LIMIT occurs after DISTINCT. Ticket #749. (CVS 1823)

FossilOrigin-Name: e6bc8aa80824a9156e78fc99b5ac7045b97d29c3

manifest

@@ -1,5 +1,5 @@
-C more\suses\sof\ssqlite3.pc\s(CVS\s1822)
+C LIMIT\soccurs\safter\sDISTINCT.\s\sTicket\s#749.\s(CVS\s1823)
-D 2004-07-19T22:28:43
+D 2004-07-19T23:16:39
 F Makefile.in 4a5e570a9e2d35b09c31b3cf01b78cea764ade4b
 F Makefile.linux-gcc a9e5a0d309fa7c38e7c14d3ecf7690879d3a5457
 F README f1de682fbbd94899d50aca13d387d1b3fd3be2dd
@@ -57,7 +57,7 @@ F src/parse.y 51c8e696276c409618e66a4ccf316fcff245506e
 F src/pragma.c 8326df8c400f573eb43004dfb8e53e5102acb3e4
 F src/printf.c 36090f6d7b4946539de97c1850675ce55ef66c16
 F src/random.c eff68e3f257e05e81eae6c4d50a51eb88beb4ff3
-F src/select.c 6f0bbf8da5b68f9afeb6f51a28ff7526a2f37238
+F src/select.c d4585c55c460dad2019964e5d0ae18f9b91cd142
 F src/shell.c ebec5da57ea401f4886eefc790917b939d94d595
 F src/sqlite.h.in aaf46c8d458efd8aca694ec4f18c6ecf616ee55e
 F src/sqliteInt.h aeae6793d1db335ec1179ad9f26b0affc0ec658a
@@ -129,7 +129,7 @@ F test/join3.test 8d989e52413199065bd630b3d0a6b2329d173099
 F test/join4.test 8dec387d06b3a4685e1104048065cf5236b99b93
 F test/lastinsert.test 31382f88b9b0270333ac9e4a17f2c2f4732da718
 F test/laststmtchanges.test 417aa27eb2b5cdfafb46e390e2c9ddd0a20eba43
-F test/limit.test 60d7f856ee7846f7130dee67f10f0e726cd70b5d
+F test/limit.test 404a540e3fede22cab5667e12d7e3788617b07dc
 F test/lock.test 1dbf1d06b0a7eb36237b4f107cfb3da9726b449e
 F test/lock2.test 4108cabaa108a142e5eed83de3b13b6e579c12cf
 F test/main.test e8c4d9ca6d1e5f5e55e6550d31aec488883b2ed9
@@ -237,7 +237,7 @@ F www/tclsqlite.tcl 19191cf2a1010eaeff74c51d83fd5f5a4d899075
 F www/vdbe.tcl 59288db1ac5c0616296b26dce071c36cb611dfe9
 F www/version3.tcl 092a01f5ef430d2c4acc0ae558d74c4bb89638a0
 F www/whentouse.tcl a8335bce47cc2fddb07f19052cb0cb4d9129a8e4
-P 511ee6392472d250b542961d1f715cc7453598e6
+P a0f107ca66f825cc1fd10b15157b22fd9cc0f95c
-R a1278fd30ec90b30144977a9a291265d
+R 2a77d36b9d379fa39cee995a7b6ac780
-U dougcurrie
+U drh
-Z 2a946161d6ace42bcae6f510d88d5b18
+Z ebf8b5ec73a9dc2627883459f07e7b7c

manifest.uuid

@@ -1 +1 @@
-a0f107ca66f825cc1fd10b15157b22fd9cc0f95c
+e6bc8aa80824a9156e78fc99b5ac7045b97d29c3

src/select.c

@@ -12,7 +12,7 @@
 ** This file contains C code routines that are called by the parser
 ** to handle SELECT statements in SQLite.
 **
-** $Id: select.c,v 1.197 2004/07/18 21:33:02 drh Exp $
+** $Id: select.c,v 1.198 2004/07/19 23:16:39 drh Exp $
 */
 #include "sqliteInt.h"
 
@@ -320,6 +320,31 @@ static void pushOntoSorter(Parse *pParse, Vdbe *v, ExprList *pOrderBy){
   sqlite3VdbeAddOp(v, OP_SortPut, 0, 0);
 }
 
