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https://issues.apache.org/jira/browse/DRILL-7089?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16812298#comment-16812298
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ASF GitHub Bot commented on DRILL-7089:
---------------------------------------
vvysotskyi commented on pull request #1728: DRILL-7089: Implement caching for
TableMetadataProvider at query level and adapt statistics to use Drill
metastore API
URL: https://github.com/apache/drill/pull/1728#discussion_r272964601
##########
File path:
exec/java-exec/src/main/java/org/apache/drill/exec/planner/logical/DrillTable.java
##########
@@ -49,9 +50,7 @@
private final String userName;
private GroupScan scan;
private SessionOptionManager options;
- // Stores the statistics(rowcount, NDV etc.) associated with the table
- private DrillStatsTable statsTable;
- private TupleMetadata schema;
+ private MetadataProviderManager metadataProviderManager;
Review comment:
This solution wasn't a result of following a particular Design Pattern. It
was done in order to allow caching of `MetadataProvider` and preserve lazy
initialization. `MetadataProviderManager` will be stored to the cache and once
`MetadataProvider` is created, `MetadataProviderManager` will receive a link to
it and it will be reused for constructing all further `MetadataProvider`
instances.
Yes, that's correct that "there's a 1-to-many relationship between
Manager-->Provider and a 1-to-1 relationship between a Provider and its
associated DrillTable".
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> Implement caching of BaseMetadata classes
> -----------------------------------------
>
> Key: DRILL-7089
> URL: https://issues.apache.org/jira/browse/DRILL-7089
> Project: Apache Drill
> Issue Type: Sub-task
> Affects Versions: 1.16.0
> Reporter: Volodymyr Vysotskyi
> Assignee: Volodymyr Vysotskyi
> Priority: Major
> Fix For: 1.16.0
>
>
> In the scope of DRILL-6852 were introduced new classes for metadata usage.
> These classes may be reused in other GroupScan instances to preserve heap
> usage for the case when metadata is large.
> The idea is to store {{BaseMetadata}} inheritors in {{DrillTable}} and pass
> them to the {{GroupScan}}, so in the scope of the single query, it will be
> possible to reuse them.
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