Fix thinko introduced in 2bef06d516460 et al.

The callers for GetOldestSafeDecodingTransactionId() all inverted the
argument for the argument introduced in 2bef06d516460. Luckily this
appears to be inconsequential for the moment, as we wait for
concurrent in-progress transaction when assembling a
snapshot. Additionally this could only make a difference when adding a
second logical slot, because only a pre-existing slot could cause an
issue by lowering the returned xid dangerously much.

Reported-By: Antonin Houska
Discussion: https://postgr.es/m/32704.1496993134@localhost
Backport: 9.4-, where 2bef06d516460 was backpatched to.

diff --git a/src/backend/replication/logical/logical.c b/src/backend/replication/logical/logical.c
index 1b92c056b89af8c8f90153a2193313aa6d5329e1..855f0035410b36e3f07c9d7ec71a9dcc8b744b0a 100644 (file)
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -327,7 +327,7 @@ CreateInitDecodingContext(char *plugin,
         */
        LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
 
-       xmin_horizon = GetOldestSafeDecodingTransactionId(need_full_snapshot);
+       xmin_horizon = GetOldestSafeDecodingTransactionId(!need_full_snapshot);
 
        slot->effective_catalog_xmin = xmin_horizon;
        slot->data.catalog_xmin = xmin_horizon;

diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index 981f3978323ea5cbac40e4a7ab25cac417c7bcbb..f4b1fea0f8459e8777337884a7446cd68cf96d3d 100644 (file)
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -594,7 +594,7 @@ SnapBuildExportSnapshot(SnapBuild *builder)
                TransactionId safeXid;
 
                LWLockAcquire(ProcArrayLock, LW_SHARED);
-               safeXid = GetOldestSafeDecodingTransactionId(true);
+               safeXid = GetOldestSafeDecodingTransactionId(false);
                LWLockRelease(ProcArrayLock);
 
                Assert(TransactionIdPrecedesOrEquals(safeXid, snap->xmin));