I’m trying to understand how SQL processing works and I have some questions about different execution methods.
First question: From what I understand, when you send a single SQL command like SELECT * FROM customers or UPDATE products SET price = 100, each one gets processed individually by the database server. But when you group multiple commands together in a batch (separated by GO statements), they all get compiled into one execution plan together. Is this the main difference - that individual commands are compiled separately while batched commands are compiled as one unit?
Second question: I think stored procedures are precompiled and saved in the database, while batches need to be compiled each time they run. Is this correct?
Any help explaining these concepts would be great. Thanks!
yep, you’re on the right track! individual sql cmds each get their own plan, even in a batch. batching mainly helps with reducing network trips which is a plus. and yeah, stored procedures being precompiled def gives them a performance edge!
Your understanding has some accuracy but needs clarification on the compilation aspect. Individual SQL statements within a batch are actually compiled separately, not together as a single unit. The GO statement is primarily a batch separator used by client tools like SQL Server Management Studio to divide commands into separate batches for transmission.
Regarding stored procedures, while they do have compilation advantages, modern database systems employ plan caching mechanisms that store execution plans for frequently used ad-hoc queries as well. This means that repeated execution of the same parameterized query can benefit from cached plans without requiring stored procedures.
The primary benefits of batching relate to reduced network round trips and transaction management rather than compilation efficiency. Each statement still generates its own execution plan, but you save the overhead of multiple client-server communications. For optimal performance, focus on proper indexing and query design rather than solely relying on batching or stored procedures.
hmm interesting questions! i’m curious though - have you actually tested the performance differance between these approaches in your own environment? also, what database system are you working with specifically since the behavior can vary quite a bit between sql server, mysql, postgres etc. would love to hear about any real-world scenarios where you’ve noticed these compilation differences affecting your query performance!