# NebulaGraph 3.4.0 release notes¶

## Enhancement¶

• Modify the default value of the Graph service parameter session_reclaim_interval_secs to 60 seconds. #5246
• Adjust the default level of stderrthreshold in the configuration file. #5188
• Limit the maximum depth of the plan tree in the optimizer to avoid stack overflows. #5050
• Optimize the treatment scheme when the pattern expressions are used as predicates. #4916

## Bugfix¶

• Fix the bug about query plan generation and optimization. #4863 #4813
• Fix the bugs related to indexes:

• Fix the bugs related to DDL and DML statements:

• Fix the bugs related to other functions:

## Change¶

• The added property name can not be the same as an existing or deleted property name, otherwise, the operation of adding a property fails. #5130
• Limit the type conversion when modifying the schema. #5098
• The default value must be specified when creating a property of type NOT NULL. #5105
• Add the multithreaded query parameter query_concurrently to the configuration file with a default value of true. #5119
• Remove the parameter kv_separation of the KV separation storage function from the configuration file, which is turned off by default. #5119
• Modify the default value of local_config in the configuration file to true. #5119
• Consistent use of v.tag.property to get property values, because it is necessary to specify the Tag. Using v.property to access the property of a Tag on v was incorrectly allowed in the previous version. #5230
• Remove the column HTTP port from the command SHOW HOSTS. #5056
• Disable the queries of the form OPTIONAL MATCH <pattern> WHERE <condition>. #5273
• Disable TOSS. #5119
• Rename Listener's pid filename and log directory name. #5119

## Notes for upgrading¶

To upgrade to v3.4.0, follow the upgrade guide:

## Legacy versions¶

Release notes of legacy versions

Last update: March 23, 2023