diff --git a/src/backend/utils/adt/encode.c b/src/backend/utils/adt/encode.c
index b8d9ec7e00..5be5739501 100644
--- a/src/backend/utils/adt/encode.c
+++ b/src/backend/utils/adt/encode.c
@@ -20,10 +20,10 @@
 
 struct pg_encoding
 {
-	unsigned	(*encode_len) (const char *data, unsigned dlen);
-	unsigned	(*decode_len) (const char *data, unsigned dlen);
-	unsigned	(*encode) (const char *data, unsigned dlen, char *res);
-	unsigned	(*decode) (const char *data, unsigned dlen, char *res);
+	uint64		(*encode_len) (const char *data, size_t dlen);
+	uint64		(*decode_len) (const char *data, size_t dlen);
+	uint64		(*encode) (const char *data, size_t dlen, char *res);
+	uint64		(*decode) (const char *data, size_t dlen, char *res);
 };
 
 static const struct pg_encoding *pg_find_encoding(const char *name);
@@ -39,9 +39,9 @@ binary_encode(PG_FUNCTION_ARGS)
 	Datum		name = PG_GETARG_DATUM(1);
 	text	   *result;
 	char	   *namebuf;
-	int			datalen,
-				resultlen,
-				res;
+	size_t		datalen;
+	uint64		res;
+	uint64		resultlen;
 	const struct pg_encoding *enc;
 
 	datalen = VARSIZE_ANY_EXHDR(data);
@@ -75,9 +75,9 @@ binary_decode(PG_FUNCTION_ARGS)
 	Datum		name = PG_GETARG_DATUM(1);
 	bytea	   *result;
 	char	   *namebuf;
-	int			datalen,
-				resultlen,
-				res;
+	size_t		datalen;
+	uint64		resultlen;
+	uint64		res;
 	const struct pg_encoding *enc;
 
 	datalen = VARSIZE_ANY_EXHDR(data);
@@ -122,8 +122,8 @@ static const int8 hexlookup[128] = {
 	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
 };
 
-unsigned
-hex_encode(const char *src, unsigned len, char *dst)
+uint64
+hex_encode(const char *src, size_t len, char *dst)
 {
 	const char *end = src + len;
 
@@ -133,7 +133,7 @@ hex_encode(const char *src, unsigned len, char *dst)
 		*dst++ = hextbl[*src & 0xF];
 		src++;
 	}
-	return len * 2;
+	return (int64)len * 2;
 }
 
 static inline char
@@ -152,8 +152,8 @@ get_hex(char c)
 	return (char) res;
 }
 
-unsigned
-hex_decode(const char *src, unsigned len, char *dst)
+uint64
+hex_decode(const char *src, size_t len, char *dst)
 {
 	const char *s,
 			   *srcend;
@@ -184,16 +184,16 @@ hex_decode(const char *src, unsigned len, char *dst)
 	return p - dst;
 }
 
-static unsigned
-hex_enc_len(const char *src, unsigned srclen)
+static uint64
+hex_enc_len(const char *src, size_t srclen)
 {
-	return srclen << 1;
+	return (uint64)srclen << 1;
 }
 
-static unsigned
-hex_dec_len(const char *src, unsigned srclen)
+static uint64
+hex_dec_len(const char *src, size_t srclen)
 {
-	return srclen >> 1;
+	return (uint64)srclen >> 1;
 }
 
 /*
@@ -214,8 +214,8 @@ static const int8 b64lookup[128] = {
 	41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1,
 };
 
-static unsigned
-pg_base64_encode(const char *src, unsigned len, char *dst)
+static uint64
+pg_base64_encode(const char *src, size_t len, char *dst)
 {
 	char	   *p,
 			   *lend = dst + 76;
@@ -261,8 +261,8 @@ pg_base64_encode(const char *src, unsigned len, char *dst)
 	return p - dst;
 }
 
-static unsigned
-pg_base64_decode(const char *src, unsigned len, char *dst)
+static uint64
+pg_base64_decode(const char *src, size_t len, char *dst)
 {
 	const char *srcend = src + len,
 			   *s = src;
@@ -331,17 +331,17 @@ pg_base64_decode(const char *src, unsigned len, char *dst)
 }
 
 
-static unsigned
-pg_base64_enc_len(const char *src, unsigned srclen)
+static uint64
+pg_base64_enc_len(const char *src, size_t srclen)
 {
 	/* 3 bytes will be converted to 4, linefeed after 76 chars */
-	return (srclen + 2) * 4 / 3 + srclen / (76 * 3 / 4);
+	return ((uint64)srclen + 2) * 4 / 3 + (uint64)srclen / (76 * 3 / 4);
 }
 
