Mark correctly initial slot snapshots with MVCC type when built

When building an initial slot snapshot, snapshots are marked with
historic MVCC snapshots as type with the marker field being set in
SnapBuildBuildSnapshot() but not overriden in SnapBuildExportSnapshot().
Existing callers of SnapBuildBuildSnapshot() do not care about the type
of snapshot used, but extensions calling it actually may, as reported.

Author: Antonin Houska
Reviewed-by: Álvaro Herrera, Michael Paquier
Discussion: https://postgr.es/m/23215.1527665193@localhost
Backpatch-through: 9.4

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index 7fb7057fa32baf0e4310710e790dcd79e5234ffd..98bdecfcfaf2f76a598802afb2ebf00ed14031f8 100644 (file)
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -636,6 +636,8 @@ SnapBuildExportSnapshot(SnapBuild *builder)
                TransactionIdAdvance(xid);
        }
 
+       /* adjust remaining snapshot fields as needed */
+       snap->satisfies = HeapTupleSatisfiesMVCC;
        snap->xcnt = newxcnt;
        snap->xip = newxip;