| Subject | RE: [firebird-support] Slow query because an index is not picked up during sort |
|---|---|
| Author | Svein Erling Tysvær |
| Post date | 2012-06-05T06:12:06Z |
>Svein, the selectivity of source_id is 0.000446 and commit_number is 0.000001. So, it is not clearI'd agree, Alec, if your where clause had involved "PHYSICAL_COPY."COMMIT_NUMBER" = 10000000", but >= and = are two very different operators. I'd be shocked if Firebird hadn't come up with the best plan if you'd compared for equality. The selectivity of >=, however, certainly isn't 0.000001 for commit_number, but more like 0.5.
>why FB is not using index on commit_number to filter AND sort on.
Set