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https://issues.apache.org/jira/browse/KUDU-2437?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Adar Dembo resolved KUDU-2437.
------------------------------
Resolution: Fixed
Fix Version/s: 1.8.0
Fixed in commit d4ded71bc0edadcbe2564d5677d319f35e48dad8. Thanks, [~oclarms]!
> Split a tablet into primary key ranges by size
> ----------------------------------------------
>
> Key: KUDU-2437
> URL: https://issues.apache.org/jira/browse/KUDU-2437
> Project: Kudu
> Issue Type: Improvement
> Components: client, tablet
> Reporter: Xu Yao
> Assignee: Xu Yao
> Priority: Major
> Fix For: 1.8.0
>
>
> When reading data in a kudu table using spark, if there is a large amount of
> data in the tablet, reading the data takes a long time. The reason is that
> KuduRDD uses a tablet to generate the scanToken, so a spark task needs to
> process all the data in a tablet.
> We think that TabletServer should provide an RPC interface, which can be
> split tablet into multiple primary key ranges by size. The kudu-client can
> choose whether to perform parallel scan according to the case.
> RPC interface:
> {code:java}
> // A split key range request. Split tablet to key ranges, the request
> // doesn't change layout of tablet.
> message SplitKeyRangeRequestPB {
> required bytes tablet_id = 1;
> // Encoded primary key to begin scanning at (inclusive).
> optional bytes start_primary_key = 2 [(kudu.REDACT) = true];
> // Encoded primary key to stop scanning at (exclusive).
> optional bytes stop_primary_key = 3 [(kudu.REDACT) = true];
> // Number of bytes to try to return in each chunk. This is a hint.
> // The tablet server may return chunks larger or smaller than this value.
> optional uint64 target_chunk_size_bytes = 4;
> // The columns to consider when chunking.
> // If specified, then the size estimate used for 'target_chunk_size_bytes'
> // should only include these columns. This can be used if a query will
> // only scan a certain subset of the columns.
> repeated ColumnSchemaPB columns = 5;
> }
> // The primary key range of a Kudu tablet.
> message KeyRangePB {
> // Encoded primary key to begin scanning at (inclusive).
> optional bytes start_primary_key = 1 [(kudu.REDACT) = true];
> // Encoded primary key to stop scanning at (exclusive).
> optional bytes stop_primary_key = 2 [(kudu.REDACT) = true];
> // Number of bytes in chunk.
> required uint64 size_bytes_estimates = 3;
> }
> message SplitKeyRangeResponsePB {
> // The error, if an error occurred with this request.
> optional TabletServerErrorPB error = 1;
> repeated KeyRangePB ranges = 2;
> }
> {code}
>
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