pg_test_fsync
pg_test_fsync
pg_test_fsync - determine fastest
wal_sync_method
for
PostgreSQL
Synopsis
pg_test_fsync
[
option
...]
Description
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 write-ahead 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
.
Options
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_waldirectory is or will be placed in. (pg_walcontains the WAL files.) The default ispg_test_fsync.outin 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.
Environment
The environment variable
PG_COLOR
specifies whether to use
color in diagnostic messages. Possible values are
always
,
auto
and
never
.