diff --git a/src/backend/access/common/heaptuple.c b/src/backend/access/common/heaptuple.c
index f89769f379..04b27f1e6e 100644
--- a/src/backend/access/common/heaptuple.c
+++ b/src/backend/access/common/heaptuple.c
@@ -736,7 +736,6 @@ expand_tuple(HeapTuple *targetHeapTuple,
 {
 	AttrMissing *attrmiss = NULL;
 	int			attnum;
-	int			firstmissingnum = 0;
 	bool		hasNulls = HeapTupleHasNulls(sourceTuple);
 	HeapTupleHeader targetTHeader;
 	HeapTupleHeader sourceTHeader = sourceTuple->t_data;
@@ -765,6 +764,8 @@ expand_tuple(HeapTuple *targetHeapTuple,
 	if (tupleDesc->constr &&
 		tupleDesc->constr->missing)
 	{
+	    int			firstmissingnum;
+
 		/*
 		 * If there are missing values we want to put them into the tuple.
 		 * Before that we have to compute the extra length for the values
diff --git a/src/backend/access/gin/ginbtree.c b/src/backend/access/gin/ginbtree.c
index 8d08b05f51..82788a5c36 100644
--- a/src/backend/access/gin/ginbtree.c
+++ b/src/backend/access/gin/ginbtree.c
@@ -241,7 +241,6 @@ ginFindParents(GinBtree btree, GinBtreeStack *stack)
 
 	blkno = root->blkno;
 	buffer = root->buffer;
-	offset = InvalidOffsetNumber;
 
 	ptr = (GinBtreeStack *) palloc(sizeof(GinBtreeStack));
 
diff --git a/src/backend/access/gist/gistutil.c b/src/backend/access/gist/gistutil.c
index dd975b164c..cc126236a1 100644
--- a/src/backend/access/gist/gistutil.c
+++ b/src/backend/access/gist/gistutil.c
@@ -32,7 +32,7 @@
 void
 gistfillbuffer(Page page, IndexTuple *itup, int len, OffsetNumber off)
 {
-	OffsetNumber l = InvalidOffsetNumber;
+	OffsetNumber l;
 	int			i;
 
 	if (off == InvalidOffsetNumber)
diff --git a/src/backend/access/hash/hashsearch.c b/src/backend/access/hash/hashsearch.c
index 995498e48d..d56ffe3b3e 100644
--- a/src/backend/access/hash/hashsearch.c
+++ b/src/backend/access/hash/hashsearch.c
@@ -470,7 +470,7 @@ _hash_readpage(IndexScanDesc scan, Buffer *bufP, ScanDirection dir)
 
 	if (ScanDirectionIsForward(dir))
 	{
-		BlockNumber prev_blkno = InvalidBlockNumber;
+		BlockNumber prev_blkno;
 
 		for (;;)
 		{
diff --git a/src/backend/access/nbtree/nbtsearch.c b/src/backend/access/nbtree/nbtsearch.c
index 8ff49ce6d6..32e80337b0 100644
--- a/src/backend/access/nbtree/nbtsearch.c
+++ b/src/backend/access/nbtree/nbtsearch.c
@@ -1863,7 +1863,7 @@ _bt_steppage(IndexScanDesc scan, ScanDirection dir)
 {
 	BTScanOpaque so = (BTScanOpaque) scan->opaque;
 	BlockNumber blkno = InvalidBlockNumber;
-	bool		status = true;
+	bool		status;
 
 	Assert(BTScanPosIsValid(so->currPos));
 
@@ -1972,7 +1972,7 @@ _bt_readnextpage(IndexScanDesc scan, BlockNumber blkno, ScanDirection dir)
 	Relation	rel;
 	Page		page;
 	BTPageOpaque opaque;
-	bool		status = true;
+	bool		status;
 
 	rel = scan->indexRelation;
 
diff --git a/src/backend/access/nbtree/nbtsplitloc.c b/src/backend/access/nbtree/nbtsplitloc.c
index 8ba055be9e..15ac106525 100644
--- a/src/backend/access/nbtree/nbtsplitloc.c
+++ b/src/backend/access/nbtree/nbtsplitloc.c
@@ -812,7 +812,6 @@ _bt_bestsplitloc(FindSplitData *state, int perfectpenalty,
 
