logical replication: fix OID type mapping mechanism

The logical replication type map seems to have been misused by its only
caller -- it would try to use the remote OID as input for local type
routines, which unsurprisingly could result in bogus "cache lookup
failed for type XYZ" errors, or random other type names being picked up
if they happened to use the right OID.  Fix that, changing
Oid logicalrep_typmap_getid(Oid remoteid) to
char *logicalrep_typmap_gettypname(Oid remoteid)
which is more useful.  If the remote type is not part of the typmap,
this simply prints "unrecognized type" instead of choking trying to
figure out -- a pointless exercise (because the only input for that
comes from replication messages, which are not under the local node's
control) and dangerous to boot, when called from within an error context
callback.

Once that is done, it comes to light that the local OID in the typmap
entry was not being used for anything; the type/schema names are what we
need, so remove local type OID from that struct.

Once you do that, it becomes pointless to attach a callback to regular
syscache invalidation.  So remove that also.

Reported-by: Dang Minh Huong
Author: Masahiko Sawada
Reviewed-by: Álvaro Herrera, Petr Jelínek, Dang Minh Huong, Atsushi Torikoshi
Discussion: https://postgr.es/m/75DB81BEEA95B445AE6D576A0A5C9E936A6BE964@BPXM05GP.gisp.nec.co.jp
Discussion: https://postgr.es/m/75DB81BEEA95B445AE6D576A0A5C9E936A6C4B0A@BPXM05GP.gisp.nec.co.jp

src/backend/replication/logical/relation.c

@@ -35,8 +35,6 @@ static MemoryContext LogicalRepRelMapContext = NULL;
 static HTAB *LogicalRepRelMap = NULL;
 static HTAB *LogicalRepTypMap = NULL;
 
-static void logicalrep_typmap_invalidate_cb(Datum arg, int cacheid,
-								uint32 hashvalue);
 
 /*
  * Relcache invalidation callback for our relation map cache.
@@ -115,8 +113,6 @@ logicalrep_relmap_init(void)
 	/* Watch for invalidation events. */
 	CacheRegisterRelcacheCallback(logicalrep_relmap_invalidate_cb,
 								  (Datum) 0);
-	CacheRegisterSyscacheCallback(TYPEOID, logicalrep_typmap_invalidate_cb,
-								  (Datum) 0);
 }
 
 /*
@@ -375,27 +371,6 @@ logicalrep_rel_close(LogicalRepRelMapEntry *rel, LOCKMODE lockmode)
 	rel->localrel = NULL;
 }
 
-
-/*
- * Type cache invalidation callback for our type map cache.
- */
-static void
-logicalrep_typmap_invalidate_cb(Datum arg, int cacheid, uint32 hashvalue)
-{
-	HASH_SEQ_STATUS status;
-	LogicalRepTyp *entry;
-
-	/* Just to be sure. */
-	if (LogicalRepTypMap == NULL)
-		return;
-
-	/* invalidate all cache entries */
-	hash_seq_init(&status, LogicalRepTypMap);
-
-	while ((entry = (LogicalRepTyp *) hash_seq_search(&status)) != NULL)
-		entry->typoid = InvalidOid;
-}
-
 /*
  * Free the type map cache entry data.
  */
@@ -404,8 +379,6 @@ logicalrep_typmap_free_entry(LogicalRepTyp *entry)
 {
 	pfree(entry->nspname);
 	pfree(entry->typname);
-
-	entry->typoid = InvalidOid;
 }
 
 /*
@@ -436,58 +409,53 @@ logicalrep_typmap_update(LogicalRepTyp *remotetyp)
 	entry->nspname = pstrdup(remotetyp->nspname);
 	entry->typname = pstrdup(remotetyp->typname);
 	MemoryContextSwitchTo(oldctx);
-	entry->typoid = InvalidOid;
 }
 
 /*
- * Fetch type info from the cache.
+ * Fetch type name from the cache by remote type OID.
+ *
+ * Return a substitute value if we cannot find the data type; no message is
+ * sent to the log in that case, because this is used by error callback
+ * already.
  */
-Oid
-logicalrep_typmap_getid(Oid remoteid)
+char *
+logicalrep_typmap_gettypname(Oid remoteid)
 {
 	LogicalRepTyp *entry;
 	bool		found;
-	Oid			nspoid;
 
