diff --git a/contrib/citext/citext--1.4--1.5.sql b/contrib/citext/citext--1.4--1.5.sql
index 97942cb7bf..5ae522b7da 100644
--- a/contrib/citext/citext--1.4--1.5.sql
+++ b/contrib/citext/citext--1.4--1.5.sql
@@ -12,3 +12,77 @@ ALTER OPERATOR >= (citext, citext) SET (
     RESTRICT   = scalargesel,
     JOIN       = scalargejoinsel
 );
+
+CREATE FUNCTION citext_pattern_lt( citext, citext )
+RETURNS bool
+AS 'MODULE_PATHNAME'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
+CREATE FUNCTION citext_pattern_le( citext, citext )
+RETURNS bool
+AS 'MODULE_PATHNAME'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
+CREATE FUNCTION citext_pattern_gt( citext, citext )
+RETURNS bool
+AS 'MODULE_PATHNAME'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
+CREATE FUNCTION citext_pattern_ge( citext, citext )
+RETURNS bool
+AS 'MODULE_PATHNAME'
+LANGUAGE C IMMUTABLE STRICT PARALLEL SAFE;
+
+CREATE OPERATOR ~<~ (
+    LEFTARG    = CITEXT,
+    RIGHTARG   = CITEXT,
+    NEGATOR    = ~>=~,
+    COMMUTATOR = ~>~,
+    PROCEDURE  = citext_pattern_lt,
+    RESTRICT   = scalarltsel,
+    JOIN       = scalarltjoinsel
+);
+
+CREATE OPERATOR ~<=~ (
+    LEFTARG    = CITEXT,
+    RIGHTARG   = CITEXT,
+    NEGATOR    = ~>~,
+    COMMUTATOR = ~>=~,
+    PROCEDURE  = citext_pattern_le,
+    RESTRICT   = scalarltsel,
+    JOIN       = scalarltjoinsel
+);
+
+CREATE OPERATOR ~>=~ (
+    LEFTARG    = CITEXT,
+    RIGHTARG   = CITEXT,
+    NEGATOR    = ~<~,
+    COMMUTATOR = ~<=~,
+    PROCEDURE  = citext_pattern_ge,
+    RESTRICT   = scalargtsel,
+    JOIN       = scalargtjoinsel
+);
+
+CREATE OPERATOR ~>~ (
+    LEFTARG    = CITEXT,
+    RIGHTARG   = CITEXT,
+    NEGATOR    = ~<=~,
+    COMMUTATOR = ~<~,
+    PROCEDURE  = citext_pattern_gt,
+    RESTRICT   = scalargtsel,
+    JOIN       = scalargtjoinsel
+);
+
+CREATE FUNCTION citext_pattern_cmp(citext, citext)
+RETURNS int4
+AS 'MODULE_PATHNAME'
+LANGUAGE C STRICT IMMUTABLE PARALLEL SAFE;
+
+CREATE OPERATOR CLASS citext_pattern_ops
+FOR TYPE CITEXT USING btree AS
+    OPERATOR    1   ~<~  (citext, citext),
+    OPERATOR    2   ~<=~ (citext, citext),
+    OPERATOR    3   =    (citext, citext),
+    OPERATOR    4   ~>=~ (citext, citext),
+    OPERATOR    5   ~>~  (citext, citext),
+    FUNCTION    1   citext_pattern_cmp(citext, citext);
diff --git a/contrib/citext/citext.c b/contrib/citext/citext.c
index 0ba47828ba..2c0e48e2bc 100644
--- a/contrib/citext/citext.c
+++ b/contrib/citext/citext.c
@@ -18,6 +18,7 @@ PG_MODULE_MAGIC;
  */
 
 static int32 citextcmp(text *left, text *right, Oid collid);
+static int32 internal_citext_pattern_cmp(text *left, text *right, Oid collid);
 
 /*
  *		=================
@@ -58,6 +59,41 @@ citextcmp(text *left, text *right, Oid collid)
 	return result;
 }
 
+/*
+ * citext_pattern_cmp()
+ * Internal character-by-character comparison function for citext strings.
+ * Returns int32 negative, zero, or positive.
