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Add contrib/file_fdw foreign-data wrapper for reading files via COPY.

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This is both very useful in its own right, and an important test case
for the core FDW support.

This commit includes a small refactoring of copy.c to expose its option
checking code as a separately callable function.  The original patch
submission duplicated hundreds of lines of that code, which seemed pretty
unmaintainable.

Shigeru Hanada, reviewed by Itagaki Takahiro and Tom Lane
This commit is contained in:
Tom Lane
2011-02-20 14:06:59 -05:00
parent bb74240794
commit 7c5d0ae707
19 changed files with 1171 additions and 55 deletions
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1
doc/src/sgml/contrib.sgml
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@ -100,6 +100,7 @@ CREATE EXTENSION <replaceable>module_name</> FROM unpackaged;
&dict-xsyn;
&dummy-seclabel;
&earthdistance;
&file-fdw;
&fuzzystrmatch;
&hstore;
&intagg;

127
doc/src/sgml/file-fdw.sgml Normal file
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@ -0,0 +1,127 @@
<!-- doc/src/sgml/file-fdw.sgml -->
<sect1 id="file-fdw">
<title>file_fdw</title>
<indexterm zone="file-fdw">
<primary>file_fdw</primary>
</indexterm>
<para>
The <filename>file_fdw</> module provides the foreign-data wrapper
<function>file_fdw</function>, which can be used to access data
files in the server's filesystem. Data files must be in a format
that can be read by <command>COPY FROM</command>;
see <xref linkend="sql-copy"> for details.
</para>
<para>
A foreign table created using this wrapper can have the following options:
</para>
<variablelist>
<varlistentry>
<term><literal>filename</literal></term>
<listitem>
<para>
Specifies the file to be read. Required. Must be an absolute path name.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>format</literal></term>
<listitem>
<para>
Specifies the file's format,
the same as <command>COPY</>'s <literal>FORMAT</literal> option.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>header</literal></term>
<listitem>
<para>
Specifies whether the file has a header line,
the same as <command>COPY</>'s <literal>HEADER</literal> option.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>delimiter</literal></term>
<listitem>
<para>
Specifies the file's delimiter character,
the same as <command>COPY</>'s <literal>DELIMITER</literal> option.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>quote</literal></term>
<listitem>
<para>
Specifies the file's quote character,
the same as <command>COPY</>'s <literal>QUOTE</literal> option.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>escape</literal></term>
<listitem>
<para>
Specifies the file's escape character,
the same as <command>COPY</>'s <literal>ESCAPE</literal> option.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>null</literal></term>
<listitem>
<para>
Specifies the file's null string,
the same as <command>COPY</>'s <literal>NULL</literal> option.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
<command>COPY</>'s <literal>OIDS</literal>, <literal>FORCE_QUOTE</literal>,
and <literal>FORCE_NOT_NULL</literal> options are currently not supported by
<literal>file_fdw</>.
</para>
<para>
These options can only be specified for a foreign table, not in the
options of the <literal>file_fdw</> foreign-data wrapper, nor in the
options of a server or user mapping using the wrapper.
</para>
<para>
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.
</para>
<para>
For a foreign table using <literal>file_fdw</>, <command>EXPLAIN</> shows
the name of the file to be read. Unless <literal>COSTS OFF</> is
specified, the file size (in bytes) is shown as well.
</para>
</sect1>

1
doc/src/sgml/filelist.sgml
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@ -106,6 +106,7 @@
<!entity dict-xsyn SYSTEM "dict-xsyn.sgml">
<!entity dummy-seclabel SYSTEM "dummy-seclabel.sgml">
<!entity earthdistance SYSTEM "earthdistance.sgml">
<!entity file-fdw SYSTEM "file-fdw.sgml">
<!entity fuzzystrmatch SYSTEM "fuzzystrmatch.sgml">
<!entity hstore SYSTEM "hstore.sgml">
<!entity intagg SYSTEM "intagg.sgml">