diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/where.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/src/where.c b/src/where.c index f9deb3d41..7a994943c 100644 --- a/src/where.c +++ b/src/where.c @@ -2771,14 +2771,6 @@ static int isOrderedColumn( ** The table being queried has a cursor number of "base". pIdx is the ** index that is postulated for use to access the table. ** -** nEqCol is the number of columns of pIdx that are used as equality -** constraints and where the other side of the == is an ordered column -** or constant. An "order column" in the previous sentence means a column -** in table from an outer loop whose values will always appear in the -** correct order due to othre index, or because the outer loop generates -** a unique result. Any of the first nEqCol columns of pIdx may be missing -** from the ORDER BY clause and the match can still be a success. -** ** The *pbRev value is set to 0 order 1 depending on whether or not ** pIdx should be run in the forward order or in reverse order. */ @@ -2894,6 +2886,8 @@ static int isSortingIndex( /* termSortOrder is 0 or 1 for whether or not the access loop should ** run forward or backwards (respectively) in order to satisfy this ** term of the ORDER BY clause. */ + assert( pOBItem->sortOrder==0 || pOBItem->sortOrder==1 ); + assert( iSortOrder==0 || iSortOrder==1 ); termSortOrder = iSortOrder ^ pOBItem->sortOrder; /* If X is the column in the index and ORDER BY clause, check to see @@ -2903,12 +2897,15 @@ static int isSortingIndex( if( pConstraint==0 ){ isEq = 0; }else if( pConstraint->eOperator==WO_IN ){ + /* Constraints of the form: "X IN ..." cannot be used with an ORDER BY + ** because we do not know in what order the values on the RHS of the IN + ** operator will occur. */ break; }else if( pConstraint->eOperator==WO_ISNULL ){ uniqueNotNull = 0; - isEq = 1; + isEq = 1; /* "X IS NULL" means X has only a single value */ }else if( pConstraint->prereqRight==0 ){ - isEq = 1; + isEq = 1; /* Constraint "X=constant" means X has only a single value */ }else{ Expr *pRight = pConstraint->pExpr->pRight; if( pRight->op==TK_COLUMN ){ @@ -2916,15 +2913,19 @@ static int isSortingIndex( pRight->iTable, pRight->iColumn)); isEq = isOrderedColumn(p, pRight->iTable, pRight->iColumn); WHERETRACE((" -> isEq=%d\n", isEq)); + + /* If the constraint is of the form X=Y where Y is an ordered value + ** in an outer loop, then make sure the sort order of Y matches the + ** sort order required for X. */ if( isMatch && isEq>=2 && isEq!=pOBItem->sortOrder+2 ){ + testcase( isEq==2 ); + testcase( isEq==3 ); break; } }else{ - isEq = 0; + isEq = 0; /* "X=expr" places no ordering constraints on X */ } } - assert( pOBItem->sortOrder==0 || pOBItem->sortOrder==1 ); - assert( iSortOrder==0 || iSortOrder==1 ); if( !isMatch ){ if( isEq==0 ){ break; @@ -2943,7 +2944,10 @@ static int isSortingIndex( if( iColumn<0 ){ seenRowid = 1; break; - }else if( pTab->aCol[iColumn].notNull==0 && isEq==0 ){ + }else if( pTab->aCol[iColumn].notNull==0 && isEq!=1 ){ + testcase( isEq==0 ); + testcase( isEq==2 ); + testcase( isEq==3 ); uniqueNotNull = 0; } } |