Re: Performance problem with gin index
| От | Jeff Janes |
|---|---|
| Тема | Re: Performance problem with gin index |
| Дата | |
| Msg-id | CAMkU=1zD4hsT0xZSHx3R9_Q9C5oyBO-ZiZ_99P_q9MJKuT5LXg@mail.gmail.com обсуждение исходный текст |
| Ответ на | Performance problem with gin index (Bertrand Paquet <bertrand.paquet@doctolib.fr>) |
| Ответы |
Re: Performance problem with gin index
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| Список | pgsql-performance |
On Tue, Sep 29, 2015 at 8:45 AM, Bertrand Paquet <bertrand.paquet@doctolib.fr> wrote:
Hi,We have got big slow down on our production plateform (PG 9.4.4).
What is it slow compared to? Did your version change, or your workload/usage change?
After analyzing wals with pg_xlogdump, we see lot of writing in Gin Indexes.We suspect slow down are related to the write of pending update on the index.So, is there any method to see- what is the current config of gin_pending_list_limit on a given index ?
gin_pending_list_limit will be introduced in 9.5. In 9.4 and before, there is no such parameter. Instead, the limit is tied to the setting of work_mem in those versions.
- the current size of pending list on a given index ?
You can use this from the pgstattuple contrib module:
SELECT * FROM pgstatginindex('test_gin_index');
Your best bet may be to turn off fastupdate. It will slow down most inserts/updates, but you will not have the huge latency spikes you get with fastupdate turned on.
Also, you might (or might not) have a higher overall throughput with fastupdate turned off, depending on a lot of things like the size of the index, the size of ram and shared_buffers, the number of spindles in your RAID, the amount of parallelization in your insert/update activity, and the distribution of "keys" among the data you are inserting/updating.
Cheers,
Jeff
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