/ Check-in [f9c053b2]
Login
SQLite training in Houston TX on 2019-11-05 (details)
Part of the 2019 Tcl Conference

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

Overview
Comment:Fix a division-by-zero error that might occur if the sqlite_stat1 table is corrupt.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | stat4-avgeq
Files: files | file ages | folders
SHA1: f9c053b23ece877a7fdbe82204a10592f2d24a2d
User & Date: dan 2014-10-03 19:29:39
Context
2014-10-04
00:07
Avoid leaking Index.aiRowEst memory if an OOM causes a rollback which deletes the index before the aiRowEst deletion code in sqlite3AnalysisLoad() routine has a chance to run. Since the aiRowEst now might be deleted from freeIndex() which does not always have a db pointer, make sure the aiRowEst memory is not held in lookaside. check-in: efd87ba1 user: drh tags: stat4-avgeq
2014-10-03
19:29
Fix a division-by-zero error that might occur if the sqlite_stat1 table is corrupt. check-in: f9c053b2 user: dan tags: stat4-avgeq
19:16
Improve the accuracy of the estimates used when searching an index for values not present in any stat4 samples under some circumstances. check-in: e6f7f97d user: dan tags: stat4-avgeq
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to src/analyze.c.

1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
      int i;                    /* Used to iterate through samples */
      tRowcnt sumEq = 0;        /* Sum of the nEq values */
      tRowcnt avgEq = 0;
      tRowcnt nRow;             /* Number of rows in index */
      i64 nSum100 = 0;          /* Number of terms contributing to sumEq */
      i64 nDist100;             /* Number of distinct values in index */

      if( pIdx->aiRowEst==0 ){
        nRow = pFinal->anLt[iCol];
        nDist100 = (i64)100 * pFinal->anDLt[iCol];
        nSample--;
      }else{
        nRow = pIdx->aiRowEst[0];
        nDist100 = ((i64)100 * pIdx->aiRowEst[0]) / pIdx->aiRowEst[iCol+1];
      }







|







1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
      int i;                    /* Used to iterate through samples */
      tRowcnt sumEq = 0;        /* Sum of the nEq values */
      tRowcnt avgEq = 0;
      tRowcnt nRow;             /* Number of rows in index */
      i64 nSum100 = 0;          /* Number of terms contributing to sumEq */
      i64 nDist100;             /* Number of distinct values in index */

      if( pIdx->aiRowEst==0 || pIdx->aiRowEst[iCol+1]==0 ){
        nRow = pFinal->anLt[iCol];
        nDist100 = (i64)100 * pFinal->anDLt[iCol];
        nSample--;
      }else{
        nRow = pIdx->aiRowEst[0];
        nDist100 = ((i64)100 * pIdx->aiRowEst[0]) / pIdx->aiRowEst[iCol+1];
      }