SQLite

/*
** 2004 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.
**
*************************************************************************
** $Id: btree.c,v 1.210 2004/11/05 15:45:10 danielk1977 Exp $
**
** This file implements a external (disk-based) database using BTrees.
** For a detailed discussion of BTrees, refer to
**
**     Donald E. Knuth, THE ART OF COMPUTER PROGRAMMING, Volume 3:
**     "Sorting And Searching", pages 473-480. Addison-Wesley
**     Publishing Company, Reading, Massachusetts.

  sqlite3pager_read_fileheader(pBt->pPager, sizeof(zDbHeader), zDbHeader);
  pBt->pageSize = get2byte(&zDbHeader[16]);
  if( pBt->pageSize<512 || pBt->pageSize>SQLITE_MAX_PAGE_SIZE ){
    pBt->pageSize = SQLITE_DEFAULT_PAGE_SIZE;
    pBt->maxEmbedFrac = 64;   /* 25% */
    pBt->minEmbedFrac = 32;   /* 12.5% */
    pBt->minLeafFrac = 32;    /* 12.5% */
    if( zFilename && strcmp(zFilename,":memory:") ){
      pBt->autoVacuum = SQLITE_DEFAULT_AUTOVACUUM;
    }
    nReserve = 0;
  }else{
    nReserve = zDbHeader[20];
    pBt->maxEmbedFrac = zDbHeader[21];
    pBt->minEmbedFrac = zDbHeader[22];
    pBt->minLeafFrac = zDbHeader[23];
    pBt->pageSizeFixed = 1;
#ifndef SQLITE_OMIT_AUTOVACUUM
    pBt->autoVacuum = (get4byte(&zDbHeader[36 + 4*4])?1:0);
#endif
  }
  pBt->usableSize = pBt->pageSize - nReserve;
  pBt->psAligned = FORCE_ALIGNMENT(pBt->pageSize);
  sqlite3pager_set_pagesize(pBt->pPager, pBt->pageSize);
  *ppBtree = pBt;






  return SQLITE_OK;
}

/*
** Close an open database and invalidate all cursors.
*/
int sqlite3BtreeClose(Btree *pBt){

*/
int sqlite3BtreeGetPageSize(Btree *pBt){
  return pBt->pageSize;
}
int sqlite3BtreeGetReserve(Btree *pBt){
  return pBt->pageSize - pBt->usableSize;
}

/*
** Change the 'auto-vacuum' property of the database. If the 'autoVacuum'
** parameter is non-zero, then auto-vacuum mode is enabled. If zero, it
** is disabled. The default value for the auto-vacuum property is 
** determined by the SQLITE_DEFAULT_AUTOVACUUM macro.
*/
int sqlite3BtreeSetAutoVacuum(Btree *pBt, int autoVacuum){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return SQLITE_READONLY
#else
  if( pBt->pageSizeFixed ){
    return SQLITE_READONLY;
  }
  pBt->autoVacuum = (autoVacuum?1:0);
  return SQLITE_OK;
#endif
}

/*
** Return the value of the 'auto-vacuum' property. If auto-vacuum is 
** enabled 1 is returned. Otherwise 0.
*/
int sqlite3BtreeGetAutoVacuum(Btree *pBt){
#ifdef SQLITE_OMIT_AUTOVACUUM
  return 0;
#else
  return pBt->autoVacuum;
#endif
}


/*
** Get a reference to pPage1 of the database file.  This will
** also acquire a readlock on that file.
**
** SQLITE_OK is returned on success.  If the file is not a
** well-formed database file, then SQLITE_CORRUPT is returned.

**    May you share freely, never taking more than you give.
**
*************************************************************************
** This header file defines the interface that the sqlite B-Tree file
** subsystem.  See comments in the source code for a detailed description
** of what each interface routine does.
**
** @(#) $Id: btree.h,v 1.60 2004/11/05 15:45:10 danielk1977 Exp $
*/
#ifndef _BTREE_H_
#define _BTREE_H_

/* TODO: This definition is just included so other modules compile. It
** needs to be revisited.
*/
#define SQLITE_N_BTREE_META 10

/*
** If defined as non-zero, auto-vacuum is enabled by default. Otherwise
** it must be turned on for each database using "PRAGMA auto_vacuum = 1".
*/
#ifndef SQLITE_DEFAULT_AUTOVACUUM
  #define SQLITE_DEFAULT_AUTOVACUUM 0
#endif

/*
** Forward declarations of structure
*/
typedef struct Btree Btree;
typedef struct BtCursor BtCursor;

int sqlite3BtreeClose(Btree*);
int sqlite3BtreeSetBusyHandler(Btree*,BusyHandler*);
int sqlite3BtreeSetCacheSize(Btree*,int);
int sqlite3BtreeSetSafetyLevel(Btree*,int);
int sqlite3BtreeSetPageSize(Btree*,int,int);
int sqlite3BtreeGetPageSize(Btree*);
int sqlite3BtreeGetReserve(Btree*);
int sqlite3BtreeSetAutoVacuum(Btree *, int);
int sqlite3BtreeGetAutoVacuum(Btree *);
int sqlite3BtreeBeginTrans(Btree*,int);
int sqlite3BtreeCommit(Btree*);
int sqlite3BtreeRollback(Btree*);
int sqlite3BtreeBeginStmt(Btree*);
int sqlite3BtreeCommitStmt(Btree*);
int sqlite3BtreeRollbackStmt(Btree*);
int sqlite3BtreeCreateTable(Btree*, int*, int flags);

