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SQLite training in Houston TX on 2019-11-05 (details)
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Overview
Comment:When searching a list of freelist trunk pages looking for a specific page to allocate, avoid unnecessary journalling of the unchanged trunk pages towards the start of the list.
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1: d03d63d77ed144ac2c02a0245c4b4b070b79c88e
User & Date: drh 2011-04-07 14:47:01
References
2011-04-07
15:24
Add test case to verify [d03d63d77e] works. check-in: bf78acb9 user: dan tags: trunk
Context
2011-04-07
15:24
Add test case to verify [d03d63d77e] works. check-in: bf78acb9 user: dan tags: trunk
14:47
When searching a list of freelist trunk pages looking for a specific page to allocate, avoid unnecessary journalling of the unchanged trunk pages towards the start of the list. check-in: d03d63d7 user: drh tags: trunk
14:05
Avoid running thread1.test or thread2.test if SQLITE_MUTEX_NOOP is defined. check-in: 532ae32e user: dan tags: trunk
Changes
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Changes to src/btree.c.

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        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }

      k = get4byte(&pTrunk->aData[4]);
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
        rc = sqlite3PagerWrite(pTrunk->pDbPage);
        if( rc ){
................................................................................
        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
#endif
      }else if( k>0 ){
        /* Extract a leaf from the trunk */
        u32 closest;
        Pgno iPage;
        unsigned char *aData = pTrunk->aData;
        rc = sqlite3PagerWrite(pTrunk->pDbPage);
        if( rc ){
          goto end_allocate_page;
        }
        if( nearby>0 ){
          u32 i;
          int dist;
          closest = 0;
          dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby);
          for(i=1; i<k; i++){
            int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby);
................................................................................
        testcase( iPage==mxPage );
        if( !searchList || iPage==nearby ){
          int noContent;
          *pPgno = iPage;
          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
                 ": %d more free pages\n",
                 *pPgno, closest+1, k, pTrunk->pgno, n-1));


          if( closest<k-1 ){
            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
          }
          put4byte(&aData[4], k-1);
          assert( sqlite3PagerIswriteable(pTrunk->pDbPage) );
          noContent = !btreeGetHasContent(pBt, *pPgno);
          rc = btreeGetPage(pBt, *pPgno, ppPage, noContent);
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
            if( rc!=SQLITE_OK ){
              releasePage(*ppPage);
            }
................................................................................
      releasePage(*ppPage);
      return SQLITE_CORRUPT_BKPT;
    }
    (*ppPage)->isInit = 0;
  }else{
    *ppPage = 0;
  }

  return rc;
}

/*
** This function is used to add page iPage to the database file free-list. 
** It is assumed that the page is not already a part of the free-list.
**







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        rc = btreeGetPage(pBt, iTrunk, &pTrunk, 0);
      }
      if( rc ){
        pTrunk = 0;
        goto end_allocate_page;
      }

      k = get4byte(&pTrunk->aData[4]); /* # of leaves on this trunk page */
      if( k==0 && !searchList ){
        /* The trunk has no leaves and the list is not being searched. 
        ** So extract the trunk page itself and use it as the newly 
        ** allocated page */
        assert( pPrevTrunk==0 );
        rc = sqlite3PagerWrite(pTrunk->pDbPage);
        if( rc ){
................................................................................
        TRACE(("ALLOCATE: %d trunk - %d free pages left\n", *pPgno, n-1));
#endif
      }else if( k>0 ){
        /* Extract a leaf from the trunk */
        u32 closest;
        Pgno iPage;
        unsigned char *aData = pTrunk->aData;




        if( nearby>0 ){
          u32 i;
          int dist;
          closest = 0;
          dist = sqlite3AbsInt32(get4byte(&aData[8]) - nearby);
          for(i=1; i<k; i++){
            int d2 = sqlite3AbsInt32(get4byte(&aData[8+i*4]) - nearby);
................................................................................
        testcase( iPage==mxPage );
        if( !searchList || iPage==nearby ){
          int noContent;
          *pPgno = iPage;
          TRACE(("ALLOCATE: %d was leaf %d of %d on trunk %d"
                 ": %d more free pages\n",
                 *pPgno, closest+1, k, pTrunk->pgno, n-1));
          rc = sqlite3PagerWrite(pTrunk->pDbPage);
          if( rc ) goto end_allocate_page;
          if( closest<k-1 ){
            memcpy(&aData[8+closest*4], &aData[4+k*4], 4);
          }
          put4byte(&aData[4], k-1);

          noContent = !btreeGetHasContent(pBt, *pPgno);
          rc = btreeGetPage(pBt, *pPgno, ppPage, noContent);
          if( rc==SQLITE_OK ){
            rc = sqlite3PagerWrite((*ppPage)->pDbPage);
            if( rc!=SQLITE_OK ){
              releasePage(*ppPage);
            }
................................................................................
      releasePage(*ppPage);
      return SQLITE_CORRUPT_BKPT;
    }
    (*ppPage)->isInit = 0;
  }else{
    *ppPage = 0;
  }
  assert( rc!=SQLITE_OK || sqlite3PagerIswriteable((*ppPage)->pDbPage) );
  return rc;
}

/*
** This function is used to add page iPage to the database file free-list. 
** It is assumed that the page is not already a part of the free-list.
**