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https://issues.apache.org/jira/browse/HIVE-7341?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14101601#comment-14101601
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Sushanth Sowmyan commented on HIVE-7341:
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Ugh, sorry for not catching it at review, but this patch did cause some
backward incompatibility that broke compilation for Falcon that depends on this
api. Rather than reverting this patch back, I figure that opening a new bug
(*MUST* be resolved in 0.14) to put the old exception behaviour back is a less
destructive way of doing so.
HIVE-7770 tracks that change.
> Support for Table replication across HCatalog instances
> -------------------------------------------------------
>
> Key: HIVE-7341
> URL: https://issues.apache.org/jira/browse/HIVE-7341
> Project: Hive
> Issue Type: New Feature
> Components: HCatalog
> Affects Versions: 0.13.1
> Reporter: Mithun Radhakrishnan
> Assignee: Mithun Radhakrishnan
> Fix For: 0.14.0
>
> Attachments: HIVE-7341.1.patch, HIVE-7341.2.patch, HIVE-7341.3.patch,
> HIVE-7341.4.patch, HIVE-7341.5.patch
>
>
> The HCatClient currently doesn't provide very much support for replicating
> HCatTable definitions between 2 HCatalog Server (i.e. Hive metastore)
> instances.
> Systems similar to Apache Falcon might find the need to replicate partition
> data between 2 clusters, and keep the HCatalog metadata in sync between the
> two. This poses a couple of problems:
> # The definition of the source table might change (in column schema, I/O
> formats, record-formats, serde-parameters, etc.) The system will need a way
> to diff 2 tables and update the target-metastore with the changes. E.g.
> {code}
> targetTable.resolve( sourceTable, targetTable.diff(sourceTable) );
> hcatClient.updateTableSchema(dbName, tableName, targetTable);
> {code}
> # The current {{HCatClient.addPartitions()}} API requires that the
> partition's schema be derived from the table's schema, thereby requiring that
> the table-schema be resolved *before* partitions with the new schema are
> added to the table. This is problematic, because it introduces race
> conditions when 2 partitions with differing column-schemas (e.g. right after
> a schema change) are copied in parallel. This can be avoided if each
> HCatAddPartitionDesc kept track of the partition's schema, in flight.
> # The source and target metastores might be running different/incompatible
> versions of Hive.
> The impending patch attempts to address these concerns (with some caveats).
> # {{HCatTable}} now has
> ## a {{diff()}} method, to compare against another HCatTable instance
> ## a {{resolve(diff)}} method to copy over specified table-attributes from
> another HCatTable
> ## a serialize/deserialize mechanism (via {{HCatClient.serializeTable()}} and
> {{HCatClient.deserializeTable()}}), so that HCatTable instances constructed
> in other class-loaders may be used for comparison
> # {{HCatPartition}} now provides finer-grained control over a Partition's
> column-schema, StorageDescriptor settings, etc. This allows partitions to be
> copied completely from source, with the ability to override specific
> properties if required (e.g. location).
> # {{HCatClient.updateTableSchema()}} can now update the entire
> table-definition, not just the column schema.
> # I've cleaned up and removed most of the redundancy between the HCatTable,
> HCatCreateTableDesc and HCatCreateTableDesc.Builder. The prior API failed to
> separate the table-attributes from the add-table-operation's attributes. By
> providing fluent-interfaces in HCatTable, and composing an HCatTable instance
> in HCatCreateTableDesc, the interfaces are cleaner(ish). The old setters are
> deprecated, in favour of those in HCatTable. Likewise, HCatPartition and
> HCatAddPartitionDesc.
> I'll post a patch for trunk shortly.
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