diff --git a/manifest b/manifest
index d0b503fce2..b6a738dd26 100644
--- a/manifest
+++ b/manifest
@@ -1,5 +1,5 @@
-C The\sability\sto\sload\sextensions\sis\sturned\soff\sby\sdefault.\s\sIt\smust\sbe\nenabled\sby\scalling\ssqlite3_enable_load_extension()\sbefore\sit\swill\swork.\nThis\sprevents\ssecurity\sproblems\sin\slegacy\sapplications.\s\sTicket\s#1863.\s(CVS\s3311)
-D 2006-06-27T15:16:15
+C Prevent\sdatabases\sfrom\sbeing\sDETACHed\swhile\sthey\sare\sin\suse.\sFix\sfor\s#1873.\s(CVS\s3312)
+D 2006-06-27T16:34:57
 F Makefile.in f839b470345d3cb4b0644068474623fe2464b5d3
 F Makefile.linux-gcc 2d8574d1ba75f129aba2019f0b959db380a90935
 F README 9c4e2d6706bdcc3efdd773ce752a8cdab4f90028
@@ -32,10 +32,10 @@ F sqlite3.def f756049b1bf3e8442baf6862db393ca423225262
 F sqlite3.pc.in 985b9bf34192a549d7d370e0f0b6b34a4f61369a
 F src/alter.c eba661e77bfd00282fbfa316cdb6aef04856fedc
 F src/analyze.c 7d2b7ab9a9c2fd6e55700f69064dfdd3e36d7a8a
-F src/attach.c 27a31d3b89d7ebb5b358847607b1ec795384123c
+F src/attach.c b11eb4d5d3fb99a10a626956bccc7215f6b68b16
 F src/auth.c 902f4722661c796b97f007d9606bd7529c02597f
-F src/btree.c ed343b3dbcbc7da9ac481ef2b98c4239fe6d9629
-F src/btree.h 40055cfc09defd1146bc5b922399c035f969e56d
+F src/btree.c fc077741b35efd2015b0f56e62d00370bed1fcc8
+F src/btree.h 061c50e37de7f50b58528e352d400cf33ead7418
 F src/build.c ef710ff6b3a91d4c1dd4c7009a8800ff38660613
 F src/callback.c fd9bb39f7ff6b52bad8365617abc61c720640429
 F src/complete.c 7d1a44be8f37de125fcafd3d3a018690b3799675
@@ -271,6 +271,7 @@ F test/tkt1537.test e3a14332de9770be8ff14bd15c19a49cbec10808
 F test/tkt1567.test 18023cc3626a365f0118e17b66decedec93b1a6f
 F test/tkt1644.test 80b6a2bb17885f3cf1cb886d97cdad13232bb869
 F test/tkt1667.test ef52c857940755ea5eab24d68f808826e7dcdc94
+F test/tkt1873.test 7159a1c1bf627bbb03f11362e4ad4de11d6ff316
 F test/trace.test 75ffc1b992c780d054748a656e3e7fd674f18567
 F test/trans.test 06bff0246886858793fca3748721936e2f65e3df
 F test/trigger1.test e8c717e959c2f98c8181cd9466e140fa7aac781f
@@ -374,7 +375,7 @@ F www/tclsqlite.tcl bb0d1357328a42b1993d78573e587c6dcbc964b9
 F www/vdbe.tcl 87a31ace769f20d3627a64fa1fade7fed47b90d0
 F www/version3.tcl 890248cf7b70e60c383b0e84d77d5132b3ead42b
 F www/whentouse.tcl 97e2b5cd296f7d8057e11f44427dea8a4c2db513
-P 783369e870df9d189fc75c98fa574fe4fc9843d0
-R 03b010c340d22a562ee989d0414f81c5
-U drh
-Z b75df8d7be6621720643222d3b606d63
+P 4692319ccf28b0ebe64d5c5d189f444034fe0cb2
+R 00197d0cb5b5b0794b65c7727c5ea79d
+U danielk1977
+Z 1504eda4a9a7a809d58a186051ca9568
diff --git a/manifest.uuid b/manifest.uuid
index 7dd2e0b0ef..12d551a704 100644
--- a/manifest.uuid
+++ b/manifest.uuid
@@ -1 +1 @@
-4692319ccf28b0ebe64d5c5d189f444034fe0cb2
\ No newline at end of file
+70a48b250bab99c5d9b4ad17c471663b8628e8d2
\ No newline at end of file
diff --git a/src/attach.c b/src/attach.c
index a6a72a333c..8e5442991b 100644
--- a/src/attach.c
+++ b/src/attach.c
@@ -11,7 +11,7 @@
 *************************************************************************
 ** This file contains code used to implement the ATTACH and DETACH commands.
 **
-** $Id: attach.c,v 1.52 2006/05/25 11:52:38 drh Exp $
+** $Id: attach.c,v 1.53 2006/06/27 16:34:57 danielk1977 Exp $
 */
 #include "sqliteInt.h"
 
