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From "James Taylor (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-6) Support ON DUPLICATE KEY construct
Date Tue, 04 Oct 2016 20:03:20 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-6?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15546487#comment-15546487
] 

James Taylor commented on PHOENIX-6:
------------------------------------

Yes, agreed, [~cameron.hatfield]. If these two statements are in the same commit batch, the
result would be 0, 0:
{code}
UPSERT INTO T (PK, COUNTER1, COUNTER2) VALUES ('a',0,0) 
ON DUPLICATE KEY COUNTER1 = COUNTER2 + 1, COUNTER2 = COUNTER1 + 1;
UPSERT INTO T (PK, COUNTER1, COUNTER2) VALUES ('a',0,0) 
ON DUPLICATE KEY COUNTER1 = COUNTER2 + 1, COUNTER2 = COUNTER1 + 1;
-- With auto commit off, the result would be 'a', 0, 0
{code}


> 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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