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'\" t .\" Title: pg_test_fsync .\" Author: The PostgreSQL Global Development Group .\" Generator: DocBook XSL Stylesheets v1.76.1 <http://docbook.sf.net/> .\" Date: 2014 .\" Manual: PostgreSQL 9.3.5 Documentation .\" Source: PostgreSQL 9.3.5 .\" Language: English .\" .TH "PG_TEST_FSYNC" "1" "2014" "PostgreSQL 9.3.5" "PostgreSQL 9.3.5 Documentation" .\" ----------------------------------------------------------------- .\" * Define some portability stuff .\" ----------------------------------------------------------------- .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .\" http://bugs.debian.org/507673 .\" http://lists.gnu.org/archive/html/groff/2009-02/msg00013.html .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" ----------------------------------------------------------------- .\" * set default formatting .\" ----------------------------------------------------------------- .\" disable hyphenation .nh .\" disable justification (adjust text to left margin only) .ad l .\" ----------------------------------------------------------------- .\" * MAIN CONTENT STARTS HERE * .\" ----------------------------------------------------------------- .SH "NAME" pg_test_fsync \- determine fastest wal_sync_method for PostgreSQL .\" pg_test_fsync .SH "SYNOPSIS" .HP \w'\fBpg_test_fsync\fR\ 'u \fBpg_test_fsync\fR [\fIoption\fR...] .SH "DESCRIPTION" .PP 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\&. .SH "OPTIONS" .PP pg_test_fsync accepts the following command\-line options: .PP \fB\-f\fR, \fB\-\-filename\fR .RS 4 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\&. .RE .PP \fB\-s\fR, \fB\-\-secs\-per\-test\fR .RS 4 Specifies the number of seconds for each test\&. The more time per test, the greater the test\*(Aqs accuracy, but the longer it takes to run\&. The default is 5 seconds, which allows the program to complete in under 2 minutes\&. .RE .PP \fB\-V\fR, \fB\-\-version\fR .RS 4 Print the pg_test_fsync version and exit\&. .RE .PP \fB\-?\fR, \fB\-\-help\fR .RS 4 Show help about pg_test_fsync command line arguments, and exit\&. .RE .SH "AUTHOR" .PP Bruce Momjian <bruce@momjian\&.us> .SH "SEE ALSO" \fBpostgres\fR(1)