What is an outer apply?
OUTER APPLY returns both rows that produce a result set, and rows that do not, with NULL values in the columns produced by the table-valued function. OUTER APPLY work as LEFT OUTER JOIN.
What is the difference between cross Outer apply and joins in T SQL?
JOIN operations in SQL Server are used to join two or more tables. On the other hand, OUTER APPLY retrieves all the records from both the table valued function and the table, irrespective of the match. In this article we will take a look at the CROSS APPLY and OUTER APPLY operators.
When to use clustered index or table scan?
Here we can see that this query is doing a Table Scan, so when a table has a Clustered Index it will do a Clustered Index Scan and when the table does not have a clustered index it will do a Table Scan. Since this table does not have a clustered index and there is not a WHERE clause SQL Server scans the entire table to return all rows.
Why does the SQL Server forcescan hint exist?
Which it chooses will depend on the parameters supplied to the query and the cardinality estimates of the rows that will return (which will in turn rely on the presence of statistics and how up-to-date they are).
Why do I need to do an index scan in SQL Server?
An index scan or table scan is when SQL Server has to scan the data or index pages to find the appropriate records. A scan is the opposite of a seek, where a seek uses the index to pinpoint the records that are needed to satisfy the query. The reason you would want to find and fix your scans is because they generally require more I/O
How to use outer apply in SQL Server?
The key is how you constructed your ORDER BY clause along with the search conditions. If there’s any row that matches x.sedolcode = b.breakdowncode then you want to take that row, otherwise you go to the next condition. With the right indexes we can avoid the sort by splitting up the APPLY.