diff --git a/manifest b/manifest
index b03446390d..32b602d228 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C Website\schanges\sfor\sversion\s2.8.14.\s(CVS\s1553)
-D 2004-06-09T23:15:22
+C Check\sfor\sschema\supdates\sif\sthe\sparser\sfails\sto\sfind\sa\stable.\s\sMore\slocking\ntest\supdates.\s(CVS\s1555)
+D 2004-06-10T00:29:09
 F Makefile.in ab7b0d5118e2da97bac66be8684a1034e3500f5a
 F Makefile.linux-gcc a9e5a0d309fa7c38e7c14d3ecf7690879d3a5457
 F README f1de682fbbd94899d50aca13d387d1b3fd3be2dd
@@ -27,7 +27,7 @@ F src/attach.c 93b8ecec4a8d7b4e9f2479e2327d90c9d01765e8
 F src/auth.c 5c2f0bea4729c98c2be3b69d6b466fc51448fe79
 F src/btree.c 281af87aa117de024f5b6c2728a2339cba9ef584
 F src/btree.h 589427ac13bb544d298cd99726e2572a6fe4bdaa
-F src/build.c 4ea78aba171f02b96254dd7a312e4266d3693bfe
+F src/build.c 9ee417777c8d1be293773482c28adbf5cd59981b
 F src/date.c 8e6fa3173386fb29fdef012ee08a853c1e9908b2
 F src/delete.c b30f08250c9ed53a25a13c7c04599c1e8753992d
 F src/encode.c a876af473d1d636faa3dca51c7571f2e007eea37
@@ -37,7 +37,7 @@ F src/hash.c 440c2f8cb373ee1b4e13a0988489c7cd95d55b6f
 F src/hash.h 762d95f1e567664d1eafc1687de755626be962fb
 F src/insert.c 4268d9e3959cc845ea243fb4ec7507269404dad9
 F src/legacy.c ad23746f15f67e34577621b1875f639c94839e1f
-F src/main.c 3df17ac486ff1772af8b537cf0bbd0aabba6e863
+F src/main.c 185b7bbac8bbc341b7b6028625c569a651a7fdd6
 F src/md5.c 4302e84ae516c616bb079c4e6d038c0addb33481
 F src/os.h 23c69c5084e71b5fe199ff1c4e35a4aded0f1380
 F src/os_common.h 6393ac67a3a7b4aea19ff17529980ecf77eb2348
@@ -56,7 +56,7 @@ F src/random.c eff68e3f257e05e81eae6c4d50a51eb88beb4ff3
 F src/select.c 1f8355e702f109f6771f82a9bfe7aac4c82cbaf2
 F src/shell.c ca519519dcbbc582f6d88f7d0e7583b857fd3469
 F src/sqlite.h.in 6ad05abc7fd72da74691e1eb45f0eff4117eba4e
-F src/sqliteInt.h f384e81fa635b6323aa6297011d9dc2d976868fb
+F src/sqliteInt.h 52b73ec6ebd5fe342cc15007771c63ccaf767cbe
 F src/table.c af14284fa36c8d41f6829e3f2819dce07d3e2de2
 F src/tclsqlite.c f5c5116720baefb7de5d6acf18baedf1e42756cc
 F src/test1.c f78d6ac0675bc5db48dac9c5379c965bdadb9113
@@ -119,7 +119,7 @@ F test/join2.test c97e4c5aa65dea462145529e58212a709b4722b8
 F test/lastinsert.test 31382f88b9b0270333ac9e4a17f2c2f4732da718
 F test/laststmtchanges.test cabd11bdfbaf73a4486c50b58297d9c2038ccc18
 F test/limit.test 60d7f856ee7846f7130dee67f10f0e726cd70b5d
-F test/lock.test bf3beb32eb792dd328c499c57b81a7fc15024d53
+F test/lock.test 65b98e8812489e157a2bd51fb44c520f6bc76e32
 F test/main.test 6a851b5992c4881a725a3d9647e629199df8de9d
 F test/malloc.test 4e19b96d9cd7d61f4826e6fce03849ad5ad526dd
 F test/memdb.test befe8f26d430d07ba65692243a893a0e82a0b866
@@ -218,7 +218,7 @@ F www/support.tcl 1801397edd271cc39a2aadd54e701184b5181248
 F www/tclsqlite.tcl 19191cf2a1010eaeff74c51d83fd5f5a4d899075
 F www/vdbe.tcl 59288db1ac5c0616296b26dce071c36cb611dfe9
 F www/whentouse.tcl a8335bce47cc2fddb07f19052cb0cb4d9129a8e4
-P 39b4ba95c4a16b28b5e8c7a3331e09cb5796e258
-R 44b229b6f9f8c0c03939e9b1fc2349f9
+P 73afa14a04e8aa22de71aac7d08abc0ec68dc327
+R 4a457b2bb951374d999015f4602a5043
 U drh
-Z 46184513a3c8accdddcddf8998ee3516
+Z 0642bdc31cc4198c64ee7082ebf04a73
diff --git a/manifest.uuid b/manifest.uuid
index 390537de40..ff03c08d75 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-73afa14a04e8aa22de71aac7d08abc0ec68dc327
\ No newline at end of file
+a22283512afe2df09d5783d189fbd7389ed313ad
\ No newline at end of file
diff --git a/src/build.c b/src/build.c
index 25cbb93fb5..afb1fb47e9 100644
--- a/src/build.c
+++ b/src/build.c
@@ -23,7 +23,7 @@
 **     ROLLBACK
 **     PRAGMA
 **
-** $Id: build.c,v 1.212 2004/06/09 12:30:05 danielk1977 Exp $
+** $Id: build.c,v 1.213 2004/06/10 00:29:09 drh Exp $
 */
 #include "sqliteInt.h"
 #include <ctype.h>
@@ -164,6 +164,7 @@ Table *sqlite3LocateTable(Parse *pParse, const char *zName, const char *zDbase){
     }else{
       sqlite3ErrorMsg(pParse, "no such table: %s", zName);
     }
+    pParse->checkSchema = 1;
   }
   return p;
 }
@@ -1385,6 +1386,7 @@ Table *sqlite3TableFromToken(Parse *pParse, Token *pTok){
   sqliteFree(zName);
   if( pTab==0 ){
     sqlite3ErrorMsg(pParse, "no such table: %T", pTok);
+    pParse->checkSchema = 1;
   }
   return pTab;
 }
@@ -1985,6 +1987,7 @@ void sqlite3DropIndex(Parse *pParse, SrcList *pName){
   pIndex = sqlite3FindIndex(db, pName->a[0].zName, pName->a[0].zDatabase);
   if( pIndex==0 ){
     sqlite3ErrorMsg(pParse, "no such index: %S", pName, 0);
+    pParse->checkSchema = 1;
     goto exit_drop_index;
   }
   if( pIndex->autoIndex ){
diff --git a/src/main.c b/src/main.c
index 53b5c4472a..2e15479d12 100644
--- a/src/main.c
+++ b/src/main.c
@@ -14,7 +14,7 @@
 ** other files are for internal use by SQLite and should not be
 ** accessed by users of the library.
 **
-** $Id: main.c,v 1.210 2004/06/09 20:03:09 drh Exp $
+** $Id: main.c,v 1.211 2004/06/10 00:29:09 drh Exp $
 */
 #include "sqliteInt.h"
 #include "os.h"
@@ -855,6 +855,34 @@ int sqlite3_errcode(sqlite3 *db){
   return db->errCode;
 }
 
