svn commit: r372919 - /db/derby/docs/trunk/src/devguide/cdevconcepts842385.dita

[jt...@apache.org]

Author: jta
Date: Fri Jan 27 09:18:41 2006
New Revision: 372919

URL: http://svn.apache.org/viewcvs?rev=372919&view=rev
Log:
DERBY-678 Applied Eric Radzinski's patch that updates the Developer's Guide
with update lock behavior changes.

Modified:
    db/derby/docs/trunk/src/devguide/cdevconcepts842385.dita

Modified: db/derby/docs/trunk/src/devguide/cdevconcepts842385.dita
URL: http://svn.apache.org/viewcvs/db/derby/docs/trunk/src/devguide/cdevconcepts842385.dita?rev=372919&r1=372918&r2=372919&view=diff
==============================================================================
--- db/derby/docs/trunk/src/devguide/cdevconcepts842385.dita (original)
+++ db/derby/docs/trunk/src/devguide/cdevconcepts842385.dita Fri Jan 27 09:18:41 2006
@@ -1,4 +1,7 @@
 <?xml version="1.0" encoding="utf-8"?>
+
+<!DOCTYPE concept PUBLIC "-//IBM//DTD DITA Concept//EN"
+ "../dtd/concept.dtd">
 <!-- 
 Copyright 1997, 2005 The Apache Software Foundation or its licensors, as applicable.  
 
@@ -14,25 +17,19 @@
 See the License for the specific language governing permissions and  
 limitations under the License.
 -->
-<!DOCTYPE concept PUBLIC "-//IBM//DTD DITA Concept//EN" "../dtd/concept.dtd">
-<concept xml:lang="en-us" id="cdevconcepts842385">
+<concept id="cdevconcepts842385" xml:lang="en-us">
 <title>Update locks</title>
 <prolog><metadata>
-<keywords>
-<indexterm>Update locks</indexterm>
-</keywords>
-</metadata>
-</prolog>
+<keywords><indexterm>Update locks</indexterm></keywords>
+</metadata></prolog>
 <conbody>
 <p>When a user-defined update cursor (created with the FOR UPDATE clause)
-reads data, its transaction obtains an <i>update </i>lock
-on the data. If the user-defined update cursor updates the data, the update
-lock is converted to an exclusive lock. If the cursor does not update the
-row, when the transaction steps through to the next row, transactions using
-the TRANSACTION_READ_COMMITTED isolation level release the lock, and transactions
-using the TRANSACTION_SERIALIZABLE or TRANSACTION_REPEATABLE_READ isolation
-level downgrade it to a shared lock until the transaction is committed. (For
-update locks, the TRANSACTION_READ_UNCOMMITTED isolation level acts the same
-way as TRANSACTION_READ_COMMITTED.)</p>
+reads data, its transaction obtains an <i>update</i> lock on the data. If
+the user-defined update cursor updates the data, the update lock is converted
+to an exclusive lock. If the cursor does not update the row, when the transaction
+steps through to the next row, transactions using the TRANSACTION_READ_COMMITTED
+isolation level release the lock. (For update locks, the TRANSACTION_READ_UNCOMMITTED
+isolation level acts the same way as TRANSACTION_READ_COMMITTED.)</p>
 <p>Update locks help minimize deadlocks.</p>
-</conbody></concept>
+</conbody>
+</concept>