Don't try to print data type names in slot_store_error_callback().

The existing code tried to do syscache lookups in an already-failed
transaction, which is problematic to say the least.  After some
consideration of alternatives, the best fix seems to be to just drop
type names from the error message altogether.  The table and column
names seem like sufficient localization.  If the user is unsure what
types are involved, she can check the local and remote table
definitions.

Having done that, we can also discard the LogicalRepTypMap hash
table, which had no other use.  Arguably, LOGICAL_REP_MSG_TYPE
replication messages are now obsolete as well; but we should
probably keep them in case some other use emerges.  (The complexity
of removing something from the replication protocol would likely
outweigh any savings anyhow.)

Masahiko Sawada and Bharath Rupireddy, per complaint from Andres
Freund.  Back-patch to v10 where this code originated.

Discussion: https://postgr.es/m/20210106020229.ne5xnuu6wlondjpe@alap3.anarazel.de

src/backend/replication/logical/relation.c

@@ -17,7 +17,6 @@
 
 #include "postgres.h"
 
-#include "access/sysattr.h"
 #include "access/table.h"
 #include "catalog/namespace.h"
 #include "catalog/pg_subscription_rel.h"
@@ -25,16 +24,12 @@
 #include "nodes/makefuncs.h"
 #include "replication/logicalrelation.h"
 #include "replication/worker_internal.h"
-#include "utils/builtins.h"
 #include "utils/inval.h"
-#include "utils/lsyscache.h"
+
-#include "utils/memutils.h"
-#include "utils/syscache.h"
 
 static MemoryContext LogicalRepRelMapContext = NULL;
 
 static HTAB *LogicalRepRelMap = NULL;
-static HTAB *LogicalRepTypMap = NULL;
 
 /*
  * Partition map (LogicalRepPartMap)
@@ -118,15 +113,6 @@ logicalrep_relmap_init(void)
 	LogicalRepRelMap = hash_create("logicalrep relation map cache", 128, &ctl,
 								   HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
 
-	/* Initialize the type hash table. */
-	ctl.keysize = sizeof(Oid);
-	ctl.entrysize = sizeof(LogicalRepTyp);
-	ctl.hcxt = LogicalRepRelMapContext;
-
-	/* This will usually be small. */
-	LogicalRepTypMap = hash_create("logicalrep type map cache", 2, &ctl,
-								   HASH_ELEM | HASH_BLOBS | HASH_CONTEXT);
-
 	/* Watch for invalidation events. */
 	CacheRegisterRelcacheCallback(logicalrep_relmap_invalidate_cb,
 								  (Datum) 0);
@@ -450,95 +436,6 @@ logicalrep_rel_close(LogicalRepRelMapEntry *rel, LOCKMODE lockmode)
 	rel->localrel = NULL;
 }
 
-/*
- * Free the type map cache entry data.
- */
-static void
-logicalrep_typmap_free_entry(LogicalRepTyp *entry)
-{
-	pfree(entry->nspname);
-	pfree(entry->typname);
-}
-
-/*
- * Add new entry or update existing entry in the type map cache.
- */
-void
-logicalrep_typmap_update(LogicalRepTyp *remotetyp)
-{
-	MemoryContext oldctx;
-	LogicalRepTyp *entry;
-	bool		found;
-
-	if (LogicalRepTypMap == NULL)
-		logicalrep_relmap_init();
-
-	/*
-	 * HASH_ENTER returns the existing entry if present or creates a new one.
-	 */
-	entry = hash_search(LogicalRepTypMap, (void *) &remotetyp->remoteid,
-						HASH_ENTER, &found);
-
-	if (found)
-		logicalrep_typmap_free_entry(entry);
-
-	/* Make cached copy of the data */
-	entry->remoteid = remotetyp->remoteid;
-	oldctx = MemoryContextSwitchTo(LogicalRepRelMapContext);
-	entry->nspname = pstrdup(remotetyp->nspname);
-	entry->typname = pstrdup(remotetyp->typname);
-	MemoryContextSwitchTo(oldctx);
-}
-
-/*
- * 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.
- */
-char *
-logicalrep_typmap_gettypname(Oid remoteid)
-{
-	LogicalRepTyp *entry;
-	bool		found;
-
-	/* Internal types are mapped directly. */
-	if (remoteid < FirstGenbkiObjectId)
-	{
-		if (!get_typisdefined(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)
-	{
-		/*
-		 * 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);
-	}
-
-	/* search the mapping */
-	entry = hash_search(LogicalRepTypMap, (void *) &remoteid,
-						HASH_FIND, &found);
-	if (!found)
-		return psprintf("unrecognized %u", remoteid);
-
-	Assert(OidIsValid(entry->remoteid));
-	return psprintf("%s.%s", entry->nspname, entry->typname);
-}
-
 /*
  * Partition cache: look up partition LogicalRepRelMapEntry's
  *

src/backend/replication/logical/worker.c

@@ -132,7 +132,6 @@ static dlist_head lsn_mapping = DLIST_STATIC_INIT(lsn_mapping);
 typedef struct SlotErrCallbackArg
 {
 	LogicalRepRelMapEntry *rel;
-	int			local_attnum;
 	int			remote_attnum;
 } SlotErrCallbackArg;
 
