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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 >file_fdw</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="Additional Supplied Modules" HREF="contrib.html"><LINK REL="PREVIOUS" TITLE="earthdistance" HREF="earthdistance.html"><LINK REL="NEXT" TITLE="fuzzystrmatch" HREF="fuzzystrmatch.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="SECT1" ><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="earthdistance" HREF="earthdistance.html" ACCESSKEY="P" >Prev</A ></TD ><TD WIDTH="10%" ALIGN="left" VALIGN="top" ><A HREF="contrib.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="60%" ALIGN="center" VALIGN="bottom" >Appendix F. Additional Supplied Modules</TD ><TD WIDTH="20%" ALIGN="right" VALIGN="top" ><A TITLE="fuzzystrmatch" HREF="fuzzystrmatch.html" ACCESSKEY="N" >Next</A ></TD ></TR ></TABLE ><HR ALIGN="LEFT" WIDTH="100%"></DIV ><DIV CLASS="SECT1" ><H1 CLASS="SECT1" ><A NAME="FILE-FDW" >F.14. file_fdw</A ></H1 ><P > The <TT CLASS="FILENAME" >file_fdw</TT > module provides the foreign-data wrapper <CODE CLASS="FUNCTION" >file_fdw</CODE >, which can be used to access data files in the server's file system. Data files must be in a format that can be read by <TT CLASS="COMMAND" >COPY FROM</TT >; see <A HREF="sql-copy.html" >COPY</A > for details. </P ><P > A foreign table created using this wrapper can have the following options: </P ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><TT CLASS="LITERAL" >filename</TT ></DT ><DD ><P > Specifies the file to be read. Required. Must be an absolute path name. </P ></DD ><DT ><TT CLASS="LITERAL" >format</TT ></DT ><DD ><P > Specifies the file's format, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >FORMAT</TT > option. </P ></DD ><DT ><TT CLASS="LITERAL" >header</TT ></DT ><DD ><P > Specifies whether the file has a header line, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >HEADER</TT > option. </P ></DD ><DT ><TT CLASS="LITERAL" >delimiter</TT ></DT ><DD ><P > Specifies the file's delimiter character, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >DELIMITER</TT > option. </P ></DD ><DT ><TT CLASS="LITERAL" >quote</TT ></DT ><DD ><P > Specifies the file's quote character, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >QUOTE</TT > option. </P ></DD ><DT ><TT CLASS="LITERAL" >escape</TT ></DT ><DD ><P > Specifies the file's escape character, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >ESCAPE</TT > option. </P ></DD ><DT ><TT CLASS="LITERAL" >null</TT ></DT ><DD ><P > Specifies the file's null string, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >NULL</TT > option. </P ></DD ><DT ><TT CLASS="LITERAL" >encoding</TT ></DT ><DD ><P > Specifies the file's encoding, the same as <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >ENCODING</TT > option. </P ></DD ></DL ></DIV ><P > A column of a foreign table created using this wrapper can have the following options: </P ><P ></P ><DIV CLASS="VARIABLELIST" ><DL ><DT ><TT CLASS="LITERAL" >force_not_null</TT ></DT ><DD ><P > This is a Boolean option. If true, it specifies that values of the column should not be matched against the null string (that is, the file-level <TT CLASS="LITERAL" >null</TT > option). This has the same effect as listing the column in <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >FORCE_NOT_NULL</TT > option. </P ></DD ></DL ></DIV ><P > <TT CLASS="COMMAND" >COPY</TT >'s <TT CLASS="LITERAL" >OIDS</TT > and <TT CLASS="LITERAL" >FORCE_QUOTE</TT > options are currently not supported by <TT CLASS="LITERAL" >file_fdw</TT >. </P ><P > These options can only be specified for a foreign table or its columns, not in the options of the <TT CLASS="LITERAL" >file_fdw</TT > foreign-data wrapper, nor in the options of a server or user mapping using the wrapper. </P ><P > Changing table-level options requires superuser privileges, for security reasons: only a superuser should be able to determine which file is read. In principle non-superusers could be allowed to change the other options, but that's not supported at present. </P ><P > For a foreign table using <TT CLASS="LITERAL" >file_fdw</TT >, <TT CLASS="COMMAND" >EXPLAIN</TT > shows the name of the file to be read. Unless <TT CLASS="LITERAL" >COSTS OFF</TT > is specified, the file size (in bytes) is shown as well. </P ><DIV CLASS="EXAMPLE" ><A NAME="AEN148264" ></A ><P ><B >Example F-1. Create a Foreign Table for PostgreSQL CSV Logs</B ></P ><P > One of the obvious uses for the <TT CLASS="LITERAL" >file_fdw</TT > is to make the PostgreSQL activity log available as a table for querying. To do this, first you must be logging to a CSV file, which here we will call <TT CLASS="LITERAL" >pglog.csv</TT >. First, install <TT CLASS="LITERAL" >file_fdw</TT > as an extension: </P ><PRE CLASS="PROGRAMLISTING" >CREATE EXTENSION file_fdw;</PRE ><P > Then create a foreign server: </P><PRE CLASS="PROGRAMLISTING" >CREATE SERVER pglog FOREIGN DATA WRAPPER file_fdw;</PRE ><P> </P ><P > Now you are ready to create the foreign data table. Using the <TT CLASS="COMMAND" >CREATE FOREIGN TABLE</TT > command, you will need to define the columns for the table, the CSV file name, and its format: </P><PRE CLASS="PROGRAMLISTING" >CREATE FOREIGN TABLE pglog ( log_time timestamp(3) with time zone, user_name text, database_name text, process_id integer, connection_from text, session_id text, session_line_num bigint, command_tag text, session_start_time timestamp with time zone, virtual_transaction_id text, transaction_id bigint, error_severity text, sql_state_code text, message text, detail text, hint text, internal_query text, internal_query_pos integer, context text, query text, query_pos integer, location text, application_name text ) SERVER pglog OPTIONS ( filename '/home/josh/9.1/data/pg_log/pglog.csv', format 'csv' );</PRE ><P> </P ><P > That's it — now you can query your log directly. In production, of course, you would need to define some way to adjust to log rotation. </P ></DIV ></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="earthdistance.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="fuzzystrmatch.html" ACCESSKEY="N" >Next</A ></TD ></TR ><TR ><TD WIDTH="33%" ALIGN="left" VALIGN="top" >earthdistance</TD ><TD WIDTH="34%" ALIGN="center" VALIGN="top" ><A HREF="contrib.html" ACCESSKEY="U" >Up</A ></TD ><TD WIDTH="33%" ALIGN="right" VALIGN="top" >fuzzystrmatch</TD ></TR ></TABLE ></DIV ></BODY ></HTML >