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Support pg_read_[binary_]file (filename, missing_ok).

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There wasn't an especially nice way to read all of a file while
passing missing_ok = true.  Add an additional overloaded variant
to support that use-case.

While here, refactor the C code to avoid a rats-nest of PG_NARGS
checks, instead handling the argument collection in the outer
wrapper functions.  It's a bit longer this way, but far more
straightforward.

(Upon looking at the code coverage report for genfile.c, I was
impelled to also add a test case for pg_stat_file() -- tgl)

Kyotaro Horiguchi

Discussion: https://postgr.es/m/20220607.160520.1984541900138970018.horikyota.ntt@gmail.com
This commit is contained in:
Tom Lane
2022-07-29 15:38:49 -04:00
parent fd96d14d95
commit 283129e325
7 changed files with 254 additions and 72 deletions
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18
doc/src/sgml/func.sgml
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@@ -28411,13 +28411,23 @@ SELECT pg_size_pretty(sum(pg_relation_size(relid))) AS total_size
considered.
</para>
<para>
When granting privilege on these functions, note that the table entries
showing optional parameters are mostly implemented as several physical
functions with different parameter lists. Privilege must be granted
separately on each such function, if it is to be
used. <application>psql</application>'s <command>\df</command> command
can be useful to check what the actual function signatures are.
</para>
<para>
Some of these functions take an optional <parameter>missing_ok</parameter>
parameter, which specifies the behavior when the file or directory does
not exist. If <literal>true</literal>, the function
returns <literal>NULL</literal> or an empty result set, as appropriate.
If <literal>false</literal>, an error is raised. The default
is <literal>false</literal>.
If <literal>false</literal>, an error is raised. (Failure conditions
other than <quote>file not found</quote> are reported as errors in any
case.) The default is <literal>false</literal>.
</para>
<table id="functions-admin-genfile-table">
@@ -28636,7 +28646,7 @@ SELECT pg_size_pretty(sum(pg_relation_size(relid))) AS total_size
<indexterm>
<primary>pg_read_file</primary>
</indexterm>
<function>pg_read_file</function> ( <parameter>filename</parameter> <type>text</type> <optional>, <parameter>offset</parameter> <type>bigint</type>, <parameter>length</parameter> <type>bigint</type> <optional>, <parameter>missing_ok</parameter> <type>boolean</type> </optional></optional> )
<function>pg_read_file</function> ( <parameter>filename</parameter> <type>text</type> <optional>, <parameter>offset</parameter> <type>bigint</type>, <parameter>length</parameter> <type>bigint</type> </optional> <optional>, <parameter>missing_ok</parameter> <type>boolean</type> </optional> )
<returnvalue>text</returnvalue>
</para>
<para>
@@ -28661,7 +28671,7 @@ SELECT pg_size_pretty(sum(pg_relation_size(relid))) AS total_size
<indexterm>
<primary>pg_read_binary_file</primary>
</indexterm>
<function>pg_read_binary_file</function> ( <parameter>filename</parameter> <type>text</type> <optional>, <parameter>offset</parameter> <type>bigint</type>, <parameter>length</parameter> <type>bigint</type> <optional>, <parameter>missing_ok</parameter> <type>boolean</type> </optional></optional> )
<function>pg_read_binary_file</function> ( <parameter>filename</parameter> <type>text</type> <optional>, <parameter>offset</parameter> <type>bigint</type>, <parameter>length</parameter> <type>bigint</type> </optional> <optional>, <parameter>missing_ok</parameter> <type>boolean</type> </optional> )
<returnvalue>bytea</returnvalue>
</para>
<para>