Remove unused function.

I think this is some kind of a debugging function, but since it's not
exposed in pg_proc.h, there's no easy way to use it. Seems better to just
remove it, than try to expose it.

src/backend/utils/time/sharedsnapshot.c

@@ -931,109 +931,3 @@ LogDistributedSnapshotInfo(Snapshot snapshot, const char *prefix)
 
 	elog(LOG, "%s}", message);
 }
-
-struct mpp_xid_map_entry {
-	pid_t				pid;
-	TransactionId		global;
-	TransactionId		local;
-};
-
-struct mpp_xid_map {
-	int			size;
-	int			cur;
-	struct mpp_xid_map_entry map[1];
-};
-
-/*
- * mpp_global_xid_map
- */
-Datum
-mpp_global_xid_map(PG_FUNCTION_ARGS)
-{
-	FuncCallContext *funcctx;
-	struct mpp_xid_map *ctx;
-	bool	nulls[3];
-	int			i, j;
-
-	if (SRF_IS_FIRSTCALL())
-	{
-		TupleDesc	tupdesc;
-		MemoryContext oldcontext;
-		volatile SharedSnapshotStruct *arrayP = sharedSnapshotArray;
-
-		/* create a function context for cross-call persistence */
-		funcctx = SRF_FIRSTCALL_INIT();
-
-		/*
-		 * switch to memory context appropriate for multiple function calls
-		 */
-		oldcontext = MemoryContextSwitchTo(funcctx->multi_call_memory_ctx);
-
-		/* build tupdesc for result tuples */
-		/* this had better match pg_locks view in system_views.sql */
-		tupdesc = CreateTemplateTupleDesc(3, false);
-		TupleDescInitEntry(tupdesc, (AttrNumber) 1, "pid",
-						   INT4OID, -1, 0);
-		TupleDescInitEntry(tupdesc, (AttrNumber) 2, "localxid",
-						   XIDOID, -1, 0);
-		TupleDescInitEntry(tupdesc, (AttrNumber) 3, "globalxid",
-						   XIDOID, -1, 0);
-
-		funcctx->tuple_desc = BlessTupleDesc(tupdesc);
-
-		/* figure out how many slots we need */
-
-		ctx = (struct mpp_xid_map *)palloc0(sizeof(struct mpp_xid_map) +
-											arrayP->maxSlots * sizeof(struct mpp_xid_map_entry));
-
-		j = 0;
-		LWLockAcquire(SharedSnapshotLock, LW_EXCLUSIVE);
-		for (i = 0; i < arrayP->maxSlots; i++)
-		{
-			SharedSnapshotSlot *testSlot = &arrayP->slots[i];
-
-			if (testSlot->slotid != -1)
-			{
-				ctx->map[j].pid = testSlot->pid;
-				ctx->map[j].local = testSlot->xid;
-				ctx->map[j].global = testSlot->QDxid;
-				j++;
-			}
-		}
-		LWLockRelease(SharedSnapshotLock);
-		ctx->size = j;
-
-		funcctx->user_fctx = (void *)ctx;
-
-		MemoryContextSwitchTo(oldcontext);
-	}
-
-	funcctx = SRF_PERCALL_SETUP();
-	ctx = (struct mpp_xid_map *)funcctx->user_fctx;
-
-	MemSet(nulls, false, sizeof(nulls));
-	while (ctx->cur < ctx->size)
-	{
-		Datum		values[3];
-
-		HeapTuple	tuple;
-		Datum		result;
-
-		/*
-		 * Form tuple with appropriate data.
-		 */
-		MemSet(values, 0, sizeof(values));
-
-		values[0] = Int32GetDatum(ctx->map[ctx->cur].pid);
-		values[1] = TransactionIdGetDatum(ctx->map[ctx->cur].local);
-		values[2] = TransactionIdGetDatum(ctx->map[ctx->cur].global);
-
-		ctx->cur++;
-
-		tuple = heap_form_tuple(funcctx->tuple_desc, values, nulls);
-		result = HeapTupleGetDatum(tuple);
-		SRF_RETURN_NEXT(funcctx, result);
-	}
-
-	SRF_RETURN_DONE(funcctx);
-}

src/include/utils/builtins.h

@@ -1096,9 +1096,6 @@ extern Datum pg_prepared_statement(PG_FUNCTION_ARGS);
 /* utils/mmgr/portalmem.c */
 extern Datum pg_cursor(PG_FUNCTION_ARGS);
 
-/* tqual.c */
-extern Datum mpp_global_xid_map(PG_FUNCTION_ARGS);
-
 /* utils/resscheduler/resqueue.c */
 extern Datum pg_resqueue_status(PG_FUNCTION_ARGS);
 extern Datum pg_resqueue_status_kv(PG_FUNCTION_ARGS);