SQLite

** The pager is used to access a database disk file.  It implements
** atomic commit and rollback through the use of a journal file that
** is separate from the database file.  The pager also implements file
** locking to prevent two processes from writing the same database
** file simultaneously, or one process from reading the database while
** another is writing.
**
** @(#) $Id: pager.c,v 1.481 2008/08/26 21:07:27 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"

/*
** Macros for troubleshooting.  Normally turned off
*/

** value before returning.
*/
int sqlite3PagerSetPagesize(Pager *pPager, u16 *pPageSize){
  int rc = SQLITE_OK;
  u16 pageSize = *pPageSize;
  assert( pageSize==0 || (pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE) );
  if( pageSize && pageSize!=pPager->pageSize 
   && (pPager->memDb==0 || pPager->dbSize==0)
   && sqlite3PcacheRefCount(pPager->pPCache)==0 
  ){
    char *pNew = (char *)sqlite3PageMalloc(pageSize);
    if( !pNew ){
      rc = SQLITE_NOMEM;
    }else{
      pager_reset(pPager);
      pPager->pageSize = pageSize;
      if( !pPager->memDb ) setSectorSize(pPager);
      sqlite3PageFree(pPager->pTmpSpace);
      pPager->pTmpSpace = pNew;
      sqlite3PcacheSetPageSize(pPager->pPCache, pageSize);
    }
  }
  *pPageSize = pPager->pageSize;
  return rc;

}

/*
** Sync the pager file to disk.
*/
int sqlite3PagerSync(Pager *pPager){
  int rc;
  if( MEMDB ){
    rc = SQLITE_OK;
  }else{
    rc = sqlite3OsSync(pPager->fd, pPager->sync_flags);
  }
  return rc;
}

/*
** Sync the database file for the pager pPager. zMaster points to the name
** of a master journal file that should be written into the individual
** journal file. zMaster may be NULL, which is interpreted as no master

**
*************************************************************************
** This file contains code used to implement the VACUUM command.
**
** Most of the code in this file may be omitted by defining the
** SQLITE_OMIT_VACUUM macro.
**
** $Id: vacuum.c,v 1.83 2008/08/26 21:07:27 drh Exp $
*/
#include "sqliteInt.h"
#include "vdbeInt.h"

#if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
/*
** Execute zSql on database db. Return an error code.

/*
** This routine implements the OP_Vacuum opcode of the VDBE.
*/
int sqlite3RunVacuum(char **pzErrMsg, sqlite3 *db){
  int rc = SQLITE_OK;     /* Return code from service routines */
  Btree *pMain;           /* The database being vacuumed */
  Pager *pMainPager;      /* Pager for database being vacuumed */
  Btree *pTemp;           /* The temporary database we vacuum into */
  char *zSql = 0;         /* SQL statements */
  int saved_flags;        /* Saved value of the db->flags */
  int saved_nChange;      /* Saved value of db->nChange */
  int saved_nTotalChange; /* Saved value of db->nTotalChange */
  Db *pDb = 0;            /* Database to detach at end of vacuum */
  int isMemDb;            /* True is vacuuming a :memory: database */
  int nRes;

  /* Save the current value of the write-schema flag before setting it. */
  saved_flags = db->flags;
  saved_nChange = db->nChange;
  saved_nTotalChange = db->nTotalChange;
  db->flags |= SQLITE_WriteSchema | SQLITE_IgnoreChecks;

  if( !db->autoCommit ){
    sqlite3SetString(pzErrMsg, db, "cannot VACUUM from within a transaction");
    rc = SQLITE_ERROR;
    goto end_of_vacuum;
  }
  pMain = db->aDb[0].pBt;
  pMainPager = sqlite3BtreePager(pMain);
  isMemDb = sqlite3PagerFile(pMainPager)->pMethods==0;

  /* Attach the temporary database as 'vacuum_db'. The synchronous pragma
  ** can be set to 'off' for this file, as it is not recovered if a crash
  ** occurs anyway. The integrity of the database is maintained by a
  ** (possibly synchronous) transaction opened on the main database before
  ** sqlite3BtreeCopyFile() is called.
  **

    char *zKey;
    sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
    if( nKey ) db->nextPagesize = 0;
  }
#endif

  if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes)
   || (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes))
   || db->mallocFailed 
  ){
    rc = SQLITE_NOMEM;
    goto end_of_vacuum;
  }
  rc = execSql(db, "PRAGMA vacuum_db.synchronous=OFF");
  if( rc!=SQLITE_OK ){

# 2004 September 2
#
# 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.
# This file implements tests for the page_size PRAGMA.
#
# $Id: pagesize.test,v 1.13 2008/08/26 21:07:27 drh Exp $


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

# This test script depends entirely on "PRAGMA page_size". So if this
# pragma is not available, omit the whole file.

    }
  } 8192
}  
foreach PGSZ {512 2048 4096 8192} {
  if {[info exists SQLITE_MAX_PAGE_SIZE]
           && $SQLITE_MAX_PAGE_SIZE<$PGSZ} continue
  ifcapable memorydb {
    do_test pagesize-2.$PGSZ.0.1 {
      db close
      sqlite3 db :memory:
      execsql "PRAGMA page_size=$PGSZ;"
      execsql {PRAGMA page_size}
    } $PGSZ
    do_test pagesize-2.$PGSZ.0.2 {
      execsql {CREATE TABLE t1(x UNIQUE, y UNIQUE, z UNIQUE)}
      execsql {PRAGMA page_size}
    } $PGSZ
    do_test pagesize-2.$PGSZ.0.3 {
      execsql {
        INSERT INTO t1 VALUES(1,2,3);
        INSERT INTO t1 VALUES(2,3,4);
        SELECT * FROM t1;
      }
    } {1 2 3 2 3 4}
  }
  do_test pagesize-2.$PGSZ.1 {
    db close
    file delete -force test.db
    sqlite3 db test.db
    execsql "PRAGMA page_size=$PGSZ"
    execsql {

#    May you share freely, never taking more than you give.
#
#***********************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this file is changing the database page size using a 
# VACUUM statement.
#
# $Id: vacuum3.test,v 1.9 2008/08/26 21:07:27 drh Exp $

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

# If the VACUUM statement is disabled in the current build, skip all
# the tests in this file.
#

  execsql {
    PRAGMA page_size=1024;
    VACUUM;
  }
  execsql { SELECT * FROM abc } db2
} {1 2 3 4 5 6}

# Unable to change the page-size of an in-memory using vacuum.
db2 close
sqlite3 db2 :memory:
do_test vacuum3-5.1 {
  db2 eval {
    CREATE TABLE t1(x);
    INSERT INTO t1 VALUES(1234);
    PRAGMA page_size=4096;
    VACUUM;
    SELECT * FROM t1;
  }
} {1234}
do_test vacuum3-5.2 {
  db2 eval {
    PRAGMA page_size
  }
} {1024}

set create_database_sql {
  BEGIN; 
  CREATE TABLE t1(a, b, c); 
  INSERT INTO t1 VALUES(1, randstr(50,50), randstr(50,50)); 
  INSERT INTO t1 SELECT a+2, b||'-'||rowid, c||'-'||rowid FROM t1; 
  INSERT INTO t1 SELECT a+4, b||'-'||rowid, c||'-'||rowid FROM t1;