Details
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Sub-task
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Status: Closed
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Major
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Resolution: Fixed
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3.0.0
Description
For multi-statement txns, it is possible that write on a table happens after a read. Let's see the below scenario.
- Committed txn=9 writes on table T1 with writeId=5.
- Open txn=10. ValidTxnList(open:null, txn_HWM=10),
- Read table T1 from txn=10. ValidWriteIdList(open:null, write_HWM=5).
- Open txn=11, writes on table T1 with writeid=6.
- Read table T1 from txn=10. ValidWriteIdList(open:null, write_HWM=5).
- Write table T1 from txn=10 with writeId=7.
- Read table T1 from txn=10. ValidWriteIdList(open:null, write_HWM=7). – This read will able to see rows added by txn=11 which is still open.
So, it is needed to rebuild the open/aborted list of ValidWriteIdList based on txn_HWM. Any writeId allocated by txnId > txn_HWM should be marked as open. In this example, ValidWriteIdList(open:6, write_HWM=7) should be generated.
Attachments
Attachments
Issue Links
- is related to
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HIVE-18192 Introduce WriteID per table rather than using global transaction ID
- Closed
- links to