Fix a few more misc typos in comments.

src/backend/replication/logical/snapbuild.c

@@ -29,7 +29,7 @@
  * As the percentage of transactions modifying the catalog normally is fairly
  * small in comparisons to ones only manipulating user data, we keep track of
  * the committed catalog modifying ones inside (xmin, xmax) instead of keeping
- * track of all running transactions like its done in a normal snapshot. Note
+ * track of all running transactions like it's done in a normal snapshot. Note
  * that we're generally only looking at transactions that have acquired an
  * xid. That is we keep a list of transactions between snapshot->(xmin, xmax)
  * that we consider committed, everything else is considered aborted/in
@@ -81,7 +81,7 @@
  *
  * Initially the machinery is in the START stage. When a xl_running_xacts
  * record is read that is sufficiently new (above the safe xmin horizon),
- * there's a state transation. If there were no running xacts when the
+ * there's a state transition. If there were no running xacts when the
  * runnign_xacts record was generated, we'll directly go into CONSISTENT
  * state, otherwise we'll switch to the FULL_SNAPSHOT state. Having a full
  * snapshot means that all transactions that start henceforth can be decoded
@@ -412,7 +412,7 @@ SnapBuildSnapDecRefcount(Snapshot snap)
 
 	Assert(snap->active_count);
 
-	/* slightly more likely, so its checked even without casserts */
+	/* slightly more likely, so it's checked even without casserts */
 	if (snap->copied)
 		elog(ERROR, "cannot free a copied snapshot");
 
@@ -451,7 +451,7 @@ SnapBuildBuildSnapshot(SnapBuild *builder, TransactionId xid)
 	 *
 	 * In the 'xip' array we store transactions that have to be treated as
 	 * committed. Since we will only ever look at tuples from transactions
-	 * that have modified the catalog its more efficient to store those few
+	 * that have modified the catalog it's more efficient to store those few
 	 * that exist between xmin and xmax (frequently there are none).
 	 *
 	 * Snapshots that are used in transactions that have modified the catalog
@@ -1117,7 +1117,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 		SnapBuildSerialize(builder, lsn);
 
 	/*
-	 * Update range of interesting xids base don the running xacts
+	 * Update range of interesting xids based on the running xacts
 	 * information. We don't increase ->xmax using it, because once we are in
 	 * a consistent state we can do that ourselves and much more efficiently
 	 * so, because we only need to do it for catalog transactions since we
@@ -1125,7 +1125,7 @@ SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn, xl_running_xact
 	 *
 	 * NB: Because of that xmax can be lower than xmin, because we only
 	 * increase xmax when a catalog modifying transaction commits. While odd
-	 * looking, its correct and actually more efficient this way since we hit
+	 * looking, it's correct and actually more efficient this way since we hit
 	 * fast paths in tqual.c.
 	 */
 	builder->xmin = running->oldestRunningXid;

src/include/access/htup.h

@@ -16,7 +16,7 @@
 
 #include "storage/itemptr.h"
 
-/* typedefs and forward declarations for structs defined in htup.h */
+/* typedefs and forward declarations for structs defined in htup_details.h */
 
 typedef struct HeapTupleHeaderData HeapTupleHeaderData;