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 1.197 2004/11/02 14:24:34 drh 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.

int sqlite3BtreeSetSafetyLevel(Btree *pBt, int level){
  sqlite3pager_set_safety_level(pBt->pPager, level);
  return SQLITE_OK;
}

/*
** Change the default pages size and the number of reserved bytes per page.
**
** The page size must be a power of 2 between 512 and 65536.  If the page
** size supplied does not meet this constraint then the page size is not
** changed.
**
** Page sizes are constrained to be a power of two so that the region
** of the database file used for locking (beginning at PENDING_BYTE,
** the first byte past the 1GB boundary, 0x40000000) needs to occur
** at the beginning of a page.
*/
int sqlite3BtreeSetPageSize(Btree *pBt, int pageSize, int nReserve){
  if( pBt->pageSizeFixed ){
    return SQLITE_READONLY;
  }
  if( nReserve<0 ){
    nReserve = pBt->pageSize - pBt->usableSize;
  }
  if( pageSize>=512 && pageSize<=SQLITE_MAX_PAGE_SIZE &&
        ((pageSize-1)&pageSize)==0 ){
    pBt->pageSize = pageSize;
    pBt->psAligned = FORCE_ALIGNMENT(pageSize);
    sqlite3pager_set_pagesize(pBt->pPager, pageSize);
  }
  pBt->usableSize = pBt->pageSize - nReserve;
  return 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 1.5 2004/11/02 14:24:35 drh Exp $


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

do_test pagesize-1.1 {
  execsql {PRAGMA page_size}

} 8192
do_test pagesize-1.7 {
  execsql {
    PRAGMA page_size=65537;
    PRAGMA page_size;
  }
} 8192
do_test pagesize-1.8 {
  execsql {
    PRAGMA page_size=1234;
    PRAGMA page_size
  }
} 8192

foreach PGSZ {512 2048 4096 8192} {
  do_test pagesize-2.$PGSZ.1 {
    db close
    file delete -force test.db
    sqlite3 db test.db
    execsql "PRAGMA page_size=$PGSZ"
    execsql {
      CREATE TABLE t1(x);