Changes between Initial Version and Version 1 of Ticket #35918
- Timestamp:
- Nov 18, 2024, 11:06:02 PM (5 days ago)
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Ticket #35918 – Description
initial v1 1 1 (This refactor is motivated by an ongoing experiment to integrate async cursor work into the ORM, by simplifying some cursor management) 2 2 3 In ` `django.cdb.models.sql.compiler.Compiler.execute_sql``, we can pass in the following result types: ``SINGLE``, ``MULTI``, ``NO_RESULTS``, and ``CURSOR``.3 In `django.cdb.models.sql.compiler.Compiler.execute_sql`, we can pass in the following result types: `SINGLE`, `MULTI`, `NO_RESULTS`, and `CURSOR`. 4 4 5 ` `execute_sql``'s docstring to that effect does not reflect this.5 `execute_sql`'s docstring to that effect does not reflect this. 6 6 7 - ` `SINGLE`` returns a single row. It closes the cursor it uses to query.8 - ` `MULTI`` returns many rows (wrapped in a cursor iterator). This either closes the cursor it uses to query, or returns an iterator that takes ownership of the cursor to close the cursor once reading of all the results are done.9 - ` `NO_RESULTS`` returns nothing. It closes the cursor it uses to query.10 - ` `CURSOR`` returns the cursor, without closing the cursor, effectively making the caller in charge of closing the cursor7 - `SINGLE` returns a single row. It closes the cursor it uses to query. 8 - `MULTI` returns many rows (wrapped in a cursor iterator). This either closes the cursor it uses to query, or returns an iterator that takes ownership of the cursor to close the cursor once reading of all the results are done. 9 - `NO_RESULTS` returns nothing. It closes the cursor it uses to query. 10 - `CURSOR` returns the cursor, without closing the cursor, effectively making the caller in charge of closing the cursor 11 11 12 12 13 ` `CURSOR`` returns an unclosed cursor that has to be manage by the caller. In practice, though, apart from a single test usage, Django's codebase currently only uses ``CURSOR`` to do one thing: get the number of rows, then close the cursor.13 `CURSOR` returns an unclosed cursor that has to be manage by the caller. In practice, though, apart from a single test usage, Django's codebase currently only uses `CURSOR` to do one thing: get the number of rows, then close the cursor. 14 14 15 15 To simplify cursor resource management, I have a two-pronged proposal: 16 - a new result type, ` `ROW_COUNT``, returns the rows and closes the cursor for you. This covers all non-test usage of ``CURSOR`` in Django currently.17 - ` `CURSOR`` is renamed to ``LEAK_CURSOR``, as a way to more strongly indicate that you are now in charge of the cursor16 - a new result type, `ROW_COUNT`, returns the rows and closes the cursor for you. This covers all non-test usage of `CURSOR` in Django currently. 17 - `CURSOR` is renamed to `LEAK_CURSOR`, as a way to more strongly indicate that you are now in charge of the cursor 18 18 19 19 Main point here is to reduce the number of places an open cursor might come into play.