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https://issues.apache.org/jira/browse/LENS-656?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Rajat Khandelwal updated LENS-656:
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Issue Type: Sub-task (was: Improvement)
Parent: LENS-657
> make Storage class more important
> ---------------------------------
>
> Key: LENS-656
> URL: https://issues.apache.org/jira/browse/LENS-656
> Project: Apache Lens
> Issue Type: Sub-task
> Reporter: Rajat Khandelwal
>
> Current usage of Stogage in lens:
> * Storages are crated with xml, where only class name is required. It has to
> be a subclass of org.apache.lens.cube.metadata.Storage. Two subclasses are
> already provided: org.apache.lens.cube.metadata.HDFSStorage, and
> org.apache.lens.storage.db.DBStorage.
> * Current requirement of storage subclass is to implement methods of
> org.apache.lens.cube.metadata.PartitionMetahook (will be shown below). The
> two provided subclasses provide a no-op implementations of this.
> Issues:
> * DBStorage has a dbUrl variable supposed to capture DB url. But that is not
> used anywhere and is redundant. In the current design, the db url is required
> in configuration of JDBCDriver. This means that drivers and storages are
> deeply coupled.
> * For querying partitions, Storage is not queried. Instead a map of storage
> name to partitions is maintained elsewhere. Another example of deep coupling
> Proposed changes:
> * Storage as an independent entity. Basically removing the deep coupling
> * Facts will have Storage instances instead of storage names. With loose
> coupling, one storage will have only one instance.
> * Driver conf has a property "supported storages". That is currently used in
> the resolvers. Instead the property will become an attribute of the driver.
> {noformat}
> public interface PartitionMetahook {
> void preAddPartitions(List<StoragePartitionDesc> storagePartitionDesc)
> throws HiveException;
> void commitAddPartitions(List<StoragePartitionDesc> storagePartitionDesc)
> throws HiveException;
> void rollbackAddPartitions(List<StoragePartitionDesc> storagePartitionDesc)
> throws HiveException;
> void preDropPartition(String storageTableName, List<String> partVals)
> throws HiveException;
> void commitDropPartition(String storageTableName, List<String> partVals)
> throws HiveException;
> void rollbackDropPartition(String storageTableName, List<String> partVals)
> throws HiveException;
> }
> {noformat}
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