SQLite

    int pageSize;
    int usableSize;
    u8 *page1 = pPage1->aData;
    rc = SQLITE_NOTADB;
    if( memcmp(page1, zMagicHeader, 16)!=0 ){
      goto page1_init_failed;
    }
    if( page1[18]>2 ){
      pBt->readOnly = 1;
    }
    if( page1[19]>2 ){
      goto page1_init_failed;
    }

    /* If the write version is set to 2, turn on write-ahead logging mode. */
    if( page1[19]==2 ){
      int isOpen = 0;
      rc = sqlite3PagerOpenLog(pBt->pPager, &isOpen);
      if( rc!=SQLITE_OK ){
        goto page1_init_failed;
      }else if( isOpen==0 ){
        releasePage(pPage1);
        return SQLITE_OK;
      }
    }

    /* The maximum embedded fraction must be exactly 25%.  And the minimum
    ** embedded fraction must be 12.5% for both leaf-data and non-leaf-data.
    ** The original design allowed these amounts to vary, but as of
    ** version 3.6.0, we require them to be fixed.
    */
    if( memcmp(&page1[21], "\100\040\040",3)!=0 ){

  assert( cursorHoldsMutex(pCur) );
  assert( sqlite3_mutex_held(pCur->pBtree->db->mutex) );
  assert(!pCur->isIncrblobHandle);
  assert(!pCur->aOverflow);
  pCur->isIncrblobHandle = 1;
}
#endif

/*
** Set both the "read version" (single byte at byte offset 18) and 
** "write version" (single byte at byte offset 19) fields in the database
** header to iVersion.
*/
int sqlite3BtreeSetVersion(Btree *pBtree, int iVersion){
  BtShared *pBt = pBtree->pBt;
  int rc;                         /* Return code */
 
  assert( pBtree->inTrans==TRANS_WRITE );
  assert( pBt->pPage1 );
  assert( iVersion==1 || iVersion==2 );

  rc = sqlite3PagerWrite(pBt->pPage1->pDbPage);
  if( rc==SQLITE_OK ){
    u8 *aData = pBt->pPage1->aData;
    aData[18] = (u8)iVersion;
    aData[19] = (u8)iVersion;
  }

  return rc;
}

char *sqlite3BtreeIntegrityCheck(Btree*, int *aRoot, int nRoot, int, int*);
struct Pager *sqlite3BtreePager(Btree*);

int sqlite3BtreePutData(BtCursor*, u32 offset, u32 amt, void*);
void sqlite3BtreeCacheOverflow(BtCursor *);
void sqlite3BtreeClearCursor(BtCursor *);

int sqlite3BtreeSetVersion(Btree *pBt, int iVersion);

#ifndef NDEBUG
int sqlite3BtreeCursorIsValid(BtCursor*);
#endif

#ifndef SQLITE_OMIT_BTREECOUNT
int sqlite3BtreeCount(BtCursor *, i64 *);

      pager_error(pPager, rc);
      pPager->journalOff = 0;
      pPager->journalStarted = 0;
    }else{
      /* This branch may be executed with Pager.journalMode==MEMORY if
      ** a hot-journal was just rolled back. In this case the journal
      ** file should be closed and deleted. If this connection writes to
      ** the database file, it will do so using an in-memory journal. 
      */
      assert( pPager->journalMode==PAGER_JOURNALMODE_DELETE 
           || pPager->journalMode==PAGER_JOURNALMODE_MEMORY 
           || pPager->journalMode==PAGER_JOURNALMODE_WAL 
      );
      sqlite3OsClose(pPager->jfd);
      if( !pPager->tempFile ){
        rc = sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
      }
    }

      }
    }
  }

  return rc;
}


















































/*
** This function is called to obtain a shared lock on the database file.
** It is illegal to call sqlite3PagerAcquire() until after this function
** has been successfully called. If a shared-lock is already held when
** this function is called, it is a no-op.
**

    if( isOpen(pPager->jfd) || pPager->zJournal ){
      isErrorReset = 1;
    }
    pPager->errCode = SQLITE_OK;
    pager_reset(pPager);
  }

  if( pagerUseLog(pPager) ){

    int changed = 0;              /* True if the cache must be flushed */







    /* Open a log snapshot to read from. */
    rc = sqlite3LogOpenSnapshot(pPager->pLog, &changed);
    if( rc==SQLITE_OK ){
      int dummy;
      if( changed ){
        pager_reset(pPager);
        assert( pPager->errCode || pPager->dbSizeValid==0 );
      }
      rc = sqlite3PagerPagecount(pPager, &dummy);
    }
    pPager->state = PAGER_SHARED;