 		if (penalty <= perfectpenalty)
 		{
-			bestpenalty = penalty;
 			lowsplit = i;
 			break;
 		}
diff --git a/src/backend/access/spgist/spgtextproc.c b/src/backend/access/spgist/spgtextproc.c
index b5ec81937c..08972e83c6 100644
--- a/src/backend/access/spgist/spgtextproc.c
+++ b/src/backend/access/spgist/spgtextproc.c
@@ -187,7 +187,6 @@ spg_text_choose(PG_FUNCTION_ARGS)
 	char	   *inStr = VARDATA_ANY(inText);
 	int			inSize = VARSIZE_ANY_EXHDR(inText);
 	char	   *prefixStr = NULL;
-	int			prefixSize = 0;
 	int			commonLen = 0;
 	int16		nodeChar = 0;
 	int			i = 0;
@@ -196,6 +195,7 @@ spg_text_choose(PG_FUNCTION_ARGS)
 	if (in->hasPrefix)
 	{
 		text	   *prefixText = DatumGetTextPP(in->prefixDatum);
+	    int			prefixSize;
 
 		prefixStr = VARDATA_ANY(prefixText);
 		prefixSize = VARSIZE_ANY_EXHDR(prefixText);
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 7621fc05e2..1491b047ed 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -10825,7 +10825,6 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 	FILE	   *fp;
 	char		ch;
 	int			seconds_before_warning;
-	int			waits = 0;
 	bool		reported_waiting = false;
 	char	   *remaining;
 	char	   *ptr;
@@ -11146,6 +11145,8 @@ do_pg_stop_backup(char *labelfile, bool waitforarchive, TimeLineID *stoptli_p)
 		((!backup_started_in_recovery && XLogArchivingActive()) ||
 		 (backup_started_in_recovery && XLogArchivingAlways())))
 	{
+	    int			waits;
+
 		XLByteToPrevSeg(stoppoint, _logSegNo, wal_segment_size);
 		XLogFileName(lastxlogfilename, stoptli, _logSegNo, wal_segment_size);
 
diff --git a/src/backend/catalog/storage.c b/src/backend/catalog/storage.c
index fddfbf1d8c..3f48a44e66 100644
--- a/src/backend/catalog/storage.c
+++ b/src/backend/catalog/storage.c
@@ -434,7 +434,6 @@ smgrDoPendingDeletes(bool isCommit)
 	PendingRelDelete *prev;
 	PendingRelDelete *next;
 	int			nrels = 0,
-				i = 0,
 				maxrels = 0;
 	SMgrRelation *srels = NULL;
 
@@ -483,6 +482,8 @@ smgrDoPendingDeletes(bool isCommit)
 
 	if (nrels > 0)
 	{
+		int i;
+
 		smgrdounlinkall(srels, nrels, false);
 
 		for (i = 0; i < nrels; i++)
diff --git a/src/backend/parser/parse_utilcmd.c b/src/backend/parser/parse_utilcmd.c
index c1911411d0..37e8a61c4b 100644
--- a/src/backend/parser/parse_utilcmd.c
+++ b/src/backend/parser/parse_utilcmd.c
@@ -1633,12 +1633,7 @@ generateClonedIndexStmt(RangeVar *heapRel, Relation source_idx,
 		if (AttributeNumberIsValid(attnum))
 		{
 			/* Simple index column */
-			char	   *attname;
-
-			attname = get_attname(indrelid, attnum, false);
-			keycoltype = get_atttype(indrelid, attnum);
-
-			iparam->name = attname;
+			iparam->name = get_attname(indrelid, attnum, false);
 			iparam->expr = NULL;
 		}
 		else
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index ffcb54968f..1dd57d9162 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -878,7 +878,7 @@ process_pipe_input(char *logbuffer, int *bytes_in_logbuffer)
 {
 	char	   *cursor = logbuffer;
 	int			count = *bytes_in_logbuffer;
-	int			dest = LOG_DESTINATION_STDERR;
+	int			dest;
 
 	/* While we have enough for a header, process data... */
 	while (count >= (int) (offsetof(PipeProtoHeader, data) + 1))
diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index f45a619deb..df4030f626 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2821,7 +2821,6 @@ CancelDBBackends(Oid databaseid, ProcSignalReason sigmode, bool conflictPending)
 {
 	ProcArrayStruct *arrayP = procArray;
 	int			index;
-	pid_t		pid = 0;
 
 	/* tell all backends to die */
 	LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
@@ -2834,6 +2833,7 @@ CancelDBBackends(Oid databaseid, ProcSignalReason sigmode, bool conflictPending)
 		if (databaseid == InvalidOid || proc->databaseId == databaseid)
 		{
 			VirtualTransactionId procvxid;
+	        pid_t		pid;
 
