check this, his 2nd part introduces Stream Replication Implementation and tell you px_log retention and wal archive related parameters.
2017-02-18 2:30 GMT+08:00 Ray Stell <stellr@xxxxxx>:
I was "planning" to turn on WAL archiving on a postgresql 9.4.11 server that currently is running with "wal_level=hot_standby" and streaming to a standby. I thought there would be a relationship between the rate of pg_xlog files and archive generation. When I turned up the archive_command/mode I found the scale of the archive target was wrong as I had based it on the pg_xlog file creation rate.
When I turned on the archive command for a few minutes, pg_xlog dir contained these files for the time period:
-rw------- 1 postgres postgres 16777216 Feb 17 06:47 00000001000023AC0000007F
-rw------- 1 postgres postgres 16777216 Feb 17 06:45 00000001000023AC0000007E
The archive command wrote 126, 16MB files:
-rw------- 1 postgres postgres 16777216 Feb 17 06:47 000000010000237700000056
-rw------- 1 postgres postgres 16777216 Feb 17 06:47 000000010000237700000055
-rw------- 1 postgres postgres 16777216 Feb 17 06:47 000000010000237700000054
-rw------- 1 postgres postgres 16777216 Feb 17 06:47 000000010000237700000053
...
-rw------- 1 postgres postgres 16777216 Feb 17 06:45 0000000100002376000000DC
-rw------- 1 postgres postgres 16777216 Feb 17 06:45 0000000100002376000000DB
-rw------- 1 postgres postgres 16777216 Feb 17 06:45 0000000100002376000000DA
-rw------- 1 postgres postgres 16777216 Feb 17 06:45 0000000100002376000000D9
On servers that are not nearly as busy, I observe a one-to-one relationship between these files/rates.
Is there a good WAL archive space planning guide?
Is the way to collect planning data for this to turn on wal_debug?
TIA!
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