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Date: Mon, 12 Apr 2021 19:16:32 +0100
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To: PHP internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] Allow commit() without transaction?
From: davidgebler@gmail.com (David Gebler)

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Good example of why commit() should throw an exception, I think - it's just
alerted the developer that executing their previous statement has caused an
implicit commit. Imagine if they had a complex sequence of queries and
didn't realise they'd added one which ended the transaction, thinking they
could safely rollback later if necessary. The exception catches this early
on.

Regards,
David Gebler

On Mon, Apr 12, 2021 at 1:07 PM Nikita Popov <nikita.ppv@gmail.com> wrote:

> Hi internals,
>
> Since PHP 8.0, PDO fully supports MySQL transactions -- this means that
> inTransaction() will report the actual connection transaction state, as
> opposed to an emulated (incorrect) transaction state tracked by PDO itself.
>
> This has two primary effects: PDO is aware of transactions created without
> going through it's APIs (e.g. by manually issuing a START TRANSACTION
> query) and is aware of implicit commits (see
> https://dev.mysql.com/doc/refman/8.0/en/implicit-commit.html for more
> information).
>
> The latter means that code like
>
> $pdo->beginTransaction()
> $pdo->exec('DROP TABLE foobar'); // Implicitly commits transaction
> $pdo->exec('DROP TABLE barfoo'); // Transaction not active anymore
> $pdo->commit(); // Throws because no transaction active
>
> now throws an exception, because commit() is called without an active
> transaction. It's possible to use if ($pdo->inTransaction())
> $pdo->commit(); if you don't care about the lack of active transaction.
>
> I believe this behavior is correct, but I could see an argument made in
> favor of always allowing commit() calls (but not rollBack() calls) even if
> there is no active transaction. That would change the meaning of commit()
> from "commit an active transaction" towards "commit if an active
> transaction exists".
>
> Any opinions on that?
>
> Regards,
> Nikita
>

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