On Mon, Jan 20, 2020, at 2:26 PM, Mike Bayer wrote:
>
>
> On Mon, Jan 20, 2020, at 1:46 PM, Andrei Pashkin wrote:
>> Hello!
>>
>> I wonder - is it possible to parametrize where expression as a whole like
>> that:
>> select([users_table]).where(bindparam('criteria'))
>
> nope, that's not how SQL bound parameters work.
>
>>
>> ?
>>
>> My use case is that I'd like to pre-compile a complex SQLAlchemy expression
>> to avoid redundant computations and achieve the same effect as Bakery has
>> for the ORM but only for a low-level SA expression.
>
> Wait for SQLAlchemy 1.4, this will have that feature.
noting also, there is a cache feature for Core statements right now, you just
have to use the same statement object each time, since currently the statement
object itself is the cache key. See
https://docs.sqlalchemy.org/en/13/core/connections.html?highlight=compiled_cache#sqlalchemy.engine.Connection.execution_options.params.compiled_cache
. This is what BakedQuery ultimately uses also and the unit of work uses it
also.
In 1.4 all statements will be able to generate a separate cache key that is
repeatable for multiple instances of the same statement.
>
>
>
>
>>
>>
>>
>>
>> --
>> SQLAlchemy -
>> The Python SQL Toolkit and Object Relational Mapper
>>
>> http://www.sqlalchemy.org/
>>
>> To post example code, please provide an MCVE: Minimal, Complete, and
>> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
>> description.
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>
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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