Determining the OID of a certain type
Hi *,
I wanted to ask, if there is a method to determine the oid of a certain type using the C backend interface? I need to get access to a specific type for an IAM and therefore i want to construct an IndexTuple using the specified methods. However, I need the OID of the specific type for it. I considered writing some auxiliary function that returns the OID of the type using plpgsql. This works fine. However, I thought about something that I can use directly in C (server side) to get the oid, or do I have to set up a query to the database? Querying is currently the way I go here. However, it does not feel so right, to return the OID for the type I want to use, using a query. I hope, that there is some predefined function that I haven't found yet to determine the OID of some type (or relation etc).
Best regards,
Carsten Kropf
Carsten Kropf <ckropf2@fh-hof.de> writes:
I wanted to ask, if there is a method to determine the oid of a
certain type using the C backend interface?
Starting from what?
For built-in types it's usual practice to use the #define from
pg_type.h, if there is one. If you have a string name for the type,
there's a parser function to derive an OID, which I forget the name
of but it's probably in parse_type.c.
regards, tom lane
Thanks a lot,
basically I looked inside these functions in parse_type.c and did not find an "easy to use" application here. So I considered trying to construct the required arguments passed to typenameType. However, during the development, I found the following function:
Oid
TypenameGetTypid(const char *typname)
which does indeed do the lookup of my particular type in the cache and system catalog tables. Thanks a lot for the hint!
Best regards
Carsten Kropf
Am 22.03.2010 um 13:18 schrieb Tom Lane:
Show quoted text
Carsten Kropf <ckropf2@fh-hof.de> writes:
I wanted to ask, if there is a method to determine the oid of a
certain type using the C backend interface?Starting from what?
For built-in types it's usual practice to use the #define from
pg_type.h, if there is one. If you have a string name for the type,
there's a parser function to derive an OID, which I forget the name
of but it's probably in parse_type.c.regards, tom lane
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Carsten Kropf <ckropf2@fh-hof.de> writes:
basically I looked inside these functions in parse_type.c and did not find an "easy to use" application here. So I considered trying to construct the required arguments passed to typenameType. However, during the development, I found the following function:
Oid
TypenameGetTypid(const char *typname)
which does indeed do the lookup of my particular type in the cache and system catalog tables. Thanks a lot for the hint!
Actually, parseTypeString() is what I was thinking of. TypenameGetTypid
won't cope with schema-qualified names, nor a lot of other cases.
regards, tom lane
Oh, thanks, that's right, I see that this function I used before, searches only in the currently used schema. The usage of parseTypeString is comparable easy, as well, so based on your hints, I will probably use this function.
Best regards
Carsten Kropf
Am 22.03.2010 um 16:23 schrieb Tom Lane:
Show quoted text
Carsten Kropf <ckropf2@fh-hof.de> writes:
basically I looked inside these functions in parse_type.c and did not find an "easy to use" application here. So I considered trying to construct the required arguments passed to typenameType. However, during the development, I found the following function:
Oid
TypenameGetTypid(const char *typname)
which does indeed do the lookup of my particular type in the cache and system catalog tables. Thanks a lot for the hint!Actually, parseTypeString() is what I was thinking of. TypenameGetTypid
won't cope with schema-qualified names, nor a lot of other cases.regards, tom lane
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