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https://issues.apache.org/jira/browse/IOTDB-2042?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Zhong Wang reassigned IOTDB-2042:
---------------------------------
Assignee: Zhong Wang
> Data loss after restart
> -----------------------
>
> Key: IOTDB-2042
> URL: https://issues.apache.org/jira/browse/IOTDB-2042
> Project: Apache IoTDB
> Issue Type: Bug
> Reporter: Zhong Wang
> Assignee: Zhong Wang
> Priority: Major
> Labels: Cluster
>
> Way to reproduce:
> 1. Enable time partitioning. Set the partition_interval to 2592000 (30 days).
> 2. Start a 3 node cluster with 2 replicas.
> 3. Insert the following values on node 3:
> {code:sql}
> insert into root.group_1.d_1(timestamp, s_1)
> values(2018-07-18T00:00:00.000+08:00, 18.0)
> insert into root.group_1.d_1(timestamp, s_1)
> values(2018-07-19T00:00:00.000+08:00, 19.0)
> insert into root.group_1.d_1(timestamp, s_1)
> values(2019-08-19T00:00:00.000+08:00, 20.0)
> {code}
> 4. Restart the cluster.
> 5. Execute the following query on each node. Node 2 will return an empty
> result set:
> {code:sql}
> SELECT * FROM root
> {code}
> Some of the TSFiles are empty after recovery, which is unexpected.
> Reason:
> When time partitioning is enabled, although the data of a time series can be
> distributed across the whole cluster, its metadata is only stored in the data
> group corresponding to the hash value calculated from its storage group and
> timestamp 0.
> When a node from another data group receives insertions of the time series,
> it will send a request to whoever has the metadata and cache the response,
> but the cache will not be persisted. Thus, if the node crashes, it is not
> able to recover from the WAL since the cache is not available anymore.
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