  }else if( pPager->state==PAGER_UNLOCK || isErrorReset ){
    sqlite3_vfs * const pVfs = pPager->pVfs;
    int isHotJournal = 0;
    assert( !MEMDB );
    assert( sqlite3PcacheRefCount(pPager->pPCache)==0 );
    if( pPager->noReadlock ){
      assert( pPager->readOnly );

      }

      if( memcmp(pPager->dbFileVers, dbFileVers, sizeof(dbFileVers))!=0 ){
        pager_reset(pPager);
      }
    }
    assert( pPager->exclusiveMode || pPager->state==PAGER_SHARED );

    if( pPager->journalMode==PAGER_JOURNALMODE_WAL ){
      pPager->journalMode = PAGER_JOURNALMODE_DELETE;
    }
  }

 failed:
  if( rc!=SQLITE_OK ){
    /* pager_unlock() is a no-op for exclusive mode and in-memory databases. */
    pager_unlock(pPager);
  }

      ** The busy-handler is not invoked if another connection already
      ** holds the write-lock. If possible, the upper layer will call it.
      */
      rc = sqlite3LogWriteLock(pPager->pLog, 1);
      if( rc==SQLITE_OK ){
        pPager->dbOrigSize = pPager->dbSize;
        pPager->state = PAGER_RESERVED;
        pPager->journalOff = 0;
      }
    }else{
      /* Obtain a RESERVED lock on the database file. If the exFlag parameter
      ** is true, then immediately upgrade this to an EXCLUSIVE lock. The
      ** busy-handler callback can be used when upgrading to the EXCLUSIVE
      ** lock, but not when obtaining the RESERVED lock.
      */

    */
    rc = sqlite3PagerBegin(pPager, 0, pPager->subjInMemory);
    if( rc!=SQLITE_OK ){
      return rc;
    }
    if( !isOpen(pPager->jfd) 
     && pPager->journalMode!=PAGER_JOURNALMODE_OFF 
     && !pagerUseLog(pPager)
    ){
      assert( pPager->useJournal );
      rc = pager_open_journal(pPager);
      if( rc!=SQLITE_OK ) return rc;
    }
    pPager->dbModified = 1;
  

**    PAGER_JOURNALMODE_TRUNCATE
**    PAGER_JOURNALMODE_PERSIST
**    PAGER_JOURNALMODE_OFF
**    PAGER_JOURNALMODE_MEMORY
**    PAGER_JOURNALMODE_WAL
**
** If the parameter is not _QUERY, then the journal_mode is set to the
** value specified if the change is allowed. The change may be disallowed
** for the following reasons:
**
**   *  An in-memory database can only have its journal_mode set to _OFF
**      or _MEMORY.
**
**   *  The journal mode may not be changed while a transaction is active.
**
** The returned indicate the current (possibly updated) journal-mode.
*/
int sqlite3PagerJournalMode(Pager *pPager, int eMode){
  assert( eMode==PAGER_JOURNALMODE_QUERY
            || eMode==PAGER_JOURNALMODE_DELETE
            || eMode==PAGER_JOURNALMODE_TRUNCATE
            || eMode==PAGER_JOURNALMODE_PERSIST
            || eMode==PAGER_JOURNALMODE_OFF 
            || eMode==PAGER_JOURNALMODE_WAL 
            || eMode==PAGER_JOURNALMODE_MEMORY );
  assert( PAGER_JOURNALMODE_QUERY<0 );

