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https://issues.apache.org/jira/browse/KUDU-3353?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17775857#comment-17775857
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ASF subversion and git services commented on KUDU-3353:
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Commit 1b015d7ee9cc8af262f398961cf471f76bb225ea in kudu's branch
refs/heads/master from Marton Greber
[ https://gitbox.apache.org/repos/asf?p=kudu.git;h=1b015d7ee ]
[Python] KUDU-3353 add support for UPSERT IGNORE
This patch is a follow-up to commit:
ec3a9f75b6924a70ecbf08e3805228ad9b92b9f0, it adds UPSERT IGNORE support
to the Python client.
Extended the already existing tests:
* added write op metrics verification for immutable column tests,
* extended immutable column tests with UPSERT IGNORE test,
* addressed an UPSERT IGNORE TODO in the auto-incrementing column tests.
Change-Id: I9112b96a5688287352307c05e60030a217154cbd
Reviewed-on: http://gerrit.cloudera.org:8080/20527
Tested-by: Kudu Jenkins
Reviewed-by: Yingchun Lai <[email protected]>
> Add an immutable attribute on column schema
> -------------------------------------------
>
> Key: KUDU-3353
> URL: https://issues.apache.org/jira/browse/KUDU-3353
> Project: Kudu
> Issue Type: New Feature
> Components: api, server
> Reporter: Yingchun Lai
> Assignee: Yingchun Lai
> Priority: Major
>
> h1. motivation
> In some usage scenarios, Kudu table has a column with semantic of "create
> time", which means it represent the create timestamp of the row. The other
> columns have the similar semantic as before, for example, the user properties
> like age, address, and etc.
> Upstream and Kudu user doesn't know whether a row is exist or not, and every
> cell data is the lastest ingested from, for example, event stream.
> If without the "create time" column, Kudu user can use UPSERT operations to
> write data to the table, every columns with data will overwrite the old data.
> But if with the "create time" column, the cell data will be overwrote by the
> following UPSERT ops, which is not what we expect.
> To achive the goal, we have to read the column out to judge whether the
> column is NULL or not, if it's NULL, we can fill the row with the cell, if
> not NULL, we will drop it from the data before UPSERT, to avoid overwite
> "create time".
> It's expensive, is there a way to avoid a read from Kudu?
> h1. Resolvation
> We can implement column schema with semantic of "update if null". That means
> cell data in changelist will update the base data if the latter is NULL, and
> will ignore updates if it is not NULL.
> So we can use Kudu similarly as before, but only defined the column as
> "update if null" when create table or add column.
>
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