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Overview
| Comment: | Use randomness to prevent slowness in the generated-column-name uniqueness checking. |
|---|---|
| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | trunk |
| Files: | files | file ages | folders |
| SHA1: |
6266712968a2cdcd6f5a3007d60c2cf1 |
| User & Date: | drh 2015-11-14 16:47:23 |
| Original Comment: | Use randomness to prevent showness in the generated-column-name uniqueness checking. |
Context
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2015-11-14
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| 20:52 | Use a hash table to improve the preformance of column name uniqueness checking. check-in: 5b08f29f user: drh tags: trunk | |
| 16:47 | Use randomness to prevent slowness in the generated-column-name uniqueness checking. check-in: 62667129 user: drh tags: trunk | |
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2015-11-13
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| 20:52 | Fix a memory leak in the fuzzcheck utility. check-in: dfd6d9f4 user: drh tags: trunk | |
Changes
Changes to src/select.c.
1592 1592 Parse *pParse, /* Parsing context */ 1593 1593 ExprList *pEList, /* Expr list from which to derive column names */ 1594 1594 i16 *pnCol, /* Write the number of columns here */ 1595 1595 Column **paCol /* Write the new column list here */ 1596 1596 ){ 1597 1597 sqlite3 *db = pParse->db; /* Database connection */ 1598 1598 int i, j; /* Loop counters */ 1599 - int cnt; /* Index added to make the name unique */ 1599 + u32 cnt; /* Index added to make the name unique */ 1600 1600 Column *aCol, *pCol; /* For looping over result columns */ 1601 1601 int nCol; /* Number of columns in the result set */ 1602 1602 Expr *p; /* Expression for a single result column */ 1603 1603 char *zName; /* Column name */ 1604 1604 int nName; /* Size of name in zName[] */ 1605 1605 1606 1606 if( pEList ){ ................................................................................ 1655 1655 for(j=cnt=0; j<i; j++){ 1656 1656 if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){ 1657 1657 char *zNewName; 1658 1658 int k; 1659 1659 for(k=nName-1; k>1 && sqlite3Isdigit(zName[k]); k--){} 1660 1660 if( k>=0 && zName[k]==':' ) nName = k; 1661 1661 zName[nName] = 0; 1662 - zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt); 1662 + zNewName = sqlite3MPrintf(db, "%s:%u", zName, ++cnt); 1663 1663 sqlite3DbFree(db, zName); 1664 1664 zName = zNewName; 1665 1665 j = -1; 1666 1666 if( zName==0 ) break; 1667 + if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt); 1667 1668 } 1668 1669 } 1669 1670 pCol->zName = zName; 1670 1671 } 1671 1672 if( db->mallocFailed ){ 1672 1673 for(j=0; j<i; j++){ 1673 1674 sqlite3DbFree(db, aCol[j].zName);