+/*
+** Check schema cookies in all databases except TEMP.  If any cookie is out
+** of date, return 0.  If all schema cookies are current, return 1.
+*/
+static int schemaIsValid(sqlite *db){
+  int iDb;
+  int rc;
+  BtCursor *curTemp;
+  int cookie;
+  int allOk = 1;
+
+  for(iDb=0; allOk && iDb<db->nDb; iDb++){
+    Btree *pBt;
+    if( iDb==1 ) continue;
+    pBt = db->aDb[iDb].pBt;
+    if( pBt==0 ) continue;
+    rc = sqlite3BtreeCursor(pBt, MASTER_ROOT, 0, 0, 0, &curTemp);
+    if( rc==SQLITE_OK ){
+      rc = sqlite3BtreeGetMeta(pBt, 1, &cookie);
+      if( rc==SQLITE_OK && cookie!=db->aDb[iDb].schema_cookie ){
+        allOk = 0;
+      }
+      sqlite3BtreeCloseCursor(curTemp);
+    }
+  }
+  return allOk;
+}
+
 /*
 ** Compile the UTF-8 encoded SQL statement zSql into a statement handle.
 */
@@ -911,6 +939,9 @@ int sqlite3_prepare(
     goto prepare_out;
   }
   if( sParse.rc==SQLITE_DONE ) sParse.rc = SQLITE_OK;
+  if( sParse.checkSchema && !schemaIsValid(db) ){
+    sParse.rc = SQLITE_SCHEMA;
+  }
   if( sParse.rc==SQLITE_SCHEMA ){
     sqlite3ResetInternalSchema(db, 0);
   }
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index 61998e9e3d..18fa040718 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -11,7 +11,7 @@
 *************************************************************************
 ** Internal interface definitions for SQLite.
 **
-** @(#) $Id: sqliteInt.h,v 1.276 2004/06/09 20:03:09 drh Exp $
+** @(#) $Id: sqliteInt.h,v 1.277 2004/06/10 00:29:10 drh Exp $
 */
 #include "config.h"
 #include "sqlite3.h"
@@ -1010,6 +1010,7 @@ struct Parse {
   u8 nameClash;        /* A permanent table name clashes with temp table name */
   u8 useAgg;           /* If true, extract field values from the aggregator
                        ** while generating expressions.  Normally false */
+  u8 checkSchema;      /* Causes schema cookie check after an error */
   int nErr;            /* Number of errors seen */
   int nTab;            /* Number of previously allocated VDBE cursors */
   int nMem;            /* Number of memory cells used so far */
diff --git a/test/lock.test b/test/lock.test
index b135e8a0f1..4e7d48fa3c 100644
--- a/test/lock.test
+++ b/test/lock.test
@@ -11,7 +11,7 @@
 # This file implements regression tests for SQLite library.  The
 # focus of this script is database locks.
 #
-# $Id: lock.test,v 1.22 2004/06/09 23:15:22 drh Exp $
+# $Id: lock.test,v 1.23 2004/06/10 00:29:12 drh Exp $
 
