Improve subscriber's error message for wrong publication relkind.

Pre-v13 versions only support logical replication from plain tables,
while v13 and later also allow partitioned tables to be published.
If you tried to subscribe an older server to such a publication,
you got "table XXX not found on publisher", which is pretty
unhelpful/confusing.  Arrange to deliver a more on-point error
message.  As commit c314c147c did in v13, remove the relkind check
from the query WHERE clause altogether, so that "not there"
is distinguishable from "wrong relkind".

Per report from Radoslav Nedyalkov.  Patch v10-v12.

Discussion: https://postgr.es/m/2952568.1644876730@sss.pgh.pa.us

diff --git a/src/backend/replication/logical/tablesync.c b/src/backend/replication/logical/tablesync.c
index 14f69a6338e42369dcf60c6b9540ad87a9a0226b..b9fea15739eb7b15d7d210f52993b430c83d90f9 100644 (file)
--- a/src/backend/replication/logical/tablesync.c
+++ b/src/backend/replication/logical/tablesync.c
@@ -659,9 +659,10 @@ fetch_remote_table_info(char *nspname, char *relname,
        WalRcvExecResult *res;
        StringInfoData cmd;
        TupleTableSlot *slot;
-       Oid                     tableRow[2] = {OIDOID, CHAROID};
+       Oid                     tableRow[3] = {OIDOID, CHAROID, CHAROID};
        Oid                     attrRow[4] = {TEXTOID, OIDOID, INT4OID, BOOLOID};
        bool            isnull;
+       char            relkind;
        int                     natt;
 
        lrel->nspname = nspname;
@@ -669,13 +670,12 @@ fetch_remote_table_info(char *nspname, char *relname,
 
        /* First fetch Oid and replica identity. */
        initStringInfo(&cmd);
-       appendStringInfo(&cmd, "SELECT c.oid, c.relreplident"
+       appendStringInfo(&cmd, "SELECT c.oid, c.relreplident, c.relkind"
                                         "  FROM pg_catalog.pg_class c"
                                         "  INNER JOIN pg_catalog.pg_namespace n"
                                         "        ON (c.relnamespace = n.oid)"
                                         " WHERE n.nspname = %s"
-                                        "   AND c.relname = %s"
-                                        "   AND c.relkind = 'r'",
+                                        "   AND c.relname = %s",
                                         quote_literal_cstr(nspname),
                                         quote_literal_cstr(relname));
        res = walrcv_exec(LogRepWorkerWalRcvConn, cmd.data,
@@ -696,6 +696,19 @@ fetch_remote_table_info(char *nspname, char *relname,
        Assert(!isnull);
        lrel->replident = DatumGetChar(slot_getattr(slot, 2, &isnull));
        Assert(!isnull);
+       relkind = DatumGetChar(slot_getattr(slot, 3, &isnull));
+       Assert(!isnull);
+
+       /*
+        * Newer PG versions allow things that aren't plain tables to appear in
+        * publications.  We don't handle that in this version, but try to provide
+        * a useful error message.
+        */
+       if (relkind != RELKIND_RELATION)
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("logical replication source relation \"%s.%s\" is not a table",
+                                               nspname, relname)));
 
        ExecDropSingleTupleTableSlot(slot);
        walrcv_clear_result(res);