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https://issues.apache.org/jira/browse/PHOENIX-2271?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14905452#comment-14905452
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Cameron Hatfield commented on PHOENIX-2271:
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Would you be thinking of extending the standard merge statement (which, from
what I can tell without access to the ISO doc, only supports working on direct
table references) with non-standard support for a value constructor, ala the
syntax I stole from TSQL? Without that, it seems relatively hard to use it for
our use case (compare-and-set for a row).
The other minus I would see is the inability to mix and match transactions and
compare-and-set within the same table, forcing you to have to choose one or the
other. Though I am unsure how much sense that would make anyways.
The another issue, with either decision should, would be if the MERGE / UPSERT
would need to be extended to return information on success or not of the
UPSERT, similar to POSTGRESQLs RETURNING. Currently we don't have a requirement
for this, though I know there are use cases for doing so.
> Upsert - CheckAndPut like functionality
> ---------------------------------------
>
> Key: PHOENIX-2271
> URL: https://issues.apache.org/jira/browse/PHOENIX-2271
> Project: Phoenix
> Issue Type: Improvement
> Reporter: Babar Tareen
> Attachments: patch.diff
>
>
> The Upsert statement does not support HBase's checkAndPut api, thus making it
> difficult to conditionally update a row. Based on the comments from
> PHOENIX-6, I have implemented such functionality. The Upsert statement is
> modified to support compare clause, which allows us to pass in an expression.
> The expression is evaluated against the current record and Upsert is only
> performed when the expression evaluates to true. More details
> [here|https://github.com/babartareen/phoenix].
> h4. Examples
> Given that the FirstName is always set for the users, create a user record if
> one doesn't already exist.
> {code:sql}
> UPSERT INTO User (UserId, FirstName, LastName, Phone, Address, PIN) VALUES
> (1, 'Alice', 'A', '123 456 7890', 'Some St. in a city', 1122) COMPARE
> FirstName IS NULL;
> {code}
> Update the phone number for UserId '1' if the FirstName is set. Given that
> the FirstName is always set for the users, this will only update the record
> if it already exists.
> {code:sql}
> UPSERT INTO User (UserId, Phone) VALUES (1, '987 654 3210') COMPARE FirstName
> IS NOT NULL;
> {code}
> Update the phone number if the first name for UserId '1' starts with 'Al' and
> last name is 'A'
> {code:sql}
> UPSERT INTO User (UserId, Phone) VALUES (1, '987 654 3210') COMPARE FirstName
> LIKE 'Al%' AND LastName = 'A';
> {code}
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