Lock Timeout:
Lock timeout mean, one user is accessing data same
time if other one user wants to access it, it will lock wait timeout for the
second user and after some time it will be time out for the second user.
How
to resolve them?
Setting
the SQL Server Lock_Timeout Interval
If you don't want to wait forever for a lock to become
available, SQL Server offers the lock_timeout interval, which case is set as
follows:
SET LOCK_TIMEOUT {Millisecond}
You specify the timeout interval in milliseconds, i.e.
for a 10 second interval use the below code:
SET LOCK_TIMEOUT 10000
Setting
the SQL Server Lock_Timeout Interval with Query Re-attempt Logic
We can use the lock_timeout to check for blocking that
exceeds a certain limit and instead of failing the process due to the
lock_timeout or waiting indefinitely for the locks to become free, we can set a
delay and re-attempt the command again.
This could also be helpful for deadlock situations.
SQL
Timeout:
Increase the timeout you allow the query to run before
a timeout is thrown i.e.
cmd.CommandTimeout = 180; // number of seconds
The Optimation steps would be:
1) Check if the table contains redundancy, if so
normalize it
2) Use Index for speed search.
3) Use pagination to display. So that no needs to
fetch that much record in a single query
4) If your business logic depends on that much records
(some calculation of something), use a stored procedure to do that or use
appropriate aggregate queries.
5) Repository pattern with identity mapper is a good
way to reuse the previously obtained records.
Note:
One of the first lines of defense in determining the
causes of database slowdowns is to use sp_who2. sp_who2 shows all the sessions
that are currently established in the database. These are denoted as SPID‘s, or
Server process Id’s.
EXEC sp_who2
There are four main things to look for when diagnosing
slowdowns.
1) Blocking
2) High CPU usage
3) High IO usage
4) Multiple entries for the same SPID representing
parallelism
Reference Links:
https://blog.sqlauthority.com/2013/01/28/sql-server-basic-explanation-of-set-lock_timeout-how-to-not-wait-on-locked-query/
https://www.mssqltips.com/sqlservertip/6279/prevent-sql-server-blocking-using-locktimeout/
https://www.mssqltips.com/sqlservertip/6279/prevent-sql-server-blocking-using-locktimeout/