Gordo programming-Small Talk about the optimization analysis of SQL statements

In SQL Server Big Data query, avoid the query efficiency slow, discard hardware reasons and version reasons, only from the perspective of SQL statement analysis.

I. SQL statement performance is not standard, the main reasons for a few points:

1. Index not built, search results in full table scan

2. Indexes are built, but index invalidation is caused by non-indexing, and then full table scan.

3. No valid indexed view

Two. SQL statement optimization

1. Analyze and compare execution time plan reads

(1) View execution time and CPU elapsed time and query operation on I/O

I. Execute a SQL with more than 4 million data first

Set Statistics Time,io

 on Select *  from

Set Statistics off

II. Open your query after the message inside can see.

Gordo programming-Small Talk about the optimization analysis of SQL statements