 
 set testdir [file dirname $argv0]
@@ -47,7 +47,6 @@ do_test lock-1.7.1 {
   catchsql {SELECT * FROM t1} db2
 } {1 {no such table: t1}}
 do_test lock-1.7.2 {
-  execsql {SELECT * FROM sqlite_master LIMIT 1} db2
   catchsql {SELECT * FROM t1} db2
 } {0 {1 2}}
 do_test lock-1.8 {
@@ -64,7 +63,7 @@ do_test lock-1.10 {
 } {2 1}
 do_test lock-1.11 {
   catchsql {SELECT * FROM t1} db2
-} {1 {database is locked}}
+} {0 {2 1}}
 do_test lock-1.12 {
   execsql {ROLLBACK}
   catchsql {SELECT * FROM t1}
@@ -151,7 +150,8 @@ if {$::tcl_platform(platform)=="unix"} {
 integrity_check lock-1.23
 
 # If one thread has a transaction another thread cannot start
-# a transaction.
+# a transaction.  -> Not true in version 3.0.  But if one thread
+# as a RESERVED lock another thread cannot acquire one.
 #
 do_test lock-2.1 {
   execsql {BEGIN TRANSACTION}
@@ -162,15 +162,14 @@ do_test lock-2.1 {
   lappend r $msg
 } {1 {database is locked}}
 
-# Nor can the other thread do a query.
+# A thread can read when another has a RESERVED lock.
 #
 do_test lock-2.2 {
-  set r [catch {execsql {SELECT * FROM t2} db2} msg]
-  lappend r $msg
-} {1 {database is locked}}
+  catchsql {SELECT * FROM t2} db2
+} {0 {9 8}}
 
