pg_test_fsync — determine fastest wal_sync_method for PostgreSQL™
pg_test_fsync
[option
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pg_test_fsync is intended to give you a reasonable
idea of what the fastest wal_sync_method is on your
specific system,
as well as supplying diagnostic information in the event of an identified I/O
problem. However, differences shown by
pg_test_fsync might not make any significant
difference in real database throughput, especially since many database servers
are not speed-limited by their transaction logs.
pg_test_fsync reports average file sync operation
time in microseconds for each wal_sync_method
, which can also be used to
inform efforts to optimize the value of commit_delay.
pg_test_fsync accepts the following command-line options:
-f
, --filename
Specifies the file name to write test data in.
This file should be in the same file system that the
pg_xlog
directory is or will be placed in.
(pg_xlog
contains the WAL files.)
The default is pg_test_fsync.out
in the current
directory.
-s
, --secs-per-test
Specifies the number of seconds for each test. The more time per test, the greater the test's accuracy, but the longer it takes to run. The default is 5 seconds, which allows the program to complete in under 2 minutes.
-V
, --version
Print the pg_test_fsync version and exit.
-?
, --help
Show help about pg_test_fsync command line arguments, and exit.