+ */
+static int32
+internal_citext_pattern_cmp(text *left, text *right, Oid collid)
+{
+	char	   *lcstr,
+			   *rcstr;
+	int			llen,
+				rlen;
+	int32		result;
+
+	lcstr = str_tolower(VARDATA_ANY(left), VARSIZE_ANY_EXHDR(left), DEFAULT_COLLATION_OID);
+	rcstr = str_tolower(VARDATA_ANY(right), VARSIZE_ANY_EXHDR(right), DEFAULT_COLLATION_OID);
+
+	llen = strlen(lcstr);
+	rlen = strlen(rcstr);
+
+	result = memcmp((void *) lcstr, (void *) rcstr, Min(llen, rlen));
+	if (result == 0)
+	{
+		if (llen < rlen)
+			result = -1;
+		else if (llen > rlen)
+			result = 1;
+	}
+
+	pfree(lcstr);
+	pfree(rcstr);
+
+	return result;
+}
+
 /*
  *		==================
  *		INDEXING FUNCTIONS
@@ -81,6 +117,23 @@ citext_cmp(PG_FUNCTION_ARGS)
 	PG_RETURN_INT32(result);
 }
 
+PG_FUNCTION_INFO_V1(citext_pattern_cmp);
+
+Datum
+citext_pattern_cmp(PG_FUNCTION_ARGS)
+{
+	text	   *left = PG_GETARG_TEXT_PP(0);
+	text	   *right = PG_GETARG_TEXT_PP(1);
+	int32		result;
+
+	result = internal_citext_pattern_cmp(left, right, PG_GET_COLLATION());
+
+	PG_FREE_IF_COPY(left, 0);
+	PG_FREE_IF_COPY(right, 1);
+
+	PG_RETURN_INT32(result);
+}
+
 PG_FUNCTION_INFO_V1(citext_hash);
 
 Datum
@@ -234,6 +287,74 @@ citext_ge(PG_FUNCTION_ARGS)
 	PG_RETURN_BOOL(result);
 }
 
+PG_FUNCTION_INFO_V1(citext_pattern_lt);
+
+Datum
+citext_pattern_lt(PG_FUNCTION_ARGS)
+{
+	text	   *left = PG_GETARG_TEXT_PP(0);
+	text	   *right = PG_GETARG_TEXT_PP(1);
+	bool		result;
+
+	result = internal_citext_pattern_cmp(left, right, PG_GET_COLLATION()) < 0;
+
+	PG_FREE_IF_COPY(left, 0);
+	PG_FREE_IF_COPY(right, 1);
+
+	PG_RETURN_BOOL(result);
+}
+
+PG_FUNCTION_INFO_V1(citext_pattern_le);
+
+Datum
+citext_pattern_le(PG_FUNCTION_ARGS)
+{
+	text	   *left = PG_GETARG_TEXT_PP(0);
+	text	   *right = PG_GETARG_TEXT_PP(1);
+	bool		result;
+
+	result = internal_citext_pattern_cmp(left, right, PG_GET_COLLATION()) <= 0;
+
+	PG_FREE_IF_COPY(left, 0);
+	PG_FREE_IF_COPY(right, 1);
+
+	PG_RETURN_BOOL(result);
+}
+
+PG_FUNCTION_INFO_V1(citext_pattern_gt);
+
+Datum
+citext_pattern_gt(PG_FUNCTION_ARGS)
+{
+	text	   *left = PG_GETARG_TEXT_PP(0);
+	text	   *right = PG_GETARG_TEXT_PP(1);
+	bool		result;
+
+	result = internal_citext_pattern_cmp(left, right, PG_GET_COLLATION()) > 0;
+
+	PG_FREE_IF_COPY(left, 0);
+	PG_FREE_IF_COPY(right, 1);
+
+	PG_RETURN_BOOL(result);
+}
+
+PG_FUNCTION_INFO_V1(citext_pattern_ge);
+
+Datum
+citext_pattern_ge(PG_FUNCTION_ARGS)
+{
+	text	   *left = PG_GETARG_TEXT_PP(0);
+	text	   *right = PG_GETARG_TEXT_PP(1);
+	bool		result;
+
+	result = internal_citext_pattern_cmp(left, right, PG_GET_COLLATION()) >= 0;
+
+	PG_FREE_IF_COPY(left, 0);
+	PG_FREE_IF_COPY(right, 1);
+
+	PG_RETURN_BOOL(result);
+}
+
 /*
  *		===================
  *		AGGREGATE FUNCTIONS
diff --git a/contrib/citext/expected/citext.out b/contrib/citext/expected/citext.out
index 9cc94f4c1b..56fb0e9036 100644
--- a/contrib/citext/expected/citext.out
+++ b/contrib/citext/expected/citext.out
@@ -2351,3 +2351,373 @@ SELECT * FROM citext_matview ORDER BY id;
   5 | 
 (5 rows)
 
+-- test citext_pattern_cmp() function explicitly.