 	/* Internal types are mapped directly. */
 	if (remoteid < FirstNormalObjectId)
 	{
 		if (!get_typisdefined(remoteid))
-			ereport(ERROR,
-					(errmsg("built-in type %u not found", remoteid),
-					 errhint("This can be caused by having a publisher with a higher PostgreSQL major version than the subscriber.")));
-		return remoteid;
+		{
+			/*
+			 * This can be caused by having a publisher with a higher
+			 * PostgreSQL major version than the subscriber.
+			 */
+			return psprintf("unrecognized %u", remoteid);
+		}
+
+		return format_type_be(remoteid);
 	}
 
 	if (LogicalRepTypMap == NULL)
-		logicalrep_relmap_init();
+	{
+		/*
+		 * If the typemap is not initialized yet, we cannot possibly attempt
+		 * to search the hash table; but there's no way we know the type
+		 * locally yet, since we haven't received a message about this type,
+		 * so this is the best we can do.
+		 */
+		return psprintf("unrecognized %u", remoteid);
+	}
 
-	/* Try finding the mapping. */
+	/* search the mapping */
 	entry = hash_search(LogicalRepTypMap, (void *) &remoteid,
 						HASH_FIND, &found);
-
 	if (!found)
-		elog(ERROR, "no type map entry for remote type %u",
-			 remoteid);
-
-	/* Found and mapped, return the oid. */
-	if (OidIsValid(entry->typoid))
-		return entry->typoid;
-
-	/* Otherwise, try to map to local type. */
-	nspoid = LookupExplicitNamespace(entry->nspname, true);
-	if (OidIsValid(nspoid))
-		entry->typoid = GetSysCacheOid2(TYPENAMENSP,
-										PointerGetDatum(entry->typname),
-										ObjectIdGetDatum(nspoid));
-	else
-		entry->typoid = InvalidOid;
-
-	if (!OidIsValid(entry->typoid))
-		ereport(ERROR,
-				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),
-				 errmsg("data type \"%s.%s\" required for logical replication does not exist",
-						entry->nspname, entry->typname)));
+		return psprintf("unrecognized %u", remoteid);
 
-	return entry->typoid;
+	Assert(OidIsValid(entry->remoteid));
+	return psprintf("%s.%s", entry->nspname, entry->typname);
 }

src/backend/replication/logical/worker.c

@@ -100,8 +100,9 @@ static dlist_head lsn_mapping = DLIST_STATIC_INIT(lsn_mapping);
 
 typedef struct SlotErrCallbackArg
 {
-	LogicalRepRelation *rel;
-	int			attnum;
+	LogicalRepRelMapEntry *rel;
+	int			local_attnum;
+	int			remote_attnum;
 } SlotErrCallbackArg;
 
 static MemoryContext ApplyMessageContext = NULL;
@@ -282,19 +283,29 @@ static void
 slot_store_error_callback(void *arg)
 {
 	SlotErrCallbackArg *errarg = (SlotErrCallbackArg *) arg;
+	LogicalRepRelMapEntry *rel;
+	char	   *remotetypname;
 	Oid			remotetypoid,
 				localtypoid;
 
-	if (errarg->attnum < 0)
+	/* Nothing to do if remote attribute number is not set */
+	if (errarg->remote_attnum < 0)
 		return;
 
-	remotetypoid = errarg->rel->atttyps[errarg->attnum];
-	localtypoid = logicalrep_typmap_getid(remotetypoid);
+	rel = errarg->rel;
+	remotetypoid = rel->remoterel.atttyps[errarg->remote_attnum];
+
+	/* Fetch remote type name from the LogicalRepTypMap cache */
+	remotetypname = logicalrep_typmap_gettypname(remotetypoid);
+
+	/* Fetch local type OID from the local sys cache */
+	localtypoid = get_atttype(rel->localreloid, errarg->local_attnum + 1);
+
 	errcontext("processing remote data for replication target relation \"%s.%s\" column \"%s\", "
 			   "remote type %s, local type %s",
-			   errarg->rel->nspname, errarg->rel->relname,
-			   errarg->rel->attnames[errarg->attnum],
-			   format_type_be(remotetypoid),
+			   rel->remoterel.nspname, rel->remoterel.relname,
+			   rel->remoterel.attnames[errarg->remote_attnum],
+			   remotetypname,
 			   format_type_be(localtypoid));
 }
 
