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 85721ead3eca9b2641f88431bff044810f29f177..efb9785f25e5fc23f2c5149dee9e617706400e94 100644 (file)
--- a/src/backend/replication/logical/logical.c
+++ b/src/backend/replication/logical/logical.c
@@ -288,7 +288,7 @@ 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 281b7ab869f5af0c2ef74ff30e9a95b0c3b339c3..153d1712ef3a2cef4452f8f00a03a722ba6e4057 100644 (file)
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -574,7 +574,7 @@ SnapBuildInitialSnapshot(SnapBuild *builder)
                TransactionId safeXid;
 
                LWLockAcquire(ProcArrayLock, LW_SHARED);
-               safeXid = GetOldestSafeDecodingTransactionId(true);
+               safeXid = GetOldestSafeDecodingTransactionId(false);
                LWLockRelease(ProcArrayLock);
 
                Assert(TransactionIdPrecedesOrEquals(safeXid, snap->xmin));