Обсуждение: determining a type oid from the name
Say I'm writing an extension X, and I want to process data values from another extension that creates type Y (e.g. an hstore), what's the best way to determine the Oid of type Y in my module X code? SPI code that runs "select 'something'::Y" and then examines the oid in SPI_tuptable? Or do we have a utility function I have missed that, given a type name and the current search path will give me back the type Oid? cheers andrew
On 22 February 2012 18:00, Andrew Dunstan <andrew@dunslane.net> wrote:
> Say I'm writing an extension X, and I want to process data values from
> another extension that creates type Y (e.g. an hstore), what's the best way
> to determine the Oid of type Y in my module X code? SPI code that runs
> "select 'something'::Y" and then examines the oid in SPI_tuptable? Or do we
> have a utility function I have missed that, given a type name and the
> current search path will give me back the type Oid?
Does this help?
test=# SELECT pg_typeof('4834.34'::numeric)::oid;pg_typeof
----------- 1700
(1 row)
--
Thom
Thom Brown <thom@linux.com> wrote:
> Does this help?
>
> test=# SELECT pg_typeof('4834.34'::numeric)::oid;
> pg_typeof
> -----------
> 1700
> (1 row)
Wouldn't it be easier to do this instead?
test=# SELECT 'numeric'::regtype::oid;oid
------1700
(1 row)
-Kevin
On 22 February 2012 18:34, Kevin Grittner <Kevin.Grittner@wicourts.gov> wrote:
> Thom Brown <thom@linux.com> wrote:
>> Does this help?
>>
>> test=# SELECT pg_typeof('4834.34'::numeric)::oid;
>> pg_typeof
>> -----------
>> 1700
>> (1 row)
>
> Wouldn't it be easier to do this instead?
>
> test=# SELECT 'numeric'::regtype::oid;
> oid
> ------
> 1700
> (1 row)
Well I may have misread the problem. I thought it was that for a
particular data value, the oid of the type of that value was needed.
--
Thom
On 02/22/2012 01:36 PM, Thom Brown wrote:
> On 22 February 2012 18:34, Kevin Grittner<Kevin.Grittner@wicourts.gov> wrote:
>> Thom Brown<thom@linux.com> wrote:
>>> Does this help?
>>>
>>> test=# SELECT pg_typeof('4834.34'::numeric)::oid;
>>> pg_typeof
>>> -----------
>>> 1700
>>> (1 row)
>> Wouldn't it be easier to do this instead?
>>
>> test=# SELECT 'numeric'::regtype::oid;
>> oid
>> ------
>> 1700
>> (1 row)
> Well I may have misread the problem. I thought it was that for a
> particular data value, the oid of the type of that value was needed.
Maybe I need to be more clear. The C code I'm writing will process
composites. I want to cache the Oids of certain non-builtin types in the
function info's fn_extra, and then be able to test whether or not the
fields in the composites are of those types.
cheers
andrew
Andrew Dunstan <andrew@dunslane.net> writes:
> Maybe I need to be more clear. The C code I'm writing will process
> composites. I want to cache the Oids of certain non-builtin types in the
> function info's fn_extra, and then be able to test whether or not the
> fields in the composites are of those types.
What's your basis for identifying those types in the first place?
Name? Doesn't seem terribly robust if the other extension can be
installed in some random schema. But anyway, something in
parser/parse_type.c ought to help you with that --- maybe
parseTypeString?
regards, tom lane
On 02/22/2012 03:20 PM, Tom Lane wrote: > Andrew Dunstan<andrew@dunslane.net> writes: >> Maybe I need to be more clear. The C code I'm writing will process >> composites. I want to cache the Oids of certain non-builtin types in the >> function info's fn_extra, and then be able to test whether or not the >> fields in the composites are of those types. > What's your basis for identifying those types in the first place? > Name? Doesn't seem terribly robust if the other extension can be > installed in some random schema. But anyway, something in > parser/parse_type.c ought to help you with that --- maybe > parseTypeString? > > Thanks, that might do the trick. I fully agree it's not bulletproof, but I'm not sure what alternative there is. cheers andrew
Andrew Dunstan <andrew@dunslane.net> writes: > I fully agree it's not bulletproof, but I'm not sure what alternative there > is. If you know the type has been installed as an extension you can look at the extension's content in pg_depend, much like \dx+ does, limiting to only types whose name matches. Regards, -- Dimitri Fontaine http://2ndQuadrant.fr PostgreSQL : Expertise, Formation et Support