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https://issues.apache.org/jira/browse/HIVE-21114?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Eugene Koifman updated HIVE-21114:
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Description:
With HIVE-21036 we have a way to indicate that a txn is read only.
We should (at least in auto-commit mode) determine if the single stmt is a read
and mark the txn accordingly.
Then we can optimize {{TxnHandler.commitTxn()}} so that it doesn't do any
checks in write_set etc.
{{TxnHandler.commitTxn()}} already starts with {{lockTransactionRecord(stmt,
txnid, TXN_OPEN)}} so it can read the txn type in the same SQL stmt.
HiveOperation only has QUERY, which includes Insert and Select, so this
requires figuring out how to determine if a query is a SELECT. By the time
{{Driver.openTransaction();}} is called, we have already parsed the query so
there should be a way to know if the statement only reads.
For multi-stmt txns (once these are supported) we should allow user to indicate
that a txn is read-only and then not allow any statements that can make
modifications in this txn. This should be a different jira.
cc [~ikryvenko]
was:
With HIVE-21036 we have a way to indicate that a txn is read only.
We should (at least in auto-commit mode) determine if the single stmt is a read
and mark the txn accordingly.
Then we can optimize {{TxnHandler.commitTxn()}} so that it doesn't do any
checks in write_set etc.
HiveOperation only has QUERY, which includes Insert and Select, so this
requires figuring out how to determine if a query is a SELECT. By the time
{{Driver.openTransaction();}} is called, we have already parsed the query so
there should be a way to know if the statement only reads.
For multi-stmt txns (once these are supported) we should allow user to indicate
that a txn is read-only and then not allow any statements that can make
modifications in this txn. This should be a different jira.
cc [~ikryvenko]
> Create read-only transactions
> -----------------------------
>
> Key: HIVE-21114
> URL: https://issues.apache.org/jira/browse/HIVE-21114
> Project: Hive
> Issue Type: Bug
> Components: Transactions
> Affects Versions: 4.0.0
> Reporter: Eugene Koifman
> Priority: Major
>
> With HIVE-21036 we have a way to indicate that a txn is read only.
> We should (at least in auto-commit mode) determine if the single stmt is a
> read and mark the txn accordingly.
> Then we can optimize {{TxnHandler.commitTxn()}} so that it doesn't do any
> checks in write_set etc.
> {{TxnHandler.commitTxn()}} already starts with {{lockTransactionRecord(stmt,
> txnid, TXN_OPEN)}} so it can read the txn type in the same SQL stmt.
> HiveOperation only has QUERY, which includes Insert and Select, so this
> requires figuring out how to determine if a query is a SELECT. By the time
> {{Driver.openTransaction();}} is called, we have already parsed the query so
> there should be a way to know if the statement only reads.
> For multi-stmt txns (once these are supported) we should allow user to
> indicate that a txn is read-only and then not allow any statements that can
> make modifications in this txn. This should be a different jira.
> cc [~ikryvenko]
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