/*
** 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 1.74 2004/11/05 15:45:11 danielk1977 Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>

#if defined(SQLITE_DEBUG) || defined(SQLITE_TEST)
# include "pager.h"
# include "btree.h"

      int size = pBt ? sqlite3BtreeGetPageSize(pBt) : 0;
      returnSingleInt(pParse, "page_size", size);
    }else{
      sqlite3BtreeSetPageSize(pBt, atoi(zRight), sqlite3BtreeGetReserve(pBt));
    }
  }else

  /*
  **  PRAGMA [database.]auto_vacuum
  **  PRAGMA [database.]auto_vacuum=N
  **
  ** Get or set the (boolean) value of the database 'auto-vacuum' parameter.
  */
#ifndef SQLITE_OMIT_AUTOVACUUM
  if( sqlite3StrICmp(zLeft,"auto_vacuum")==0 ){
    Btree *pBt = pDb->pBt;
    if( !zRight ){
      int auto_vacuum = 
          pBt ? sqlite3BtreeGetAutoVacuum(pBt) : SQLITE_DEFAULT_AUTOVACUUM;
      returnSingleInt(pParse, "auto_vacuum", auto_vacuum);
    }else{
      sqlite3BtreeSetAutoVacuum(pBt, getBoolean(zRight));
    }
  }else
#endif

  /*
  **  PRAGMA [database.]cache_size
  **  PRAGMA [database.]cache_size=N
  **
  ** The first form reports the current local setting for the
  ** page cache size.  The local setting can be different from
  ** the persistent cache size value that is stored in the database

# 2001 September 15
#
# 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 SELECT statement.
#
# $Id: autovacuum.test,v 1.9 2004/11/05 15:45:11 danielk1977 Exp $

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

# Return a string $len characters long. The returned string is $char repeated
# over and over. For example, [make_str abc 8] returns "abcabcab".
proc make_str {char len} {
  set str [string repeat $char. $len]
  return [string range $str 0 [expr $len-1]]
}

# Return the number of pages in the file test.db by looking at the file system.
proc file_pages {} {
  return [expr [file size test.db] / 1024]
}

#-------------------------------------------------------------------------
# Test cases autovacuum-1.* work as follows:
#
# 1. A table with a single indexed field is created.
# 2. Approximately 20 rows are inserted into the table. Each row is long 
#    enough such that it uses at least 2 overflow pages for both the table 
#    and index entry.
# 3. The rows are deleted in a psuedo-random order. Sometimes only one row

lappend delete_orders {{19 8 17 15} {16 11 9 14} {18 5 3 1} {13 20 7 2} {6 12}}

# The length of each table entry. 
set ENTRY_LEN 3500

do_test autovacuum-1.1 {
  execsql {
    PRAGMA auto_vacuum = 1;
    CREATE TABLE av1(a);
    CREATE INDEX av1_idx ON av1(a);
  }
} {}

set tn 0
foreach delete_order $delete_orders {

  # All rows have been deleted. Ensure the file has shrunk to 4 pages.
  do_test autovacuum-1.$tn.3 {
    file_pages
  } {4}
}

#---------------------------------------------------------------------------
# Tests cases autovacuum-2.* test that root pages are allocated 
# and deallocated correctly at the start of the file. Operation is roughly as
# follows:
#
# autovacuum-2.1.*: Drop the tables that currently exist in the database.
# autovacuum-2.2.*: Create some tables. Ensure that data pages can be
#                   moved correctly to make space for new root-pages.

  execsql BEGIN
  for {set i 3} {$i<=530} {incr i} {
    execsql "DROP TABLE av$i"
  }
  execsql COMMIT
  file_pages
} 1

#--------------------------------------------------------------------------
# Test cases autovacuum-3.* test the operation of the "PRAGMA auto_vacuum"
# command.
#
do_test autovacuum-3.1 {
  execsql {
    PRAGMA auto_vacuum;
  }
} {1}
do_test autovacuum-3.2 {
  db close
  sqlite3 db test.db
  execsql {
    PRAGMA auto_vacuum;
  }
} {1}
do_test autovacuum-3.3 {
  execsql {
    PRAGMA auto_vacuum = 0;
    PRAGMA auto_vacuum;
  }
} {1}

do_test autovacuum-3.4 {
  db close
  file delete -force test.db
  sqlite3 db test.db
  execsql {
    PRAGMA auto_vacuum;
  }
} {0}
do_test autovacuum-3.5 {
  execsql {
    CREATE TABLE av1(x);
    PRAGMA auto_vacuum;
  }
} {0}
do_test autovacuum-3.6 {
  execsql {
    PRAGMA auto_vacuum = 1;
    PRAGMA auto_vacuum;
  }
} {0}
do_test autovacuum-3.7 {
  execsql {
    DROP TABLE av1;
  }
  file_pages
} {2}

finish_test