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 1.21 2001/09/18 02:02:23 drh Exp $
*/
#include "sqliteInt.h"
#include "pager.h"
#include <fcntl.h>
#include <sys/stat.h>
#include <unistd.h>
#include <assert.h>

**
** If the number of references to the page drop to zero, then the
** page is added to the LRU list.  When all references to all pages
** are released, a rollback occurs and the lock on the database is
** removed.
*/
int sqlitepager_unref(void *pData){

  PgHdr *pPg;

  /* Decrement the reference count for this page
  */
  pPg = DATA_TO_PGHDR(pData);
  assert( pPg->nRef>0 );

  pPg->nRef--;
  REFINFO(pPg);

  /* When the number of references to a page reach 0, call the
  ** destructor and add the page to the freelist.
  */
  if( pPg->nRef==0 ){
    Pager *pPager;
    pPager = pPg->pPager;
    pPg->pNextFree = 0;
    pPg->pPrevFree = pPager->pLast;
    pPager->pLast = pPg;
    if( pPg->pPrevFree ){
      pPg->pPrevFree->pNextFree = pPg;
    }else{
      pPager->pFirst = pPg;

** type to the other occurs as necessary.
** 
** Most of the code in this file is taken up by the sqliteVdbeExec()
** function which does the work of interpreting a VDBE program.
** But other routines are also provided to help in building up
** a program instruction by instruction.
**
** $Id: vdbe.c,v 1.71 2001/09/18 02:02:23 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
#include <unistd.h>

/*
** SQL is translated into a sequence of instructions to be

      ux.zBuf[3] = x&0xff;
      ux.zBuf[2] = (x>>8)&0xff;
      ux.zBuf[1] = (x>>16)&0xff;
      ux.zBuf[0] = (x>>24)&0xff;
      v = ux.i;
      rx = sqliteBtreeMoveto(p->aCsr[i].pCursor, &v, sizeof(v), &res);
      cnt++;
    }while( cnt<200 && rx==SQLITE_OK && res==0 );
    if( rx==SQLITE_OK && res==0 ){
      rc = SQLITE_FULL;
      goto abort_due_to_error;
    }
  }
  VERIFY( NeedStack(p, p->tos+1); )
  p->tos++;
  aStack[p->tos].i = v;
  aStack[p->tos].flags = STK_Int;
  break;
}

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This module contains C code that generates VDBE code used to process
** the WHERE clause of SQL statements.  Also found here are subroutines
** to generate VDBE code to evaluate expressions.
**
** $Id: where.c,v 1.21 2001/09/18 02:02:23 drh Exp $
*/
#include "sqliteInt.h"

/*
** The query generator uses an array of instances of this structure to
** help it analyze the subexpressions of the WHERE clause.  Each WHERE
** clause subexpression is separated from the others by an AND operator.

          break;
        }
      }
      sqliteVdbeAddOp(v, OP_AddImm, 0, 0, 0, 0);
      if( i==pTabList->nId-1 && pushKey ){
        haveKey = 1;
      }else{
        sqliteVdbeAddOp(v, OP_NotFound, base+idx, brk, 0, 0);
        haveKey = 0;
      }
    }else if( pIdx==0 ){
      /* Case 2:  There was no usable index.  We must do a complete
      ** scan of the table.
      */
      sqliteVdbeAddOp(v, OP_Rewind, base+idx, 0, 0, 0);

#    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 magic ROWID column that is
# found on all tables.
#
# $Id: rowid.test,v 1.5 2001/09/18 02:02:23 drh Exp $

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

# Basic ROWID functionality tests.
#
do_test rowid-1.1 {

  execsql $sql
} {3}
do_test rowid-1.7 {
  global x2rowid
  set sql "SELECT x FROM t1 WHERE _rowid_==$x2rowid(1)"
  execsql $sql
} {1}
do_test rowid-1.7.1 {
  while 1 {
    set norow [expr {int(rand()*1000000)}]
    if {$norow!=$x2rowid(1) && $norow!=$x2rowid(3)} break
  }
  execsql "SELECT x FROM t1 WHERE rowid=$norow"
} {}
do_test rowid-1.8 {
  global x2rowid
  set v [execsql {SELECT x, oid FROM t1 order by x}]
  set v2 [list 1 $x2rowid(1) 3 $x2rowid(3)]
  expr {$v==$v2}
} {1}
do_test rowid-1.9 {

} {256}
do_test rowid-4.5 {
  execsql {CREATE INDEX idxt2 ON t2(y)}
  execsql {
    SELECT t1.x, fcnt() FROM t2, t1 
    WHERE t2.y==256 AND t1.rowid==t2.rowid
  }
} {4 1}
do_test rowid-4.5.1 {
  execsql {
    SELECT t1.x, fcnt() FROM t2, t1 
    WHERE t1.OID==t2.rowid AND t2.y==81
  }
} {3 1}
do_test rowid-4.6 {
  execsql {
    SELECT t1.x FROM t1, t2
    WHERE t2.y==256 AND t1.rowid==t2.rowid
  }
} {4}

do_test rowid-5.1 {
  execsql {DELETE FROM t1 WHERE _rowid_ IN (SELECT oid FROM t1 WHERE x>8)}
  execsql {SELECT max(x) FROM t1}
} {8}

finish_test