From ed0097e4f9e6b1227935e01fa67f12a238b66064 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 13 Aug 2016 18:31:14 -0400 Subject: Add SQL-accessible functions for inspecting index AM properties. Per discussion, we should provide such functions to replace the lost ability to discover AM properties by inspecting pg_am (cf commit 65c5fcd35). The added functionality is also meant to displace any code that was looking directly at pg_index.indoption, since we'd rather not believe that the bit meanings in that field are part of any client API contract. As future-proofing, define the SQL API to not assume that properties that are currently AM-wide or index-wide will remain so unless they logically must be; instead, expose them only when inquiring about a specific index or even specific index column. Also provide the ability for an index AM to override the behavior. In passing, document pg_am.amtype, overlooked in commit 473b93287. Andrew Gierth, with kibitzing by me and others Discussion: <87mvl5on7n.fsf@news-spur.riddles.org.uk> --- src/backend/access/index/amapi.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) (limited to 'src/backend/access/index/amapi.c') diff --git a/src/backend/access/index/amapi.c b/src/backend/access/index/amapi.c index d347ebcba4..28f6cde896 100644 --- a/src/backend/access/index/amapi.c +++ b/src/backend/access/index/amapi.c @@ -47,9 +47,12 @@ GetIndexAmRoutine(Oid amhandler) /* * GetIndexAmRoutineByAmId - look up the handler of the index access method * with the given OID, and get its IndexAmRoutine struct. + * + * If the given OID isn't a valid index access method, returns NULL if + * noerror is true, else throws error. */ IndexAmRoutine * -GetIndexAmRoutineByAmId(Oid amoid) +GetIndexAmRoutineByAmId(Oid amoid, bool noerror) { HeapTuple tuple; Form_pg_am amform; @@ -58,25 +61,43 @@ GetIndexAmRoutineByAmId(Oid amoid) /* Get handler function OID for the access method */ tuple = SearchSysCache1(AMOID, ObjectIdGetDatum(amoid)); if (!HeapTupleIsValid(tuple)) + { + if (noerror) + return NULL; elog(ERROR, "cache lookup failed for access method %u", amoid); + } amform = (Form_pg_am) GETSTRUCT(tuple); - /* Check if it's index access method */ + /* Check if it's an index access method as opposed to some other AM */ if (amform->amtype != AMTYPE_INDEX) + { + if (noerror) + { + ReleaseSysCache(tuple); + return NULL; + } ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("access method \"%s\" is not of type %s", NameStr(amform->amname), "INDEX"))); + } amhandler = amform->amhandler; /* Complain if handler OID is invalid */ if (!RegProcedureIsValid(amhandler)) + { + if (noerror) + { + ReleaseSysCache(tuple); + return NULL; + } ereport(ERROR, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("index access method \"%s\" does not have a handler", NameStr(amform->amname)))); + } ReleaseSysCache(tuple); @@ -107,7 +128,7 @@ amvalidate(PG_FUNCTION_ARGS) ReleaseSysCache(classtup); - amroutine = GetIndexAmRoutineByAmId(amoid); + amroutine = GetIndexAmRoutineByAmId(amoid, false); if (amroutine->amvalidate == NULL) elog(ERROR, "function amvalidate is not defined for index access method %u", -- cgit v1.2.1