Contents
How use inner join index in SQL Server?
Force using an Index in Inner Join SELECT [closed]
- Table1 has clustered index in t1.Id.
- IndSearch is a nonclustered index with (t1.Id, t1.date and other fields)
- Table2 has a nonclustered index with (t2.id, t2.field3, field4)
- Table1 contains more than 5M rows.
- Table2 contains more than 11M rows.
Do indexes help joins?
Indexes can help improve the performance of a nested-loop join in several ways. The biggest benefit often comes when you have a clustered index on the joining column in one of the tables. The presence of a clustered index on a join column frequently determines which table SQL Server chooses as the inner table.
How to force index on inner joined tables?
FROM foo FORCE INDEX (a) INNER JOIN bar FORCE INDEX (b) ON foo.rel_id = bar.rel_id WHERE foo.status = 1 AND bar.status = 1 The obvious thing would be to create a covering index on rel_id and status of both tables to satisfy the join and where requirement.
How to make join columns indexed in mssqltips?
[Parent] P INNER JOIN [dbo]. [Child] C ON P.ParentID=C.ParentID WHERE P.ParentID=32433 Looking at the explain plan for this query we can see that the SQL Optimizer has to perform an index scan on the Child table even though we are only looking for a specific ParentID from the Parent table.
When to use force index in MySQL 4.0?
From MySQL 4.0.9 on, you can also use FORCE INDEX, which acts like USE INDEX (index_list) but with the addition that a table scan is assumed to be very expensive. In other words, a table scan is used only if there is no way to use one of the given indexes to find rows in the table.
When to use an index in a query?
There are many different scenarios when an index can help the performance of a query and ensuring that the columns that make up your JOIN predicate is an important one. In order to illustrate this point let’s take a look at a simple query that joins the Parent and Child tables.