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 3ea80253d36aad44a3d6acea632d1d6903618ea3..f44533eb7f75b8ee26aa8963eaf2eacd1342df76 100644 (file)
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -284,7 +284,7 @@ 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 43ec8e494399a62646614ba3dfeff3594b211df9..901e95ede4f6aa70f0c852f6572f8d43ec03f283 100644 (file)
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -592,7 +592,7 @@ SnapBuildExportSnapshot(SnapBuild *builder)
                TransactionId safeXid;
 
                LWLockAcquire(ProcArrayLock, LW_SHARED);
-               safeXid = GetOldestSafeDecodingTransactionId(true);
+               safeXid = GetOldestSafeDecodingTransactionId(false);
                LWLockRelease(ProcArrayLock);
 
                Assert(TransactionIdPrecedesOrEquals(safeXid, snap->xmin));