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From bpendle...@apache.org
Subject svn commit: r542864 - /db/derby/docs/trunk/src/adminguide/cadminhubbkup01.dita
Date Wed, 30 May 2007 16:31:37 GMT
Author: bpendleton
Date: Wed May 30 09:31:36 2007
New Revision: 542864

URL: http://svn.apache.org/viewvc?view=rev&rev=542864
Log:
DERBY-2364: Improve docs to explain logged/unlogged operations during backup

This change modifies the backup page in the Admin guide to include more
information about logged versus unlogged operations.

The information was extracted from a derby-user mailing list posting
made by Suresh Thalamati (suresh.thalamati@gmail.com).


Modified:
    db/derby/docs/trunk/src/adminguide/cadminhubbkup01.dita

Modified: db/derby/docs/trunk/src/adminguide/cadminhubbkup01.dita
URL: http://svn.apache.org/viewvc/db/derby/docs/trunk/src/adminguide/cadminhubbkup01.dita?view=diff&rev=542864&r1=542863&r2=542864
==============================================================================
--- db/derby/docs/trunk/src/adminguide/cadminhubbkup01.dita (original)
+++ db/derby/docs/trunk/src/adminguide/cadminhubbkup01.dita Wed May 30 09:31:36 2007
@@ -62,6 +62,11 @@
 <note>Do not back up different databases with the same name to the same backup
 directory. If a database of the same name already exists in the backup directory,
 it is assumed to be an older version and is overwritten.</note>
+<section><title>Unlogged Operations</title>
+<p>
+For some operations, Derby does not log because it can keep the database
+consistent without logging the data.
+</p>
 <p>The SYSCS_UTIL.SYSCS_BACKUP_DATABASE procedure will issue an error if there
 are any unlogged operations in the same transaction as the backup procedure.</p>
 <p>If any unlogged operations are in progress in other transactions in the
@@ -76,5 +81,31 @@
 This procedure issues an error immediately at the start of the backup if there
 are any transactions in progress with unlogged operations, instead of waiting
 for those transactions to complete.</p>
+<p>Unlogged operations include:
+<ol>
+<li>Index creation.
+<p>
+Only CREATE INDEX is logged, not all the data inserts into the
+index. The reason inserts into the index are not logged is:
+if there is a failure , it will just drop the index.
+</p><p>
+If you create an index when the backup is in progress, it will be
+slower because it has to be logged.
+</p><p>
+Foreign Keys , Primary Keys create backing indexes. Adding those keys
+to an existing table with data will also run slower.
+</p></li>
+<li>Import to an empty table or replacing all the data in a table.
+<p>
+In this case also, data inserts into table are not logged. Internally,
+Derby creates a new table for the import and changes the catalogs to
+point to the new table and drops the original table when import
+completes.
+</p><p>
+If you perform such an import operation when backup is in progress ,
+it will be slower because data is logged.
+</p></li>
+</ol>
+</p></section>
 </conbody>
 </concept>



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