@@ -315,8 +326,9 @@ slot_store_cstrings(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 	ExecClearTuple(slot);
 
 	/* Push callback + info on the error context stack */
-	errarg.rel = &rel->remoterel;
-	errarg.attnum = -1;
+	errarg.rel = rel;
+	errarg.local_attnum = -1;
+	errarg.remote_attnum = -1;
 	errcallback.callback = slot_store_error_callback;
 	errcallback.arg = (void *) &errarg;
 	errcallback.previous = error_context_stack;
@@ -334,14 +346,17 @@ slot_store_cstrings(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 			Oid			typinput;
 			Oid			typioparam;
 
-			errarg.attnum = remoteattnum;
+			errarg.local_attnum = i;
+			errarg.remote_attnum = remoteattnum;
 
 			getTypeInputInfo(att->atttypid, &typinput, &typioparam);
-			slot->tts_values[i] = OidInputFunctionCall(typinput,
-													   values[remoteattnum],
-													   typioparam,
-													   att->atttypmod);
+			slot->tts_values[i] =
+				OidInputFunctionCall(typinput, values[remoteattnum],
+									 typioparam, att->atttypmod);
 			slot->tts_isnull[i] = false;
+
+			errarg.local_attnum = -1;
+			errarg.remote_attnum = -1;
 		}
 		else
 		{
@@ -380,8 +395,9 @@ slot_modify_cstrings(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 	ExecClearTuple(slot);
 
 	/* Push callback + info on the error context stack */
-	errarg.rel = &rel->remoterel;
-	errarg.attnum = -1;
+	errarg.rel = rel;
+	errarg.local_attnum = -1;
+	errarg.remote_attnum = -1;
 	errcallback.callback = slot_store_error_callback;
 	errcallback.arg = (void *) &errarg;
 	errcallback.previous = error_context_stack;
@@ -404,14 +420,17 @@ slot_modify_cstrings(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 			Oid			typinput;
 			Oid			typioparam;
 
-			errarg.attnum = remoteattnum;
+			errarg.local_attnum = i;
+			errarg.remote_attnum = remoteattnum;
 
 			getTypeInputInfo(att->atttypid, &typinput, &typioparam);
-			slot->tts_values[i] = OidInputFunctionCall(typinput,
-													   values[remoteattnum],
-													   typioparam,
-													   att->atttypmod);
+			slot->tts_values[i] =
+				OidInputFunctionCall(typinput, values[remoteattnum],
+									 typioparam, att->atttypmod);
 			slot->tts_isnull[i] = false;
+
+			errarg.local_attnum = -1;
+			errarg.remote_attnum = -1;
 		}
 		else
 		{

src/include/replication/logicalproto.h

@@ -55,10 +55,9 @@ typedef struct LogicalRepRelation
 /* Type mapping info */
 typedef struct LogicalRepTyp
 {
-	Oid			remoteid;		/* unique id of the type */
-	char	   *nspname;		/* schema name */
-	char	   *typname;		/* name of the type */
-	Oid			typoid;			/* local type Oid */
+	Oid			remoteid;		/* unique id of the remote type */
+	char	   *nspname;		/* schema name of remote type */
+	char	   *typname;		/* name of the remote type */
 } LogicalRepTyp;
 
 /* Transaction info */

src/include/replication/logicalrelation.h

@@ -37,6 +37,6 @@ extern void logicalrep_rel_close(LogicalRepRelMapEntry *rel,
 					 LOCKMODE lockmode);
 
 extern void logicalrep_typmap_update(LogicalRepTyp *remotetyp);
-extern Oid	logicalrep_typmap_getid(Oid remoteid);
+extern char *logicalrep_typmap_gettypname(Oid remoteid);
 
 #endif							/* LOGICALRELATION_H */