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Re: Estimates on partial index - Mailing list pgsql-performance

From Victor Yegorov
Subject Re: Estimates on partial index
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Msg-id CAGnEbog+daoCHOwAZHXnf1Ua_f3DS_4+ktEcstq2AJO1kUxyeA@mail.gmail.com
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In response to Re: Estimates on partial index  (Victor Yegorov <vyegorov@gmail.com>)
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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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