On Thursday, March 31, 2016 at 9:43:11 AM UTC-4, Mike Bayer wrote:
>
> this is more of a Postgresql optimization question so I dont have any
> insight on that.
>
FWIW, I generally handle these types of "optimize postgres" queries using a
function to apply the filter - like this:
def filter_Table_field_a(query, value, optimize=False):
"""Table.field_a has a partial index on a substring of field_a
it will only be consulted by the planner if used in a query."""
query = query.filter(model.core.Table.field_a = value, )
if optimize:
query = query.filter(func.substr(model.core.Table.field_a, 0,
5)) == value[:4], )
return query
def filter_Table_field_b(query, value, optimize=False):
"""Table.field_b has a uniqueindex on a lower(field_b);
it will only be consulted by the planner if used in a query."""
query = query.filter(model.core.Table.field_b = value, )
if optimize:
query = query.filter(func.lower(model.core.Table.field_b)) ==
value.lower(), )
return query
q = s.query(TableA)
q = filter_Table_field_b(q, 'hello', optimize=True)
I toggle the optimization, because some queries will perform better with it
off.
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