| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | "Gunnar \"Nick\" Bluth" <gunnar(dot)bluth(at)pro-open(dot)de> |
| Cc: | pgsql-hackers(at)lists(dot)postgresql(dot)org, gkokolatos(at)protonmail(dot)com |
| Subject: | Re: [PATCH] pg_stat_toast |
| Date: | 2021-12-12 23:41:13 |
| Message-ID: | 20211212234113.6rhmqxi5uzgipwx2@alap3.anarazel.de |
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| Thread: | |
| Lists: | pgsql-hackers |
Hi,
On 2021-12-13 00:00:23 +0100, Gunnar "Nick" Bluth wrote:
> Regarding stats size; it adds one PgStat_BackendToastEntry
> (PgStat_BackendAttrIdentifier + PgStat_ToastCounts, should be 56-64 bytes or
> something in that ballpark) per TOASTable attribute, I can't see that make
> any system break sweat ;-)
That's actually a lot. The problem is that all the stats data for a database
is loaded into private memory for each connection to that database, and that
the stats collector regularly writes out all the stats data for a database.
> A quick run comparing 1.000.000 INSERTs (2 TOASTable columns each) with and
> without "pgstat_track_toast" resulted in 12792.882 ms vs. 12810.557 ms. So
> at least the call overhead seems to be neglectible.
Yea, you'd probably need a few more tables and a few more connections for it
to have a chance of mattering meaningfully.
Greetings,
Andres Freund
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