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From jkr...@apache.org
Subject svn commit: r1575030 - /kafka/site/081/design.html
Date Thu, 06 Mar 2014 20:27:21 GMT
Author: jkreps
Date: Thu Mar  6 20:27:21 2014
New Revision: 1575030

URL: http://svn.apache.org/r1575030
Log:
Further clarify log compaction guarantees.

Modified:
    kafka/site/081/design.html

Modified: kafka/site/081/design.html
URL: http://svn.apache.org/viewvc/kafka/site/081/design.html?rev=1575030&r1=1575029&r2=1575030&view=diff
==============================================================================
--- kafka/site/081/design.html (original)
+++ kafka/site/081/design.html Thu Mar  6 20:27:21 2014
@@ -272,10 +272,10 @@ The compaction is done in the background
 
 Log compaction guarantees the following:
 <ol>
-<li>Any consumer that stays caught-up to within the head of the log will see a message
for each offset.
+<li>Any consumer that stays caught-up to within the head of the log will every message
that is written and messages will have sequential offsets.
 <li>Message order is always maintained (that is, compaction will never re-order messages
just remove some).
 <li>The offset for a message never changes, it is the permanent identifier for a position
in the log.
-<li>Any read from offset 0 will see the final state of all records (in order) provided
it reaches the head of the log in a time period less than the topic's delete.retention.ms
setting (the default is 24 hours). This is important as delete marker removal happens concurrently
with read.
+<li>Any read progressing from offset 0 will see at least the final state of all records
in the order they were written. All delete markers for deleted records will be seen provided
the reader reaches the head of the log in a time period less than the topic's delete.retention.ms
setting (the default is 24 hours). This is important as delete marker removal happens concurrently
with read (and thus it is important that we not remove any delete marker prior to the reader
seeing it).
 </ol>
 
 <h4>Log Compaction Details</h4>



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