Thread: TODO: You can alter it, but you can't view it
All,
While working on some database maintenance, I was just tripped up by the
fact that there is no good way to query reloptions for tables. By "no
good way" I mean "no way which does not involve UNNEST and regexps or
procedural code".
This puts us in the wierd place that while one can ALTER various
reloptions, one cannot check them to see if they *need* to be altered.
That's a particularly bad situation given that changing reloptions
requires a lock on the table (though less of one in 9.1).
I propose that we have an additional system view, pg_class_reloptions
(or pg_table_reloptions if reloptions aren't relevant for views and
indexes). It would have the following columns:
relid
name
setting_numeric
setting_boolean
setting_text
comments/objections/something I missed in the internal functions or 9.1
patches which already does this?
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com
On Mon, Sep 27, 2010 at 2:19 PM, Josh Berkus <josh@agliodbs.com> wrote: > While working on some database maintenance, I was just tripped up by the > fact that there is no good way to query reloptions for tables. By "no good > way" I mean "no way which does not involve UNNEST and regexps or procedural > code". Can you use pg_options_to_table() for your purpose? =# CREATE TABLE tbl (i integer) with (fillfactor = 70); =# SELECT (pg_options_to_table(reloptions)).* FROM pg_class WHERE oid = 'tbl'::regclass;option_name | option_value -------------+--------------fillfactor | 70 -- Itagaki Takahiro
> Can you use pg_options_to_table() for your purpose?
Yes, thanks. What version did that get added in? Even for 9.0, that
function doesn't seem to appear in the docs.
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com
On Mon, Sep 27, 2010 at 4:39 PM, Josh Berkus <josh@agliodbs.com> wrote: >> Can you use pg_options_to_table() for your purpose? > > Yes, thanks. What version did that get added in? Even for 9.0, that > function doesn't seem to appear in the docs. I found it in 8.4 and newer versions. It might be an internal API (for pg_dump?), but it'd be better to add documentation for it. -- Itagaki Takahiro
--On 27. September 2010 16:54:32 +0900 Itagaki Takahiro <itagaki.takahiro@gmail.com> wrote: > I found it in 8.4 and newer versions. It might be an internal API > (for pg_dump?), but it'd be better to add documentation for it. Additionally we could extend pg_tables with an additional column? This would make the query more user-friendly, too. -- Thanks Bernd
Itagaki Takahiro wrote: > On Mon, Sep 27, 2010 at 2:19 PM, Josh Berkus <josh@agliodbs.com> wrote: > > While working on some database maintenance, I was just tripped up by the > > fact that there is no good way to query reloptions for tables. ?By "no good > > way" I mean "no way which does not involve UNNEST and regexps or procedural > > code". > > Can you use pg_options_to_table() for your purpose? > > =# CREATE TABLE tbl (i integer) with (fillfactor = 70); > =# SELECT (pg_options_to_table(reloptions)).* FROM pg_class WHERE oid > = 'tbl'::regclass; > option_name | option_value > -------------+-------------- > fillfactor | 70 Right now pg_options_to_table() is not documented. Should it be? -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. +
> Right now pg_options_to_table() is not documented. Should it be?
Yes, I think so.
-- -- Josh Berkus PostgreSQL Experts Inc.
http://www.pgexperts.com
Josh Berkus wrote: > > > Right now pg_options_to_table() is not documented. Should it be? > > Yes, I think so. Done, with the attached, applied patch. -- Bruce Momjian <bruce@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml index 736eb67..c620142 100644 *** a/doc/src/sgml/func.sgml --- b/doc/src/sgml/func.sgml *************** SELECT pg_type_is_visible('myschema.widg *** 13244,13249 **** --- 13244,13253 ---- </indexterm> <indexterm> + <primary>pg_options_to_table</primary> + </indexterm> + + <indexterm> <primary>pg_tablespace_databases</primary> </indexterm> *************** SELECT pg_type_is_visible('myschema.widg *** 13380,13385 **** --- 13384,13394 ---- <entry>get underlying <command>SELECT</command> command for view</entry> </row> <row> + <entry><literal><function>pg_options_to_table(<parameter>reloptions</parameter>)</function></literal></entry> + <entry><type>name, option</type></entry> + <entry>get the set of option name/value pairs from <structname>pg_class</>.<structfield>reloptions</></entry> + </row> + <row> <entry><literal><function>pg_tablespace_databases(<parameter>tablespace_oid</parameter>)</function></literal></entry> <entry><type>setof oid</type></entry> <entry>get the set of database OIDs that have objects in the tablespace</entry> *************** SELECT pg_type_is_visible('myschema.widg *** 13475,13480 **** --- 13484,13495 ---- </para> <para> + <function>pg_options_to_table</function> returns the set of option + name/value pairs when passed + <structname>pg_class</>.<structfield>reloptions</>. + </para> + + <para> <function>pg_tablespace_databases</function> allows a tablespace to be examined. It returns the set of OIDs of databases that have objects stored in the tablespace. If this function returns any rows, the tablespace is not
bruce wrote:
> Josh Berkus wrote:
> >
> > > Right now pg_options_to_table() is not documented. Should it be?
> >
> > Yes, I think so.
>
> Done, with the attached, applied patch.
Oh, here is an example usage:
test=> select pg_options_to_table(reloptions) from pg_class;
pg_options_to_table
----------------------------------
(fillfactor,50)
(autovacuum_freeze_table_age,10)
(2 rows)
It also works for pg_attribute.attoptions, so I documented that too.
I also fixed the documented return type in my previous patch.
--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ It's impossible for everything to be true. +
diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index edb7795..9c8e19f 100644
*** a/doc/src/sgml/func.sgml
--- b/doc/src/sgml/func.sgml
*************** SELECT pg_type_is_visible('myschema.widg
*** 13385,13392 ****
</row>
<row>
<entry><literal><function>pg_options_to_table(<parameter>reloptions</parameter>)</function></literal></entry>
! <entry><type>name, option</type></entry>
! <entry>get the set of option name/value pairs from <structname>pg_class</>.<structfield>reloptions</></entry>
</row>
<row>
<entry><literal><function>pg_tablespace_databases(<parameter>tablespace_oid</parameter>)</function></literal></entry>
--- 13385,13392 ----
</row>
<row>
<entry><literal><function>pg_options_to_table(<parameter>reloptions</parameter>)</function></literal></entry>
! <entry><type>setof record</type></entry>
! <entry>get the set of storage option name/value pairs</></entry>
</row>
<row>
<entry><literal><function>pg_tablespace_databases(<parameter>tablespace_oid</parameter>)</function></literal></entry>
*************** SELECT pg_type_is_visible('myschema.widg
*** 13484,13492 ****
</para>
<para>
! <function>pg_options_to_table</function> returns the set of option
name/value pairs when passed
! <structname>pg_class</>.<structfield>reloptions</>.
</para>
<para>
--- 13484,13493 ----
</para>
<para>
! <function>pg_options_to_table</function> returns the set of storage option
name/value pairs when passed
! <structname>pg_class</>.<structfield>reloptions</> or
! <structname>pg_attribute</>.<structfield>attoptions</>.
</para>
<para>