 			GET_VXID_FROM_PGPROC(procvxid, *proc);
 
diff --git a/src/backend/tsearch/spell.c b/src/backend/tsearch/spell.c
index 8aab96d3b0..7091fb8e04 100644
--- a/src/backend/tsearch/spell.c
+++ b/src/backend/tsearch/spell.c
@@ -1710,7 +1710,6 @@ void
 NISortDictionary(IspellDict *Conf)
 {
 	int			i;
-	int			naffix = 0;
 	int			curaffix;
 
 	/* compress affixes */
@@ -1760,6 +1759,8 @@ NISortDictionary(IspellDict *Conf)
 	/* Otherwise fill Conf->AffixData here */
 	else
 	{
+	    int			naffix;
+
 		/* Count the number of different flags used in the dictionary */
 		qsort((void *) Conf->Spell, Conf->nspell, sizeof(SPELL *),
 			  cmpspellaffix);
@@ -1879,7 +1880,6 @@ mkANode(IspellDict *Conf, int low, int high, int level, int type)
 		data->naff = naff;
 		data->aff = (AFFIX **) cpalloc(sizeof(AFFIX *) * naff);
 		memcpy(data->aff, aff, sizeof(AFFIX *) * naff);
-		naff = 0;
 	}
 
 	pfree(aff);
@@ -2124,7 +2124,6 @@ CheckAffix(const char *word, size_t len, AFFIX *Affix, int flagflags, char *neww
 	}
 	else
 	{
-		int			err;
 		pg_wchar   *data;
 		size_t		data_len;
 		int			newword_len;
@@ -2134,7 +2133,7 @@ CheckAffix(const char *word, size_t len, AFFIX *Affix, int flagflags, char *neww
 		data = (pg_wchar *) palloc((newword_len + 1) * sizeof(pg_wchar));
 		data_len = pg_mb2wchar_with_len(newword, data, newword_len);
 
-		if (!(err = pg_regexec(&(Affix->reg.regex), data, data_len, 0, NULL, 0, NULL, 0)))
+		if (!pg_regexec(&(Affix->reg.regex), data, data_len, 0, NULL, 0, NULL, 0))
 		{
 			pfree(data);
 			return newword;
diff --git a/src/backend/tsearch/to_tsany.c b/src/backend/tsearch/to_tsany.c
index e7cd6264db..3304066b94 100644
--- a/src/backend/tsearch/to_tsany.c
+++ b/src/backend/tsearch/to_tsany.c
@@ -480,13 +480,7 @@ add_to_tsvector(void *_state, char *elem_value, int elem_len)
 static void
 pushval_morph(Datum opaque, TSQueryParserState state, char *strval, int lenval, int16 weight, bool prefix)
 {
-	int32		count = 0;
 	ParsedText	prs;
-	uint32		variant,
-				pos = 0,
-				cntvar = 0,
-				cntpos = 0,
-				cnt = 0;
 	MorphOpaque *data = (MorphOpaque *) DatumGetPointer(opaque);
 
 	prs.lenwords = 4;
@@ -498,6 +492,13 @@ pushval_morph(Datum opaque, TSQueryParserState state, char *strval, int lenval,
 
 	if (prs.curwords > 0)
 	{
+	    int32	count = 0;
+	    uint32	variant,
+				pos = 0,
+				cntvar = 0,
+				cntpos = 0,
+				cnt = 0;
+
 		while (count < prs.curwords)
 		{
 			/*
diff --git a/src/backend/tsearch/wparser_def.c b/src/backend/tsearch/wparser_def.c
index 898466fcef..66eeb55993 100644
--- a/src/backend/tsearch/wparser_def.c
+++ b/src/backend/tsearch/wparser_def.c
@@ -2133,8 +2133,8 @@ mark_hl_fragments(HeadlineParsedText *prs, TSQuery query, int highlight,
 				maxstretch,
 				posmarker;
 
