[
https://issues.apache.org/jira/browse/IOTDB-125?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Yuan Tian reassigned IOTDB-125:
-------------------------------
Assignee: Yuan Tian
> [potential] a concurrency conflict may occur when a delete command and
> insertion command appears concurrently
> --------------------------------------------------------------------------------------------------------------
>
> Key: IOTDB-125
> URL: https://issues.apache.org/jira/browse/IOTDB-125
> Project: Apache IoTDB
> Issue Type: Bug
> Reporter: xiangdong Huang
> Assignee: Yuan Tian
> Priority: Major
> Labels: medium
>
> * Hi,
> we find a potential bug,
> Suppose client A calls a delete time series root.sg1.*, then
> OverflowQPExecutor.java's operateMetadata() will be called.
> At the same time, client B calls a insertion command insert into
> root.sg1.d1.s1 ..., then the bug may appear:
> 1. B checks the schema and find sg1.d1.s1 is valid, then B is waiting for the
> write lock of related StorageGroupProcessor,
> 2. A removes the definition of time series in SG1, all data files of SG1 and
> then return back;
> 3. B gets the write lock and write data successfully; finally, the data is
> flushed on disk.
> Then, if client C calls `select * from root.sg1`, C gets nothing because
> there is no time series defined under the storage group.
> Now client C creates sg1.d1.s1 again, and then executes `select * from
> root.sg1`, C will find the data that B wrote....
>
> A solution is set a database-level read write lock. For all operations which
> will modify the schema, the write lock is needed; For all other operations
> (e.g., insertion), the read lock is needed.
> (We need to consider the cost of calling the read lock for each insertion
> operation)
>
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
