Fix misc typos in comments.

Author: hlinnaka

src/backend/replication/logical/logical.c

@@ -21,7 +21,7 @@
  *	  one to prepare a data write, and a final one for actually writing since
  *	  their implementation depends on the type of consumer.  Check
  *	  logicalfuncs.c for an example implementation of a fairly simple consumer
- *	  and a implementation of a WAL reading callback that's suitable for
+ *	  and an implementation of a WAL reading callback that's suitable for
  *	  simple consumers.
  *-------------------------------------------------------------------------
  */
@@ -291,7 +291,7 @@ CreateInitDecodingContext(char *plugin,
 	 * decoding from, to avoid starting from a running xacts record referring
 	 * to xids whose rows have been vacuumed or pruned
 	 * already. GetOldestSafeDecodingTransactionId() returns such a value, but
-	 * without further interlock it's return value might immediately be out of
+	 * without further interlock its return value might immediately be out of
 	 * date.
 	 *
 	 * So we have to acquire the ProcArrayLock to prevent computation of new
@@ -772,7 +772,7 @@ LogicalIncreaseXminForSlot(XLogRecPtr current_lsn, TransactionId xmin)
  * Mark the minimal LSN (restart_lsn) we need to read to replay all
  * transactions that have not yet committed at current_lsn.
  *
- * Just like IncreaseRestartDecodingForSlot this nly takes effect when the
+ * Just like IncreaseRestartDecodingForSlot this only takes effect when the
  * client has confirmed to have received current_lsn.
  */
 void

src/backend/storage/ipc/procarray.c

@@ -1928,7 +1928,7 @@ GetOldestActiveTransactionId(void)
  * much more conservative than what really has been affected by vacuum, but we
  * currently don't have better data available.
  *
- * This is useful to initalize the cutoff xid after which a new changeset
+ * This is useful to initialize the cutoff xid after which a new changeset
  * extraction replication slot can start decoding changes.
  *
  * Must be called with ProcArrayLock held either shared or exclusively,