1 width=4) (never executed)" ?

Because nothing comes out of the first index-scan.

--
  Richard Huxton
  Archonet Ltd

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