Re: Temporarily very slow planning time after a big delete
| От | Walter Smith |
|---|---|
| Тема | Re: Temporarily very slow planning time after a big delete |
| Дата | |
| Msg-id | CAOERZXje4G37KTPzQ-s-ar0mH4HG8ZVsk0ZDBmQdDiPnyOznuQ@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: Temporarily very slow planning time after a big delete (Walter Smith <walter@carezone.com>) |
| Список | pgsql-performance |
Tom Lane <tgl@sss.pgh.pa.us> writes:
>I'm assuming your problem
>query involved a join on the indexed column --- whether or not the
>final plan did a mergejoin, the planner would consider this
>query involved a join on the indexed column --- whether or not the
>final plan did a mergejoin, the planner would consider this
There's no join -- the query is
And the whole query plan is one step:
SELECT "notifications".*
FROM "notifications"
WHERE "notifications"."person_id" = ? AND
"notifications"."app_category" = ? AND
(id > ?)
ORDER BY created_at DESC
LIMIT ?
And the whole query plan is one step:
Index Scan using index_notifications_on_person_id_and_created_at on notifications (cost=0.57..212.16 rows=52 width=231)
>Subsequent vacuuming would eventually delete the dead index entries
>and return things to normal; although usually the performance comes
>back all-of-a-sudden at the next (auto)VACUUM of the table. So I'm
>a bit intrigued by your seeing it "gradually" improve. Maybe you
>had old open transactions that were limiting VACUUM's ability to
>remove rows?'
>and return things to normal; although usually the performance comes
>back all-of-a-sudden at the next (auto)VACUUM of the table. So I'm
>a bit intrigued by your seeing it "gradually" improve. Maybe you
>had old open transactions that were limiting VACUUM's ability to
>remove rows?'
We shouldn't have any long-running transactions at all, certainly not open for a couple of hours.
Thanks,
Walter
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