  if( eMode==PAGER_JOURNALMODE_WAL 
   && pPager->journalMode==PAGER_JOURNALMODE_DELETE
  ){
    pPager->journalMode = PAGER_JOURNALMODE_WAL;
  }else if( eMode>=0
   && (pPager->tempFile==0 || eMode!=PAGER_JOURNALMODE_WAL)
   && (!MEMDB || eMode==PAGER_JOURNALMODE_MEMORY||eMode==PAGER_JOURNALMODE_OFF)
   && !pPager->dbModified
   && (!isOpen(pPager->jfd) || 0==pPager->journalOff)
  ){
    if( isOpen(pPager->jfd) ){
      sqlite3OsClose(pPager->jfd);
    }
    assert( (PAGER_JOURNALMODE_TRUNCATE & 1)==1 );
    assert( (PAGER_JOURNALMODE_PERSIST & 1)==1 );
    assert( (PAGER_JOURNALMODE_DELETE & 1)==0 );
    assert( (PAGER_JOURNALMODE_MEMORY & 1)==0 );
    assert( (PAGER_JOURNALMODE_OFF & 1)==0 );
    if( (pPager->journalMode & 1)==1 && (eMode & 1)==0
         && !pPager->exclusiveMode ){
      sqlite3OsDelete(pPager->pVfs, pPager->zJournal, 0);
    }








    pPager->journalMode = (u8)eMode;
  }
  return (int)pPager->journalMode;
}

/*
** Get/set the size-limit used for persistent journal files.

  }
  return rc;
}

int sqlite3PagerLogCallback(Pager *pPager){
  return sqlite3LogCallback(pPager->pLog);
}

/*
** Open a connection to the write-ahead log file for pager pPager. If
** the log connection is already open, this function is a no-op.
**
** The caller must be holding a SHARED lock on the database file to call
** this function.
*/
int sqlite3PagerOpenLog(Pager *pPager, int *pisOpen){
  int rc = SQLITE_OK;             /* Return code */

#ifdef SQLITE_DEBUG
  int locktype;
  sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_LOCKSTATE, &locktype);
  assert( locktype==SQLITE_LOCK_SHARED );
  assert( pPager->state>=PAGER_SHARED );
#endif

  if( !pPager->pLog ){

    /* Open the connection to the log file. If this operation fails, 
    ** (e.g. due to malloc() failure), unlock the database file and 
    ** return an error code.
    */
    rc = sqlite3LogOpen(pPager->pVfs, pPager->zFilename, &pPager->pLog);
    if( rc==SQLITE_OK ){
      pPager->journalMode = PAGER_JOURNALMODE_WAL;
    }
  }else{
    *pisOpen = 1;
  }

  return rc;
}


/*
** This function is called to close the connection to the log file prior
** to switching from WAL to rollback mode.
**
** Before closing the log file, this function attempts to take an 
** EXCLUSIVE lock on the database file. If this cannot be obtained, an
** error (SQLITE_BUSY) is returned and the log connection is not closed.
** If successful, the EXCLUSIVE lock is not released before returning.
*/
int sqlite3PagerCloseLog(Pager *pPager){
  int rc = SQLITE_OK;
  if( pPager->pLog ){

    /* Try to obtain an EXCLUSIVE lock on the database file. */
    rc = pager_wait_on_lock(pPager, EXCLUSIVE_LOCK);

    /* If the EXCLUSIVE lock was obtained, checkpoint and close the log. */
    if( rc==SQLITE_OK ){
      rc = sqlite3LogClose(pPager->pLog, pPager->fd,
        (pPager->noSync ? 0 : pPager->sync_flags), 
        (u8*)pPager->pTmpSpace
      );
      pPager->pLog = 0;
    }

    /* Make sure the EXCLUSIVE lock has not been lost somehow */
#ifdef SQLITE_DEBUG
    {
      int locktype;
      sqlite3OsFileControl(pPager->fd, SQLITE_FCNTL_LOCKSTATE, &locktype);
      assert( locktype==SQLITE_LOCK_EXCLUSIVE );
    }
#endif

  }
  return rc;
}

#endif /* SQLITE_OMIT_DISKIO */

int sqlite3PagerRollback(Pager*);
int sqlite3PagerOpenSavepoint(Pager *pPager, int n);
int sqlite3PagerSavepoint(Pager *pPager, int op, int iSavepoint);
int sqlite3PagerSharedLock(Pager *pPager);

int sqlite3PagerCheckpoint(Pager *pPager);
int sqlite3PagerLogCallback(Pager *pPager);
int sqlite3PagerOpenLog(Pager *pPager, int *pisOpen);
int sqlite3PagerCloseLog(Pager *pPager);