+SELECT citext_pattern_cmp('aardvark'::citext, 'aardvark'::citext) AS zero;
+ zero 
+------
+    0
+(1 row)
+
+SELECT citext_pattern_cmp('aardvark'::citext, 'aardVark'::citext) AS zero;
+ zero 
+------
+    0
+(1 row)
+
+SELECT citext_pattern_cmp('AARDVARK'::citext, 'AARDVARK'::citext) AS zero;
+ zero 
+------
+    0
+(1 row)
+
+SELECT citext_pattern_cmp('B'::citext, 'a'::citext) > 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('a'::citext, 'B'::citext) < 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('A'::citext, 'b'::citext) < 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('ABCD'::citext, 'abc'::citext) > 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('ABC'::citext, 'abcd'::citext) < 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+-- test operator functions
+-- lt
+SELECT citext_pattern_lt('a'::citext, 'b'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_lt('A'::citext, 'b'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_lt('a'::citext, 'B'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_lt('b'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_lt('B'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_lt('b'::citext, 'A'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+-- le
+SELECT citext_pattern_le('a'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('a'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('A'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('A'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('a'::citext, 'B'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('A'::citext, 'b'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('a'::citext, 'B'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('b'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_le('B'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_le('b'::citext, 'A'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+-- gt
+SELECT citext_pattern_gt('a'::citext, 'b'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_gt('A'::citext, 'b'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_gt('a'::citext, 'B'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_gt('b'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_gt('B'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_gt('b'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+-- ge
+SELECT citext_pattern_ge('a'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('a'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('A'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('A'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('a'::citext, 'B'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_ge('A'::citext, 'b'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_ge('a'::citext, 'B'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_ge('b'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('B'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('b'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+-- Test ~<~ and ~<=~
+SELECT 'a'::citext ~<~  'B'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'b'::citext ~<~  'A'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'à'::citext ~<~  'À'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'a'::citext ~<=~ 'B'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~<=~ 'A'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'à'::citext ~<=~ 'À'::citext AS t;
+ t 
+---
+ f
+(1 row)
+
+-- Test ~>~ and ~>=~
+SELECT 'B'::citext ~>~  'a'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'b'::citext ~>~  'A'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'à'::citext ~>~  'À'::citext AS f;
+ f 
+---
+ t
+(1 row)
+
+SELECT 'B'::citext ~>~  'b'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'B'::citext ~>=~ 'b'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'à'::citext ~>=~ 'À'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+-- Test implicit casting. citext casts to text, but not vice-versa.
+SELECT 'B'::citext ~<~  'a'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'B'::citext ~<=~ 'a'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>~  'B'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>=~ 'B'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+-- Test implicit casting. citext casts to varchar, but not vice-versa.
+SELECT 'B'::citext ~<~  'a'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'B'::citext ~<=~ 'a'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>~  'B'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>=~ 'B'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
diff --git a/contrib/citext/expected/citext_1.out b/contrib/citext/expected/citext_1.out
index d1fb1e14e0..95549c5888 100644
--- a/contrib/citext/expected/citext_1.out
+++ b/contrib/citext/expected/citext_1.out
@@ -2351,3 +2351,373 @@ SELECT * FROM citext_matview ORDER BY id;
   5 | 
 (5 rows)
 
+-- test citext_pattern_cmp() function explicitly.
