Use DataQuery in Compiler instead of render DECLARE in DBAPI

[LuckySting]

Problem

Now rendering of a DECLARE clause happens in the Cursor.execute, which is bad because of the following.

1. At the execution stage the information about the bound variable is incomplete, it impossible to use powerful SQLAlchemy type engine, so we able only guess about the bound variable type by the value.
2. It becomes harder to change the Cursor implementation, because you have to implement the DECLARE rendering again.
3. It is impossible to use SQLAlchemy caching of rendered queries, because the query becomes completely rendered right before the execution.

Suggested solution

Move rendering of a DECLARE clause to the Compilation stage, use information about the table and SQLAlchemy Type engine to determine types.

Workaround

It's impossible to render the DECLARE clause at the Compilation stage, because of "postcompile" variables. Instead it is possible to determine types of the bound variables right before the execution and pass it to the DataQuery.

Results

All tests are passed, even those that were previously failed.

[rekby]

It is difficult to read and understand many operations in one line.
Better to split code for simpler steps - for easy read in future.

parameter_names_sets = [set(parameters_dict.keys()) for parameters_dict in post_compile_parameters]
common_keys = set.intersection(parameter_names_sets)

post_compile_parameters_new = {}
for k in common_keys:
    values = [dic[k] for dic in post_compile_parameters]
    post_compile_parameters_new[k] = values
post_compile_parameters = post_compile_parameters_new

[LuckySting]

Tried to make code easier to read

[rekby]

What about:
use dataclasses with default values?

Similar to ydb sdk

[LuckySting]

Done

[rekby]

It will be great to explicit declare all public interface in all (similar to ydb sdk, topics), may be later - before release.

And hide all modules as implementation details to private (_prefix) files if them already imported to root of namespace.

[LuckySting]

I think that we should do it before the release

[rekby]

ydb has own object "Operation" and YdbOperation may confuse to understand code.

What about rename the class to YdbQuery (because the class always use for queries)?

And move is_ddl above parameters_types with default value False, for user can omit the parameter while make most queries (DML query with params)

[LuckySting]

You're right, done