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Overview
Comment:Enhance the query planner so that it is able to use indexed expressions to help fulfill an ORDER BY clause.
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SHA1: 668fc1ebaf426f9eed3ed7865e41f1023dafebfb
User & Date: drh 2015-09-24 18:47:59.761
Context
2015-09-25
01:09
Fix a problem computing affinities for indexes during skip-scan code generation when SQLITE_ENABLE_STAT4 is on. Bug introduced by check-in [1ee089a72d789002]. (check-in: 1350dd42d0 user: drh tags: trunk)
2015-09-24
18:47
Enhance the query planner so that it is able to use indexed expressions to help fulfill an ORDER BY clause. (check-in: 668fc1ebaf user: drh tags: trunk)
17:38
Fix over-length source code lines in where.c. No logic changes. (check-in: 1c8c5380a8 user: drh tags: trunk)
Changes
Unified Diff Ignore Whitespace Patch
Changes to src/where.c.
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*/
static int indexMightHelpWithOrderBy(
  WhereLoopBuilder *pBuilder,
  Index *pIndex,
  int iCursor
){
  ExprList *pOB;

  int ii, jj;

  if( pIndex->bUnordered ) return 0;
  if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
  for(ii=0; ii<pOB->nExpr; ii++){
    Expr *pExpr = sqlite3ExprSkipCollate(pOB->a[ii].pExpr);
    if( pExpr->op!=TK_COLUMN ) return 0;
    if( pExpr->iTable==iCursor ){
      if( pExpr->iColumn<0 ) return 1;
      for(jj=0; jj<pIndex->nKeyCol; jj++){
        if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1;







      }
    }
  }
  return 0;
}

/*








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*/
static int indexMightHelpWithOrderBy(
  WhereLoopBuilder *pBuilder,
  Index *pIndex,
  int iCursor
){
  ExprList *pOB;
  ExprList *aColExpr;
  int ii, jj;

  if( pIndex->bUnordered ) return 0;
  if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
  for(ii=0; ii<pOB->nExpr; ii++){
    Expr *pExpr = sqlite3ExprSkipCollate(pOB->a[ii].pExpr);

    if( pExpr->op==TK_COLUMN && pExpr->iTable==iCursor ){
      if( pExpr->iColumn<0 ) return 1;
      for(jj=0; jj<pIndex->nKeyCol; jj++){
        if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1;
      }
    }else if( (aColExpr = pIndex->aColExpr)!=0 ){
      for(jj=0; jj<pIndex->nKeyCol; jj++){
        if( pIndex->aiColumn[jj]!=(-2) ) continue;
        if( sqlite3ExprCompare(pExpr,aColExpr->a[jj].pExpr,iCursor)==0 ){
          return 1;
        }
      }
    }
  }
  return 0;
}

/*
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        isMatch = 0;
        for(i=0; bOnce && i<nOrderBy; i++){
          if( MASKBIT(i) & obSat ) continue;
          pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
          testcase( wctrlFlags & WHERE_GROUPBY );
          testcase( wctrlFlags & WHERE_DISTINCTBY );
          if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0;

          if( pOBExpr->op!=TK_COLUMN ) continue;
          if( pOBExpr->iTable!=iCur ) continue;
          if( pOBExpr->iColumn!=iColumn ) continue;





          if( iColumn>=0 ){
            pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
            if( !pColl ) pColl = db->pDfltColl;
            if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue;
          }
          isMatch = 1;
          break;








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        isMatch = 0;
        for(i=0; bOnce && i<nOrderBy; i++){
          if( MASKBIT(i) & obSat ) continue;
          pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
          testcase( wctrlFlags & WHERE_GROUPBY );
          testcase( wctrlFlags & WHERE_DISTINCTBY );
          if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0;
          if( iColumn>=(-1) ){
            if( pOBExpr->op!=TK_COLUMN ) continue;
            if( pOBExpr->iTable!=iCur ) continue;
            if( pOBExpr->iColumn!=iColumn ) continue;
          }else{
            if( sqlite3ExprCompare(pOBExpr,pIndex->aColExpr->a[j].pExpr,iCur) ){
              continue;
            }
          }
          if( iColumn>=0 ){
            pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
            if( !pColl ) pColl = db->pDfltColl;
            if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue;
          }
          isMatch = 1;
          break;
︙︙
Changes to test/indexexpr1.test.
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} {1 1 1}
do_execsql_test indexexpr1-160eqp {
  EXPLAIN QUERY PLAN
  SELECT rowid, b, c FROM t1
   WHERE substr(a,27,3)=='ord' AND d>=29;
} {/USING INDEX t1a2/}



















