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https://issues.apache.org/jira/browse/TRAFODION-3311?focusedWorklogId=247600&page=com.atlassian.jira.plugin.system.issuetabpanels:worklog-tabpanel#worklog-247600
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ASF GitHub Bot logged work on TRAFODION-3311:
---------------------------------------------
Author: ASF GitHub Bot
Created on: 23/May/19 18:11
Start Date: 23/May/19 18:11
Worklog Time Spent: 10m
Work Description: selvaganesang commented on pull request #1843:
[TRAFODION-3311] Trafodion to start transactions for select statements with FOR
UPDATE
URL: https://github.com/apache/trafodion/pull/1843
A CQD BEGIN_TRANSACTION_FOR_SELECT is introduced. This CQD can take a value
1,2 or any numeric value. Default is 1.
1 - means mark the statement as transaction required if it is SELECT ... FOR
UPDATE
2 - means mark the statement as transaction required if it is SELECT
statement with
isolation other than SKIP CONFLICT ACCESS or READ UNCOMMITTED ACCESS.
Any other value - SELECT statement is not marked to begin transaction.
Trafodion always change the isolation level to READ COMMITTED ACCESS when it
is
READ UNCOMMITTED ACCESS.
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Issue Time Tracking
-------------------
Worklog Id: (was: 247600)
Time Spent: 10m
Remaining Estimate: 0h
> Trafodion to start transactions for select statements with FOR UPDATE
> ---------------------------------------------------------------------
>
> Key: TRAFODION-3311
> URL: https://issues.apache.org/jira/browse/TRAFODION-3311
> Project: Apache Trafodion
> Issue Type: Improvement
> Components: sql-general
> Reporter: Selvaganesan Govindarajan
> Assignee: Selvaganesan Govindarajan
> Priority: Major
> Time Spent: 10m
> Remaining Estimate: 0h
>
> Currently, Trafodion doesn't start transactions for any select statement.
> However the standard seem to imply the transaction needs to be started for
> select. See Ansi SQL 92 spec at
> [http://www.contrib.andrew.cmu.edu/~shadow/sql/sql1992.txt]
>
> Trafodion uses MVCC for concurrency control and uses 2 phase commit to
> rollback conflicting transactions. To avoid many conflicting access, the
> transaction will be started with FOR UPDATE select statements
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