On Tue, Sep 29, 2015 at 8:45 AM, Bertrand Paquet < bertrand.paq...@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