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Hikari support for TRANSACTION_LAST_COMMITED and TRANSACTION_CURSOR_STABILITY #1950

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liamsorsby opened this issue Jul 13, 2022 · 0 comments
Open

Hikari support for TRANSACTION_LAST_COMMITED and TRANSACTION_CURSOR_STABILITY #1950

liamsorsby opened this issue Jul 13, 2022 · 0 comments

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@liamsorsby
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Using the Informix jdbc plugin we have a use case where we need to use TRANSACTION_LAST_COMMITED however that doesn't look like it's support in the enum
https://github.com/brettwooldridge/HikariCP/blob/dev/src/main/java/com/zaxxer/hikari/util/IsolationLevel.java#L19
Documentation of the allowed Isolation Levels here: https://www.ibm.com/docs/en/informix-servers/12.10?topic=database-informix-environment-variables-informix-jdbc-driver

The map to the following:

0 Equivalent to TRANSACTION_NONE
1 Dirty Read (equivalent to TRANSACTION_READ_UNCOMMITTED),
2 Committed Read (equivalent to TRANSACTION_READ_COMMITTED),
3 Cursor Stability (equivalent to TRANSACTION_READ_COMMITTED),
4 Repeatable Read (equivalent to TRANSACTION_REPEATABLE_READ)
5 Committed Read LAST COMMITTED (equivalent to TRANSACTION_LAST_COMMITTED)
8 Equivalent to TRANSACTION_SERIALIZABLE

Would there be any objection to implementing the missing ENUM's or was there a reason they weren't added?

3 Cursor Stability (equivalent to TRANSACTION_READ_COMMITTED),
5 Committed Read LAST COMMITTED (equivalent to TRANSACTION_LAST_COMMITTED)
liamsorsby pushed a commit to liamsorsby/HikariCP that referenced this issue Jul 14, 2022
[brettwooldridge#1950] Adds support for TRANSACTION_CURSOR_STABILITY …
427561a 
…and TRANSACTION_LAST_COMMITTED

TRANSACTION_LAST_COMMITTED - This allows a readonly user to access a row and read the last commited data while Informix has an open lock against the data.
Unlike TRANSACTION_READ_UNCOMMITTED which would also accomplish the same but would end up allowing dirty reads. This would lead to us reading data that's potentially either rolledback or never actually commited.

TRANSACTION_CURSOR_STABILITY - Cursor stability will place a lock on a row as it's fetched which ensures that the data doesn't change while the program reads the data.
Documentation for cursor stability can be found here https://www.ibm.com/docs/en/informix-servers/12.10?topic=level-informix-cursor-stability-isolation

Documentation on Informix transaction isolation levels are here https://www.ibm.com/docs/en/informix-servers/12.10?topic=database-informix-environment-variables-informix-jdbc-driver
lfbayer pushed a commit that referenced this issue Sep 15, 2023
@liamsorsby
[#1950] Adds support for TRANSACTION_CURSOR_STABILITY and TRANSACTION…
d15560e 
…_LAST_COMMITTED (#1952)

TRANSACTION_LAST_COMMITTED - This allows a readonly user to access a row and read the last commited data while Informix has an open lock against the data.
Unlike TRANSACTION_READ_UNCOMMITTED which would also accomplish the same but would end up allowing dirty reads. This would lead to us reading data that's potentially either rolledback or never actually commited.

TRANSACTION_CURSOR_STABILITY - Cursor stability will place a lock on a row as it's fetched which ensures that the data doesn't change while the program reads the data.
Documentation for cursor stability can be found here https://www.ibm.com/docs/en/informix-servers/12.10?topic=level-informix-cursor-stability-isolation

Documentation on Informix transaction isolation levels are here https://www.ibm.com/docs/en/informix-servers/12.10?topic=database-informix-environment-variables-informix-jdbc-driver

Co-authored-by: Liam Sorsby <liam.sorsby@skybettingandgaming.com>
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