Prevent nested transactions. #3789
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googlebot
added
the
cla: yes
| @@ -79,6 +79,7 @@ def __init__(self, database_id, instance, ddl_statements=(), pool=None): | |||
| self.database_id = database_id | |||
| self._instance = instance | |||
| self._ddl_statements = _check_ddl_statements(ddl_statements) | |||
| self._transaction_running = False | |||
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@vkedia If this works for you, I will merge it. |
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FWIW, this seems like a bunch of fragile mechanism to prevent (incompletely) a very rare kind of user error. |
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Yeah, I have a hard time seeing a situation where a user does this by accident, even before this check was in place. |
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There are databases that support nested transactions so it is not all the inconcievable that some user might expect cloud spanner to behave in the same way. Before this check, they would start using nested transactions and nothing would fail since as far as spanner is concerned these are independent transactions. They might incorrectly assume that this is actually working as a nested transaction. That is why it is worthwhile to have this check even if it does not work in all cases. |
Fixes #3476.
/cc @vkedia
Note that there is still some limitation on how much we can stop people from firing a blowgun into their foot. Someone could conceivably have two database objects, for example. But this is well within the limits of what we need to check for, in my opinion, especially given that you have to do pretty unusual stuff to even get this far.