-static unsigned
-pg_base64_dec_len(const char *src, unsigned srclen)
+static uint64
+pg_base64_dec_len(const char *src, size_t srclen)
 {
-	return (srclen * 3) >> 2;
+	return ((uint64)srclen * 3) >> 2;
 }
 
 /*
@@ -361,12 +361,12 @@ pg_base64_dec_len(const char *src, unsigned srclen)
 #define VAL(CH)			((CH) - '0')
 #define DIG(VAL)		((VAL) + '0')
 
-static unsigned
-esc_encode(const char *src, unsigned srclen, char *dst)
+static uint64
+esc_encode(const char *src, size_t srclen, char *dst)
 {
 	const char *end = src + srclen;
 	char	   *rp = dst;
-	int			len = 0;
+	uint64		len = 0;
 
 	while (src < end)
 	{
@@ -400,12 +400,12 @@ esc_encode(const char *src, unsigned srclen, char *dst)
 	return len;
 }
 
-static unsigned
-esc_decode(const char *src, unsigned srclen, char *dst)
+static uint64
+esc_decode(const char *src, size_t srclen, char *dst)
 {
 	const char *end = src + srclen;
 	char	   *rp = dst;
-	int			len = 0;
+	uint64		len = 0;
 
 	while (src < end)
 	{
@@ -448,11 +448,11 @@ esc_decode(const char *src, unsigned srclen, char *dst)
 	return len;
 }
 
-static unsigned
-esc_enc_len(const char *src, unsigned srclen)
+static uint64
+esc_enc_len(const char *src, size_t srclen)
 {
 	const char *end = src + srclen;
-	int			len = 0;
+	uint64		len = 0;
 
 	while (src < end)
 	{
@@ -469,11 +469,11 @@ esc_enc_len(const char *src, unsigned srclen)
 	return len;
 }
 
-static unsigned
-esc_dec_len(const char *src, unsigned srclen)
+static uint64
+esc_dec_len(const char *src, size_t srclen)
 {
 	const char *end = src + srclen;
-	int			len = 0;
+	uint64		len = 0;
 
 	while (src < end)
 	{
diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 907b5ab7b0..47aa5be3a9 100644
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -388,7 +388,7 @@ byteaout(PG_FUNCTION_ARGS)
 	{
 		/* Print traditional escaped format */
 		char	   *vp;
-		int			len;
+		int64		len;
 		int			i;
 
 		len = 1;				/* empty string has 1 char */
@@ -3455,7 +3455,7 @@ Datum
 byteaGetBit(PG_FUNCTION_ARGS)
 {
 	bytea	   *v = PG_GETARG_BYTEA_PP(0);
-	int32		n = PG_GETARG_INT32(1);
+	int64		n = PG_GETARG_INT64(1);
 	int			byteNo,
 				bitNo;
 	int			len;
@@ -3463,14 +3463,17 @@ byteaGetBit(PG_FUNCTION_ARGS)
 
 	len = VARSIZE_ANY_EXHDR(v);
 
-	if (n < 0 || n >= len * 8)
+	if (n < 0 || n >= (int64)len * 8)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-				 errmsg("index %d out of valid range, 0..%d",
-						n, len * 8 - 1)));
-
-	byteNo = n / 8;
-	bitNo = n % 8;
+				 errmsg("index "INT64_FORMAT" out of valid range, 0.."INT64_FORMAT,
+						n, (int64)len * 8 - 1)));
+	/*
+	 * The value of 'n' is smaller than 'len * 8', and 'len' is by int type,
+	 * so it is safe to downcasting 'n' from int64 to int.
+	 */
+	byteNo = (int)(n / 8);
+	bitNo = (int)(n % 8);
 
 	byte = ((unsigned char *) VARDATA_ANY(v))[byteNo];
 
@@ -3524,7 +3527,7 @@ Datum
 byteaSetBit(PG_FUNCTION_ARGS)
 {
 	bytea	   *res = PG_GETARG_BYTEA_P_COPY(0);
-	int32		n = PG_GETARG_INT32(1);
+	int64		n = PG_GETARG_INT64(1);
 	int32		newBit = PG_GETARG_INT32(2);
 	int			len;
 	int			oldByte,
@@ -3534,14 +3537,17 @@ byteaSetBit(PG_FUNCTION_ARGS)
 
 	len = VARSIZE(res) - VARHDRSZ;
 
