In this blog post, we will dive into the world of active sessions and requests in SQL Server. We will learn how to extract valuable information about these sessions using a T-SQL query. Don’t worry if you’re new to SQL Server or T-SQL, as we will break down the query step by step.
Understanding Active Sessions
When users interact with a SQL Server database, they establish sessions. These sessions represent the connection between the user and the database server. Within each session, users can send requests to the server, such as executing queries or performing updates.
The SQL Query to find Active Sessions
Let’s take a look at the T-SQL query we will be discussing:
Breaking Down the Query
- Retrieving Session Information:
SPID: The Session ID representing a unique identifier for each session.
original_login_name: The original login name used to establish the session.
status: The current status of the session.
Blk by: The ID of the blocking session, if any.
command: The command being executed in the session.
Database: The name of the database associated with the session.
- Analyzing Request Details:
Object ID: The ID of the object (e.g., table, stored procedure) involved in the current request.
% Done: The percentage of completion for the current request.
Duration: The duration of the request in hours, minutes, and seconds.
ETA (Min): The estimated time of completion for the request in minutes.
input stream/text: The input stream or text of the request.
Executing_sql_statement: The SQL statement being executed.
- Monitoring Wait Times and Resources:
wait_resource: The resource causing the request to wait.
wait_time (sec): The amount of time the request has been waiting, in seconds.
last_wait_type: The type of the most recent wait the request encountered.
- Tracking Session and Request Timings:
login_time: The time when the session was established.
last_request_start_time: The start time of the last request made in the session.
last_request_end_time: The end time of the last request made in the session.
- Additional Information:
host_name: The name of the machine from which the session originates.
program_name: The name of the program associated with the session (including SQL Agent job name if applicable).
open_transaction_count: The number of open transactions in the session.
transaction_isolation_level: The isolation level of the session’s transactions.
cpu_time: The amount of CPU time consumed by the request.
logical_reads: The number of reads, writes, and logical reads performed by the request.
lock_timeout: The timeout setting for locks in the session.
row_count: The number of rows affected by the request.
Understanding and monitoring active sessions and requests in SQL Server is crucial for database administrators and developers. By using the provided T-SQL query, we can gather valuable insights into ongoing activities, performance metrics, and potential issues within the server.
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