Re: Estimates on partial index
| От | Victor Yegorov |
|---|---|
| Тема | Re: Estimates on partial index |
| Дата | |
| Msg-id | CAGnEbog+daoCHOwAZHXnf1Ua_f3DS_4+ktEcstq2AJO1kUxyeA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Estimates on partial index (Victor Yegorov <vyegorov@gmail.com>) |
| Список | pgsql-performance |
2016-08-18 21:40 GMT+03:00 Victor Yegorov <vyegorov@gmail.com>:
Oh, that's interesting. I was under impression, that r_p_c reflects IO speed, like — make it smaller for SSDs.To make this query prefer BitmapScan, I need to bump r_p_c to 5.8. And 6.0 makes it switch to SeqScan.
I was looking into different databases and queries around — many of them prefers to use indexes over SeqScans, even if index is not a "perfect" match,
like using index on the 2-nd column of the index (like searching for `rev` via IndexScan over `id,rev` index).
I need to bump r_p_c to 6 (at least) to make things shift towards BtimapScans, and I feel uncertain about such increase.
This makes me thinking — can this situation be an indication, that tables are bloated?
(I've performed reindexing recently, touching majority of indexes around, while tables were not touched.)
Victor Y. Yegorov
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