-# If the other thread (the one that does not hold the transaction)
-# tries to start a transaction, we get a busy callback.
+# If the other thread (the one that does not hold the transaction with
+# a RESERVED lock) tries to get a RESERVED lock, we get a busy callback.
 #
 do_test lock-2.3 {
   proc callback {args} {
@@ -179,7 +178,7 @@ do_test lock-2.3 {
   }
   set ::callback_value {}
   db2 busy callback
-  set r [catch {execsql {BEGIN TRANSACTION} db2} msg]
+  set r [catch {execsql {UPDATE t1 SET a=b, b=a} db2} msg]
   lappend r $msg
   lappend r $::callback_value
 } {1 {database is locked} {{} 1}}
@@ -190,7 +189,7 @@ do_test lock-2.4 {
   }
   set ::callback_value {}
   db2 busy callback
-  set r [catch {execsql {BEGIN TRANSACTION} db2} msg]
+  set r [catch {execsql {UPDATE t1 SET a=b, b=a} db2} msg]
   lappend r $msg
   lappend r $::callback_value
 } {1 {database is locked} {1 2 3 4 5}}
@@ -204,7 +203,7 @@ do_test lock-2.5 {
   set r [catch {execsql {SELECT * FROM t1} db2} msg]
   lappend r $msg
   lappend r $::callback_value
-} {1 {database is locked} {1 2 3 4 5}}
+} {0 {2 1} {}}
 
 # In this test, the 3rd invocation of the busy callback causes
 # the first thread to release its transaction.  That allows the
@@ -222,10 +221,8 @@ do_test lock-2.6 {
   set r [catch {execsql {SELECT * FROM t2} db2} msg]
   lappend r $msg
   lappend r $::callback_value
-} {0 {9 8} {1 2 3}}
+} {0 {9 8} {}}
 do_test lock-2.7 {
-  execsql {BEGIN TRANSACTION}
-  execsql {UPDATE t1 SET a = 0 WHERE 0}
   proc callback {file count} {
     lappend ::callback_value $count
     if {$count>2} {
@@ -276,12 +273,11 @@ do_test lock-4.1 {
   db eval BEGIN
   db eval {UPDATE t1 SET a=0 WHERE 0}
   sqlite db2 ./test.db
-  set rc [catch {db2 eval {SELECT * FROM t1}} msg]
-  lappend rc $msg
+  catchsql {UPDATE t1 SET a=0} db2
 } {1 {database is locked}}
 do_test lock-4.2 {
   set ::callback_value {}
-  set rc [catch {db2 eval {SELECT * FROM t1}} msg]
+  set rc [catch {db2 eval {UPDATE t1 SET a=0}} msg]
   lappend rc $msg $::callback_value
 } {1 {database is locked} {}}
 do_test lock-4.3 {
@@ -290,14 +286,15 @@ do_test lock-4.3 {
     if {$count>4} break
   }
   db2 busy callback
-  set rc [catch {db2 eval {SELECT * FROM t1}} msg]
+  set rc [catch {db2 eval {UPDATE t1 SET a=0}} msg]
   lappend rc $msg $::callback_value
 } {1 {database is locked} {1 2 3 4 5}}
 execsql {ROLLBACK}
 
 # When one thread is writing, other threads cannot read.  Except if the
 # writing thread is writing to its temporary tables, the other threads
-# can still read.
+# can still read.  -> Not so in 3.0.  One thread can read while another
+# holds a RESERVED lock.
 #
 proc tx_exec {sql} {
   db2 eval $sql
@@ -312,7 +309,7 @@ do_test lock-5.2 {
   catchsql {
     INSERT INTO t1(a,b) SELECT 3, tx_exec('SELECT y FROM t2 LIMIT 1');
   }
-} {1 {database is locked}}
+} {0 {}}
 do_test lock-5.3 {
   execsql {
     CREATE TEMP TABLE t3(x);
@@ -333,12 +330,12 @@ do_test lock-5.6 {
   catchsql {
     UPDATE t1 SET a=tx_exec('SELECT x FROM t2');
   }
-} {1 {database is locked}}
+} {0 {}}
 do_test lock-5.7 {
   execsql {
     SELECT * FROM t1;
   }
-} {2 1}
+} {9 1 9 8}
 do_test lock-5.8 {
   catchsql {
     UPDATE t3 SET x=tx_exec('SELECT x FROM t2');