-	int32		startpos = 0,
-				endpos = 0,
+	int32		startpos,
+				endpos,
 				p = 0,
 				q = 0;
 
diff --git a/src/backend/utils/adt/arrayfuncs.c b/src/backend/utils/adt/arrayfuncs.c
index 7a4a5aaa86..e2a1d06bc5 100644
--- a/src/backend/utils/adt/arrayfuncs.c
+++ b/src/backend/utils/adt/arrayfuncs.c
@@ -2787,7 +2787,6 @@ array_set_slice(Datum arraydatum,
 				overheadlen,
 				oldoverheadlen,
 				addedbefore,
-				addedafter,
 				lenbefore,
 				lenafter,
 				itemsbefore,
@@ -2865,7 +2864,7 @@ array_set_slice(Datum arraydatum,
 	memcpy(lb, ARR_LBOUND(array), ndim * sizeof(int));
 
 	newhasnulls = (ARR_HASNULL(array) || ARR_HASNULL(srcArray));
-	addedbefore = addedafter = 0;
+	addedbefore = 0;
 
 	/*
 	 * Check subscripts
@@ -2893,8 +2892,7 @@ array_set_slice(Datum arraydatum,
 		{
 			if (lowerIndx[0] > (dim[0] + lb[0]))
 				newhasnulls = true; /* will insert nulls */
-			addedafter = upperIndx[0] - (dim[0] + lb[0]) + 1;
-			dim[0] += addedafter;
+			dim[0] += upperIndx[0] - (dim[0] + lb[0]) + 1;
 		}
 	}
 	else
diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index 95f7d0538e..2a30ae4c69 100644
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -4931,7 +4931,7 @@ static char *
 int_to_roman(int number)
 {
 	int			len = 0,
-				num = 0;
+				num;
 	char	   *p = NULL,
 			   *result,
 				numstr[12];
diff --git a/src/backend/utils/adt/tsrank.c b/src/backend/utils/adt/tsrank.c
index f4b0200f1e..e680f649ef 100644
--- a/src/backend/utils/adt/tsrank.c
+++ b/src/backend/utils/adt/tsrank.c
@@ -854,7 +854,7 @@ calc_rank_cd(const float4 *arrdata, TSVector txt, TSQuery query, int method)
 	double		invws[lengthof(weights)];
 	double		SumDist = 0.0,
 				PrevExtPos = 0.0,
-				CurExtPos = 0.0;
+				CurExtPos;
 	int			NExtent = 0;
 	QueryRepresentation qr;
 
diff --git a/src/backend/utils/adt/tsvector_op.c b/src/backend/utils/adt/tsvector_op.c
index 24525879b7..89913ad8fb 100644
--- a/src/backend/utils/adt/tsvector_op.c
+++ b/src/backend/utils/adt/tsvector_op.c
@@ -1263,7 +1263,7 @@ checkcondition_str(void *checkval, QueryOperand *val, ExecPhraseData *data)
 	WordEntry  *StopLow = chkval->arrb;
 	WordEntry  *StopHigh = chkval->arre;
 	WordEntry  *StopMiddle = StopHigh;
-	int			difference = -1;
+	int			difference;
 	bool		res = false;
 
 	/* Loop invariant: StopLow <= val < StopHigh */
diff --git a/src/backend/utils/sort/tuplesort.c b/src/backend/utils/sort/tuplesort.c
index d02e676aa3..ab84297975 100644
--- a/src/backend/utils/sort/tuplesort.c
+++ b/src/backend/utils/sort/tuplesort.c
@@ -2565,7 +2565,6 @@ mergeruns(Tuplesortstate *state)
 				svTape,
 				svRuns,
 				svDummy;
-	int			numTapes;
 	int			numInputTapes;
 
 	Assert(state->status == TSS_BUILDRUNS);
@@ -2606,7 +2605,7 @@ mergeruns(Tuplesortstate *state)
 	 * If we had fewer runs than tapes, refund the memory that we imagined we
 	 * would need for the tape buffers of the unused tapes.
 	 *
-	 * numTapes and numInputTapes reflect the actual number of tapes we will
+	 * numInputTapes reflect the actual number of tapes we will
 	 * use.  Note that the output tape's tape number is maxTapes - 1, so the
 	 * tape numbers of the used tapes are not consecutive, and you cannot just
 	 * loop from 0 to numTapes to visit all used tapes!
@@ -2614,13 +2613,11 @@ mergeruns(Tuplesortstate *state)
 	if (state->Level == 1)
 	{
 		numInputTapes = state->currentRun;
-		numTapes = numInputTapes + 1;
-		FREEMEM(state, (state->maxTapes - numTapes) * TAPE_BUFFER_OVERHEAD);
+		FREEMEM(state, (state->maxTapes - numInputTapes + 1) * TAPE_BUFFER_OVERHEAD);
 	}
 	else
 	{
 		numInputTapes = state->tapeRange;
-		numTapes = state->maxTapes;
 	}
 
 	/*