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 1.270 2006/06/28 18:18:09 drh Exp $
*/
#ifndef SQLITE_OMIT_DISKIO
#include "sqliteInt.h"
#include "os.h"
#include "pager.h"
#include <assert.h>
#include <string.h>

    /* Failure to rehash is not an error.  It is only a performance hit. */
    return;
  }
  sqliteFree(pPager->aHash);
  pPager->nHash = N;
  pPager->aHash = aHash;
  for(pPg=pPager->pAll; pPg; pPg=pPg->pNextAll){
    int h;
    if( pPg->pgno==0 ){
      assert( pPg->pNextHash==0 && pPg->pPrevHash==0 );
      continue;
    }
    h = pPg->pgno & (N-1);
    pPg->pNextHash = aHash[h];
    if( aHash[h] ){
      aHash[h]->pPrevHash = pPg;
    }
    aHash[h] = pPg;
    pPg->pPrevHash = 0;
  }

** Unlink pPg from it's hash chain. Also set the page number to 0 to indicate
** that the page is not part of any hash chain. This is required because the
** sqlite3pager_movepage() routine can leave a page in the 
** pNextFree/pPrevFree list that is not a part of any hash-chain.
*/
static void unlinkHashChain(Pager *pPager, PgHdr *pPg){
  if( pPg->pgno==0 ){
    assert( pPg->pNextHash==0 && pPg->pPrevHash==0 );
    return;
  }
  if( pPg->pNextHash ){
    pPg->pNextHash->pPrevHash = pPg->pPrevHash;
  }
  if( pPg->pPrevHash ){
    assert( pPager->aHash[pPg->pgno & (pPager->nHash-1)]!=pPg );
    pPg->pPrevHash->pNextHash = pPg->pNextHash;
  }else{
    int h = pPg->pgno & (pPager->nHash-1);

    pPager->aHash[h] = pPg->pNextHash;
  }
  if( MEMDB ){
    clearHistory(PGHDR_TO_HIST(pPg, pPager));
  }
  pPg->pgno = 0;
  pPg->pNextHash = pPg->pPrevHash = 0;

      }else{
        TEST_INCR(pPager->nRead);
      }
    }

    /* Link the page into the page hash table */
    h = pgno & (pPager->nHash-1);
    assert( pgno!=0 );
    pPg->pNextHash = pPager->aHash[h];
    pPager->aHash[h] = pPg;
    if( pPg->pNextHash ){
      assert( pPg->pNextHash->pPrevHash==0 );
      pPg->pNextHash->pPrevHash = pPg;
    }

      pPg->inJournal = 1;
      pPg->needSync = 1;
      assert( pPager->needSync );
    }
  }

  /* Change the page number for pPg and insert it into the new hash-chain. */
  assert( pgno!=0 );
  pPg->pgno = pgno;
  h = pgno & (pPager->nHash-1);
  if( pPager->aHash[h] ){
    assert( pPager->aHash[h]->pPrevHash==0 );
    pPager->aHash[h]->pPrevHash = pPg;
  }
  pPg->pNextHash = pPager->aHash[h];

**
** Various scripts scan this source file in order to generate HTML
** documentation, headers files, or other derived files.  The formatting
** of the code in this file is, therefore, important.  See other comments
** in this file for details.  If in doubt, do not deviate from existing
** commenting and indentation practices when changing or adding code.
**
** $Id: vdbe.c,v 1.570 2006/06/28 18:18:09 drh Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include "vdbeInt.h"

/*

** then a zero is pushed onto the stack.
**
** See also: Clear
*/
case OP_Destroy: {
  int iMoved;
  Vdbe *pVdbe;
  int iCnt;
#ifndef SQLITE_OMIT_VIRTUALTABLE
  iCnt = 0;
  for(pVdbe=db->pVdbe; pVdbe; pVdbe=pVdbe->pNext){
    if( pVdbe->magic==VDBE_MAGIC_RUN && pVdbe->inVtabMethod<2 && pVdbe->pc>=0 ){
      iCnt++;
    }
  }
#else
  iCnt = db->activeVdbeCnt;
#endif
  if( iCnt>1 ){
    rc = SQLITE_LOCKED;
  }else{
    assert( iCnt==1 );
    rc = sqlite3BtreeDropTable(db->aDb[pOp->p2].pBt, pOp->p1, &iMoved);
    pTos++;
    pTos->flags = MEM_Int;
    pTos->i = iMoved;
#ifndef SQLITE_OMIT_AUTOVACUUM
    if( rc==SQLITE_OK && iMoved!=0 ){
      sqlite3RootPageMoved(&db->aDb[pOp->p2], iMoved, pOp->p1);
    }
#endif
  }
  break;
}

/* Opcode: Clear P1 P2 *
**
** Delete all contents of the database table or index whose root page

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

ifcapable legacyformat {
  finish_test
  return
}

# The size of the database depends on whether or not autovacuum
# is enabled.
#
if {[db one {PRAGMA auto_vacuum}]} {
  set small 3072
  set large 5120
} else {
  set small 2048
  set large 4096
}

do_test format4-1.1 {
  execsql {
    CREATE TABLE t1(x0,x1,x2,x3,x4,x5,x6,x7,x8,x9);
    INSERT INTO t1 VALUES(0,0,0,0,0,0,0,0,0,0);
    INSERT INTO t1 SELECT * FROM t1;
    INSERT INTO t1 SELECT * FROM t1;
    INSERT INTO t1 SELECT * FROM t1;
    INSERT INTO t1 SELECT * FROM t1;
    INSERT INTO t1 SELECT * FROM t1;
    INSERT INTO t1 SELECT * FROM t1;
  }
  file size test.db
} $small
do_test format4-1.2 {
  execsql {
    UPDATE t1 SET x0=1, x1=1, x2=1, x3=1, x4=1, x5=1, x6=1, x7=1, x8=1, x9=1
  }
  file size test.db
} $small
do_test format4-1.3 {
  execsql {
    UPDATE t1 SET x0=2, x1=2, x2=2, x3=2, x4=2, x5=2, x6=2, x7=2, x8=2, x9=2
  }
  file size test.db
} $large


finish_test

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

ifcapable !vacuum {
  finish_test
  return
}
if {[db one {PRAGMA auto_vacuum}]} {
  finish_test
  return
}

do_test tkt1512-1.1 {
  execsql {
    CREATE TABLE t1(a,b);
    INSERT INTO t1 VALUES(1,2);
    INSERT INTO t1 VALUES(3,4);

#***********************************************************************
# This file implements regression tests for SQLite library.
#
# This file implements tests for joins, including outer joins involving
# virtual tables. The test cases in this file are copied from the file
# join.test, and some of the comments still reflect that.
#
# $Id: vtab6.test,v 1.2 2006/06/28 18:18:10 drh Exp $

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

ifcapable !vtab {
  finish_test
  return
}

register_echo_module [sqlite3_connection_pointer db]

execsql {
  CREATE TABLE real_t1(a,b,c);
  CREATE TABLE real_t2(b,c,d);
  CREATE TABLE real_t3(c,d,e);