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Index Scans and Table Scans

There are several things that you can do to improve performance by throwing more hardware at the problem, but usually the place you get the most benefit from is when you tune your queries. One common problem that exists is the lack of indexes or incorrect indexes and therefore SQL Server has to process more data to find the records that meet the queries criteria. These issues are known as Index Scans and Table Scans.

External Article

Purging Data from a Large Table in SQL Server

Purging data from a table is a common database maintenance task to prevent it from growing too large or to stay in compliance with data retention. When dealing with small amounts of data, this can be accomplished by a simple delete with no issues; however, with larger tables, this task can be problematic. Deleting records requires a lock that can block other processes from writing or even reading the data (depending on your isolation level). In this article I will share a technique I have used to work with some very large tables.

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Question of the Day

Estimated Rows

I have two calls to the GENERATE_SERIES TVF in this code: 

SELECT   TOP 10 gs.value
FROM     GENERATE_SERIES(1, 10) AS gs
ORDER BY NEWID ()
OPTION (RECOMPILE);
go
DECLARE @a int = 10;
SELECT   TOP (@a) gs.value
FROM     GENERATE_SERIES(1, @a) AS gs
ORDER BY NEWID ()
OPTION (RECOMPILE);
In the actual query plans, what is the estimated number of rows for each batch in SQL Server 2022?

See possible answers