Potential Issue with exact on Fields

[Alex Rothberg]

The docs indicate that exact=True means no post filtering is needed:

shillelagh/src/shillelagh/fields.py

Lines 121 to 125 in 97197bd

     Finally, the field also indicates that the filtering is exact, and no 
     post-filtering is needed to be done by the backend. In some cases it's 
     useful to have adapters perform an initial coarse filtering (say, at 
     the daily level), and have the backend perform the final fine filtering 
     (say, at the second level), to simplify the logic in the adapter. 

however that value seems to be passed to apsw:

shillelagh/src/shillelagh/backends/apsw/vt.py

Line 305 in 14579e4

 constraints_used.append((filter_index, column_type.exact)) 

and the docs for that indicate that False means sqlalachemy won't do any double checking :

shillelagh/src/shillelagh/typing.py

Lines 16 to 17 in 14579e4

 #         By default SQLite will check what you return. If you set the boolean 
 #         to False then SQLite won’t do that double checking. 

(also consistent with the apsw docs page)

Am I misunderstanding something here?

[Alex Rothberg]

Ok this might just be an issue with the apsw docs as from sqlite docs:

If aConstraintUsage[].omit is true, then the constraint is assumed to be fully handled by the virtual table and might not be checked again by the byte code.

[Alex Rothberg]

I filed this upstream: rogerbinns/apsw#328

[Alex Rothberg]

Closing this for now as I think the issue is entirely upstream in apsw.