Hi,
If you got slowness complaint from customer, you need to monitor SQL Server Instance and database which sql is consuming a lots of resource.
SQL Server DBA should monitor database everytime and if there are many sqls which is running long execution time or consuming a lots of IO resource then it should be reported to the developer and developer and dba should examine these sqls.
You can find TOP 50 IO queries in SQL Server database with following query.
select
q.[text],
SUBSTRING(q.text, (highest_cpu_queries.statement_start_offset/2)+1,
((CASE highest_cpu_queries.statement_end_offset
WHEN -1 THEN DATALENGTH(q.text)
ELSE highest_cpu_queries.statement_end_offset
END - highest_cpu_queries.statement_start_offset)/2) + 1) AS statement_text,
highest_cpu_queries.total_worker_time,
highest_cpu_queries.total_logical_reads,
highest_cpu_queries.last_execution_time,
highest_cpu_queries.execution_count,
q.dbid,
q.objectid,
q.number,
q.encrypted,
highest_cpu_queries.plan_handle
from
(select top 50
qs.last_execution_time,
qs.execution_count,
qs.plan_handle,
qs.total_worker_time,
qs.statement_start_offset,
qs.statement_end_offset,
qs.total_logical_reads
from
sys.dm_exec_query_stats qs
order by qs.total_worker_time desc) as highest_cpu_queries
cross apply sys.dm_exec_sql_text(plan_handle) as q
order by highest_cpu_queries.total_logical_reads desc;
Do you want to learn Microsoft SQL Server DBA Tutorials for Beginners, then read the following articles.
https://ittutorial.org/sql-server-tutorials-microsoft-database-for-beginners/