Performance improvements. Performance for outbound replication from a source cluster to a destination has been improved. CPU utilization on destination clusters has been reduced for better performance.

Improved Error Handling and Logging. More information about documents and the size of documents awaiting replication now available.

UI Improvements for XDCR in the Couchbase Web Console.

Now provide timestamp for when a TAP queue backfill starts. The TAP backfill queue is used to send a snapshot of a vbucket to another node.

Issues: MB-6753

Couchbase Server had created new checkpoints even in the case where empty, current checkpoints were available. The server provided extraneous notifications when various changes to checkpoints ID occurred due to constant polling by XDCR. Now when an empty checkpoint is available, the server uses this checkpoint for additional replication and provide this checkpoint ID to XDCR. The server also pushes a single notification to XDCR when a checkpoint is empty.

In the past if you set the disk path for data to be the same path as that for index files, Couchbase Server would fail to start. This is fixed.

Issues: MB-6995

In the past, if you used a symbolic link to reference a data directory for Couchbase Server, the server determined remaining free only for the partition that contained the symbolic link. This resulted in two issues: 1) incorrect information in the Couchbase Web Console, 2) more significantly, it would accidentally inhibit the data compaction process because of incorrect information about free disk space. This has been fixed in 2.0.

Issues: MB-7307

During Couchbase Server warmup or rebalance, if you delete a data bucket, it will cause the node to crash.

Issues: MB-7272

Performing a touch operation and providing an expiration of 0, to indicate no expiration did not function. This is now fixed.

Issues: MB-7342

We now log all vBucket state changes as mccouch events.

Issues: MB-7057

To handle current limitations on open file descriptors allowed on MacOS, the number of vBuckets on MacOS have been reduced to 64 from 1024. This reduces the number of files that are created for data as well as for indexes. Overall this provides improved CPU and disk I/O for MacOS.

Issues: MB-6781

Check-and-set value was not returned in response to a successful delete request. Now it is returned as part of the response.

Issues: MB-6661

In the past, the server would delete items even if a provided CAS value was a mismatch. This has been fixed.

Issues: MB-6985

Get-and-touch function were not providing the correct error information from the server. Get-and-touch now returns ENOENT if key does not exist.

Issues: MB-6840

The Couchbase REST-API has changed to enable you to change the default maximum number of buckets used in a Couchbase cluster. The maximum allowed buckets in this request is 128, however the maximum suggested number of buckets is ten per cluster. This is a safety mechanism to ensure that a cluster does not have resource and CPU overuse due to too many buckets. The following illustrates the endpoint and parameters used:

shell>	curl -X -u admin:password -d maxBucketCount=6 http://ip_address:8091/internalSettings

For this request you need to provide administrative credentials for the cluster. The following HTTP request will be sent:

About to connect() to 127.0.0.1 port 8091 (#0)
Trying 127.0.0.1...
connected
Connected to 127.0.0.1 (127.0.0.1) port 8091 (#0)
Server auth using Basic with user 'Administrator'
POST /internalSettings HTTP/1.1

If Couchbase Server successfully changes the bucket limit for the cluster, you will get a HTTP 200 response:

HTTP/1.1 200 OK
Server: Couchbase Server 2.0.0r_501_gb614829
Pragma: no-cache
Date: Wed, 31 Oct 2012 21:21:48 GMT
Content-Type: application/json
Content-Length: 2
Cache-Control: no-cache

If you provide an invalid number, such as 0, a negative number, or an amount over 128 buckets, you will get this error message:

["Unexpected server error, request logged."]

For more information about setting buckets per cluster via REST-API, see Section 8.7.11, “Setting Maximum Buckets for Clusters”.

Issues: MB-5684

We have removed the automatic 5-minute timeout for Couchbase Web Console. This inhibited people from performing ongoing work and demonstrations of the server.

For Mac OSX, we had provided a drop-down UI menu for logs that pointed to the wrong location. This menu option has been removed since it is already provided in the Web Console.

Issues: MB-7075

We now provide memcached logs in the diagnostic reports available from the Couchbase Web Console.

Issues: MB-7048

Several command line tools have been deprecated, superceded, or moved. This includes cbflushctl which has been superceded by cbepctl. For more information, see Chapter 7, Command-line Interface for Administration.

Issues: MB-6912

For Mac OSX, the tool for collecting statistics for Couchbase technical support cbcollect_info was not functioning. We have fixed it.

Issues: MB-6958

Incorrect message had been sent in response to a cbstats vkey command. Server had returned the string 'not found' for valid request. Now correct the memcached protocol error is returned. For more information about cbstats, see Section 7.5, “cbstats Tool”.

Issues: MB-6751

cbepctl help options now show option for setting the expiry_pager, a maintenance process for removing deleted items from disk.

