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Introduce new extended routines for FDW and foreign server lookups

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The cache lookup routines for foreign-data wrappers and foreign servers
are extended with an extra argument to handle a set of flags.  The only
value which can be used now is to indicate if a missing object should
result in an error or not, and are designed to be extensible on need.
Those new routines are added into the existing set of user-visible
FDW APIs and documented in consequence.  They will be used for future
patches to improve the SQL interface for object addresses.

Author: Michael Paquier
Reviewed-by: Álvaro Herrera
Discussion: https://postgr.es/m/CAB7nPqSZxrSmdHK-rny7z8mi=EAFXJ5J-0RbzDw6aus=wB5azQ@mail.gmail.com
This commit is contained in:
Michael Paquier
2018-12-14 08:59:35 +09:00
parent 09568ec3d3
commit 8fb569e978
3 changed files with 78 additions and 2 deletions
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36
src/backend/foreign/foreign.c
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@@ -33,6 +33,18 @@
*/
ForeignDataWrapper *
GetForeignDataWrapper(Oid fdwid)
{
return GetForeignDataWrapperExtended(fdwid, 0);
}
/*
* GetForeignDataWrapperExtended - look up the foreign-data wrapper
* by OID. If flags uses FDW_MISSING_OK, return NULL if the object cannot
* be found instead of raising an error.
*/
ForeignDataWrapper *
GetForeignDataWrapperExtended(Oid fdwid, bits16 flags)
{
Form_pg_foreign_data_wrapper fdwform;
ForeignDataWrapper *fdw;
@@ -43,7 +55,11 @@ GetForeignDataWrapper(Oid fdwid)
tp = SearchSysCache1(FOREIGNDATAWRAPPEROID, ObjectIdGetDatum(fdwid));
if (!HeapTupleIsValid(tp))
elog(ERROR, "cache lookup failed for foreign-data wrapper %u", fdwid);
{
if ((flags & FDW_MISSING_OK) == 0)
elog(ERROR, "cache lookup failed for foreign-data wrapper %u", fdwid);
return NULL;
}
fdwform = (Form_pg_foreign_data_wrapper) GETSTRUCT(tp);
@@ -91,6 +107,18 @@ GetForeignDataWrapperByName(const char *fdwname, bool missing_ok)
*/
ForeignServer *
GetForeignServer(Oid serverid)
{
return GetForeignServerExtended(serverid, 0);
}
/*
* GetForeignServerExtended - look up the foreign server definition. If
* flags uses FSV_MISSING_OK, return NULL if the object cannot be found
* instead of raising an error.
*/
ForeignServer *
GetForeignServerExtended(Oid serverid, bits16 flags)
{
Form_pg_foreign_server serverform;
ForeignServer *server;
@@ -101,7 +129,11 @@ GetForeignServer(Oid serverid)
tp = SearchSysCache1(FOREIGNSERVEROID, ObjectIdGetDatum(serverid));
if (!HeapTupleIsValid(tp))
elog(ERROR, "cache lookup failed for foreign server %u", serverid);
{
if ((flags & FSV_MISSING_OK) == 0)
elog(ERROR, "cache lookup failed for foreign server %u", serverid);
return NULL;
}
serverform = (Form_pg_foreign_server) GETSTRUCT(tp);