feat: autocommit sample

[AlisskaPie]

This is one of the samples that demonstrates the difference between autocommit and !autocommit modes

[snippet-bot]

Here is the summary of changes.

You added 1 region tag.

• spanner_enable_autocommit_mode in samples/samples/autocommit.py

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[AlisskaPie]

@c24t could you take a look?

[c24t]

A few comments, but the sample looks good and the test works after making a small change.

I see this sample describes how to enable autocommit, but doesn't show the difference between auto and non-auto behavior. Ideally this sample would show multiple queries each getting a separate txn in autocommit mode and getting combined in a single txn in non-auto mode. And would show manual commit calls.

Not a problem with this sample, but a problem with the library: we should respect django's autocommit setting. When DBAPI is moved out of this library I wouldn't expect users to set connection.autocommit themselves.

[AlisskaPie]

Thank you for your detailed review!

I see this sample describes how to enable autocommit, but doesn't show the difference between auto and non-auto behavior. Ideally this sample would show multiple queries each getting a separate txn in autocommit mode and getting combined in a single txn in non-auto mode. And would show manual commit calls.

I'm sorry, I wasn't correct in a comment and the sample doesn't show the difference between those two modes. I wanted to say that it shows only one of the modes. And for other mode there will be another sample. So users will see that way the difference themselves.

Not a problem with this sample, but a problem with the library: we should respect django's autocommit setting. When DBAPI is moved out of this library I wouldn't expect users to set connection.autocommit themselves.

Just to clarify: I need to use set_autocommit function instead?

[c24t]

And for other mode there will be another sample. So users will see that way the difference themselves.

That sounds fine, let's see how these samples appear in the cloud docs.

Just to clarify: I need to use set_autocommit function instead?

Ideally yes, this would just follow django's autocommit setting and the user wouldn't set this at all. But now since googleapis/python-spanner#160 moved the DBAPI package into python-spanner we might need to move these samples over too, and write different django-specific docs for this spanner-django.

[c24t]

LGTM, but let's check whether this should move into python-spanner with googleapis/python-spanner#160 before merging here.

[tmatsuo]

There is a possible violation for not having product prefix.

snippet-bot thinks it's violating a region tag rule where we should have product prefix. If you change the region tag to spanner_enable_autocommit_mode, the bot will be happy.

[AlisskaPie]

There is a possible violation for not having product prefix.

snippet-bot thinks it's violating a region tag rule where we should have product prefix. If you change the region tag to spanner_enable_autocommit_mode, the bot will be happy.

Thank you! Bot is happy now 🎉

[dinagraves]

The "Create Database" part of the test suite is failing b/c the database already exists.

From the logs:

E           	status = StatusCode.ALREADY_EXISTS
E           	details = "Database already exists: projects/precise-truck-742/instances/google-cloud-python-systest/databases/db-api-transactions-management"

Looks like it's a pre-existing issue unrelated to this PR here.

[dinagraves]

Now that the tests are passing, I only have formatting nits.

[AlisskaPie]

Thanks for your help!

[c24t]

@AlisskaPie can we close this in favor of googleapis/python-spanner#172?

[AlisskaPie]

@AlisskaPie can we close this in favor of googleapis/python-spanner#172?

Yes, sure! Sorry I forgot about it.
Thanks!