From 7d832462d64f8d8df417682cff234876ac154b41 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Thu, 13 Dec 2018 14:29:19 +0900 Subject: [PATCH 1/2] Introduce new extended routines for FDW and foreign server lookups MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 things and documented in consequence. Author: Michael Paquier Reviewed-by: Álvaro Herrera Discussion: https://postgr.es/m/CAB7nPqSZxrSmdHK-rny7z8mi=EAFXJ5J-0RbzDw6aus=wB5azQ@mail.gmail.com --- doc/src/sgml/fdwhandler.sgml | 34 +++++++++++++++++++++++++++++++++ src/backend/foreign/foreign.c | 36 +++++++++++++++++++++++++++++++++-- src/include/foreign/foreign.h | 10 ++++++++++ 3 files changed, 78 insertions(+), 2 deletions(-) diff --git a/doc/src/sgml/fdwhandler.sgml b/doc/src/sgml/fdwhandler.sgml index 4ce88dd77c..452b776b9e 100644 --- a/doc/src/sgml/fdwhandler.sgml +++ b/doc/src/sgml/fdwhandler.sgml @@ -1408,6 +1408,23 @@ ReparameterizeForeignPathByChild(PlannerInfo *root, List *fdw_private, ForeignDataWrapper * +GetForeignDataWrapperExtended(Oid fdwid, bits16 flags); + + + This function returns a ForeignDataWrapper + object for the foreign-data wrapper with the given OID. A + ForeignDataWrapper object contains properties + of the FDW (see foreign/foreign.h for details). + flags is a bitwise-or'd bit mask indicating + an extra set of options. It can take the value + FDW_MISSING_OK, in which case a NULL + result is returned to the caller instead of an error for an undefined + object. + + + + +ForeignDataWrapper * GetForeignDataWrapper(Oid fdwid); @@ -1420,6 +1437,23 @@ GetForeignDataWrapper(Oid fdwid); ForeignServer * +GetForeignServerExtended(Oid serverid, bits16 flags); + + + This function returns a ForeignServer object + for the foreign server with the given OID. A + ForeignServer object contains properties + of the server (see foreign/foreign.h for details). + flags is a bitwise-or'd bit mask indicating + an extra set of options. It can take the value + FSV_MISSING_OK, in which case a NULL + result is returned to the caller instead of an error for an undefined + object. + + + + +ForeignServer * GetForeignServer(Oid serverid); diff --git a/src/backend/foreign/foreign.c b/src/backend/foreign/foreign.c index 989a58ad78..79661526a3 100644 --- a/src/backend/foreign/foreign.c +++ b/src/backend/foreign/foreign.c @@ -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); diff --git a/src/include/foreign/foreign.h b/src/include/foreign/foreign.h index 3ca12e64d2..38c9784c8c 100644 --- a/src/include/foreign/foreign.h +++ b/src/include/foreign/foreign.h @@ -68,11 +68,21 @@ typedef struct ForeignTable List *options; /* ftoptions as DefElem list */ } ForeignTable; +/* Flags for GetForeignServerExtended */ +#define FSV_MISSING_OK 0x01 + +/* Flags for GetForeignDataWrapperExtended */ +#define FDW_MISSING_OK 0x01 + extern ForeignServer *GetForeignServer(Oid serverid); +extern ForeignServer *GetForeignServerExtended(Oid serverid, + bits16 flags); extern ForeignServer *GetForeignServerByName(const char *name, bool missing_ok); extern UserMapping *GetUserMapping(Oid userid, Oid serverid); extern ForeignDataWrapper *GetForeignDataWrapper(Oid fdwid); +extern ForeignDataWrapper *GetForeignDataWrapperExtended(Oid fdwid, + bits16 flags); extern ForeignDataWrapper *GetForeignDataWrapperByName(const char *name, bool missing_ok); extern ForeignTable *GetForeignTable(Oid relid); -- 2.20.0.rc2