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Date: Fri, 15 Sep 2017 08:44:00 +0000 (UTC)
From: =?utf-8?Q?Micael_Capit=C3=A3o_=28JIRA=29?= <jira@apache.org>
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Subject: [jira] [Commented] (TEPHRA-99) Make "long running" transactions
 usable with TransactionContext
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archived-at: Fri, 15 Sep 2017 08:44:05 -0000


    [ https://issues.apache.org/jira/browse/TEPHRA-99?page=3Dcom.atlassian.=
jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=3D16167=
543#comment-16167543 ]=20

Micael Capit=C3=A3o commented on TEPHRA-99:
--------------------------------------

Well the thing here is: when the client first requests a page I'm opening a=
 new scan, fetch records until a certain limit and then return the records =
plus the last row and the tx (the scan is closed). On the next pages the cl=
ient provides me the last row and the tx info and I repeat the procedure bu=
t starting the scan at the last row (excluded) and injecting the tx info fr=
om the first page (that is the part that I'm going to do now).
The truth is I don't really want to start a transaction on the pages after =
the first one (and on the first page I do have to start a transaction and c=
ommit it). I only need the transaction info to go with the scan so the Thep=
hra coprocessor can do its job at filtering anything that should not be see=
n by the tx I've injected. So in reality there should be no issues at all o=
r am I missing something here?

> Make "long running" transactions usable with TransactionContext
> ---------------------------------------------------------------
>
>                 Key: TEPHRA-99
>                 URL: https://issues.apache.org/jira/browse/TEPHRA-99
>             Project: Tephra
>          Issue Type: Improvement
>          Components: core
>            Reporter: Gary Helmling
>            Assignee: Gary Helmling
>
> "Long running" transactions (type =3D=3D LONG) are supported by the Tephr=
a {{TransactionManager}}, but {{TransactionContext}} does not expose any wa=
y for clients to interact with them.  I think this will require a couple ch=
anges:
> * add a {{startLong()}} method to TransactionContext
> * add a constructor to TransactionContext that takes an existing {{Transa=
ction}} instance.  Since long running transactions are often used in map re=
duce processing, the process committing the transaction may be different fr=
om the process that started the transaction.  In this situation, we need a =
way to pass the serialized transaction all the way through to the other pro=
cess.
> Regarding map reduce support, we could use additional utilities or suppor=
t in place to make transactions easier to use with map reduce.  But this wo=
uld at least serve as a first step.


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