@@ -503,36 +502,23 @@ slot_fill_defaults(LogicalRepRelMapEntry *rel, EState *estate,
 }
 
 /*
- * Error callback to give more context info about type conversion failure.
+ * Error callback to give more context info about data conversion failures
+ * while reading data from the remote server.
  */
 static void
 slot_store_error_callback(void *arg)
 {
 	SlotErrCallbackArg *errarg = (SlotErrCallbackArg *) arg;
 	LogicalRepRelMapEntry *rel;
-	char	   *remotetypname;
-	Oid			remotetypoid,
-				localtypoid;
 
 	/* Nothing to do if remote attribute number is not set */
 	if (errarg->remote_attnum < 0)
 		return;
 
 	rel = errarg->rel;
-	remotetypoid = rel->remoterel.atttyps[errarg->remote_attnum];
+	errcontext("processing remote data for replication target relation \"%s.%s\" column \"%s\"",
-
-	/* 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",
 			   rel->remoterel.nspname, rel->remoterel.relname,
-			   rel->remoterel.attnames[errarg->remote_attnum],
+			   rel->remoterel.attnames[errarg->remote_attnum]);
-			   remotetypname,
-			   format_type_be(localtypoid));
 }
 
 /*
@@ -553,7 +539,6 @@ slot_store_data(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 
 	/* Push callback + info on the error context stack */
 	errarg.rel = rel;
-	errarg.local_attnum = -1;
 	errarg.remote_attnum = -1;
 	errcallback.callback = slot_store_error_callback;
 	errcallback.arg = (void *) &errarg;
@@ -573,7 +558,6 @@ slot_store_data(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 
 			Assert(remoteattnum < tupleData->ncols);
 
-			errarg.local_attnum = i;
 			errarg.remote_attnum = remoteattnum;
 
 			if (tupleData->colstatus[remoteattnum] == LOGICALREP_COLUMN_TEXT)
@@ -622,7 +606,6 @@ slot_store_data(TupleTableSlot *slot, LogicalRepRelMapEntry *rel,
 				slot->tts_isnull[i] = true;
 			}
 
-			errarg.local_attnum = -1;
 			errarg.remote_attnum = -1;
 		}
 		else
@@ -679,7 +662,6 @@ slot_modify_data(TupleTableSlot *slot, TupleTableSlot *srcslot,
 
 	/* For error reporting, push callback + info on the error context stack */
 	errarg.rel = rel;
-	errarg.local_attnum = -1;
 	errarg.remote_attnum = -1;
 	errcallback.callback = slot_store_error_callback;
 	errcallback.arg = (void *) &errarg;
@@ -702,7 +684,6 @@ slot_modify_data(TupleTableSlot *slot, TupleTableSlot *srcslot,
 		{
 			StringInfo	colvalue = &tupleData->colvalues[remoteattnum];
 
-			errarg.local_attnum = i;
 			errarg.remote_attnum = remoteattnum;
 
 			if (tupleData->colstatus[remoteattnum] == LOGICALREP_COLUMN_TEXT)
@@ -747,7 +728,6 @@ slot_modify_data(TupleTableSlot *slot, TupleTableSlot *srcslot,
 				slot->tts_isnull[i] = true;
 			}
 
-			errarg.local_attnum = -1;
 			errarg.remote_attnum = -1;
 		}
 	}
@@ -1217,8 +1197,7 @@ apply_handle_relation(StringInfo s)
 /*
  * Handle TYPE message.
  *
- * Note we don't do local mapping here, that's done when the type is
+ * This is now vestigial; we read the info and discard it.
- * actually used.
  */
 static void
 apply_handle_type(StringInfo s)
@@ -1229,7 +1208,6 @@ apply_handle_type(StringInfo s)
 		return;
 
 	logicalrep_read_typ(s, &typ);
-	logicalrep_typmap_update(&typ);
 }
 
 /*

src/include/replication/logicalrelation.h

@@ -46,7 +46,4 @@ extern LogicalRepRelMapEntry *logicalrep_partition_open(LogicalRepRelMapEntry *r
 extern void logicalrep_rel_close(LogicalRepRelMapEntry *rel,
 								 LOCKMODE lockmode);
 
-extern void logicalrep_typmap_update(LogicalRepTyp *remotetyp);
-extern char *logicalrep_typmap_gettypname(Oid remoteid);
-
 #endif							/* LOGICALRELATION_H */