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author | Mike Bayer <mike_mp@zzzcomputing.com> | 2017-04-12 16:28:55 -0400 |
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committer | Mike Bayer <mike_mp@zzzcomputing.com> | 2017-04-12 16:28:55 -0400 |
commit | e3b4042c9c5f05e1354dc5ab87803026a757fcfc (patch) | |
tree | 65ed1f28a3922efae31cf47167ae5f709cb36ebd | |
parent | 755da1797432ee98dd3d1d309026a21529b45f75 (diff) | |
download | sqlalchemy-e3b4042c9c5f05e1354dc5ab87803026a757fcfc.tar.gz |
- typos and formatting
Change-Id: I88a304e315b68eded31e91da04265da583bc417b
-rw-r--r-- | doc/build/faq/performance.rst | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/doc/build/faq/performance.rst b/doc/build/faq/performance.rst index 61c0d6ea2..d9684a44c 100644 --- a/doc/build/faq/performance.rst +++ b/doc/build/faq/performance.rst @@ -483,11 +483,11 @@ is occurring: mailing list support is at: http://www.sqlalchemy.org/support.html#mailinglist The cache works by creating a cache key that can uniquely identify the -combination of a specific **dialect** and a specific **Core SQL expression**. +combination of a specific dialect and a specific Core SQL expression. A cache key that already exists in the cache will reuse the already-compiled SQL expression. A cache key that doesn't exist will create a *new* entry in the dictionary. When this dictionary reaches the configured threshhold, -the LRU cache will *trim the size* of the cache back down by a certain percentage. +the LRU cache will trim the size of the cache back down by a certain percentage. It is important to understand that from the above, **a compiled cache that is reaching its size limit will perform badly.** This is because not only @@ -498,7 +498,7 @@ its size back down. The primary reason the compiled caches can grow is due to the **antipattern of using a new Engine for every operation**. Because the compiled cache must key on the :class:`.Dialect` associated with an :class:`.Engine`, -calling :func`.create_engine` many times in an application will establish +calling :func:`.create_engine` many times in an application will establish new cache entries for every engine. Because the cache is self-trimming, the application won't grow in size unbounded, however the application should be repaired to not rely on an unbounded number of :class:`.Engine` |