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Overview
Comment:Avoid unnecessarily reseting the pager cache after committing a transaction that takes advantage of the SQLITE_IOCAP_ATOMIC related optimization.
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SHA1: c47144e98c0a0f9e09780c945de10c57b6a495ea
User & Date: dan 2013-04-26 18:36:58
Context
2013-04-26
19:33
Fix a formatting typo in a comment. No changes to code. check-in: 7a97226f user: drh tags: trunk
18:36
Avoid unnecessarily reseting the pager cache after committing a transaction that takes advantage of the SQLITE_IOCAP_ATOMIC related optimization. check-in: c47144e9 user: dan tags: trunk
17:00
Avoid using posix_fallocate() in WAL mode, as it is not supported by all file-systems. check-in: 1bbb4be1 user: dan tags: trunk
Changes
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Changes to src/pager.c.

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        assert( pPager->dbFileSize>0 );
        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
        if( rc==SQLITE_OK ){
          rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
          pPager->aStat[PAGER_STAT_WRITE]++;
        }
        if( rc==SQLITE_OK ){





          pPager->changeCountDone = 1;
        }
      }else{
        pPager->changeCountDone = 1;
      }
    }








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        assert( pPager->dbFileSize>0 );
        CODEC2(pPager, pPgHdr->pData, 1, 6, rc=SQLITE_NOMEM, zBuf);
        if( rc==SQLITE_OK ){
          rc = sqlite3OsWrite(pPager->fd, zBuf, pPager->pageSize, 0);
          pPager->aStat[PAGER_STAT_WRITE]++;
        }
        if( rc==SQLITE_OK ){
          /* Update the pager's copy of the change-counter. Otherwise, the
          ** next time a read transaction is opened the cache will be
          ** flushed (as the change-counter values will not match).  */
          const void *pCopy = (const void *)&((const char *)zBuf)[24];
          memcpy(&pPager->dbFileVers, pCopy, sizeof(pPager->dbFileVers));
          pPager->changeCountDone = 1;
        }
      }else{
        pPager->changeCountDone = 1;
      }
    }

Changes to test/io.test.

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#           IOCAP_SAFE_APPEND device capability flag is set (fewer 
#           fsync() calls on the journal file, no need to set nRec
#           field in the single journal header).
#
# io-5.* -  Test that the default page size is selected and used 
#           correctly.
#           





set ::nWrite 0
proc nWrite {db} {
  set bt [btree_from_db $db]
  db_enter $db
  array set stats [btree_pager_stats $bt]
  db_leave $db
................................................................................
  do_test io-5.$tn {
    execsql {
      CREATE TABLE abc(a, b, c);
    }
    expr {[file size test.db]/2}
  } $pgsize
}






























































sqlite3_simulate_device -char {} -sectorsize 0
finish_test








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#           IOCAP_SAFE_APPEND device capability flag is set (fewer 
#           fsync() calls on the journal file, no need to set nRec
#           field in the single journal header).
#
# io-5.* -  Test that the default page size is selected and used 
#           correctly.
#
# io-6.* -  Test that the pager-cache is not being flushed unnecessarily 
#           after a transaction that uses the special atomic-write path
#           is committed.
#           

set ::nWrite 0
proc nWrite {db} {
  set bt [btree_from_db $db]
  db_enter $db
  array set stats [btree_pager_stats $bt]
  db_leave $db
................................................................................
  do_test io-5.$tn {
    execsql {
      CREATE TABLE abc(a, b, c);
    }
    expr {[file size test.db]/2}
  } $pgsize
}

#----------------------------------------------------------------------
#
do_test io-6.1 {
  db close
  sqlite3_simulate_device -char atomic
  forcedelete test.db
  sqlite3 db test.db -vfs devsym
  execsql {
    PRAGMA mmap_size = 0;
    PRAGMA page_size = 1024;
    CREATE TABLE t1(x);
    CREATE TABLE t2(x);
    CREATE TABLE t3(x);
    CREATE INDEX i3 ON t3(x);
    INSERT INTO t3 VALUES(randomblob(100));
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
    INSERT INTO t3 SELECT randomblob(100) FROM t3;
  }

  db_save_and_close
} {}

foreach {tn sql} {
  1 { BEGIN;
        INSERT INTO t1 VALUES('123');
        INSERT INTO t2 VALUES('456');
      COMMIT;
  }
  2 { BEGIN;
        INSERT INTO t1 VALUES('123');
      COMMIT;
  }
} {
  db_restore
  sqlite3 db test.db -vfs devsym
  execsql {
    PRAGMA mmap_size = 0;
    SELECT x FROM t3 ORDER BY rowid;
    SELECT x FROM t3 ORDER BY x;
  }
  do_execsql_test 6.2.$tn.1 { PRAGMA integrity_check } {ok}
  do_execsql_test 6.2.$tn.2 $sql

  # Corrupt the database file on disk. This should not matter for the
  # purposes of the following "PRAGMA integrity_check", as the entire
  # database should be cached in the pager-cache. If corruption is
  # reported, it indicates that executing $sql caused the pager cache
  # to be flushed. Which is a bug.
  hexio_write test.db [expr 1024 * 5] [string repeat 00 2048]
  do_execsql_test 6.2.$tn.3 { PRAGMA integrity_check } {ok}
}

sqlite3_simulate_device -char {} -sectorsize 0
finish_test