/* Functions used to query pager state and configuration. */
u8 sqlite3PagerIsreadonly(Pager*);
int sqlite3PagerRefcount(Pager*);
int sqlite3PagerMemUsed(Pager*);
const char *sqlite3PagerFilename(Pager*);
const sqlite3_vfs *sqlite3PagerVfs(Pager*);

    default:          zName = "NO ACTION";  
                      assert( action==OE_None ); break;
  }
  return zName;
}
#endif


/*
** Parameter eMode must be one of the PAGER_JOURNALMODE_XXX constants
** defined in pager.h. This function returns the associated lowercase
** journal-mode name.
*/
const char *sqlite3JournalModename(int eMode){
  static char * const azModeName[] = {
    "delete", "persist", "off", "truncate", "memory", "wal"
  };
  assert( PAGER_JOURNALMODE_DELETE==0 );
  assert( PAGER_JOURNALMODE_PERSIST==1 );
  assert( PAGER_JOURNALMODE_OFF==2 );
  assert( PAGER_JOURNALMODE_TRUNCATE==3 );
  assert( PAGER_JOURNALMODE_MEMORY==4 );
  assert( PAGER_JOURNALMODE_WAL==5 );
  assert( eMode>=0 && eMode<=ArraySize(azModeName) );

  if( eMode==ArraySize(azModeName) ) return 0;
  return azModeName[eMode];
}

/*
** Process a pragma statement.  
**
** Pragmas are of this form:
**
**      PRAGMA [database.]id [= value]
**

  }else

  /*
  **  PRAGMA [database.]journal_mode
  **  PRAGMA [database.]journal_mode = (delete|persist|off|truncate|memory)
  */
  if( sqlite3StrICmp(zLeft,"journal_mode")==0 ){
    int eMode;                    /* One of the PAGER_JOURNALMODE_XXX symbols */

    sqlite3VdbeSetNumCols(v, 1);

    sqlite3VdbeSetColName(v, 0, COLNAME_NAME, "journal_mode", SQLITE_STATIC);

    if( zRight==0 ){
      eMode = PAGER_JOURNALMODE_QUERY;
    }else{
      const char *zMode;
      int n = sqlite3Strlen30(zRight);

      for(eMode=0; (zMode = sqlite3JournalModename(eMode)); eMode++){
        if( sqlite3StrNICmp(zRight, zMode, n)==0 ) break;
      }
      if( !zMode ){
        eMode = PAGER_JOURNALMODE_QUERY;
      }
    }
    if( pId2->n==0 && eMode==PAGER_JOURNALMODE_QUERY ){
      /* Simple "PRAGMA journal_mode;" statement. This is a query for
      ** the current default journal mode (which may be different to
      ** the journal-mode of the main database).
      */
      eMode = db->dfltJournalMode;
      sqlite3VdbeAddOp2(v, OP_String8, 0, 1);
      sqlite3VdbeChangeP4(v, -1, sqlite3JournalModename(eMode), P4_STATIC);
    }else{
      int ii;

      if( pId2->n==0 && eMode!=PAGER_JOURNALMODE_WAL ){
        /* This indicates that no database name was specified as part
        ** of the PRAGMA command. In this case the journal-mode must be
        ** set on all attached databases, as well as the main db file.
        **
        ** Also, the sqlite3.dfltJournalMode variable is set so that
        ** any subsequently attached databases also use the specified
        ** journal mode. Except, the default journal mode is never set
        ** to WAL.
        */
        db->dfltJournalMode = (u8)eMode;
      }


      for(ii=db->nDb-1; ii>=0; ii--){
        if( db->aDb[ii].pBt && (ii==iDb || pId2->n==0) ){
          sqlite3VdbeUsesBtree(v, ii);
          sqlite3VdbeAddOp3(v, OP_JournalMode, ii, 1, eMode);
        }
      }

