SQL section of toolbar assumes database supports explain

[drakej]

The SQL section of the toolbar assumes that the database supports explain (probably MySQL is being assumed) and attempts to run the SQL query with explain which results in a 500 error. The toolbar should check the driver before making any such assumptions.

[matthiask]

Postgres also suppors EXPLAIN. Which database are you referring to?

[drakej]

SQL Server but I'm sure there are other examples. For instance Oracle might not have that capability and a lot more than MySQL and Postgres are supported by django through ODBC. In fact I'm using django_pyodbc to connect to SQL Server.

[VidJa]

I'm testing django-debug-toolbar 2.0a1 and ran into this issue while using an Oracle backend
cx_Oracle.DatabaseError: ORA-01036: illegal variable name/number

djdt tries to run : QUERY = 'EXPLAIN SELECT....
while Oracle expects something like 'EXPLAIN PLAN FOR SELECT...' to get the execution plan
Note: I'm far from an oracle expert.

[matthiask]

Django has some support for .explain() since 2017 (django/django@c1c163b), maybe we could leverage this.

Or maybe insert an additional clause here: https://github.com/jazzband/django-debug-toolbar/blob/58f374a426a6b10dcf86554f6d9c71226b4b350f/debug_toolbar/panels/sql/views.py#L47-L55 -- that should work too and is probably a smaller change.

[drakej]

@matthiask Definitely, if Django does the abstraction for you, then that's the way to go.