On 2023-07-01 00:06, Tom Lane wrote:
Seino Yuki <sein...@oss.nttdata.com> writes:
I also thought that using SPI_start_transaction would be more readable
than using SPI_commit/SPI_rollback to implicitly start a transaction.
What do you think?
I think you're trying to get us to undo commit 2e517818f, which
is not going to happen. See the threads that led up to that:
Discussion:
https://postgr.es/m/3375ffd8-d71c-2565-e348-a597d6e73...@enterprisedb.com
Discussion: https://postgr.es/m/17416-ed8fe5d7213d6...@postgresql.org
It looks to me like you can just change the transaction property
settings immediately after SPI_start_transaction if you want to.
Compare this bit in SnapBuildExportSnapshot:
StartTransactionCommand();
/* There doesn't seem to a nice API to set these */
XactIsoLevel = XACT_REPEATABLE_READ;
XactReadOnly = true;
Also look at the implementation of SPI_commit_and_chain,
particularly RestoreTransactionCharacteristics.
regards, tom lane
Thanks for sharing past threads.
I was understand how SPI_start_transaction went no-operation.
I also understand how to set the transaction property.
However, it was a little disappointing that the transaction property
could not be changed only by SPI commands.
Of course, executing SET TRANSACTION ISOLATION LEVEL with SPI_execute
will result in error.
---
SPI_execute("SET TRANSACTION ISOLATION LEVEL SERIALIZABLE", false, 0);
(Log Output)
ERROR: SET TRANSACTION ISOLATION LEVEL must be called before any query
CONTEXT: SQL statement "SET TRANSACTION ISOLATION LEVEL SERIALIZABLE"
---
Thanks for answering.
