Re: Problems with adding a is not null to a query.

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От Tim Uckun
Тема Re: Problems with adding a is not null to a query.
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Msg-id AANLkTinD_Bmgy34W70ywxXM0b1xOWBBEvR8hO95y9LzS@mail.gmail.com
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Ответ на Re: Problems with adding a is not null to a query.  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: Problems with adding a is not null to a query.
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> With a table that large, you're probably going to need a larger stats
> target in order to get reasonable estimates for low-frequency values.
> Am I right in guessing that pg_stats.n_distinct is much too low for
> the domain_id column?

the domain_id is in the topical urls. A select count of domains shows
that there are 700 domains, the pg_stats shows 170 which seems kind of
low but maybe is not out of bounds because most domains are probably
inactive.


pg_stats on the consolidated_urls table shows a very low value for
index_delta. There are 1.8 million records and the n_distinct for
index_delta is 151.  It's a floating point number so that seems weird.
For index it's 818.

Both of those numbers are wildly wrong I would think.

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