do_execsql_test indexexpr1-200 {
  DROP TABLE t1;
  CREATE TABLE t1(id ANY PRIMARY KEY, a,b,c) WITHOUT ROWID;
  INSERT INTO t1(id,a,b,c)
  VALUES(1,'In_the_beginning_was_the_Word',1,1),
        (2,'and_the_Word_was_with_God',1,2),








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} {1 1 1}
do_execsql_test indexexpr1-160eqp {
  EXPLAIN QUERY PLAN
  SELECT rowid, b, c FROM t1
   WHERE substr(a,27,3)=='ord' AND d>=29;
} {/USING INDEX t1a2/}

# ORDER BY using an indexed expression
#
do_execsql_test indexexpr1-170 {
  CREATE INDEX t1alen ON t1(length(a));
  SELECT length(a) FROM t1 ORDER BY length(a);
} {20 25 27 29 38 52}
do_execsql_test indexexpr1-170eqp {
  EXPLAIN QUERY PLAN
  SELECT length(a) FROM t1 ORDER BY length(a);
} {/SCAN TABLE t1 USING INDEX t1alen/}
do_execsql_test indexexpr1-171 {
  SELECT length(a) FROM t1 ORDER BY length(a) DESC;
} {52 38 29 27 25 20}
do_execsql_test indexexpr1-171eqp {
  EXPLAIN QUERY PLAN
  SELECT length(a) FROM t1 ORDER BY length(a) DESC;
} {/SCAN TABLE t1 USING INDEX t1alen/}

do_execsql_test indexexpr1-200 {
  DROP TABLE t1;
  CREATE TABLE t1(id ANY PRIMARY KEY, a,b,c) WITHOUT ROWID;
  INSERT INTO t1(id,a,b,c)
  VALUES(1,'In_the_beginning_was_the_Word',1,1),
        (2,'and_the_Word_was_with_God',1,2),
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  CREATE INDEX t72yz ON t72(y+z);
  INSERT INTO t71(a,b,c) VALUES(1,11,2),(2,7,15),(3,5,4);
  INSERT INTO t72(x,y,z) VALUES(1,10,3),(2,8,14),(3,9,9);
  SELECT a, x, '|' FROM t71, t72
   WHERE b+c=y+z
  ORDER BY +a, +x;
} {1 1 | 2 2 |}





















finish_test









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  CREATE INDEX t72yz ON t72(y+z);
  INSERT INTO t71(a,b,c) VALUES(1,11,2),(2,7,15),(3,5,4);
  INSERT INTO t72(x,y,z) VALUES(1,10,3),(2,8,14),(3,9,9);
  SELECT a, x, '|' FROM t71, t72
   WHERE b+c=y+z
  ORDER BY +a, +x;
} {1 1 | 2 2 |}

# Collating sequences on indexes of expressions
#
do_execsql_test indexexpr1-800 {
  DROP TABLE IF EXISTS t8;
  CREATE TABLE t8(a INTEGER PRIMARY KEY, b TEXT);
  CREATE UNIQUE INDEX t8bx ON t8(substr(b,2,4) COLLATE nocase);
  INSERT INTO t8(a,b) VALUES(1,'Alice'),(2,'Bartholemew'),(3,'Cynthia');
  SELECT * FROM t8 WHERE substr(b,2,4)='ARTH' COLLATE nocase;
} {2 Bartholemew}
do_catchsql_test indexexpr1-810 {
  INSERT INTO t8(a,b) VALUES(4,'BARTHMERE');
} {1 {UNIQUE constraint failed: index 't8bx'}}
do_catchsql_test indexexpr1-820 {
  DROP INDEX t8bx;
  CREATE UNIQUE INDEX t8bx ON t8(substr(b,2,4) COLLATE rtrim);
  INSERT INTO t8(a,b) VALUES(4,'BARTHMERE');
} {0 {}}



finish_test