Index: src/main.c
==================================================================
--- src/main.c
+++ src/main.c
@@ -873,62 +873,55 @@
   }
   va_end(ap);
   return rc;
 }
 
-
-/*
-** Return true if the buffer z[0..n-1] contains all spaces.
-*/
-static int allSpaces(const char *z, int n){
-  while( n>0 && z[n-1]==' ' ){ n--; }
-  return n==0;
-}
-
 /*
 ** This is the default collating function named "BINARY" which is always
 ** available.
-**
-** If the padFlag argument is not NULL then space padding at the end
-** of strings is ignored.  This implements the RTRIM collation.
 */
 static int binCollFunc(
-  void *padFlag,
+  void *NotUsed,
   int nKey1, const void *pKey1,
   int nKey2, const void *pKey2
 ){
   int rc, n;
+  UNUSED_PARAMETER(NotUsed);
   n = nKey1<nKey2 ? nKey1 : nKey2;
   /* EVIDENCE-OF: R-65033-28449 The built-in BINARY collation compares
   ** strings byte by byte using the memcmp() function from the standard C
   ** library. */
   assert( pKey1 && pKey2 );
   rc = memcmp(pKey1, pKey2, n);
   if( rc==0 ){
-    if( padFlag
-     && allSpaces(((char*)pKey1)+n, nKey1-n)
-     && allSpaces(((char*)pKey2)+n, nKey2-n)
-    ){
-      /* EVIDENCE-OF: R-31624-24737 RTRIM is like BINARY except that extra
-      ** spaces at the end of either string do not change the result. In other
-      ** words, strings will compare equal to one another as long as they
-      ** differ only in the number of spaces at the end.
-      */
-    }else{
-      rc = nKey1 - nKey2;
-    }
+    rc = nKey1 - nKey2;
   }
   return rc;
 }
+
+/*
+** This is the collating function named "RTRIM" which is always
+** available.  Ignore trailing spaces.
+*/
+static int rtrimCollFunc(
+  void *pUser,
+  int nKey1, const void *pKey1,
+  int nKey2, const void *pKey2
+){
+  const u8 *pK1 = (const u8*)pKey1;
+  const u8 *pK2 = (const u8*)pKey2;
+  while( nKey1 && pK1[nKey1-1]==' ' ) nKey1--;
+  while( nKey2 && pK2[nKey2-1]==' ' ) nKey2--;
+  return binCollFunc(pUser, nKey1, pKey1, nKey2, pKey2);
+}
 
 /*
 ** Return true if CollSeq is the default built-in BINARY.
 */
 int sqlite3IsBinary(const CollSeq *p){
-  assert( p==0 || p->xCmp!=binCollFunc || p->pUser!=0
-            || strcmp(p->zName,"BINARY")==0 );
-  return p==0 || (p->xCmp==binCollFunc && p->pUser==0);
+  assert( p==0 || p->xCmp!=binCollFunc || strcmp(p->zName,"BINARY")==0 );
+  return p==0 || p->xCmp==binCollFunc;
 }
 
 /*
 ** Another built-in collating sequence: NOCASE. 
 **
@@ -3126,11 +3119,11 @@
   */
   createCollation(db, sqlite3StrBINARY, SQLITE_UTF8, 0, binCollFunc, 0);
   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16BE, 0, binCollFunc, 0);
   createCollation(db, sqlite3StrBINARY, SQLITE_UTF16LE, 0, binCollFunc, 0);
   createCollation(db, "NOCASE", SQLITE_UTF8, 0, nocaseCollatingFunc, 0);
-  createCollation(db, "RTRIM", SQLITE_UTF8, (void*)1, binCollFunc, 0);
+  createCollation(db, "RTRIM", SQLITE_UTF8, 0, rtrimCollFunc, 0);
   if( db->mallocFailed ){
     goto opendb_out;
   }
   /* EVIDENCE-OF: R-08308-17224 The default collating function for all
   ** strings is BINARY. 

Index: test/collate1.test
==================================================================
--- test/collate1.test
+++ test/collate1.test
@@ -398,7 +398,23 @@
 do_execsql_test 7.2 {
    SELECT 'abc' UNION ALL SELECT 'DEF'
     ORDER BY 1 COLLATE binary COLLATE binary COLLATE binary COLLATE nocase;
 } {abc DEF}
 
+# 2019-06-14
+# https://sqlite.org/src/info/f1580ba1b574e9e9
+#
+do_execsql_test 8.0 {
+  SELECT ' ' > char(20) COLLATE rtrim;
+} 0
+do_execsql_test 8.1 {
+  SELECT '' < char(20) COLLATE rtrim;
+} 1
+do_execsql_test 8.2 {
+  DROP TABLE IF EXISTS t0;
+  CREATE TABLE t0(c0 COLLATE RTRIM, c1 BLOB UNIQUE,
+                  PRIMARY KEY (c0, c1)) WITHOUT ROWID;
+  INSERT INTO t0 VALUES (123, 3), (' ', 1), ('	', 2), ('', 4);
+  SELECT * FROM t0 WHERE c1 = 1;
+} {{ } 1}
 
 finish_test