Sql server option recompile how to#
Sql server option recompile install#
Sql server option recompile software#
Sql server option recompile code#

This means either a stored procedure, function or a set of ad-hoc statements. The optimizer operates on a batch (unless there’s a recompile, but let’s ignore that for now). Let’s just look at the high-level process. There are several references available on the internals of the query optimizer, so I’m not going to go into a huge amount of detail. Great, but not so great unfortunately when the same principles are applied to the database They don’t work so well in T-SQL and they’re often not compatible with how the query optimizer behaves.Īnd so first, a brief, high-level diversion into how the query optimizer behaves. Removing duplication reduces the chance of bugs, such as if a change is made in one place but not the other, makes maintenance easier and allows future development to be faster by providing existing building blocks.

Sql server option recompile code#

If a similar task is performed in two places, the similarity should be refactored out and a function (module, method) created with the common code a function that is then called from the two places.

Sql server option recompile software#

Modern software engineering principles encourage code reuse. Part of the problem is that this is another place where good software design practices for front end languages aren’t always suitable for database queries. Those in turn lead to poor performance, unhappy users and late nights trying to figure out why that damn database call is timing out again. A confused optimizer generates sub-optimal or even plain wacky execution plans. Now, of course, confusing the optimizer isn’t something we generally want to do. There’s a very easy way to confuse the SQL Server query optimizer: write generic queries intended to be reused as much as possible. Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the 'Applies to' section.How to Confuse the SQL Server Query Optimizer - Simple Talk Skip to content This trace flag must be used with caution because it can increase number of query recompiles which could cost more than savings from better query optimization. You cannot use this trace flag with QUERYTRACEON. Note this trace flag must be ON at runtime. This trace flag does not force parameter peeking. (2) OPTION (RECOMPILE) forces the query to peek parameters and optimize the query for them. It would trigger recompile only when the row count change exceeds the predefined threshold. The query does not need to be compiled for every execution unlike OPTION (RECOMPILE). (1) It uses the same row count threshold as other tables. This trace flag differs from OPTION (RECOMPILE) in two main aspects. The trace flag 2453 allows the benefit of query recompile without OPTION (RECOMPILE). Typically, you can work around this with OPTION (RECOMPILE), which has its own overhead cost. Unlike other user or temporary tables, however, row count change in a table variable does not trigger a query recompile. To get a new query plan, it needs to be recompiled. A hash join may be a better choice under such condition. This query plan can be inefficient if the table variable has millions of rows.

For example, the query may be joining a table variable with nested loop since it is usually more efficient for small number of rows. If this table variable is populated with many rows at runtime, the pre-compiled query plan may no longer be optimal. When you use a table variable in a batch or procedure, the query is compiled and optimized for the initial empty state of table variable.

Sql server option recompile how to#

How to determine the version, edition and update level of SQL Server and its components Use Table 1 in the following article for finding more information about the latest service pack and latest cumulative update:

Sql server option recompile install#

You do not have to install a previous service pack before you install the latest service pack. Our recommendation is to apply the latest service pack and the latest cumulative update for that service pack. Each new service pack contains all the fixes that are in previous service packs, together with any new fixes.