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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <HTML ><HEAD ><TITLE >pg_test_fsync</TITLE ><META NAME="GENERATOR" CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK REV="MADE" HREF="mailto:pgsql-docs@postgresql.org"><LINK REL="HOME" TITLE="PostgreSQL 9.2.24 Documentation" HREF="index.html"><LINK REL="UP" TITLE="Server Applications" HREF="contrib-prog-server.html"><LINK REL="PREVIOUS" TITLE="pg_standby" HREF="pgstandby.html"><LINK REL="NEXT" TITLE="pg_test_timing" HREF="pgtesttiming.html"><LINK REL="STYLESHEET" TYPE="text/css" HREF="stylesheet.css"><META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=ISO-8859-1"><META NAME="creation" CONTENT="2017-11-06T22:43:11"></HEAD ><BODY CLASS="REFENTRY" ><DIV CLASS="NAVHEADER" ><TABLE SUMMARY="Header navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TH COLSPAN="5" ALIGN="center" VALIGN="bottom" ><A HREF="index.html" >PostgreSQL 9.2.24 Documentation</A ></TH ></TR ><TR ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A TITLE="pg_standby" HREF="pgstandby.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="contrib-prog-server.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" ></TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="pg_test_timing" HREF="pgtesttiming.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><H1 ><A NAME="PGTESTFSYNC" ></A ><SPAN CLASS="APPLICATION" >pg_test_fsync</SPAN ></H1 ><DIV CLASS="REFNAMEDIV" ><A NAME="AEN154154" ></A ><H2 >Name</H2 >pg_test_fsync -- determine fastest wal_sync_method for <SPAN CLASS="PRODUCTNAME" >PostgreSQL</SPAN ></DIV ><DIV CLASS="REFSYNOPSISDIV" ><A NAME="AEN154160" ></A ><H2 >Synopsis</H2 ><P ><TT CLASS="COMMAND" >pg_test_fsync</TT > [<TT CLASS="REPLACEABLE" ><I >option</I ></TT >...]</P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN154165" ></A ><H2 >Description</H2 ><P > <SPAN CLASS="APPLICATION" >pg_test_fsync</SPAN > is intended to give you a reasonable idea of what the fastest <A HREF="runtime-config-wal.html#GUC-WAL-SYNC-METHOD" >wal_sync_method</A > is on your specific system, as well as supplying diagnostic information in the event of an identified I/O problem. However, differences shown by <SPAN CLASS="APPLICATION" >pg_test_fsync</SPAN > might not make any difference in real database throughput, especially since many database servers are not speed-limited by their transaction logs. </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN154171" ></A ><H2 >Options</H2 ><P > <SPAN CLASS="APPLICATION" >pg_test_fsync</SPAN > accepts the following command-line options: <P ></P ></P><DIV CLASS="VARIABLELIST" ><DL ><DT ><TT CLASS="OPTION" >-f</TT ><BR><TT CLASS="OPTION" >--filename</TT ></DT ><DD ><P > Specifies the file name to write test data in. This file should be in the same file system that the <TT CLASS="FILENAME" >pg_xlog</TT > directory is or will be placed in. (<TT CLASS="FILENAME" >pg_xlog</TT > contains the <ACRONYM CLASS="ACRONYM" >WAL</ACRONYM > files.) The default is <TT CLASS="FILENAME" >pg_test_fsync.out</TT > in the current directory. </P ></DD ><DT ><TT CLASS="OPTION" >-s</TT ><BR><TT CLASS="OPTION" >--secs-per-test</TT ></DT ><DD ><P > 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 2 seconds, which allows the program to complete in about 30 seconds. </P ></DD ><DT ><TT CLASS="OPTION" >-V</TT ><BR><TT CLASS="OPTION" >--version</TT ></DT ><DD ><P > Print the <SPAN CLASS="APPLICATION" >pg_test_fsync</SPAN > version and exit. </P ></DD ><DT ><TT CLASS="OPTION" >-?</TT ><BR><TT CLASS="OPTION" >--help</TT ></DT ><DD ><P > Show help about <SPAN CLASS="APPLICATION" >pg_test_fsync</SPAN > command line arguments, and exit. </P ></DD ></DL ></DIV ><P> </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN154210" ></A ><H2 >Author</H2 ><P > Bruce Momjian <CODE CLASS="EMAIL" ><<A HREF="mailto:bruce@momjian.us" >bruce@momjian.us</A >></CODE > </P ></DIV ><DIV CLASS="REFSECT1" ><A NAME="AEN154214" ></A ><H2 >See Also</H2 ><A HREF="app-postgres.html" ><SPAN CLASS="APPLICATION" >postgres</SPAN ></A ></DIV ><DIV CLASS="NAVFOOTER" ><HR ALIGN="LEFT" WIDTH="100%"><TABLE SUMMARY="Footer navigation table" WIDTH="100%" BORDER="0" CELLPADDING="0" CELLSPACING="0" ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><A HREF="pgstandby.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="index.html" ACCESSKEY="H" >Home</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><A HREF="pgtesttiming.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" ><SPAN CLASS="APPLICATION" >pg_standby</SPAN ></TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="contrib-prog-server.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" ><SPAN CLASS="APPLICATION" >pg_test_timing</SPAN ></TD ></TR ></TABLE ></DIV ></BODY ></HTML >