-	if (n < 0 || n >= len * 8)
+	if (n < 0 || n >= (int64)len * 8)
 		ereport(ERROR,
 				(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
-				 errmsg("index %d out of valid range, 0..%d",
-						n, len * 8 - 1)));
-
-	byteNo = n / 8;
-	bitNo = n % 8;
+				 errmsg("index "INT64_FORMAT" out of valid range, 0.."INT64_FORMAT,
+						n, (int64)len * 8 - 1)));
+	/*
+	 * The value of 'n' is smaller than 'len * 8', and 'len' is by int type,
+	 * so it is safe to downcasting 'n' from int64 to int.
+	 */
+	byteNo = (int64)(n / 8);
+	bitNo = (int64)(n % 8);
 
 	/*
 	 * sanity check!
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index a6a708cca9..218af5ab2f 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -1403,10 +1403,10 @@
   proname => 'set_byte', prorettype => 'bytea',
   proargtypes => 'bytea int4 int4', prosrc => 'byteaSetByte' },
 { oid => '723', descr => 'get bit',
-  proname => 'get_bit', prorettype => 'int4', proargtypes => 'bytea int4',
+  proname => 'get_bit', prorettype => 'int4', proargtypes => 'bytea int8',
   prosrc => 'byteaGetBit' },
 { oid => '724', descr => 'set bit',
-  proname => 'set_bit', prorettype => 'bytea', proargtypes => 'bytea int4 int4',
+  proname => 'set_bit', prorettype => 'bytea', proargtypes => 'bytea int8 int4',
   prosrc => 'byteaSetBit' },
 { oid => '749', descr => 'substitute portion of string',
   proname => 'overlay', prorettype => 'bytea',
diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h
index e2016a8bc2..a352a8b773 100644
--- a/src/include/utils/builtins.h
+++ b/src/include/utils/builtins.h
@@ -32,8 +32,8 @@ extern int	errdatatype(Oid datatypeOid);
 extern int	errdomainconstraint(Oid datatypeOid, const char *conname);
 
 /* encode.c */
-extern unsigned hex_encode(const char *src, unsigned len, char *dst);
-extern unsigned hex_decode(const char *src, unsigned len, char *dst);
+extern uint64 hex_encode(const char *src, size_t len, char *dst);
+extern uint64 hex_decode(const char *src, size_t len, char *dst);
 
 /* int.c */
 extern int2vector *buildint2vector(const int16 *int2s, int n);
diff --git a/src/test/regress/expected/bit.out b/src/test/regress/expected/bit.out
index a1fab7ebcb..8e56289968 100644
--- a/src/test/regress/expected/bit.out
+++ b/src/test/regress/expected/bit.out
@@ -656,6 +656,40 @@ SELECT set_bit(B'0101011000100100', 15, 1);
 
 SELECT set_bit(B'0101011000100100', 16, 1);	-- fail
 ERROR:  bit index 16 out of valid range (0..15)
+SELECT get_bit(
+       set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 0, 0)
+       ,0);
+ get_bit 
+---------
+       0
+(1 row)
+
+SELECT get_bit(
+       set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 0, 1)
+       ,0);
+ get_bit 
+---------
+       1
+(1 row)
+
+select get_bit(
+        set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 
+                512::bigint * 1024 * 1024 * 8 - 1, 0)
+        ,512::bigint * 1024 * 1024 * 8 - 1);
+ get_bit 
+---------
+       0
+(1 row)
+
+select get_bit(
+        set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea,
+                512::bigint * 1024 * 1024 * 8 - 1, 1)
+       ,512::bigint * 1024 * 1024 * 8 - 1);
+ get_bit 
+---------
+       1
+(1 row)
+
 -- Overlay
 SELECT overlay(B'0101011100' placing '001' from 2 for 3);
   overlay   
diff --git a/src/test/regress/sql/bit.sql b/src/test/regress/sql/bit.sql
index 7681d4ab4d..5914095941 100644
--- a/src/test/regress/sql/bit.sql
+++ b/src/test/regress/sql/bit.sql
@@ -200,6 +200,21 @@ DROP TABLE VARBIT_SHIFT_TABLE;
 SELECT get_bit(B'0101011000100', 10);
 SELECT set_bit(B'0101011000100100', 15, 1);
 SELECT set_bit(B'0101011000100100', 16, 1);	-- fail
+SELECT get_bit(
+       set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 0, 0)
+       ,0);
+SELECT get_bit(
+       set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 0, 1)
+       ,0);
+select get_bit(
+        set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea, 
+                512::bigint * 1024 * 1024 * 8 - 1, 0)
+        ,512::bigint * 1024 * 1024 * 8 - 1);
+select get_bit(
+        set_bit((repeat('Postgres', 512 * 1024 * 1024 / 8))::bytea,
+                512::bigint * 1024 * 1024 * 8 - 1, 1)
+       ,512::bigint * 1024 * 1024 * 8 - 1);
+
 
 -- Overlay
 SELECT overlay(B'0101011100' placing '001' from 2 for 3);