Tian Jiang created IOTDB-1442:
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Summary: [Distributed] Time filter is not used during the
construction of ClusterTimeGenerator
Key: IOTDB-1442
URL: https://issues.apache.org/jira/browse/IOTDB-1442
Project: Apache IoTDB
Issue Type: Bug
Components: Core/Cluster
Reporter: Tian Jiang
Assignee: Tian Jiang
Attachments: image-2021-06-17-09-50-28-254.png,
image-2021-06-17-10-03-18-771.png
When executing a read/write workload over an IoTDB cluster where queries
involving value filters are included, the overall throughput decreases over
time and the disk usage keeps increasing and is dominated by disk reads.
We found out that the number of chunk reads was significantly high compared
with the number of queries through profiling. Considering that the query time
range was fixed, this phenomenon was abnormal.
!image-2021-06-17-09-50-28-254.png|thumbnail!
By intuition, we suspected that the time filter did not work expectedly and it
turned a range query into a full query. So we checked the code where the
readers are generated in the cluster module and found the following mistake
that time filter is not provided during the reader construction. It seems that
the time filter is included in the whole filter so it did not matter whether to
pass it separately or not previously, but recent modifications required to
extract it and pass it explicitly.
!image-2021-06-17-10-03-18-771.png|thumbnail!
The solution is rather simple, we can extract the time filter and pass it to
the constructor so the time filter will not be missing.
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