From: Tomas Vondra <tomas@2ndquadrant.com>
Date: Wed, 30 Aug 2017 21:55:30 +0000 (+0200)
Subject: Disable logical decoding as unsupported
X-Git-Tag: XL_10_R1BETA1~139
X-Git-Url: http://git.postgresql.org/gitweb/static/gitweb.js?a=commitdiff_plain;h=e71c1dd42ae9c47023f3f9aee60d6663fb1474c1;p=postgres-xl.git

Disable logical decoding as unsupported

Commit 665c224a6b2afa disabled CREATE PUBLICATION/SUBSCRIPTION, but
it was still possible to create a logical replication slot and call
pg_logical_slot_get_changes() on it.

That would however crash and burn as ReorderBufferCommit() relies on
subtransactions, and BeginInternalSubTransaction() is not expected
to fail, leading to segfaults in the PG_CATCH block.

Simply disallowing creating logical slots (and whatever else relies
on CheckLogicalDecodingRequirements) seems like the best fix.
---

diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index efb9785f25..f6774df96f 100644
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -77,6 +77,16 @@ CheckLogicalDecodingRequirements(void)
 {
 	CheckSlotRequirements();
 
+	/*
+	 * Postgres-XL does not support logical replication for now. We could create
+	 * the logical replication slot, but attempts to decode the WAL would crash
+	 * and burn as ReorderBufferCommit() uses subtransactions internally. We need
+	 */
+	ereport(ERROR,
+			(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+			 errmsg("Postgres-XL does not support logical replication"),
+			 errdetail("The feature is not currently supported")));
+
 	if (wal_level < WAL_LEVEL_LOGICAL)
 		ereport(ERROR,
 				(errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),