+/*
+** Add code to implement the OFFSET and LIMIT
+*/
+static void codeLimiter(
+  Parse *pParse,    /* Parsing context */
+  Select *p,        /* The SELECT statement being coded */
+  int iContinue,    /* Jump here to skip the current record */
+  int iBreak,       /* Jump here to end the loop */
+  int nPop          /* Number of times to pop stack when jumping */
+){
+  Vdbe *v = pParse->pVdbe;
+  if( p->iOffset>=0 ){
+    int addr = sqlite3VdbeCurrentAddr(v) + 2;
+    if( nPop>0 ) addr++;
+    sqlite3VdbeAddOp(v, OP_MemIncr, p->iOffset, addr);
+    if( nPop>0 ){
+      sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
+    }
+    sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
+  }
+  if( p->iLimit>=0 ){
+    sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, iBreak);
+  }
+}
+
 /*
 ** This routine generates the code for the inside of the inner loop
 ** of a SELECT.
@@ -345,6 +370,7 @@ static int selectInnerLoop(
 ){
   Vdbe *v = pParse->pVdbe;
   int i;
+  int hasDistinct;        /* True if the DISTINCT keyword is present */
 
   if( v==0 ) return 0;
   assert( pEList!=0 );
@@ -352,15 +378,9 @@ static int selectInnerLoop(
   /* If there was a LIMIT clause on the SELECT statement, then do the check
   ** to see if this row should be output.
   */
-  if( pOrderBy==0 ){
+  hasDistinct = distinct>=0 && pEList && pEList->nExpr>0;
-    if( p->iOffset>=0 ){
+  if( pOrderBy==0 && !hasDistinct ){
-      int addr = sqlite3VdbeCurrentAddr(v);
+    codeLimiter(pParse, p, iContinue, iBreak, 0);
-      sqlite3VdbeAddOp(v, OP_MemIncr, p->iOffset, addr+2);
-      sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
-    }
-    if( p->iLimit>=0 ){
-      sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, iBreak);
-    }
   }
 
   /* Pull the requested columns.
@@ -380,7 +400,7 @@ static int selectInnerLoop(
   ** and this row has been seen before, then do not make this row
   ** part of the result.
   */
-  if( distinct>=0 && pEList && pEList->nExpr>0 ){
+  if( hasDistinct ){
 #if NULL_ALWAYS_DISTINCT
     sqlite3VdbeAddOp(v, OP_IsNull, -pEList->nExpr, sqlite3VdbeCurrentAddr(v)+7);
 #endif
@@ -392,6 +412,9 @@ static int selectInnerLoop(
     sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
     sqlite3VdbeAddOp(v, OP_String8, 0, 0);
     sqlite3VdbeAddOp(v, OP_PutStrKey, distinct, 0);
+    if( pOrderBy==0 ){
+      codeLimiter(pParse, p, iContinue, iBreak, nColumn);
+    }
   }
 
   switch( eDest ){
@@ -559,14 +582,7 @@ static void generateSortTail(
   }
   sqlite3VdbeOp3(v, OP_Sort, 0, 0, (char*)pInfo, P3_KEYINFO_HANDOFF);
   addr = sqlite3VdbeAddOp(v, OP_SortNext, 0, end1);
-  if( p->iOffset>=0 ){
+  codeLimiter(pParse, p, addr, end2, 1);
-    sqlite3VdbeAddOp(v, OP_MemIncr, p->iOffset, addr+4);
-    sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
-    sqlite3VdbeAddOp(v, OP_Goto, 0, addr);
-  }
-  if( p->iLimit>=0 ){
-    sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, end2);
-  }
   switch( eDest ){
     case SRT_Table:
     case SRT_TempTable: {

test/limit.test

@@ -12,7 +12,7 @@
 # focus of this file is testing the LIMIT ... OFFSET ... clause
 #  of SELECT statements.
 #
-# $Id: limit.test,v 1.13 2004/05/27 17:22:56 drh Exp $
+# $Id: limit.test,v 1.14 2004/07/19 23:16:39 drh Exp $
 
 set testdir [file dirname $argv0]
 source $testdir/tester.tcl
@@ -295,4 +295,17 @@ do_test limit-7.12 {
   }
 } {30}
 
+# Tests for limit in conjunction with distinct
+#
+do_test limit-8.1 {
+  execsql {
+    SELECT DISTINCT x/100 FROM t3 LIMIT 5;
+  }
+} {0 1 2 3 4}
+do_test limit-8.2 {
+  execsql {
+    SELECT DISTINCT x/100 FROM t3 LIMIT 5 OFFSET 5;
+  }
+} {5 6 7 8 9}
+
 finish_test