Issues: MB-6764

Fix rebalance timeout failure during unidirectional replication of items via XDCR. Failure had returned message: "timeout, ns_memcached-bucket','ns_1@10.1.3.238'}, {get_vbucket,".

Issues: MB-6493

Errors had occurred performing replication via XDCR due to improper handling of non- UTF-8 characters. We now handle errors due to non- UTF-8 characters and can continue replication via XDCR for JSON documents containing non- UTF-8.

Issues: MB-7092

We have added 3 new outbound operation stats, namely, 1) data replicated, which is amount of data XDCR have replicated to the remote data center through inter- cluster network; 2) active vb replications, which shows the number of ongoing active replications to the remote clusters; 3) waiting vb replications, which is the number of vb replications in the waiting pool to wait for turn to start replication. These stats will be useful for performance monitoring and diagnosis.

Issues: MB-6919

By default, the server automatically disables flushing data from a source data bucket when XDCR replications exist for that bucket.

Issues: MB-6809

It is not possible to perform an upgrade between Couchbase Server 2.0 pre-releases including beta, or to perform an offline upgrade from Couchbase Server 1.8 to a pre-release or beta of Couchbase Server 2.0. To upgrade between these versions use cbbackup to backup your data, delete the existing installation, install the new version, and restore the stored data.

For more information, see Section 5.6, “Backup and Restore”, Appendix B, Uninstalling Couchbase Server.

By default when you perform a new install of Couchbase Server 2.0, creating a replica index for a data bucket is disabled by default. This should be the standard default setting for all new installs of the server. However, when you upgrade from 1.8.1 to 2.0, be aware it is enabled by default.

Issues: MB-7339

Documents identified as Non-JSON stored within Couchbase Server may appear as binary, or text-encoded binary data within the UI.

Issues: MB-7069

In order to upgrade from 1.8.1 to 2.0 for the Microsoft Windows platform, you need to make changes to the ip file located on the node at Couchbase\Server\var\lib\couchbase\ip as well as complete some additional steps on your node which will apply whether you are using Windows on the cloud or not. For more information about upgrading from 1.8.x to 2.0, see Section 2.7, “Upgrades Notes 1.8.1 to 2.0 +”.

Issues: MB-7289

For more information, see Section 4.6.2, “Handling Changes in IP Addresses”.

During periods of moderate CPU load on the Couchbase Server cluster, you may see warnings that IP address seems to have changed. Unable to listen to node X.X.X.X.

Issues: MB-7115, MB-7238, MB-7228

Performing an upgrade from Couchbase 1.8.1 to Couchbase 2.0.0 GA build freezes while transferring data from SQLite files to Couchstore files using cbtransfer.

Issues: MB-7341

If you use couchbase-cli to setup a Couchbase node on a non-default port, you may receive an error. Although the cluster gets initialized, the initial RAM quota is not used and the server returns an error.

Issues: MB-7268

On Ubuntu 64-bit 12.04, when you upgrade Couchbase Server from 1.8.1 to 2.0 the upgrade will work, however the server erroneously returns an error in the end when it starts. The error is: "Failed to start couchbase-server dpkg: error processing couchbase-server (‐‐install)". Ignore this error message.

Issues: MB-7298

Several incidents have been reported that after using Flush on nodes, Couchbase Server returns TMPFAIL even after a successful flush.

Issues: MB-7160

For the Windows platform, attempts to perform a rebalance of a restarted node fails due to failure to clean up old data buckets on the node. The workaround is to retry the rebalance.

Issues: MB-7202

If you reset the disk path to a path that contained corrupted data, Couchbase Server will shut down and non response. When you change the data path to a different folder, make sure it does not contain files with a different format or with incorrect permissions.

Issues: MB-7185

Be aware that you may experience delays while node is in a pending state after you change the index path for that node. This will be fixed in a point release after 2.0 GA.

Issues: MB-7337

If you query a view during cluster rebalance it will fail and return the messages "error Reason: A view spec can not consist of merges exclusively" and then "no_active_vbuckets Reason: Cannot execute view query since the node has no active vbuckets." The workaround for this situation is to handle this error and retry later in your code. Alternatively the latest version of the Java SDK will automatically retry upon these errors.

Issues: MB-7661

During a rebalance operation for clusters undergoing uni- and bi-directional replication via XDCR, the following server errors may appear, which are currently under investigation:

Server error during processing: ["web request failed", 
{path,"/pools/default"}, 
{type,exit}, 
{what, 
{timeout, 
{gen_server,call, 
[ns_doctor,get_tasks_version]}}}, 
{trace, 
[{gen_server,call,2}, 
{menelaus_web,build_pool_info,4}, 
{menelaus_web,handle_pool_info_wait,5}, 
{menelaus_web,loop,3}, 
{mochiweb_http,headers,5}, 
{proc_lib,init_p_do_apply,3}]}] (repeated 1 times)

Issues: MB-7286

One of the internal maintenance processes within Couchbase Server for checking vBuckets will stop node rebalance when you create replication via XDCR on a source cluster.

