On Wed, Feb 8, 2017 at 9:36 PM, Amit Kapila <amit.kapil...@gmail.com> wrote:
> On Tue, Feb 7, 2017 at 11:47 AM, Haribabu Kommi > <kommi.harib...@gmail.com> wrote: > > Hi Hackers, > > > > I just want to discuss adding of a new statistics view that provides > > the information of wal writing details as follows > > > > +1. I think it will be useful to observe WAL activity. > Thanks for your opinion. > postgres=# \d pg_stat_wal_writer > > View "pg_catalog.pg_stat_wal_writer" > > Column | Type | Collation | Nullable > | > > Default > > -----------------------+--------------------------+--------- > --+----------+--------- > > num_backend_writes | bigint | | > > | > > num_total_writes | bigint | | | > > num_blocks | bigint | | | > > total_write_time | bigint| | | > > stats_reset | timestamp with time zone | | > | > > > > The columns of the view are > > 1. Total number of xlog writes that are called from the backend. > > 2. Total number of xlog writes that are called from both backend > > and background workers. (This column can be changed to just > > display on the background writes). > > 3. The number of the blocks that are written. > > 4. Total write_time of the IO operation it took, this variable data is > > filled only when the track_io_timing GUC is enabled. > > So, here is *write_time* the total time system has spent in WAL > writing before the last reset? > total write_time spent in WAL writing "after" the last reset in milliseconds. I think there should be a separate column for write and sync time. > > Added. > > Or it is possible to integrate the new columns into the existing > > pg_stat_bgwriter view also. > > > > I feel separate view is better. > Ok. Following the sample out of the view after regress run. postgres=# select * from pg_stat_walwrites; -[ RECORD 1 ]--+------------------------------ backend_writes | 19092 writes | 663 write_blocks | 56116 write_time | 0 sync_time | 3064 stats_reset | 2017-02-15 13:37:09.454314+11 Currently, writer, walwriter and checkpointer processes are considered as background processes that can do the wal write mainly. Here I attached patch that implements the view. I will add this patch to next commitfest. Regards, Hari Babu Fujitsu Australia
pg_stat_walwrites_view_1.patch
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