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Test cases added. Comments fixed. Proposed solution for

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ticket [05f43be8fdda9fbd9].

FossilOrigin-Name: 6b993bd54035b67f4d84941e3f444ca79b7feee1
This commit is contained in:
drh
2015-03-06 20:49:52 +00:00
parent 8f1a7ed33f
commit a9c18a9067
8 changed files with 105 additions and 35 deletions
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19
src/where.c
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@@ -1109,7 +1109,7 @@ static void exprAnalyze(
Bitmask extraRight = 0; /* Extra dependencies on LEFT JOIN */
Expr *pStr1 = 0; /* RHS of LIKE/GLOB operator */
int isComplete = 0; /* RHS of LIKE/GLOB ends with wildcard */
int noCase = 0; /* LIKE/GLOB distinguishes case */
int noCase = 0; /* uppercase equivalent to lowercase */
int op; /* Top-level operator. pExpr->op */
Parse *pParse = pWInfo->pParse; /* Parsing context */
sqlite3 *db = pParse->db; /* Database connection */
@@ -1247,12 +1247,15 @@ static void exprAnalyze(
/* Add constraints to reduce the search space on a LIKE or GLOB
** operator.
**
** A like pattern of the form "x LIKE 'abc%'" is changed into constraints
** A like pattern of the form "x LIKE 'aBc%'" is changed into constraints
**
** x>='abc' AND x<'abd' AND x LIKE 'abc%'
** x>='ABC' AND x<'abd' AND x LIKE 'aBc%'
**
** The last character of the prefix "abc" is incremented to form the
** termination condition "abd".
** termination condition "abd". If case is not significant (the default
** for LIKE) then the lower-bound is made all uppercase and the upper-
** bound is made all lowercase so that the bounds also work when comparing
** BLOBs.
*/
if( pWC->op==TK_AND
&& isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase)
@@ -1266,7 +1269,6 @@ static void exprAnalyze(
Token sCollSeqName; /* Name of collating sequence */
const u16 wtFlags = TERM_LIKEOPT | TERM_VIRTUAL | TERM_DYNAMIC;
pTerm->wtFlags |= TERM_LIKE;
pLeft = pExpr->x.pList->a[1].pExpr;
pStr2 = sqlite3ExprDup(db, pStr1, 0);
@@ -1277,6 +1279,7 @@ static void exprAnalyze(
if( noCase && !pParse->db->mallocFailed ){
int i;
char c;
pTerm->wtFlags |= TERM_LIKE;
for(i=0; (c = pStr1->u.zToken[i])!=0; i++){
pStr1->u.zToken[i] = sqlite3Toupper(c);
pStr2->u.zToken[i] = sqlite3Tolower(c);
@@ -2502,6 +2505,12 @@ static int whereInScanEst(
** and child2 terms were added by the LIKE optimization. If both of
** the virtual child terms are valid, then testing of the parent can be
** skipped.
**
** Usually the parent term is marked as TERM_CODED. But if the parent
** term was originally TERM_LIKE, then the parent gets TERM_LIKECOND instead.
** The TERM_LIKECOND marking indicates that the term should be coded inside
** a conditional such that is only evaluated on the second pass of a
** LIKE-optimization loop, when scanning BLOBs instead of strings.
*/
static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
int nLoop = 0;