    }













    sqlite3VdbeAddOp2(v, OP_ResultRow, 1, 1);
  }else

  /*
  **  PRAGMA [database.]journal_size_limit
  **  PRAGMA [database.]journal_size_limit=N
  **

  if( sqlite3VdbeMemTooBig(pMem) ){
    goto too_big;
  }
  break;
}

/* Opcode: Checkpoint P1 * * * *
**
** Checkpoint database P1. This is a no-op if P1 is not currently in
** WAL mode.
*/
case OP_Checkpoint: {
  Btree *pBt;                     /* Btree to checkpoint */

  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );
  pBt = db->aDb[pOp->p1].pBt;
  rc = sqlite3PagerCheckpoint(sqlite3BtreePager(pBt));
  break;
};  

/* Opcode: JournalMode P1 P2 P3 * *
**
** Change the journal mode of database P1 to P3. P3 must be one of the
** PAGER_JOURNALMODE_XXX values. If changing between the various rollback
** modes (delete, truncate, persist, off and memory), this is a simple
** operation. No IO is required.
**
** If changing into or out of WAL mode the procedure is more complicated.
**
** Write a string containing the final journal-mode to register P2.
*/
case OP_JournalMode: {
  Btree *pBt;                     /* Btree to change journal mode of */
  Pager *pPager;                  /* Pager associated with pBt */
  int eNew = pOp->p3;             /* New journal mode */

  assert( eNew==PAGER_JOURNALMODE_DELETE 
       || eNew==PAGER_JOURNALMODE_TRUNCATE 
       || eNew==PAGER_JOURNALMODE_PERSIST 
       || eNew==PAGER_JOURNALMODE_OFF
       || eNew==PAGER_JOURNALMODE_MEMORY
       || eNew==PAGER_JOURNALMODE_WAL
       || eNew==PAGER_JOURNALMODE_QUERY
  );
  assert( pOp->p1>=0 && pOp->p1<db->nDb );
  assert( (p->btreeMask & (1<<pOp->p1))!=0 );

  pBt = db->aDb[pOp->p1].pBt;
  pPager = sqlite3BtreePager(pBt);

  if( eNew!=PAGER_JOURNALMODE_QUERY ){
    int eOld = sqlite3PagerJournalMode(pPager, PAGER_JOURNALMODE_QUERY);
    if( (eNew!=eOld)
     && (eOld==PAGER_JOURNALMODE_WAL || eNew==PAGER_JOURNALMODE_WAL)
    ){
      if( !db->autoCommit || db->activeVdbeCnt>1 ){
        rc = SQLITE_ERROR;
        sqlite3SetString(&p->zErrMsg, db, 
            "cannot change %s wal mode from within a transaction",
            (eNew==PAGER_JOURNALMODE_WAL ? "into" : "out of")
        );
      }else{
  
        /* If leaving WAL mode, close the log file. If successful, the call to
        ** PagerCloseLog() checkpoints and deletes the write-ahead-log file.
        ** An EXCLUSIVE lock is still held on the database file after returning.
        */
        if( eOld==PAGER_JOURNALMODE_WAL ){
          rc = sqlite3PagerCloseLog(pPager);
          if( rc!=SQLITE_OK ) goto abort_due_to_error;
          sqlite3PagerJournalMode(pPager, eNew);
        }else{
          sqlite3PagerJournalMode(pPager, PAGER_JOURNALMODE_DELETE);
        }
  
        /* Open a transaction on the database file. Regardless of the journal
        ** mode, this transaction always uses a rollback journal.
        */
        assert( sqlite3BtreeIsInTrans(pBt)==0 );
        rc = sqlite3BtreeBeginTrans(pBt, 2);
        assert( rc==SQLITE_OK || eOld!=PAGER_JOURNALMODE_WAL );
        if( rc!=SQLITE_OK ) goto abort_due_to_error;
        rc = sqlite3BtreeSetVersion(pBt, (eNew==PAGER_JOURNALMODE_WAL ? 2 : 1));
        if( rc!=SQLITE_OK ) goto abort_due_to_error;
      }
    }
  }

  eNew = sqlite3PagerJournalMode(pPager, eNew);
  pOut = &aMem[pOp->p2];
  pOut->flags = MEM_Str|MEM_Static|MEM_Term;
  pOut->z = sqlite3JournalModename(eNew);
  pOut->n = sqlite3Strlen30(pOut->z);
  pOut->enc = SQLITE_UTF8;
  sqlite3VdbeChangeEncoding(pOut, encoding);
  break;
};  

