SQLite

Check-in [6266712968]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Use randomness to prevent slowness in the generated-column-name uniqueness checking.
Downloads: Tarball | ZIP archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: 6266712968a2cdcd6f5a3007d60c2cf1b3faf912
User & Date: drh 2015-11-14 16:47:23.463
Original Comment: Use randomness to prevent showness in the generated-column-name uniqueness checking.
Context
2015-11-14
20:52
Use a hash table to improve the preformance of column name uniqueness checking. (check-in: 5b08f29f45 user: drh tags: trunk)
16:47
Use randomness to prevent slowness in the generated-column-name uniqueness checking. (check-in: 6266712968 user: drh tags: trunk)
2015-11-13
20:52
Fix a memory leak in the fuzzcheck utility. (check-in: dfd6d9f4fb user: drh tags: trunk)
Changes
Unified Diff Show Whitespace Changes Patch
Changes to src/select.c.
︙︙
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606

  Parse *pParse,          /* Parsing context */
  ExprList *pEList,       /* Expr list from which to derive column names */
  i16 *pnCol,             /* Write the number of columns here */
  Column **paCol          /* Write the new column list here */
){
  sqlite3 *db = pParse->db;   /* Database connection */
  int i, j;                   /* Loop counters */
  int cnt;                    /* Index added to make the name unique */
  Column *aCol, *pCol;        /* For looping over result columns */
  int nCol;                   /* Number of columns in the result set */
  Expr *p;                    /* Expression for a single result column */
  char *zName;                /* Column name */
  int nName;                  /* Size of name in zName[] */

  if( pEList ){








|








1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606

  Parse *pParse,          /* Parsing context */
  ExprList *pEList,       /* Expr list from which to derive column names */
  i16 *pnCol,             /* Write the number of columns here */
  Column **paCol          /* Write the new column list here */
){
  sqlite3 *db = pParse->db;   /* Database connection */
  int i, j;                   /* Loop counters */
  u32 cnt;                    /* Index added to make the name unique */
  Column *aCol, *pCol;        /* For looping over result columns */
  int nCol;                   /* Number of columns in the result set */
  Expr *p;                    /* Expression for a single result column */
  char *zName;                /* Column name */
  int nName;                  /* Size of name in zName[] */

  if( pEList ){
︙︙
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666

1667
1668
1669
1670
1671
1672
1673

    for(j=cnt=0; j<i; j++){
      if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
        char *zNewName;
        int k;
        for(k=nName-1; k>1 && sqlite3Isdigit(zName[k]); k--){}
        if( k>=0 && zName[k]==':' ) nName = k;
        zName[nName] = 0;
        zNewName = sqlite3MPrintf(db, "%s:%d", zName, ++cnt);
        sqlite3DbFree(db, zName);
        zName = zNewName;
        j = -1;
        if( zName==0 ) break;

      }
    }
    pCol->zName = zName;
  }
  if( db->mallocFailed ){
    for(j=0; j<i; j++){
      sqlite3DbFree(db, aCol[j].zName);








|




>








1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674

    for(j=cnt=0; j<i; j++){
      if( sqlite3StrICmp(aCol[j].zName, zName)==0 ){
        char *zNewName;
        int k;
        for(k=nName-1; k>1 && sqlite3Isdigit(zName[k]); k--){}
        if( k>=0 && zName[k]==':' ) nName = k;
        zName[nName] = 0;
        zNewName = sqlite3MPrintf(db, "%s:%u", zName, ++cnt);
        sqlite3DbFree(db, zName);
        zName = zNewName;
        j = -1;
        if( zName==0 ) break;
        if( cnt>3 ) sqlite3_randomness(sizeof(cnt), &cnt);
      }
    }
    pCol->zName = zName;
  }
  if( db->mallocFailed ){
    for(j=0; j<i; j++){
      sqlite3DbFree(db, aCol[j].zName);
︙︙