Re: Show lossy heap block info in EXPLAIN ANALYZE for bitmap heap scan

On 2014-01-01 21:15:46 -0500, Robert Haas wrote:
> [ sensible reasoning ] However, I'm not sure it's really worth it.
> I think what people really care about is knowing whether the bitmap
> lossified or not, and generally how much got lossified.  The counts of
> exact and lossy pages are sufficient for that, without anything
> additional

Showing the amount of memory currently required could tell you how soon
accurate bitmap scans will turn into lossy scans though. Which is not a
bad thing to know, some kinds of scans (e.g. tsearch over expression
indexes, postgis) can get ridiculously slow once lossy.

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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