January 2018 – Welcome to our SQL World!

Connection Counts By IP Address

This query returns count of SQL connections by IP address. This helps you figure where your database load is coming from and verifies connectivity from other machines.

SQL Query

SELECT ec.client_net_address, es.[program_name], es.[host_name], es.login_name,
COUNT(ec.session_id) AS [connection count]
FROM sys.dm_exec_sessions AS es WITH (NOLOCK)
INNER JOIN sys.dm_exec_connections AS ec WITH (NOLOCK)
ON es.session_id = ec.session_id
GROUP BY ec.client_net_address, es.[program_name], es.[host_name], es.login_name 
ORDER BY ec.client_net_address, es.[program_name] OPTION (RECOMPILE);

Output

References

https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-exec-sessions-transact-sql

https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-exec-connections-transact-sql

Helpful Queries for Troubleshooting

Buffer Usage By Object

This query returns buffer usage by object (table, index) in the current database. This query tells you what tables and indexes are using the most memory in the buffer cache. It can help identify possible candidates for data compression.

SQL Query

SELECT OBJECT_NAME(p.[object_id]) AS [Object Name], p.index_id,
CAST(COUNT(*)/128.0 AS DECIMAL(10, 2)) AS [Buffer size(MB)], 
COUNT(*) AS [BufferCount], p.[Rows] AS [Row Count],
p.data_compression_desc AS [Compression Type]
FROM sys.allocation_units AS a WITH (NOLOCK)
INNER JOIN sys.dm_os_buffer_descriptors AS b WITH (NOLOCK)
ON a.allocation_unit_id = b.allocation_unit_id
INNER JOIN sys.partitions AS p WITH (NOLOCK)
ON a.container_id = p.hobt_id
WHERE b.database_id = CONVERT(int, DB_ID())
AND p.[object_id] > 100
AND OBJECT_NAME(p.[object_id]) NOT LIKE N'plan_%'
AND OBJECT_NAME(p.[object_id]) NOT LIKE N'sys%'
AND OBJECT_NAME(p.[object_id]) NOT LIKE N'xml_index_nodes%'
GROUP BY p.[object_id], p.index_id, p.data_compression_desc, p.[Rows]
ORDER BY [BufferCount] DESC OPTION (RECOMPILE);

Output

References

https://docs.microsoft.com/en-us/sql/relational-databases/system-catalog-views/sys-allocation-units-transact-sql

https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-os-buffer-descriptors-transact-sql

https://docs.microsoft.com/en-us/sql/relational-databases/system-catalog-views/sys-partitions-transact-sql

Helpful Queries - General

Database Properties

This query returns database properties for all the databases on the instance. The properties include recovery model, log reuse wait description, log file size, log usage size, compatibility level, page verify option, auto_shrink, auto_close etc.

SQL Query

SELECT db.[name] AS [Database Name], SUSER_SNAME(db.owner_sid) AS [Database Owner], db.recovery_model_desc AS [Recovery Model],
db.state_desc, db.containment_desc, db.log_reuse_wait_desc AS [Log Reuse Wait Description],
CONVERT(DECIMAL(18,2), ls.cntr_value/1024.0) AS [Log Size (MB)], CONVERT(DECIMAL(18,2), lu.cntr_value/1024.0) AS [Log Used (MB)],
CAST(CAST(lu.cntr_value AS FLOAT) / CAST(ls.cntr_value AS FLOAT)AS DECIMAL(18,2)) * 100 AS [Log Used %],
db.[compatibility_level] AS [DB Compatibility Level],
db.is_mixed_page_allocation_on, db.page_verify_option_desc AS [Page Verify Option],
db.is_auto_create_stats_on, db.is_auto_update_stats_on, db.is_auto_update_stats_async_on, db.is_parameterization_forced,
db.snapshot_isolation_state_desc, db.is_read_committed_snapshot_on, db.is_auto_close_on, db.is_auto_shrink_on,
db.target_recovery_time_in_seconds, db.is_cdc_enabled, db.is_published, db.is_distributor, db.is_encrypted,
db.group_database_id, db.replica_id,db.is_memory_optimized_elevate_to_snapshot_on,
db.delayed_durability_desc, db.is_auto_create_stats_incremental_on,
db.is_query_store_on, db.is_sync_with_backup,
db.is_supplemental_logging_enabled, db.is_remote_data_archive_enabled,
db.is_encrypted, de.encryption_state, de.percent_complete, de.key_algorithm, de.key_length     
FROM sys.databases AS db WITH (NOLOCK)
INNER JOIN sys.dm_os_performance_counters AS lu WITH (NOLOCK)
ON db.name = lu.instance_name
INNER JOIN sys.dm_os_performance_counters AS ls WITH (NOLOCK)
ON db.name = ls.instance_name
LEFT OUTER JOIN sys.dm_database_encryption_keys AS de WITH (NOLOCK)
ON db.database_id = de.database_id
WHERE lu.counter_name LIKE N'Log File(s) Used Size (KB)%'
AND ls.counter_name LIKE N'Log File(s) Size (KB)%'
AND ls.cntr_value > 0
ORDER BY db.[name] OPTION (RECOMPILE);