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give up on trying to optimize startWith -- it's basically impossible when replication factor > 1 b/c of the range wrap point. 

patch by jbellis; tested by Mark Robson for CASSANDRA-348

git-svn-id: https://svn.apache.org/repos/asf/incubator/cassandra/trunk@803716 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Jonathan Ellis 2009-08-12 21:27:24 +00:00
parent cd66ac8326
commit ddf00a509a
1 changed files with 8 additions and 8 deletions
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16
src/java/org/apache/cassandra/service/StorageProxy.java
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@ -637,7 +637,7 @@ public class StorageProxy implements StorageProxyMBean
IAsyncResult iar = MessagingService.getMessagingInstance().sendRR(message, endPoint);
// read response
byte[] responseBody = new byte[0];
byte[] responseBody;
try
{
responseBody = iar.get(DatabaseDescriptor.getRpcTimeout(), TimeUnit.MILLISECONDS);
@ -649,6 +649,7 @@ public class StorageProxy implements StorageProxyMBean
RangeReply rangeReply = RangeReply.read(responseBody);
List<String> rangeKeys = rangeReply.keys;
// combine keys from most recent response with the others seen so far
if (rangeKeys.size() > 0)
{
if (allKeys.size() > 0)
@ -693,15 +694,14 @@ public class StorageProxy implements StorageProxyMBean
break;
}
// the first endpoint contains the range from the last endpoint, up to and including its own token.
// so it will include both the smallest keys, and the largest. if that is what we just scanned,
// leave startWith unchanged. Otherwise, start with the largest key found.
String newStartWith = endPoint.equals(wrapEndpoint)
? rawCommand.startWith
: allKeys.size() > 0 ? allKeys.get(allKeys.size() - 1) : command.startWith;
// set up the next query --
// it's tempting to try to optimize this by starting with the last key seen for the next node,
// but that won't work when you have a replication factor of more than one--any node, not just
// the one holding the keys where the range wraps, could include both the smallest keys, and the largest,
// so starting with the largest in our scan of the next node means we'd never see keys from the middle.
endPoint = tokenMetadata.getNextEndpoint(endPoint); // TODO move this into the Strategies & modify for RackAwareStrategy
int maxResults = endPoint == wrapEndpoint ? rawCommand.maxResults : rawCommand.maxResults - allKeys.size();
command = new RangeCommand(command.table, command.columnFamily, newStartWith, command.stopAt, maxResults);
command = new RangeCommand(command.table, command.columnFamily, command.startWith, command.stopAt, maxResults);
} while (!endPoint.equals(startEndpoint));
rangeStats.add(System.currentTimeMillis() - startTime);