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From "Lars Hofhansl (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (PHOENIX-5233) Read-your-own writes causes incorrect visibility with transactional tables (with Omid).
Date Fri, 12 Apr 2019 18:39:00 GMT

    [ https://issues.apache.org/jira/browse/PHOENIX-5233?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16816572#comment-16816572
] 

Lars Hofhansl commented on PHOENIX-5233:
----------------------------------------

Nice! Looks like this fixes issue #2. (Now I can do the change in PHOENIX-5090, which significantly
improves things for larger transactions.)

What do you think about issue #1? What appears to be happening is this:
* Omid has committed a transaction.
* If HBase now does a split, some of the scanners are restarted. The newly restart scanner
now see data that was inserted before they started.
* The upshot is that the SELECT part of UPSERT/SELECT might see more data than the previous
snapshot. This is only an issue insight a transaction.

I guess that commit should always imply a checkpoint...?
I think this should be repeatable with just HBase (no Phoenix needed). HBase splitting should
not lead to different data visibility when we have transactions.


> Read-your-own writes causes incorrect visibility with transactional tables (with Omid).
> ---------------------------------------------------------------------------------------
>
>                 Key: PHOENIX-5233
>                 URL: https://issues.apache.org/jira/browse/PHOENIX-5233
>             Project: Phoenix
>          Issue Type: Bug
>    Affects Versions: 4.14.1
>            Reporter: Lars Hofhansl
>            Assignee: Yonatan Gottesman
>            Priority: Major
>         Attachments: 5233-tests.txt, 5233-v4.txt, 5233-v5.txt, 5233-v6.txt
>
>
> (copied from my last comment on PHOENIX-5090)
> Steps to reproduce (with Omid):
>  # {{!autocommit off}}
>  # {{create table test (pk1 integer not null, pk2 integer not null, pk3 integer not null,
v1 float, v2 float, v3 integer CONSTRAINT pk PRIMARY KEY (pk1, pk2, pk3)) DISABLE_WAL=true,
TRANSACTIONAL=true;}}
>  # {{upsert into test values(rand()*10000000, rand()*10000000, rand()*10000000, rand(),
rand(), rand()*1000000);}}
>  # {{upsert into test select rand()*10000000, rand()*10000000, rand()*10000000, rand(),
rand(), rand()*1000000 from test;}}
>  # {{select count\(*) from test; – this will cause uncommitted data to sent to the
server.}}
>  # Goto #4 a few time (until you inserted 131072 rows)
>  # {{!commit}}
> In a separate sqlline session just repeat after the commit was issued in the other session.
> * {{select count\(*) from test;}}
> You'll see that number will change until it finally settles.



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