Am 12.12.21 um 22:52 schrieb Andres Freund:
Hi,
On 2021-12-12 17:20:58 +0100, Gunnar "Nick" Bluth wrote:
Please have a look at the attached patch, which implements some statistics
for TOAST.
The idea (and patch) have been lurking here for quite a while now, so I
decided to dust it off, rebase it to HEAD and send it out for review today.
A big shoutout to Georgios Kokolatos, who gave me a crash course in PG
hacking, some very useful hints and valueable feedback early this year.
I'd like to get some feedback about the general idea, approach, naming etc.
before refining this further.
I'm worried about the additional overhead this might impose. For some workload
it'll substantially increase the amount of stats traffic. Have you tried to
qualify the overheads? Both in stats size and in stats management overhead?
I'd lie if I claimed so...
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 ;-)
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.
Obviously, this was really a quick run and doesn't reflect real life.
I'll have the machine run some reasonable tests asap, also looking at
stat size, of course!
Best regards,
--
Gunnar "Nick" Bluth
Eimermacherweg 106
D-48159 Münster
Mobil +49 172 8853339
Email: gunnar.bl...@pro-open.de
__________________________________________________________________________
"Ceterum censeo SystemD esse delendam" - Cato
