Index: src/btree.c
==================================================================
--- src/btree.c
+++ src/btree.c
@@ -7,11 +7,11 @@
 **    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 1.588 2009/04/02 18:28:08 danielk1977 Exp $
+** $Id: btree.c,v 1.589 2009/04/02 20:16:59 drh Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** See the header comment on "btreeInt.h" for additional information.
 ** Including a description of file format and an overview of operation.
 */
@@ -1755,10 +1755,12 @@
 }
 
 #if !defined(SQLITE_OMIT_PAGER_PRAGMAS) || !defined(SQLITE_OMIT_VACUUM)
 /*
 ** Change the default pages size and the number of reserved bytes per page.
+** Or, if the page size has already been fixed, return SQLITE_READONLY 
+** without changing anything.
 **
 ** 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.
 **
@@ -1767,12 +1769,15 @@
 ** the first byte past the 1GB boundary, 0x40000000) needs to occur
 ** at the beginning of a page.
 **
 ** If parameter nReserve is less than zero, then the number of reserved
 ** bytes per page is left unchanged.
+**
+** If the iFix!=0 then the pageSizeFixed flag is set so that the page size
+** and autovacuum mode can no longer be changed.
 */
-int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve){
+int sqlite3BtreeSetPageSize(Btree *p, int pageSize, int nReserve, int iFix){
   int rc = SQLITE_OK;
   BtShared *pBt = p->pBt;
   assert( nReserve>=-1 && nReserve<=255 );
   sqlite3BtreeEnter(p);
   if( pBt->pageSizeFixed ){
@@ -1790,10 +1795,11 @@
     pBt->pageSize = (u16)pageSize;
     freeTempSpace(pBt);
     rc = sqlite3PagerSetPagesize(pBt->pPager, &pBt->pageSize);
   }
   pBt->usableSize = pBt->pageSize - (u16)nReserve;
+  if( iFix ) pBt->pageSizeFixed = 1;
   sqlite3BtreeLeave(p);
   return rc;
 }
 
 /*

Index: src/btree.h
==================================================================
--- src/btree.h
+++ src/btree.h
@@ -11,11 +11,11 @@
 *************************************************************************
 ** 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 1.111 2009/03/18 10:33:01 danielk1977 Exp $
+** @(#) $Id: btree.h,v 1.112 2009/04/02 20:16:59 drh Exp $
 */
 #ifndef _BTREE_H_
 #define _BTREE_H_
 
 /* TODO: This definition is just included so other modules compile. It
@@ -78,11 +78,11 @@
 
 int sqlite3BtreeClose(Btree*);
 int sqlite3BtreeSetCacheSize(Btree*,int);
 int sqlite3BtreeSetSafetyLevel(Btree*,int,int);
 int sqlite3BtreeSyncDisabled(Btree*);
-int sqlite3BtreeSetPageSize(Btree*,int,int);
+int sqlite3BtreeSetPageSize(Btree*,int,int,int);
 int sqlite3BtreeGetPageSize(Btree*);
 int sqlite3BtreeMaxPageCount(Btree*,int);
 int sqlite3BtreeGetReserve(Btree*);
 int sqlite3BtreeSetAutoVacuum(Btree *, int);
 int sqlite3BtreeGetAutoVacuum(Btree *);

Index: src/pragma.c
==================================================================
--- src/pragma.c
+++ src/pragma.c
@@ -9,11 +9,11 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
 ** This file contains code used to implement the PRAGMA command.
 **
-** $Id: pragma.c,v 1.204 2009/02/23 16:52:08 drh Exp $
+** $Id: pragma.c,v 1.205 2009/04/02 20:16:59 drh Exp $
 */
 #include "sqliteInt.h"
 
 /* Ignore this whole file if pragmas are disabled
 */
@@ -367,11 +367,11 @@
     }else{
       /* Malloc may fail when setting the page-size, as there is an internal
       ** buffer that the pager module resizes using sqlite3_realloc().
       */
       db->nextPagesize = atoi(zRight);
-      if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize, -1) ){
+      if( SQLITE_NOMEM==sqlite3BtreeSetPageSize(pBt, db->nextPagesize, -1, 0) ){
         db->mallocFailed = 1;
       }
     }
   }else
 

Index: src/vacuum.c
==================================================================
--- src/vacuum.c
+++ src/vacuum.c
@@ -12,11 +12,11 @@
 ** This file contains code used to implement the VACUUM command.
 **
 ** Most of the code in this file may be omitted by defining the
 ** SQLITE_OMIT_VACUUM macro.
 **
-** $Id: vacuum.c,v 1.86 2009/02/03 16:51:25 danielk1977 Exp $
+** $Id: vacuum.c,v 1.87 2009/04/02 20:16:59 drh Exp $
 */
 #include "sqliteInt.h"
 #include "vdbeInt.h"
 
 #if !defined(SQLITE_OMIT_VACUUM) && !defined(SQLITE_OMIT_ATTACH)
@@ -138,12 +138,12 @@
     sqlite3CodecGetKey(db, 0, (void**)&zKey, &nKey);
     if( nKey ) db->nextPagesize = 0;
   }
 #endif
 
-  if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes)
-   || (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes))
+  if( sqlite3BtreeSetPageSize(pTemp, sqlite3BtreeGetPageSize(pMain), nRes, 0)
+   || (!isMemDb && sqlite3BtreeSetPageSize(pTemp, db->nextPagesize, nRes, 0))
    || db->mallocFailed 
   ){
     rc = SQLITE_NOMEM;
     goto end_of_vacuum;
   }
@@ -266,11 +266,11 @@
     sqlite3BtreeSetAutoVacuum(pMain, sqlite3BtreeGetAutoVacuum(pTemp));
 #endif
   }
 
   if( rc==SQLITE_OK ){
-    rc = sqlite3BtreeSetPageSize(pMain, sqlite3BtreeGetPageSize(pTemp), nRes);
+    rc = sqlite3BtreeSetPageSize(pMain, sqlite3BtreeGetPageSize(pTemp), nRes,1);
   }
 
 end_of_vacuum:
   /* Restore the original value of db->flags */
   db->flags = saved_flags;