A node in a cluster may also stop rebalance when another node orchestrating rebalances is over loaded. When a node stops rebalance, it results in the error message "Resetting rebalance status since it is not really running".

Rebalance cna also fail due to the timeout in bulk_set_vbucket_state operation with continuous view queries.

Issues: MB-6481, MB-6573, MB-7212

The Couchbase Web Console will erroneously clear all summary statistics for a data bucket when a new index is being generated in the background. The workaround is to reload the page to get the current statistics.

Issues: MB-7090

Be aware that if attempt hundreds of simultaneous queries with an unlimited number of results, Couchbase Server may fail. If you have a result set from indexing that contains 10 million items or more, and you query for that entire result set, the server will fail.

Instead you should specify a reasonable limit of results when you query, such as retriving a range of results from the larger set, otherwise the server will stall and crash due to excessive memory usage. For more information about querying and specifying a subset of results, see Section 9.8, “Querying Views”.

Issues: MB-7199

If you have a cluster running Couchbase Server 1.8.1 and 2.0.0, Couchbase Web Console 2.0 will show incorrect, sometimes negative values for Disk Usage in the summary section. Ignore this error.

Issues: MB-7183

The cbbackup, cbrestore, and cbtransfer command-line tools require the zlib module for Python to have been installed. If Python was installed from source, you must have enabled zlib using the --with-zlib option during the build process.

Issues: MB-7256

For more information, see Section 5.6, “Backup and Restore”, Appendix B, Uninstalling Couchbase Server.

The sample data loader will fail to run on a cluster when the cluster contains nodes with different versions of Couchbase. The workaround is to upgrade all cluster nodes to Couchbase Server 2.0. For more information about upgrading nodes from 1.8.x to 2.0, see Section 2.7, “Upgrades Notes 1.8.1 to 2.0 +”.

Issues: MB-7171

The couchbase command line tool, couchbase-cli does not enable you to set index_path as a separate parameter as data_path. The former contains indexed data from defined views functions, while the later contains keys, metadata, and JSON documents. You can however use the REST-API to do this.

Issues: MB-7323

For more information, see Section 8.5.3, “Configuring Index Path for a Node”.

The sample data loader will also fail if there are multiple nodes in a cluster and creating a bucket in the cluster is taking longer than 10 seconds.

Issues: MB-7170

If you are using development views, be aware you may see inconsistent results if you query a development view during rebalance. For production views, you are able to query during rebalance and get results consistent with those you would have recieved if no rebalance were occurring.

Issues: MB-6967

Accessing a recently created view (with other, existing active views) may return a error if the corresponding design document and view definition have not been replicated across the cluster. The error return will be returned in error of the view output detailing the missing design document. The workaround is to add views and design documents to your node or cluster after you have performed rebalance. For more information about resolving issues with Couchbase Views, see Appendix D, Troubleshooting Views (Technical Background).

Note also that stopping a rebalance operation on a cluster may take a long time if compaction and indexing operations are in progress on the cluster at the point of rebalance. Again, the workaround is to add views and index and query views after you have performed compaction or rebalance. For more information about rebalance, and considerations on when to rebalance, see Section 5.7, “Rebalancing”.

Issues: MB-6726, MB-6339

If a map function in a design document fails while processing a document, that document will also not be computed for any other map functions in the same design document. To avoid creating errors in your views functions, see the tips and advice provided in Appendix D, Troubleshooting Views (Technical Background).

Issues: MB-6895

Couchbase Server does lazy expiration, that is, expired items are flagged as deleted rather than being immediately erased. Couchbase Server has a maintenance process that will periodically look through all information and erase expired items. This means expired items may still be indexed and appear in result sets of views. The workarounds for this behavior are available here About Document Expiration.

Issues: MB-7053

beam.smp memory usage grows to 2 GB when XDCR feature is enabled and rebalancing is in progress.

Issues: MB-6649

Under the XDCR tab for Couchbase Web Console, the link to a a destination cluster takes you to a missing URL. A simple workaround is to append ':8091' to the address in the newly opened browser tab.

Issues: MB-7211

Replication rat e may drop when the XDCR replication queue size becomes less than 500 items.

Issues: MB-6586

Be aware that if you are using XDCR for replication to a destination bucket and you remove and create a new bucket with the same name, it has a different UUIDs. Therefore any replication you had established with the deleted bucket will not apply to the new bucket.

Issues: MB-7262

Under a heavy load of write operations on two clusters and both bi-directional and uni-directional replications occurring via XDCR, Couchbase Server 2.0 may fail during rebalance.

Issues: MB-7290

ep-engine needs 1.5 minutes to create 1024 vbuckets. This may be too slow, however performance improves with setting barrier=0.

Issues: MB-6232