Zhimin Wu created KYLIN-5837:
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Summary: After turning off the computed column function, the query
cannot hit the existing recommended index
Key: KYLIN-5837
URL: https://issues.apache.org/jira/browse/KYLIN-5837
Project: Kylin
Issue Type: Bug
Components: Query Engine
Affects Versions: 5.0-beta
Reporter: Zhimin Wu
Assignee: Zhimin Wu
Fix For: 5.0.0
*Dev Design*
* The configuration parameter
"kylin.metadata.only-reuse-user-defined-computed-column=false" is designed to
enable the usage of user-defined computed columns for reusing only. This
decouples the feature of shielding columns from the configuration, which means
that the shielding column feature can still be used even with this parameter
set to false.
* By default, Kylin uses computed columns (CC) for implicit column
conversions, which means that user-defined computed columns can replace
implicit expressions. However, if the configuration parameter
"kylin.query.implicit-computed-column-convert" is set to "false", the
user-defined computed columns will not be used for implicit column conversions.
* The configuration parameter "kylin.query.agg-computed-column-rewrite" is
related to computed columns v2 and it replaces columns at the semantic RelNode
level, while "kylin.query.implicit-computed-column-convert" performs column
replacements at the SqlNode level. As a general rule, if
"kylin.query.implicit-computed-column-convert" is set to false, then
"kylin.query.agg-computed-column-rewrite" will not take effect either. However,
if "kylin.query.implicit-computed-column-convert" is set to true, then
"kylin.query.agg-computed-column-rewrite" can be set to either true or false.
* All three configurations can now be modified at the project level.
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