+SELECT citext_pattern_cmp('aardvark'::citext, 'aardvark'::citext) AS zero;
+ zero 
+------
+    0
+(1 row)
+
+SELECT citext_pattern_cmp('aardvark'::citext, 'aardVark'::citext) AS zero;
+ zero 
+------
+    0
+(1 row)
+
+SELECT citext_pattern_cmp('AARDVARK'::citext, 'AARDVARK'::citext) AS zero;
+ zero 
+------
+    0
+(1 row)
+
+SELECT citext_pattern_cmp('B'::citext, 'a'::citext) > 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('a'::citext, 'B'::citext) < 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('A'::citext, 'b'::citext) < 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('ABCD'::citext, 'abc'::citext) > 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_cmp('ABC'::citext, 'abcd'::citext) < 0 AS true;
+ true 
+------
+ t
+(1 row)
+
+-- test operator functions
+-- lt
+SELECT citext_pattern_lt('a'::citext, 'b'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_lt('A'::citext, 'b'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_lt('a'::citext, 'B'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_lt('b'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_lt('B'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_lt('b'::citext, 'A'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+-- le
+SELECT citext_pattern_le('a'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('a'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('A'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('A'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('a'::citext, 'B'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('A'::citext, 'b'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('a'::citext, 'B'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_le('b'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_le('B'::citext, 'a'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_le('b'::citext, 'A'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+-- gt
+SELECT citext_pattern_gt('a'::citext, 'b'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_gt('A'::citext, 'b'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_gt('a'::citext, 'B'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_gt('b'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_gt('B'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_gt('b'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+-- ge
+SELECT citext_pattern_ge('a'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('a'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('A'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('A'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('a'::citext, 'B'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_ge('A'::citext, 'b'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_ge('a'::citext, 'B'::citext) AS false;
+ false 
+-------
+ f
+(1 row)
+
+SELECT citext_pattern_ge('b'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('B'::citext, 'a'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+SELECT citext_pattern_ge('b'::citext, 'A'::citext) AS true;
+ true 
+------
+ t
+(1 row)
+
+-- Test ~<~ and ~<=~
+SELECT 'a'::citext ~<~  'B'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'b'::citext ~<~  'A'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'à'::citext ~<~  'À'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'a'::citext ~<=~ 'B'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~<=~ 'A'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'à'::citext ~<=~ 'À'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+-- Test ~>~ and ~>=~
+SELECT 'B'::citext ~>~  'a'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'b'::citext ~>~  'A'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'à'::citext ~>~  'À'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'B'::citext ~>~  'b'::citext AS f;
+ f 
+---
+ f
+(1 row)
+
+SELECT 'B'::citext ~>=~ 'b'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+SELECT 'à'::citext ~>=~ 'À'::citext AS t;
+ t 
+---
+ t
+(1 row)
+
+-- Test implicit casting. citext casts to text, but not vice-versa.
+SELECT 'B'::citext ~<~  'a'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'B'::citext ~<=~ 'a'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>~  'B'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>=~ 'B'::text AS t;  -- text wins.
+ t 
+---
+ t
+(1 row)
+
+-- Test implicit casting. citext casts to varchar, but not vice-versa.
+SELECT 'B'::citext ~<~  'a'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'B'::citext ~<=~ 'a'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>~  'B'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
+SELECT 'a'::citext ~>=~ 'B'::varchar AS t;  -- varchar wins.
+ t 
+---
+ t
+(1 row)
+
diff --git a/contrib/citext/sql/citext.sql b/contrib/citext/sql/citext.sql
index f70f9ebae9..e9acd4664f 100644
--- a/contrib/citext/sql/citext.sql
+++ b/contrib/citext/sql/citext.sql
@@ -752,3 +752,81 @@ SELECT *
   WHERE t.id IS NULL OR m.id IS NULL;
 REFRESH MATERIALIZED VIEW CONCURRENTLY citext_matview;
 SELECT * FROM citext_matview ORDER BY id;
+
+-- test citext_pattern_cmp() function explicitly.
