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Overview
Comment:Fix the computation of the number of rows in a table during automatic index generation.
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SHA1:edeab06a5010c82491a6cc9393cf2a35a7622ac5
User & Date: drh 2010-04-08 15:01:00
Context
2010-04-08
15:01
New test cases for automatic indices. New testcase() macros associated with column-used bitmasks. check-in: e1aa48ac user: drh tags: trunk
15:01
Fix the computation of the number of rows in a table during automatic index generation. check-in: edeab06a user: drh tags: trunk
14:38
Fix an integer overflow bug in the automatic index logic. The bug was detected by the testcase() macros added in the previous check-in. Also add some more testcase() macros, since this issue points up their importance. check-in: af97b488 user: drh tags: trunk
Changes
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Changes to src/where.c.

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  }
  if( pSrc->notIndexed ){
    /* The NOT INDEXED clause appears in the SQL. */
    return;
  }

  assert( pParse->nQueryLoop >= (double)1 );
  nTableRow = pSrc->pIndex ? pSrc->pIndex->aiRowEst[0] : 1000000;

  logN = estLog(nTableRow);
  costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1);
  if( costTempIdx>=pCost->rCost ){
    /* The cost of creating the transient table would be greater than
    ** doing the full table scan */
    return;
  }

  /* Search for any equality comparison term */
  pTable = pSrc->pTab;
  pWCEnd = &pWC->a[pWC->nTerm];
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      WHERETRACE(("auto-index reduces cost from %.2f to %.2f\n",
                    pCost->rCost, costTempIdx));
      pCost->rCost = costTempIdx;
      pCost->nRow = logN + 1;







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  }
  if( pSrc->notIndexed ){
    /* The NOT INDEXED clause appears in the SQL. */
    return;
  }

  assert( pParse->nQueryLoop >= (double)1 );
  pTable = pSrc->pTab;
  nTableRow = pTable->pIndex ? pTable->pIndex->aiRowEst[0] : 1000000;
  logN = estLog(nTableRow);
  costTempIdx = 2*logN*(nTableRow/pParse->nQueryLoop + 1);
  if( costTempIdx>=pCost->rCost ){
    /* The cost of creating the transient table would be greater than
    ** doing the full table scan */
    return;
  }

  /* Search for any equality comparison term */

  pWCEnd = &pWC->a[pWC->nTerm];
  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
      WHERETRACE(("auto-index reduces cost from %.2f to %.2f\n",
                    pCost->rCost, costTempIdx));
      pCost->rCost = costTempIdx;
      pCost->nRow = logN + 1;