SQLite

/*
** 2003 April 6
**
** 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 contains code used to implement the PRAGMA command.
**
** $Id: pragma.c,v 1.140 2007/06/24 08:00:43 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>

/* Ignore this whole file if pragmas are disabled
*/

  ** Subverting this mechanism by using "PRAGMA schema_version" to modify
  ** the schema-version is potentially dangerous and may lead to program
  ** crashes or database corruption. Use with caution!
  **
  ** The user-version is not used internally by SQLite. It may be used by
  ** applications for any purpose.
  */
  if( sqlite3StrICmp(zLeft, "schema_version")==0 
   || sqlite3StrICmp(zLeft, "user_version")==0 
   || sqlite3StrICmp(zLeft, "freelist_count")==0 
  ){

    int iCookie;   /* Cookie index. 0 for schema-cookie, 6 for user-cookie. */
    switch( zLeft[0] ){
      case 's': case 'S':
        iCookie = 0;
        break;
      case 'f': case 'F':
        iCookie = 1;
        iDb = (-1*(iDb+1));
        assert(iDb<=0);
        break;
      default:
        iCookie = 5;
        break;
    }

    if( zRight && iDb>=0 ){
      /* Write the specified cookie value */
      static const VdbeOpList setCookie[] = {
        { OP_Transaction,    0,  1,  0},    /* 0 */
        { OP_Integer,        0,  0,  0},    /* 1 */
        { OP_SetCookie,      0,  0,  0},    /* 2 */
      };
      int addr = sqlite3VdbeAddOpList(v, ArraySize(setCookie), setCookie);

**
** 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 1.628 2007/06/24 08:00:43 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include "os.h"
#include <ctype.h>
#include <math.h>
#include "vdbeInt.h"

**
** There must be a read-lock on the database (either a transaction
** must be started or there must be an open cursor) before
** executing this instruction.
*/
case OP_ReadCookie: {
  int iMeta;
  int iDb = pOp->p1;
  int iCookie = pOp->p2;

  assert( pOp->p2<SQLITE_N_BTREE_META );
  if( iDb<0 ){
    iDb = (-1*(iDb+1));
    iCookie *= -1;
  }
  assert( iDb>=0 && iDb<db->nDb );
  assert( db->aDb[iDb].pBt!=0 );
  /* The indexing of meta values at the schema layer is off by one from
  ** the indexing in the btree layer.  The btree considers meta[0] to
  ** be the number of free pages in the database (a read-only value)
  ** and meta[1] to be the schema cookie.  The schema layer considers
  ** meta[1] to be the schema cookie.  So we have to shift the index
  ** by one in the following statement.
  */
  rc = sqlite3BtreeGetMeta(db->aDb[iDb].pBt, 1 + iCookie, (u32 *)&iMeta);
  pTos++;
  pTos->u.i = iMeta;
  pTos->flags = MEM_Int;
  break;
}

/* Opcode: SetCookie P1 P2 *

# 2002 March 6
#
# 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 PRAGMA command.
#
# $Id: pragma2.test,v 1.1 2007/06/24 08:00:44 danielk1977 Exp $

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

# Test organization:
#
# pragma2-1.*: Test freelist_count pragma on the main database.
# pragma2-2.*: Test freelist_count pragma on an attached database.
# pragma2-3.*: Test trying to write to the freelist_count is a no-op.
#

ifcapable !pragma {
  finish_test
  return
}

# Delete the preexisting database to avoid the special setup
# that the "all.test" script does.
#
db close
file delete test.db test.db-journal
file delete test3.db test3.db-journal
sqlite3 db test.db; set DB [sqlite3_connection_pointer db]

do_test pragma2-1.1 {
  execsql {
    PRAGMA freelist_count;
  }
} {0}
do_test pragma2-1.2 {
  execsql {
    CREATE TABLE abc(a, b, c);
    PRAGMA freelist_count;
  }
} {0}
do_test pragma2-1.3 {
  execsql {
    DROP TABLE abc;
    PRAGMA freelist_count;
  }
} {1}
do_test pragma2-1.4 {
  execsql {
    PRAGMA main.freelist_count;
  }
} {1}

file delete -force test2.db
file delete -force test2.db-journal

do_test pragma2-2.1 {
  execsql {
    ATTACH 'test2.db' AS aux;
    PRAGMA aux.freelist_count;
  }
} {0}
do_test pragma2-2.2 {
  execsql {
    CREATE TABLE aux.abc(a, b, c);
    PRAGMA aux.freelist_count;
  }
} {0}
do_test pragma2-2.3 {
  set ::val [string repeat 0123456789 1000]
  execsql {
    INSERT INTO aux.abc VALUES(1, 2, $::val);
    PRAGMA aux.freelist_count;
  }
} {0}
do_test pragma2-2.4 {
  expr {[file size test2.db] / 1024}
} {11}
do_test pragma2-2.5 {
  execsql {
    DELETE FROM aux.abc;
    PRAGMA aux.freelist_count;
  }
} {9}

do_test pragma2-3.1 {
  execsql {
    PRAGMA aux.freelist_count;
    PRAGMA main.freelist_count;
    PRAGMA freelist_count;
  }
} {9 1 1}
do_test pragma2-3.2 {
  execsql {
    PRAGMA freelist_count = 500;
    PRAGMA freelist_count;
  }
} {1 1}
do_test pragma2-3.3 {
  execsql {
    PRAGMA aux.freelist_count = 500;
    PRAGMA aux.freelist_count;
  }
} {9 9}

finish_test

#
# Run this Tcl script to generate the pragma.html file.
#
set rcsid {$Id: pragma.tcl,v 1.26 2007/06/24 08:00:44 danielk1977 Exp $}
source common.tcl
header {Pragma statements supported by SQLite}

proc Section {name {label {}}} {
  puts "\n<hr />"
  if {$label!=""} {
    puts "<a name=\"$label\"></a>"

<a name="pragma_foreign_key_list"></a>
<li><p><b>PRAGMA foreign_key_list(</b><i>table-name</i><b>);</b></p>
    <p>For each foreign key that references a column in the argument
    table, invoke the callback function with information about that
    foreign key. The callback function will be invoked once for each
    column in each foreign key.</p></li>

<a name="pragma_freelist_count"></a>
<li><p><b>PRAGMA [database].freelist_count;</b></p>
    <p>Return the number of unused pages in the database file. Running
    a <a href="#pragma_incremental_vacuum">"PRAGMA incremental_vaccum(N);"</a> 
    command with a large value of N will shrink the database file by this
    number of pages. </p></li>

<a name="pragma_index_info"></a>
<li><p><b>PRAGMA index_info(</b><i>index-name</i><b>);</b></p>
    <p>For each column that the named index references, invoke the 
    callback function
    once with information about that column, including the column name,
    and the column number.</p></li>