Sql updating a query result set

posted by | Leave a comment

For a SQL batch request the worker that picks up that task will execute the entire SQL batch (every statement).This should settle the often asked question whether statements in a SQL batch (= 1) and create sub-tasks, each sub-task goes through exactly the same cycle: it is created as PENDING and a worker must pick it up and execute it (a different worker from the SQL batch worker, that is by definition occupied! The lists and state of workers inside SQL Server can be seen by querying .Certain individual statements inside the batch may execute with parallelism (often referred to as DOP, Degree Of Parallelism) and in their case the task will spawn new sub-tasks for executing in parallel.

sql updating a query result set-48sql updating a query result set-6sql updating a query result set-76sql updating a query result set-30

Compilation of T-SQL batches does not result in executable code similar to native CPU instructions and not even similar to CLI instructions or JVM bytecode, but instead results primarily in data access plans (or query plans).Add to this that the JOIN can be done using various strategies (nested loop, hash, merge) and you’ll see why optimization is such an important concept in SQL.SQL Server uses a cost based optimizer, meaning that it will consider all (or at least many) of the possible alternatives, try to make an educated guess about the cost of each alternative, and then choose the one with the lowest cost.The application can use one of the several client-side implementations of the protocol: the CLR managed Sql Client, Ole DB, ODBC, JDBC, PHP Driver for SQL Server or the open source Free TDS implementation.The gist of it is that when your application whats the database to do anything it will send a request over the TDS protocol.

Leave a Reply

Pantyhose chat xxx