+SELECT citext_pattern_cmp('aardvark'::citext, 'aardvark'::citext) AS zero;
+SELECT citext_pattern_cmp('aardvark'::citext, 'aardVark'::citext) AS zero;
+SELECT citext_pattern_cmp('AARDVARK'::citext, 'AARDVARK'::citext) AS zero;
+SELECT citext_pattern_cmp('B'::citext, 'a'::citext) > 0 AS true;
+SELECT citext_pattern_cmp('a'::citext, 'B'::citext) < 0 AS true;
+SELECT citext_pattern_cmp('A'::citext, 'b'::citext) < 0 AS true;
+SELECT citext_pattern_cmp('ABCD'::citext, 'abc'::citext) > 0 AS true;
+SELECT citext_pattern_cmp('ABC'::citext, 'abcd'::citext) < 0 AS true;
+
+-- test operator functions
+-- lt
+SELECT citext_pattern_lt('a'::citext, 'b'::citext) AS true;
+SELECT citext_pattern_lt('A'::citext, 'b'::citext) AS true;
+SELECT citext_pattern_lt('a'::citext, 'B'::citext) AS true;
+SELECT citext_pattern_lt('b'::citext, 'a'::citext) AS false;
+SELECT citext_pattern_lt('B'::citext, 'a'::citext) AS false;
+SELECT citext_pattern_lt('b'::citext, 'A'::citext) AS false;
+-- le
+SELECT citext_pattern_le('a'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_le('a'::citext, 'A'::citext) AS true;
+SELECT citext_pattern_le('A'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_le('A'::citext, 'A'::citext) AS true;
+SELECT citext_pattern_le('a'::citext, 'B'::citext) AS true;
+SELECT citext_pattern_le('A'::citext, 'b'::citext) AS true;
+SELECT citext_pattern_le('a'::citext, 'B'::citext) AS true;
+SELECT citext_pattern_le('b'::citext, 'a'::citext) AS false;
+SELECT citext_pattern_le('B'::citext, 'a'::citext) AS false;
+SELECT citext_pattern_le('b'::citext, 'A'::citext) AS false;
+-- gt
+SELECT citext_pattern_gt('a'::citext, 'b'::citext) AS false;
+SELECT citext_pattern_gt('A'::citext, 'b'::citext) AS false;
+SELECT citext_pattern_gt('a'::citext, 'B'::citext) AS false;
+SELECT citext_pattern_gt('b'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_gt('B'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_gt('b'::citext, 'A'::citext) AS true;
+-- ge
+SELECT citext_pattern_ge('a'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_ge('a'::citext, 'A'::citext) AS true;
+SELECT citext_pattern_ge('A'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_ge('A'::citext, 'A'::citext) AS true;
+SELECT citext_pattern_ge('a'::citext, 'B'::citext) AS false;
+SELECT citext_pattern_ge('A'::citext, 'b'::citext) AS false;
+SELECT citext_pattern_ge('a'::citext, 'B'::citext) AS false;
+SELECT citext_pattern_ge('b'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_ge('B'::citext, 'a'::citext) AS true;
+SELECT citext_pattern_ge('b'::citext, 'A'::citext) AS true;
+
+-- Test ~<~ and ~<=~
+SELECT 'a'::citext ~<~  'B'::citext AS t;
+SELECT 'b'::citext ~<~  'A'::citext AS f;
+SELECT 'à'::citext ~<~  'À'::citext AS f;
+SELECT 'a'::citext ~<=~ 'B'::citext AS t;
+SELECT 'a'::citext ~<=~ 'A'::citext AS t;
+SELECT 'à'::citext ~<=~ 'À'::citext AS t;
+
+-- Test ~>~ and ~>=~
+SELECT 'B'::citext ~>~  'a'::citext AS t;
+SELECT 'b'::citext ~>~  'A'::citext AS t;
+SELECT 'à'::citext ~>~  'À'::citext AS f;
+SELECT 'B'::citext ~>~  'b'::citext AS f;
+SELECT 'B'::citext ~>=~ 'b'::citext AS t;
+SELECT 'à'::citext ~>=~ 'À'::citext AS t;
+
+-- Test implicit casting. citext casts to text, but not vice-versa.
+SELECT 'B'::citext ~<~  'a'::text AS t;  -- text wins.
+SELECT 'B'::citext ~<=~ 'a'::text AS t;  -- text wins.
+
+SELECT 'a'::citext ~>~  'B'::text AS t;  -- text wins.
+SELECT 'a'::citext ~>=~ 'B'::text AS t;  -- text wins.
+
+-- Test implicit casting. citext casts to varchar, but not vice-versa.
+SELECT 'B'::citext ~<~  'a'::varchar AS t;  -- varchar wins.
+SELECT 'B'::citext ~<=~ 'a'::varchar AS t;  -- varchar wins.
+
+SELECT 'a'::citext ~>~  'B'::varchar AS t;  -- varchar wins.
+SELECT 'a'::citext ~>=~ 'B'::varchar AS t;  -- varchar wins.