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From "Stephen Petschulat (JIRA)" <j...@apache.org>
Subject [jira] [Created] (PHOENIX-4552) Add support for a ROW_TIMESTAMP that doesn't affect the primary key
Date Tue, 23 Jan 2018 17:09:00 GMT
Stephen Petschulat created PHOENIX-4552:
-------------------------------------------

             Summary: Add support for a ROW_TIMESTAMP that doesn't affect the primary key
                 Key: PHOENIX-4552
                 URL: https://issues.apache.org/jira/browse/PHOENIX-4552
             Project: Phoenix
          Issue Type: New Feature
            Reporter: Stephen Petschulat


By declaring a ROW_TIMESTAMP constraint on a Phoenix table, it does two things 1) expose
the hbase native timestamp as this column and 2) prepend your primary key with this timestamp
as well.

It would be useful to have a similar feature that only exposes the hbase native timestamp.
This would allow explicit setting of the timestamp when upserting data while allowing multiple
hbase versions. It is possible to then query for that specific key and version(s).

Potential approach:
{code:sql}
CREATE TABLE COMMENTS (
   COMMENT_ID INT NOT NULL,
   REVISION_NUM BIGINT NOT NULL ROW_TIMESTAMP,    // NEW use of keyword
   COMMENT_BODY TEXT
   CONSTRAINT PK PRIMARY KEY(COMMENT_ID))

UPSERT INTO COMMENTS (123, 1, 'edit 1 comment')

UPSERT INTO COMMENTS (123, 2, 'edit 2 of comment')

UPSERT INTO COMMENTS (123, 3, 'edit 3 of comment')
{code}
 

Current behavior of ROW_TIMESTAMP would create a new primary for each upsert, so querying
by primary key is no longer straightforward when you don't know the version number at query
time. 
{code:sql}
SELECT * FROM COMMENTS WHERE COMMENT_ID = 123  // => returns most recent version 'edit
3 of comment'

SELECT * FROM COMMENTS WHERE COMMENT_ID = 123 AND REVISION_NUM = 1   // => returns explicit
version 'edit 1 comment'
{code}
 

It can also be useful to return multiple versions (related: PHOENIX-590)
{code:sql}
SELECT * FROM COMMENTS WHERE COMMENT_ID = 123 AND REVISION_NUM < 3   // => returns 2
rows
{code}
 

Or just the highest version less than or equal to a particular version (allowing snapshot
queries):
{code:sql}
// set CurrentSCN=2 on connection
SELECT * FROM COMMENTS WHERE COMMENT_ID = 123 // => returns 'edit 2 of comment'
{code}
CurrentSCN already allows this type of snapshot query but not against an explicitly set timestamp
with multiple versions. The primary key injection prevents this. The above query would behave similar
to:
{code:java}
scan 'COMMENTS', {TIMERANGE => [0, <maxversionid+1>]}
{code}
 This returns the highest versioned value for each key that is less than a specified maximum
version number.

 

 



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