From 3dc9a4a2392d033f9d1bd79dd6b6ecea6281a61c Mon Sep 17 00:00:00 2001 From: Mike Bayer Date: Mon, 16 Dec 2019 17:06:43 -0500 Subject: introduce deferred lambdas The coercions system allows us to add in lambdas as arguments to Core and ORM elements without changing them at all. By allowing the lambda to produce a deterministic cache key where we can also cheat and yank out literal parameters means we can move towards having 90% of "baked" functionality in a clearer way right in Core / ORM. As a second step, we can have whole statements inside the lambda, and can then add generation with __add__(), so then we have 100% of "baked" functionality with full support of ad-hoc literal values. Adds some more short_selects tests for the moment for comparison. Other tweaks inside cache key generation as we're trying to approach a certain level of performance such that we can remove the use of "baked" from the loader strategies. As we have not yet closed #4639, however the caching feature has been fully integrated as of b0cfa7379cf8513a821a3dbe3028c4965d9f85bd, we will also add complete caching documentation here and close that issue as well. Closes: #4639 Fixes: #5380 Change-Id: If91f61527236fd4d7ae3cad1f24c38be921c90ba --- lib/sqlalchemy/engine/base.py | 1 + lib/sqlalchemy/engine/create.py | 3 +-- lib/sqlalchemy/engine/default.py | 2 +- lib/sqlalchemy/engine/result.py | 7 +++++-- 4 files changed, 8 insertions(+), 5 deletions(-) (limited to 'lib/sqlalchemy/engine') diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py index ed4133dbb..9ac61fe12 100644 --- a/lib/sqlalchemy/engine/base.py +++ b/lib/sqlalchemy/engine/base.py @@ -1046,6 +1046,7 @@ class Connection(Connectable): distilled_parameters, _EMPTY_EXECUTION_OPTS, ) + try: meth = object_._execute_on_connection except AttributeError as err: diff --git a/lib/sqlalchemy/engine/create.py b/lib/sqlalchemy/engine/create.py index cc138412b..c199c21e0 100644 --- a/lib/sqlalchemy/engine/create.py +++ b/lib/sqlalchemy/engine/create.py @@ -459,8 +459,7 @@ def create_engine(url, **kwargs): .. seealso:: - ``engine_caching`` - TODO: this will be an upcoming section describing - the SQL caching system. + :ref:`sql_caching` .. versionadded:: 1.4 diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py index 51bff223c..f1fc505ac 100644 --- a/lib/sqlalchemy/engine/default.py +++ b/lib/sqlalchemy/engine/default.py @@ -1031,7 +1031,7 @@ class DefaultExecutionContext(interfaces.ExecutionContext): if self.compiled.cache_key is None: return "no key %.5fs" % (now - self.compiled._gen_time,) elif self.cache_hit: - return "cached for %.4gs" % (now - self.compiled._gen_time,) + return "cached since %.4gs ago" % (now - self.compiled._gen_time,) else: return "generated in %.5fs" % (now - self.compiled._gen_time,) diff --git a/lib/sqlalchemy/engine/result.py b/lib/sqlalchemy/engine/result.py index f75cba57d..7df17cf22 100644 --- a/lib/sqlalchemy/engine/result.py +++ b/lib/sqlalchemy/engine/result.py @@ -963,7 +963,10 @@ class Result(InPlaceGenerative): else: return None - make_row = self._row_getter + if scalar and self._source_supports_scalars: + make_row = None + else: + make_row = self._row_getter row = make_row(row) if make_row else row @@ -1016,7 +1019,7 @@ class Result(InPlaceGenerative): if post_creational_filter: row = post_creational_filter(row) - if scalar and row: + if scalar and make_row: return row[0] else: return row -- cgit v1.2.1