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Overview
Comment:Additional comments and an assert on the sqlite3BtreeInsert() overwrite optimization.
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SHA1:c1f0ae9d2981a19875103750379ad26f2575f878
User & Date: drh 2016-12-09 18:09:42
Context
2016-12-09
19:42
When doing the sqlite3BtreeInsert() overwrite optimization, make sure the memcpy() does not extend off the end of the page. check-in: 684ef458 user: drh tags: trunk
18:09
Additional comments and an assert on the sqlite3BtreeInsert() overwrite optimization. check-in: c1f0ae9d user: drh tags: trunk
17:32
In sqlite3BtreeInsert() when replacing a re-existing row, try to overwrite the cell directly rather than deallocate and reallocate the cell. check-in: 0b86fbca user: drh tags: trunk
Changes
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Changes to src/btree.c.

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    }
    oldCell = findCell(pPage, idx);
    if( !pPage->leaf ){
      memcpy(newCell, oldCell, 4);
    }
    rc = clearCell(pPage, oldCell, &info);
    if( info.nSize==szNew && info.nLocal==info.nPayload ){
      /* Overwrite the old cell with the new */





      memcpy(oldCell, newCell, szNew);
      return SQLITE_OK;
    }
    dropCell(pPage, idx, info.nSize, &rc);
    if( rc ) goto end_insert;
  }else if( loc<0 && pPage->nCell>0 ){
    assert( pPage->leaf );







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    }
    oldCell = findCell(pPage, idx);
    if( !pPage->leaf ){
      memcpy(newCell, oldCell, 4);
    }
    rc = clearCell(pPage, oldCell, &info);
    if( info.nSize==szNew && info.nLocal==info.nPayload ){
      /* Overwrite the old cell with the new if they are the same size.
      ** We could also try to do this if the old cell is smaller, then add
      ** the leftover space to the free list.  But experiments show that
      ** doing that is no faster then skipping this optimization and just
      ** calling dropCell() and insertCell(). */
      assert( rc==SQLITE_OK ); /* clearCell never fails when nLocal==nPayload */
      memcpy(oldCell, newCell, szNew);
      return SQLITE_OK;
    }
    dropCell(pPage, idx, info.nSize, &rc);
    if( rc ) goto end_insert;
  }else if( loc<0 && pPage->nCell>0 ){
    assert( pPage->leaf );