diff --git a/src/backend/access/nbtree/nbtutils.c b/src/backend/access/nbtree/nbtutils.c
index 93fab264ae..9b172c1a19 100644
--- a/src/backend/access/nbtree/nbtutils.c
+++ b/src/backend/access/nbtree/nbtutils.c
@@ -664,7 +664,7 @@ _bt_restore_array_keys(IndexScanDesc scan)
  * scan->numberOfKeys is the number of input keys, so->numberOfKeys gets
  * the number of output keys (possibly less, never greater).
  *
- * The output keys are marked with additional sk_flag bits beyond the
+ * The output keys are marked with additional sk_flags bits beyond the
  * system-standard bits supplied by the caller.  The DESC and NULLS_FIRST
  * indoption bits for the relevant index attribute are copied into the flags.
  * Also, for a DESC column, we commute (flip) all the sk_strategy numbers
diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c
index 13aa8e1b95..0fbcb4e6fe 100644
--- a/src/backend/access/transam/slru.c
+++ b/src/backend/access/transam/slru.c
@@ -1364,7 +1364,7 @@ SlruScanDirCbDeleteAll(SlruCtl ctl, char *filename, int segpage, void *data)
 }
 
 /*
- * Scan the SimpleLRU directory and apply a callback to each file found in it.
+ * Scan the SimpleLru directory and apply a callback to each file found in it.
  *
  * If the callback returns true, the scan is stopped.  The last return value
  * from the callback is returned.
diff --git a/src/backend/access/transam/xact.c b/src/backend/access/transam/xact.c
index 1bbaeeebf4..52e9643305 100644
--- a/src/backend/access/transam/xact.c
+++ b/src/backend/access/transam/xact.c
@@ -1232,7 +1232,7 @@ RecordTransactionCommit(void)
 	if (!markXidCommitted)
 	{
 		/*
-		 * We expect that every smgrscheduleunlink is followed by a catalog
+		 * We expect that every RelationDropStorage is followed by a catalog
 		 * update, and hence XID assignment, so we shouldn't get here with any
 		 * pending deletes.  Use a real test not just an Assert to check this,
 		 * since it's a bit fragile.
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index 0d6e968ee6..c6faf48d24 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -702,7 +702,7 @@ ValidXLogRecordHeader(XLogReaderState *state, XLogRecPtr RecPtr,
  * We assume all of the record (that is, xl_tot_len bytes) has been read
  * into memory at *record.  Also, ValidXLogRecordHeader() has accepted the
  * record's header, which means in particular that xl_tot_len is at least
- * SizeOfXlogRecord.
+ * SizeOfXLogRecord.
  */
 static bool
 ValidXLogRecord(XLogReaderState *state, XLogRecord *record, XLogRecPtr recptr)
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index dc64b1e0c2..0bd1d0f954 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -269,7 +269,7 @@ static void SnapBuildSnapIncRefcount(Snapshot snap);
 
 static void SnapBuildDistributeNewCatalogSnapshot(SnapBuild *builder, XLogRecPtr lsn);
 
-/* xlog reading helper functions for SnapBuildProcessRecord */
+/* xlog reading helper functions for SnapBuildProcessRunningXacts */
 static bool SnapBuildFindSnapshot(SnapBuild *builder, XLogRecPtr lsn, xl_running_xacts *running);
 static void SnapBuildWaitSnapshot(xl_running_xacts *running, TransactionId cutoff);
 
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index 62342a69cb..dbbca8af6c 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -298,7 +298,7 @@ ReplicationSlotCreate(const char *name, bool db_specific,
 	 * We need to briefly prevent any other backend from iterating over the
 	 * slots while we flip the in_use flag. We also need to set the active
 	 * flag while holding the ControlLock as otherwise a concurrent
-	 * SlotAcquire() could acquire the slot as well.
+	 * ReplicationSlotAcquire() could acquire the slot as well.
 	 */
 	LWLockAcquire(ReplicationSlotControlLock, LW_EXCLUSIVE);
 
diff --git a/src/backend/utils/mmgr/slab.c b/src/backend/utils/mmgr/slab.c
index bd8d200982..700a91a2a3 100644
--- a/src/backend/utils/mmgr/slab.c
+++ b/src/backend/utils/mmgr/slab.c
@@ -182,7 +182,7 @@ static const MemoryContextMethods SlabMethods = {
  * chunkSize: allocation chunk size
  *
  * The chunkSize may not exceed:
- *		MAXALIGN_DOWN(SIZE_MAX) - MAXALIGN(sizeof(SlabBlock)) - SLAB_CHUNKHDRSZ
+ *		MAXALIGN_DOWN(SIZE_MAX) - MAXALIGN(sizeof(SlabBlock)) - sizeof(SlabChunk)
  */
 MemoryContext
 SlabContextCreate(MemoryContext parent,
diff --git a/src/include/access/hash_xlog.h b/src/include/access/hash_xlog.h
index 53b682c56e..7d52145a2a 100644
--- a/src/include/access/hash_xlog.h
+++ b/src/include/access/hash_xlog.h
@@ -51,19 +51,6 @@
 #define XLH_SPLIT_META_UPDATE_MASKS		(1<<0)
 #define XLH_SPLIT_META_UPDATE_SPLITPOINT		(1<<1)
 
-/*
- * This is what we need to know about a HASH index create.
- *
- * Backup block 0: metapage
- */
-typedef struct xl_hash_createidx
-{
-	double		num_tuples;
-	RegProcedure procid;
-	uint16		ffactor;
-}			xl_hash_createidx;
-#define SizeOfHashCreateIdx (offsetof(xl_hash_createidx, ffactor) + sizeof(uint16))
-
 /*
  * This is what we need to know about simple (without split) insert.
  *
diff --git a/src/include/libpq/pqcomm.h b/src/include/libpq/pqcomm.h
index baf6a4b6c0..15cd7a160b 100644
--- a/src/include/libpq/pqcomm.h
+++ b/src/include/libpq/pqcomm.h
@@ -132,8 +132,6 @@ typedef uint32 PacketLen;
 
 #define SM_DATABASE		64
 #define SM_USER			32
-/* We append database name if db_user_namespace true. */
-#define SM_DATABASE_USER (SM_DATABASE+SM_USER+1)	/* +1 for @ */
 #define SM_OPTIONS		64
 #define SM_UNUSED		64
 #define SM_TTY			64
@@ -142,7 +140,6 @@ typedef struct StartupPacket
 {
 	ProtocolVersion protoVersion;	/* Protocol version */
 	char		database[SM_DATABASE];	/* Database name */
-	/* Db_user_namespace appends dbname */
 	char		user[SM_USER];	/* User name */
 	char		options[SM_OPTIONS];	/* Optional additional args */
 	char		unused[SM_UNUSED];	/* Unused */
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index dbfd8efd26..ba0b7f6f79 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -63,7 +63,7 @@
 	(PGSIXBIT(ch1) + (PGSIXBIT(ch2) << 6) + (PGSIXBIT(ch3) << 12) + \
 	 (PGSIXBIT(ch4) << 18) + (PGSIXBIT(ch5) << 24))
 
-/* These macros depend on the fact that '0' becomes a zero in SIXBIT */
+/* These macros depend on the fact that '0' becomes a zero in PGSIXBIT */
 #define ERRCODE_TO_CATEGORY(ec)  ((ec) & ((1 << 12) - 1))
 #define ERRCODE_IS_CATEGORY(ec)  (((ec) & ~((1 << 12) - 1)) == 0)