Is there any scenario in a sane world where a transaction ceases to be in scope just because it went into an error state? I'd have expect the client to send an explicit ROLLBACK when they realize a transaction is in an error state, not for the server to end it and just notify the client. This is how psql appears to the end user.
postgres=# begin;
BEGIN
postgres=*# bork;
ERROR: syntax error at or near "bork"
LINE 1: bork;
^
postgres=!# select 1;
ERROR: current transaction is aborted, commands ignored until end of transaction block
postgres=!# rollback;
ROLLBACK
postgres=# select 1;
?column?
----------
1
(1 row)
postgres=#
Every DBMS handles errors slightly differently. In a sane world you shouldn't ever ignore errors from the database. It's unfortunate to hear that a Python MySQL client library had a bug that failed to expose errors properly in one specific situation 16 years ago, but that's not terribly relevant to today.
Postgres behavior with errors isn't even necessarily desirable -- in terms of ergonomics, why should every typo in an interactive session require me to start my transaction over from scratch?
No, the situation described upthread is about a deadlock error, not a typo. In MySQL, syntax errors throw a statement-level error but it does not affect the transaction state in any way. If you were in a transaction, you're still in a transaction after a typo.
With deadlocks in MySQL, the error you receive is "Deadlock found when trying to get lock; try restarting transaction" i.e. it specifically tells you the transaction needs to start over in that situation.
In programmatic contexts, transactions are typically represented by an object/struct type, and a correctly-implemented database driver for MySQL handles this properly and invalidates the transaction object as appropriate if the error dictates it. So this isn't really even a common foot-gun in practical terms.
Comments
Is there any scenario in a sane world where a transaction ceases to be in scope just because it went into an error state? I'd have expect the client to send an explicit ROLLBACK when they realize a transaction is in an error state, not for the server to end it and just notify the client. This is how psql appears to the end user.
Every DBMS handles errors slightly differently. In a sane world you shouldn't ever ignore errors from the database. It's unfortunate to hear that a Python MySQL client library had a bug that failed to expose errors properly in one specific situation 16 years ago, but that's not terribly relevant to today.
Postgres behavior with errors isn't even necessarily desirable -- in terms of ergonomics, why should every typo in an interactive session require me to start my transaction over from scratch?
That part would hold even for the MySQL auto-rollback implied above.
No, the situation described upthread is about a deadlock error, not a typo. In MySQL, syntax errors throw a statement-level error but it does not affect the transaction state in any way. If you were in a transaction, you're still in a transaction after a typo.
With deadlocks in MySQL, the error you receive is "Deadlock found when trying to get lock; try restarting transaction" i.e. it specifically tells you the transaction needs to start over in that situation.
In programmatic contexts, transactions are typically represented by an object/struct type, and a correctly-implemented database driver for MySQL handles this properly and invalidates the transaction object as appropriate if the error dictates it. So this isn't really even a common foot-gun in practical terms.