gh-79579: Update sqlite3.Cursor.rowcount for all data-modifying queries

[erlend-aasland]

Resolves #79579

[erlend-aasland]

@animalize, would you like to review this?

[bedevere-bot]

🤖 New build scheduled with the buildbot fleet by @erlend-aasland for commit e82adb8 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

[erlend-aasland]

cc. @zzzeek

[ghost]

Before this change, this code prints-1.
After this change, it prints 1, it seems wrong.
IMO #10913 's method is clear, it skips the leading comments when detecting dml statement.

import sqlite3
cursor = sqlite3.connect(":memory:", isolation_level=None).cursor()

cursor.execute("""CREATE TABLE foo (id INTEGER)""")

values = ((1,), (2,), (3,))
cursor.executemany("""INSERT INTO foo (id) VALUES (?)""", values)

cursor.execute("vacuum")
print(cursor.rowcount)

[erlend-aasland]

After this change, it prints 1, it seems wrong.

It seems wrong is a bit vague. Would you mind to elaborate?

Actually, this will be fixed by #93520 (which currently also encompasses this change), so it does not matter. IMO, trying to parse comments is fragile approach, and I would not recommend such a solution.

[ghost]

It seems wrong is a bit vague. Would you mind to elaborate?

In .rowcount doc:

As required by the Python DB API Spec, the rowcount attribute “is -1 in case no executeXX() has been performed on the cursor or the rowcount of the last operation is not determinable by the interface”.

IMHO, using sqlite3_stmt_readonly() to detect statement type is unreliable. It return false when the database may be modified, this may include some irrelevant statements, then give a suprise in some cases, for example:
https://bugs.python.org/issue28518
So I suggest not to use sqlite3_stmt_readonly() to detect statement type. I saw you used it in 878e726, but it's only an error message, not involving precise data.

[ghost]

IMO, trying to parse comments is fragile approach, and I would not recommend such a solution.

Yes, but IMO this is the most reliable way.
If just skip the leading comments and whitespaces, it shouldn't be very complicated.

[erlend-aasland]

It return false when the database may be modified, this may include some irrelevant statements, then give a suprise in some cases, for example:
https://bugs.python.org/issue28518

I don't think that is a valid comparison. We're not talking about transaction control here; just setting .rowcount or not. IMO, this is the best way. I don't see any problems with DB API here.

[erlend-aasland]

On hold till #93421 is resolved.

[erlend-aasland]

Closing in favour of #93623