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Overview
Comment:Reduce the average (but not maximum) size of the allocations made as part of a checkpoint.
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SHA1: 4a7fd91b7ab2c5d21fbac7f6f123820c8f4ec7f6
User & Date: dan 2010-06-25 16:34:32
Context
2010-06-25
19:09
Further test cases for pager1.test and pagerfault.test. check-in: bfd563c4 user: dan tags: trunk
16:34
Reduce the average (but not maximum) size of the allocations made as part of a checkpoint. check-in: 4a7fd91b user: dan tags: trunk
15:16
Reduce the size of the large allocation (approx 8KB for every 4000 frames in the log) that occurs during checkpoint. Use the 'scratch' memory for this allocation instead of the general purpose allocation. check-in: 29887487 user: dan tags: trunk
Changes
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Changes to src/wal.c.

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  */
  assert( pWal->ckptLock && pWal->hdr.mxFrame>0 );
  iLast = pWal->hdr.mxFrame;

  /* Allocate space for the WalIterator object. */
  nSegment = walFramePage(iLast) + 1;
  nByte = sizeof(WalIterator) 
        + (nSegment-1)*(sizeof(struct WalSegment))
        + nSegment*(HASHTABLE_NPAGE * sizeof(ht_slot));
  p = (WalIterator *)sqlite3ScratchMalloc(nByte);
  if( !p ){
    return SQLITE_NOMEM;
  }
  memset(p, 0, nByte);
  p->nSegment = nSegment;

  /* Allocate temporary space used by the merge-sort routine. This block
  ** of memory will be freed before this function returns.
  */
  aTmp = (ht_slot *)sqlite3ScratchMalloc(HASHTABLE_NPAGE * sizeof(ht_slot));


  if( !aTmp ){
    rc = SQLITE_NOMEM;
  }

  for(i=0; rc==SQLITE_OK && i<nSegment; i++){
    volatile ht_slot *aHash;
    int j;
    u32 iZero;
    int nEntry;
    volatile u32 *aPgno;
    ht_slot *aIndex;

    rc = walHashGet(pWal, i, &aHash, &aPgno, &iZero);
    if( rc==SQLITE_OK ){




      aPgno++;
      nEntry = ((i+1)==nSegment)?iLast-iZero:(u32 *)aHash-(u32 *)aPgno;

      iZero++;
  
      aIndex = &((ht_slot *)&p->aSegment[p->nSegment])[i*HASHTABLE_NPAGE];
      for(j=0; j<nEntry; j++){
        aIndex[j] = j;
      }
      walMergesort((u32 *)aPgno, aTmp, aIndex, &nEntry);
      p->aSegment[i].iZero = iZero;
      p->aSegment[i].nEntry = nEntry;
      p->aSegment[i].aIndex = aIndex;







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  */
  assert( pWal->ckptLock && pWal->hdr.mxFrame>0 );
  iLast = pWal->hdr.mxFrame;

  /* Allocate space for the WalIterator object. */
  nSegment = walFramePage(iLast) + 1;
  nByte = sizeof(WalIterator) 
        + (nSegment-1)*sizeof(struct WalSegment)
        + iLast*sizeof(ht_slot);
  p = (WalIterator *)sqlite3ScratchMalloc(nByte);
  if( !p ){
    return SQLITE_NOMEM;
  }
  memset(p, 0, nByte);
  p->nSegment = nSegment;

  /* Allocate temporary space used by the merge-sort routine. This block
  ** of memory will be freed before this function returns.
  */
  aTmp = (ht_slot *)sqlite3ScratchMalloc(
      sizeof(ht_slot) * (iLast>HASHTABLE_NPAGE?HASHTABLE_NPAGE:iLast)
  );
  if( !aTmp ){
    rc = SQLITE_NOMEM;
  }

  for(i=0; rc==SQLITE_OK && i<nSegment; i++){
    volatile ht_slot *aHash;

    u32 iZero;

    volatile u32 *aPgno;


    rc = walHashGet(pWal, i, &aHash, &aPgno, &iZero);
    if( rc==SQLITE_OK ){
      int j;                      /* Counter variable */
      int nEntry;                 /* Number of entries in this segment */
      ht_slot *aIndex;            /* Sorted index for this segment */

      aPgno++;
      nEntry = ((i+1)==nSegment)?iLast-iZero:(u32 *)aHash-(u32 *)aPgno;
      aIndex = &((ht_slot *)&p->aSegment[p->nSegment])[iZero];
      iZero++;
  

      for(j=0; j<nEntry; j++){
        aIndex[j] = j;
      }
      walMergesort((u32 *)aPgno, aTmp, aIndex, &nEntry);
      p->aSegment[i].iZero = iZero;
      p->aSegment[i].nEntry = nEntry;
      p->aSegment[i].aIndex = aIndex;