[
https://issues.apache.org/jira/browse/PHOENIX-2271?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14901277#comment-14901277
]
Babar Tareen commented on PHOENIX-2271:
---------------------------------------
Transactions might be too heavy for my use case because of the high write
volume. The application does some computations and stores the results in a
table. These results have a column(s) representing the accuracy of the
computation. I only want to update the result if it is more accurate than the
existing one, regardless of the order of the operation. There will always be a
single version of a result. In this case transaction features like snapshot
isolation are unnecessary. With results being written from many workers,
checkAndPut like api will be more performant as comparison happens on the
server side and the applications don't need to read the record.
> 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}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
