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https://issues.apache.org/jira/browse/HIVE-18864?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Sankar Hariappan updated HIVE-18864:
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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. {color:#d04437}*ValidWriteIdList(open:null,
write_HWM=7)*. – This read will able to see rows added by txn=11 which is still
open.{color}
{color:#d04437}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.{color}
{color:#333333}{color:#d04437}cc{color}{color}
[~ekoifman]{color:#333333},{color} [~thejas]
was:
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. {color:#d04437}*ValidWriteIdList(open:null,
write_HWM=7)*. – This read will able to see rows added by txn=11 which is still
open.{color}
{color:#d04437}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.{color}
{color:#d04437}{color:#333333}cc{color} [~ekoifman]{color:#333333},{color}
[~thejas]{color}
> WriteId high water mark (HWM) is incorrect if ValidWriteIdList is obtained
> after allocating writeId by current transaction.
> ---------------------------------------------------------------------------------------------------------------------------
>
> Key: HIVE-18864
> URL: https://issues.apache.org/jira/browse/HIVE-18864
> Project: Hive
> Issue Type: Sub-task
> Components: Transactions
> Affects Versions: 3.0.0
> Reporter: Sankar Hariappan
> Assignee: Sankar Hariappan
> Priority: Blocker
> Labels: ACID
> Fix For: 3.0.0
>
>
> 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. {color:#d04437}*ValidWriteIdList(open:null,
> write_HWM=7)*. – This read will able to see rows added by txn=11 which is
> still open.{color}
> {color:#d04437}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.{color}
> {color:#333333}{color:#d04437}cc{color}{color}
> [~ekoifman]{color:#333333},{color} [~thejas]
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