Xiangdong Huang created IOTDB-523:
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Summary: A potential query optimization for querying many
measurements of a device
Key: IOTDB-523
URL: https://issues.apache.org/jira/browse/IOTDB-523
Project: Apache IoTDB
Issue Type: Improvement
Components: Core/Engine
Reporter: Xiangdong Huang
Hi,
Today when I run a SQL like `select * from root` and enable the debug log on
server, I find so many DeviceMetaData and ChunkMetadata are read.
Considering that in TsFile, a device's multiply chunk data will be stored
together, is that possible to have the following optimization?
If a user query many measurements (e.g., select * from, or select more than
1/2 measurements of a device), maybe there is no need to read the
ChunkMeatadata... because if we find a ChunkGroup, if one column is needed to
be read, other columns are high probability to be read.
I am not sure whether my idea is correct. Please leave your opinions.
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