#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
/* Opcode: Vacuum * * * * *
**
** Vacuum the entire database.  This opcode will cause other virtual
** machines to be created and run.  It may not be called from within
** a transaction.

proc blob {nByte} {
  incr ::blobcnt
  return [string range [string repeat "${::blobcnt}x" $nByte] 1 $nByte]
}

proc sqlite3_wal {args} {
  eval sqlite3 $args
  [lindex $args 0] eval { PRAGMA page_size = 1024 }
  [lindex $args 0] eval { PRAGMA journal_mode = wal }
  [lindex $args 0] eval { PRAGMA synchronous = normal }
  [lindex $args 0] function blob blob
}

proc log_file_size {nFrame pgsz} {
  expr {12 + ($pgsz+16)*$nFrame}

# wal-6.*: Test creating databases with different page sizes.
#

do_test wal-0.1 {
  execsql { PRAGMA synchronous = normal }
  execsql { PRAGMA journal_mode = wal }
} {wal}
do_test wal-0.2 {
  file size test.db
} {1024}

do_test wal-1.0 {
  execsql { 
    BEGIN;
    CREATE TABLE t1(a, b); 
  }
  list [file exists test.db-journal] \
       [file exists test.db-wal]     \
       [file size test.db]
} {0 1 1024}
do_test wal-1.1 {
  execsql COMMIT
  list [file exists test.db-journal] [file exists test.db-wal]
} {0 1}
do_test wal-1.2 {
  # There are now two pages in the log.
  file size test.db-wal

db close

foreach sector {512 4096} {
  sqlite3_simulate_device -sectorsize $sector
  foreach pgsz {512 1024 2048 4096} {
    file delete -force test.db test.db-wal
    do_test wal-6.$sector.$pgsz.1 {
      sqlite3 db test.db -vfs devsym
      execsql "
        PRAGMA page_size = $pgsz;
        PRAGMA journal_mode = wal;
      "
      execsql "
        CREATE TABLE t1(a, b);
        INSERT INTO t1 VALUES(1, 2);
      "
      db close
      file size test.db

  sqlite3_wal db test.db
  execsql {
    PRAGMA page_size = 1024;
    CREATE TABLE t1(a, b);
    INSERT INTO t1 VALUES(1, 2);
  }
  list [file size test.db] [file size test.db-wal]
} [list 1024 [log_file_size 3 1024]]
do_test wal-7.2 {
  execsql { PRAGMA checkpoint }
  list [file size test.db] [file size test.db-wal]
} [list 2048 [log_file_size 3 1024]]

# Execute some transactions in auto-vacuum mode to test database file
# truncation.
#
do_test wal-8.1 {
  reopen_db
  catch { db close }
  file delete -force test.db test.db-wal

  sqlite3 db test.db
  db function blob blob
  execsql {
    PRAGMA auto_vacuum = 1;
    PRAGMA journal_mode = wal;
    PRAGMA auto_vacuum;
  }
} {wal 1}
do_test wal-8.2 {
  execsql {
    PRAGMA page_size = 1024;
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(blob(900));
    INSERT INTO t1 VALUES(blob(900));
    INSERT INTO t1 SELECT blob(900) FROM t1;       /*  4 */

# Run some "warm-body" tests to ensure that log-summary files with more
# than 256 entries (log summaries that contain index blocks) work Ok.
#
do_test wal-9.1 {
  reopen_db
  execsql {

