A case of SQL tuning in SQL Server
Analysis 2:
There are a large number of multi-table joins in this SQL. Because the algorithm of statistical information of MSSQL engine is single, when dealing with a large number of cascading joins, the actual data may seriously deviate from the statistical information.
There is a serious inconsistency between Actual Rows and Estimated Rows in the connection, which becomes more serious as the number of join tables increases:
