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https://issues.apache.org/jira/browse/PHOENIX-6?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15531383#comment-15531383
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James Taylor commented on PHOENIX-6:
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bq. but incrementing a numeric column can use the optimized path, right?
- An Increment does a read+write under row lock like we're planning for this
JIRA. See HRegion.java [1], doIncrement, applyIncrementsToColumnFamily and
getIncrementCurrentValue calls.
- Our mechanism will have only one code path - there's no need to use Increment
(and it wouldn't work in the context of Phoenix for a variety of reasons).
- Our mechanism will be more general as you can set a column value to the
evaluation of *any* expression, not just column+1
- Our mechanism also gives you the ability to define the initial value while
Increment doesn't
[1]
https://github.com/apache/hbase/blob/branch-1.2/hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java
> Support ON DUPLICATE KEY construct
> ----------------------------------
>
> Key: PHOENIX-6
> URL: https://issues.apache.org/jira/browse/PHOENIX-6
> Project: Phoenix
> Issue Type: New Feature
> Reporter: James Taylor
> Assignee: James Taylor
> Fix For: 4.9.0
>
>
> To support inserting a new row only if it doesn't already exist, we should
> support the "on duplicate key" construct for UPSERT. With this construct, the
> UPSERT VALUES statement would run atomically and would thus require a read
> before write which would obviously have a negative impact on performance. For
> an example of similar syntax , see MySQL documentation at
> http://dev.mysql.com/doc/refman/5.7/en/insert-on-duplicate.html
> See this discussion for more detail:
> https://groups.google.com/d/msg/phoenix-hbase-user/Bof-TLrbTGg/68bnc8ZcWe0J.
> A related discussion is on PHOENIX-2909.
> Initially we'd support the following:
> # This would prevent the setting of VAL to 0 if the row already exists:
> {code}
> UPSERT INTO T (PK, VAL) VALUES ('a',0)
> ON DUPLICATE KEY IGNORE;
> {code}
> # This would increment the valueS of COUNTER1 and COUNTER2 if the row already
> exists and otherwise initialize them to 0:
> {code}
> UPSERT INTO T (PK, COUNTER1, COUNTER2) VALUES ('a',0,0)
> ON DUPLICATE KEY COUNTER1 = COUNTER1 + 1, COUNTER2 = COUNTER2 + 1;
> {code}
> So the general form is:
> {code}
> UPSERT ... VALUES ... [ ON DUPLICATE KEY [IGNORE | UPDATE
> <column>=<expression>, ...] ]
> {code}
> The following restrictions will apply:
> - The <column> may not be part of the primary key constraint - only KeyValue
> columns will be allowed.
> - If the table is immutable, the <column> may not appear in a secondary
> index. This is because the mutations for indexes on immutable tables are
> calculated on the client-side, while this new syntax would potentially modify
> the value on the server-side.
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