    CREATE TABLE t1(x PRIMARY KEY);
    INSERT INTO t1 VALUES(blob(900));
    INSERT INTO t1 VALUES(blob(900));
    INSERT INTO t1 SELECT blob(900) FROM t1;       /*  4 */
    INSERT INTO t1 SELECT blob(900) FROM t1;       /*  8 */
    INSERT INTO t1 SELECT blob(900) FROM t1;       /* 16 */
    INSERT INTO t1 SELECT blob(900) FROM t1;       /* 32 */
    INSERT INTO t1 SELECT blob(900) FROM t1;       /* 64 */
    INSERT INTO t1 SELECT blob(900) FROM t1;       /* 128 */
    INSERT INTO t1 SELECT blob(900) FROM t1;       /* 256 */
  }
  file size test.db
} 1024
do_test wal-9.2 {
  sqlite3_wal db2 test.db
  execsql {PRAGMA integrity_check } db2
} {ok}

do_test wal-9.3 {
  file delete -force test2.db test2.db-wal

  reopen_db
  execsql {
    PRAGMA cache_size = 10;
    PRAGMA page_size = 1024;
    CREATE TABLE t1(x PRIMARY KEY);
  }
  list [expr [file size test.db]/1024] [expr [file size test.db-wal]/1044]
} {1 3}
do_test wal-11.2 {
  execsql { PRAGMA checkpoint }
  list [expr [file size test.db]/1024] [file size test.db-wal]
} [list 3 [log_file_size 3 1024]]
do_test wal-11.3 {
  execsql { INSERT INTO t1 VALUES( blob(900) ) }
  list [expr [file size test.db]/1024] [file size test.db-wal]

  execsql {
    PRAGMA cache_size = 10;
    BEGIN;
      INSERT INTO t1 SELECT blob(900) FROM t1;   -- 32
      SELECT count(*) FROM t1;
  }
  list [expr [file size test.db]/1024] [file size test.db-wal]
} [list 37 [log_file_size 37 1024]]
do_test wal-11.11 {
  execsql {
      SELECT count(*) FROM t1;
    ROLLBACK;
    SELECT count(*) FROM t1;
  }
} {32 16}
do_test wal-11.12 {
  list [expr [file size test.db]/1024] [file size test.db-wal]
} [list 37 [log_file_size 37 1024]]
do_test wal-11.13 {
  execsql {
    INSERT INTO t1 VALUES( blob(900) );
    SELECT count(*) FROM t1;
    PRAGMA integrity_check;
  }
} {17 ok}
do_test wal-11.14 {
  list [expr [file size test.db]/1024] [file size test.db-wal]
} [list 37 [log_file_size 37 1024]]


#-------------------------------------------------------------------------
# This block of tests, wal-12.*, tests the fix for a problem that 
# could occur if a log that is a prefix of an older log is written 
# into a reused log file.
#
reopen_db
do_test wal-12.1 {
  execsql {
    PRAGMA page_size = 1024;
    CREATE TABLE t1(x, y);
    CREATE TABLE t2(x, y);
    INSERT INTO t1 VALUES('A', 1);
  }
  list [expr [file size test.db]/1024] [file size test.db-wal]
} [list 1 [log_file_size 5 1024]]
do_test wal-12.2 {
  db close
  sqlite3 db test.db
  execsql {
    PRAGMA synchronous = normal;
    UPDATE t1 SET y = 0 WHERE x = 'A';
  }
  list [expr [file size test.db]/1024] [expr [file size test.db-wal]/1044]
} {3 1}
do_test wal-12.3 {
  execsql { INSERT INTO t2 VALUES('B', 1) }
  list [expr [file size test.db]/1024] [expr [file size test.db-wal]/1044]
} {3 2}

do_test wal-12.4 {
  file copy -force test.db test2.db
  file copy -force test.db-wal test2.db-wal
  sqlite3_wal db2 test2.db

  execsql { SELECT * FROM t2 } db2
} {B 1}
db2 close

file copy -force test.db-wal A
do_test wal-12.5 {
  execsql {

do_test wal-12.4 {
  file copy -force test.db test2.db
  file copy -force test.db-wal test2.db-wal
  sqlite3_wal db2 test2.db
  execsql { SELECT * FROM t2 } db2
} {B 2}
db2 close


finish_test

# 2010 April 19
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is testing the operation of the library in
# "PRAGMA journal_mode=WAL" mode.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl

do_test walmode-1.1 {
  execsql {
    PRAGMA journal_mode = wal;
  }
} {wal}

finish_test