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deepa12
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 Posted: Tue Oct 28, 2014 3:53 am Post subject: CICS rollback - would like to confirm |
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Pls consider the following scenario:
A VSAM File has field 1: fld1 VALUE 10
Transaction 1 sees 10 in fld1, increments and updates to 11
in the meanwhile transaction 2 sees value 11 in fld1, increments & updates the same to 12
Now transaction 1 rollsback . Now i think the fld1 in FILE will have 10
And any transaction which acceses this field after the rollback will read the value of this field as 10 & not 11
Pls confirm
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kolusu
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| Posted: Tue Oct 28, 2014 10:25 am Post subject: Re: cics rollback - would like to confirm |
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| deepa12 wrote: | Pls consider the following scenario:
A VSAM File has field 1: fld1 VALUE 10
Transaction 1 sees 10 in fld1, increments and updates to 11
in the meanwhile transaction 2 sees value 11 in fld1, increments & updates the same to 12
Now transaction 1 rollsback . Now i think the fld1 in FILE will have 10
And any transaction which acceses this field after the rollback will read the value of this field as 10 & not 11
Pls confirm |
Deepa,
1. How does transaction 2 see a value of 11 without a syncpoint? without a syncpoint , transaction 2 would only see 10.
2. Aren't you having a row-level lock for the update?
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Kolusu
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deepa12
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| Posted: Tue Oct 28, 2014 8:51 pm Post subject: |
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The file is non rls. In this environment i had seen some progams using syncpoint and some not using the syncpoint.
What i understand is:
In non rls its a ci size lock. The exclusive lock(ie read update access) is available for other transactions only after SYNCPOINT from transaction 1.
In the meanwhile that the lock is not released, the changed data is available for other transactions in read mode ( i have checked this in intertest also; i.e shared read access)
Pls confirm my understanding
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kolusu
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| Posted: Wed Oct 29, 2014 11:33 am Post subject: |
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| deepa12 wrote: | The file is non rls. In this environment i had seen some progams using syncpoint and some not using the syncpoint.
What i understand is:
In non rls its a ci size lock. The exclusive lock(ie read update access) is available for other transactions only after SYNCPOINT from transaction 1.
In the meanwhile that the lock is not released, the changed data is available for other transactions in read mode ( i have checked this in intertest also; i.e shared read access)
Pls confirm my understanding |
Deepa12,
You need to understand the importance of SHROPTIONS coded when creating the VSAM cluster.
Scroll Down to read about SHROPTIONS
After you are done reading that then please read
1.Differences between VSAM RLS access and non-RLS access
2.Locking (enqueuing on) resources in application programs
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deepa12
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| Posted: Wed Oct 29, 2014 11:25 pm Post subject: |
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Ok. Thanks
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