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James Taylor commented on PHOENIX-6: ------------------------------------ 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. -- This message was sent by Atlassian JIRA (v6.3.4#6332)