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Add pg_read_binary_file() and whole-file-at-once versions of pg_read_file().

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One of the usages of the binary version is to read files in a different
encoding from the server encoding.

Dimitri Fontaine and Itagaki Takahiro.
This commit is contained in:
Itagaki Takahiro
2010-12-16 06:56:28 +09:00
parent 16b5e08dec
commit 03db44eae3
5 changed files with 139 additions and 25 deletions
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25
doc/src/sgml/func.sgml
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@ -14449,11 +14449,18 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
</row>
<row>
<entry>
<literal><function>pg_read_file(<parameter>filename</> <type>text</>, <parameter>offset</> <type>bigint</>, <parameter>length</> <type>bigint</>)</function></literal>
<literal><function>pg_read_file(<parameter>filename</> <type>text</> [, <parameter>offset</> <type>bigint</>, <parameter>length</> <type>bigint</>])</function></literal>
</entry>
<entry><type>text</type></entry>
<entry>Return the contents of a text file</entry>
</row>
<row>
<entry>
<literal><function>pg_read_binary_file(<parameter>filename</> <type>text</> [, <parameter>offset</> <type>bigint</>, <parameter>length</> <type>bigint</>])</function></literal>
</entry>
<entry><type>bytea</type></entry>
<entry>Return the contents of a file</entry>
</row>
<row>
<entry>
<literal><function>pg_stat_file(<parameter>filename</> <type>text</>)</function></literal>
@ -14482,6 +14489,22 @@ postgres=# SELECT * FROM pg_xlogfile_name_offset(pg_stop_backup());
at the given <parameter>offset</>, returning at most <parameter>length</>
bytes (less if the end of file is reached first). If <parameter>offset</>
is negative, it is relative to the end of the file.
When <parameter>offset</> and <parameter>length</> parameters are omitted,
it returns the whole of the file.
The part of a file must be a valid text in the server encoding.
</para>
<indexterm>
<primary>pg_read_binary_file</primary>
</indexterm>
<para>
<function>pg_read_binary_file</> returns part of a file as like as
<function>pg_read_file</>, but the result is a bytea value.
One of the usages is to read a file in the specified encoding combined with
<function>convert_from</> function:
<programlisting>
SELECT convert_from(pg_read_binary_file('file_in_utf8.txt'), 'UTF8');
</programlisting>
</para>
<indexterm>