@@ -247,6 +247,10 @@ static void detachFunc(
     strcpy(zErr, "cannot DETACH database within transaction");
     goto detach_error;
   }
+  if( sqlite3BtreeIsInReadTrans(pDb->pBt) ){
+    sqlite3_snprintf(sizeof(zErr),zErr, "database %s is locked", zName);
+    goto detach_error;
+  }
 
   sqlite3BtreeClose(pDb->pBt);
   pDb->pBt = 0;
diff --git a/src/btree.c b/src/btree.c
index 7fcd54c80f..babcf6a339 100644
--- a/src/btree.c
+++ b/src/btree.c
@@ -9,7 +9,7 @@
 **    May you share freely, never taking more than you give.
 **
 *************************************************************************
-** $Id: btree.c,v 1.324 2006/04/04 01:54:55 drh Exp $
+** $Id: btree.c,v 1.325 2006/06/27 16:34:57 danielk1977 Exp $
 **
 ** This file implements a external (disk-based) database using BTrees.
 ** For a detailed discussion of BTrees, refer to
@@ -6558,6 +6558,13 @@ int sqlite3BtreeIsInStmt(Btree *p){
   return (p->pBt && p->pBt->inStmt);
 }
 
+/*
+** Return non-zero if a read (or write) transaction is active.
+*/
+int sqlite3BtreeIsInReadTrans(Btree *p){
+  return (p && (p->inTrans!=TRANS_NONE));
+}
+
 /*
 ** This call is a no-op if no write-transaction is currently active on pBt.
 **
diff --git a/src/btree.h b/src/btree.h
index 4ebb12c2cd..ae24233859 100644
--- a/src/btree.h
+++ b/src/btree.h
@@ -13,7 +13,7 @@
 ** subsystem.  See comments in the source code for a detailed description
 ** of what each interface routine does.
 **
-** @(#) $Id: btree.h,v 1.70 2006/02/11 01:25:51 drh Exp $
+** @(#) $Id: btree.h,v 1.71 2006/06/27 16:34:57 danielk1977 Exp $
 */
 #ifndef _BTREE_H_
 #define _BTREE_H_
@@ -75,6 +75,7 @@ int sqlite3BtreeRollbackStmt(Btree*);
 int sqlite3BtreeCreateTable(Btree*, int*, int flags);
 int sqlite3BtreeIsInTrans(Btree*);
 int sqlite3BtreeIsInStmt(Btree*);
+int sqlite3BtreeIsInReadTrans(Btree*);
 int sqlite3BtreeSync(Btree*, const char *zMaster);
 void *sqlite3BtreeSchema(Btree *, int, void(*)(void *));
 int sqlite3BtreeSchemaLocked(Btree *);
diff --git a/test/tkt1873.test b/test/tkt1873.test
new file mode 100644
index 0000000000..0eca230568
--- /dev/null
+++ b/test/tkt1873.test
@@ -0,0 +1,67 @@
+# 2006 June 27
+#
+# 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 to verify that ticket #1873 has been
+# fixed.  
+#
+#
+# $Id: tkt1873.test,v 1.1 2006/06/27 16:34:58 danielk1977 Exp $
+
+set testdir [file dirname $argv0]
+source $testdir/tester.tcl
+
+file delete -force test2.db test2.db-journal
+
+do_test tkt1873-1.1 {
+  execsql {
+    CREATE TABLE t1(x, y);
+    ATTACH 'test2.db' AS aux;
+    CREATE TABLE aux.t2(x, y);
+    INSERT INTO t1 VALUES(1, 2);
+    INSERT INTO t1 VALUES(3, 4);
+    INSERT INTO t2 VALUES(5, 6);
+    INSERT INTO t2 VALUES(7, 8);
+  }
+} {}
+
+do_test tkt1873-1.2 {
+  set rc [catch {
+    db eval {SELECT * FROM t2 LIMIT 1} {
+      db eval {DETACH aux}
+    }
+  } msg]
+  list $rc $msg
+} {1 {database aux is locked}}
+
+do_test tkt1873-1.3 {
+  set rc [catch {
+    db eval {SELECT * FROM t1 LIMIT 1} {
+      db eval {DETACH aux}
+    }
+  } msg]
+  list $rc $msg
+} {0 {}}
+
+do_test tkt1873-1.4 {
+  catchsql {
+    select * from t2;
+  }
+} {1 {no such table: t2}}
+
+do_test tkt1873-1.5 {
+  catchsql {
+    ATTACH 'test2.db' AS aux;
+    select * from t2;
+  }
+} {0 {5 6 7 8}}
+
+finish_test