Find out when/who dropped an object without auditing

If your environment doesn’t have any kind of auditing and you need to find since when an object was dropped.

If you have the default trace enabled (good practice) you can track when the object was dropped and determine if that was the root cause for some performance issue for example.

The point here is to find the root cause of an issue, not point the finger to who did it ūüėČ

First, let’s check what kind of events the default trace has

SELECT DISTINCT Trace.EventID
        , TraceEvents.NAME AS Event_Desc
 FROM ::fn_trace_geteventinfo(1) Trace
 JOIN sys.trace_events TraceEvents ON Trace.eventID = TraceEvents.trace_event_id 

You are going to see the events

The next step is get the default trace path

SELECT path
 FROM sys.traces
 WHERE is_default = 1;

Knowing the path you can get all the files name using xp_cmdshell for example

EXEC xp_cmdshell 'dir e:\"Program Files"\"Microsoft SQL Server"\"MSSQL10.MSSQLSERVER"\MSSQL\*.trc'

Grab the file name you want and change the script below

SELECT 
    CASE EventClass
        WHEN 46 THEN 'Object:Created'
        WHEN 47 THEN 'Object:Deleted'
        WHEN 164 THEN 'Object:Altered'
    END
    , DatabaseName
    , ObjectName
    , HostName
    , ApplicationName
    , LoginName
    , StartTime
 FROM ::fn_trace_gettable('C:\Program Files\Microsoft SQL Server\MSSQL14.MSSQLSERVER\MSSQL\Log\your_file_name.trc', DEFAULT)
 WHERE 
    EventClass IN (46,47,164) 
    AND EventSubclass = 0 
 ORDER BY StartTime DESC

In my scenario what is showing is the creating object in the bottom with some index creation, drop index, object alter (it’s not telling what kind of change), create a new object and alter (the primary key creates the index and alter the table adding the constraint).

Plus you can see the login name and when the action was made. ūüėČ

Install dbatools module without admin rights

If you have been face a issue that you don’t have rights to install any powershell module like showing the image below for dbatools, one workaround is to install it only for your user.

In this case you can use the scope parameter to install it in your user only as you can see in the message.

Install-Module dbatools -Scope currentuser



Useful transactional replication stored procedure

The scenario is when your publication settings has the option
immediate_sync configured as false (means if you run the Snapshot Agent, the snapshot files will be created for the new articles only and also a new subscriber to the existing publication, the snapshot files only get created for the new subscription)

This option immediate_sync will prevent to generate all snapshot files again when add a new article in the replication, but it still need schema lock to check all articles modification.

If you have a large number of articles and a bunch of subscribers, you might face the situation you have to add a new article in your transactional replication and after run the snapshot the article is not propagating to the subscribers.

First, check your publication settings.

exec sp_helppublication 'PublicationName'
GO

If you are using the settings immediate_sync and allow_anonymous false you can run the procedure below to solve the issue that your new article didn’t propagate to your subscribers.

exec sp_refreshsubscriptions 'PublicationName'
GO



Method to update LOB data with minimal log

Use the .WRITE (expression, @Offset,@Length) clause to perform a partial or full update of varchar(max), nvarchar(max), and varbinary(max) data types.

For example, a partial update of a varchar(max) column might delete or modify only the first 200 characters of the column, whereas a full update would delete or modify all the data in the column. .WRITE updates that insert or append new data are minimally logged if the database recovery model is set to bulk-logged or simple.

UPDATE <table_or_view_name>
SET column_name.WRITE (expression, @offset, @length)
FROM <table_source>
WHERE <search_condition>

expression is the value that is copied to column_name. expression must evaluate to or be able to be implicitly cast to the column_name type. If expression is set to NULL, @Length is ignored, and the value in column_nameis truncated at the specified @Offset.

@Offset is the starting point in the value of column_name at which expression is written. @Offset is a zero-based ordinal position, is bigint, and cannot be a negative number. If @Offset is NULL, the update operation appends expression at the end of the existing column_name value and @Length is ignored. If @Offset is greater than the length of the column_name value, the Database Engine returns an error. If @Offset plus @Length exceeds the end of the underlying value in the column, the deletion occurs up to the last character of the value. If @Offset plus LEN(expression) is greater than the underlying declared size, an error is raised.

@Length is the length of the section in the column, starting from @Offset, that is replaced by expression. @Length is bigint and cannot be a negative number. If @Length is NULL, the update operation removes all data from @Offset to the end of the column_name value.

The regular update statement results in overwriting the entire string using full logging and it’s very inefficient when dealing with large value updates.

Note: The update using WRITE method will fail if the value is null.

More information about performance in my tip on MSSQLTips

 

 

Using wait stats on SQL Server

I wrote two posts about wait stats:

  1.  What wait means
  2. About SQL Server saving wait stats on DMVs

Now, going deeper on wait stats and see “why SQL Server is running slow?”. To answer that question I like to start with the DMV sys.dm_os_wait_stats, because this DMV provides a running total of all waits encontered by executing threads in SQL Server instance.

SQL Server categorizes waits across several different type and some of these types only indicate quit period on the instance where threads stay in waiting.

The script below shows the top wait types that have accumulated since SQL Server started or was cleared.

WITH Waits AS (
SELECT  wait_type
    , CAST(wait_time_ms / 1000. AS DECIMAL(12, 2)) AS [wait_time_s]
    , CAST(100. * wait_time_ms / SUM(wait_time_ms) OVER () AS DECIMAL(12, 2)) AS [pct]
    , ROW_NUMBER() OVER (ORDER BY wait_time_ms DESC) AS rn 
FROM sys.dm_os_wait_stats WITH (NOLOCK) 
WHERE  
     wait_type NOT IN (N'CLR_SEMAPHORE', N'LAZYWRITER_SLEEP', N'RESOURCE_QUEUE', N'SLEEP_TASK', N'SLEEP_SYSTEMTASK', N'SQLTRACE_BUFFER_FLUSH', N'WAITFOR', N'LOGMGR_QUEUE', N'CHECKPOINT_QUEUE', N'REQUEST_FOR_DEADLOCK_SEARCH', N'XE_TIMER_EVENT', N'BROKER_TO_FLUSH', N'BROKER_TASK_STOP', N'CLR_MANUAL_EVENT', N'CLR_AUTO_EVENT', N'DISPATCHER_QUEUE_SEMAPHORE', N'FT_IFTS_SCHEDULER_IDLE_WAIT', N'XE_DISPATCHER_WAIT', N'XE_DISPATCHER_JOIN', N'SQLTRACE_INCREMENTAL_FLUSH_SLEEP', N'ONDEMAND_TASK_QUEUE', N'BROKER_EVENTHANDLER', N'SLEEP_BPOOL_FLUSH', N'SLEEP_DBSTARTUP', N'DIRTY_PAGE_POLL', N'HADR_FILESTREAM_IOMGR_IOCOMPLETION', N'SP_SERVER_DIAGNOSTICS_SLEEP', N'QDS_PERSIST_TASK_MAIN_LOOP_SLEEP', N'QDS_CLEANUP_STALE_QUERIES_TASK_MAIN_LOOP_SLEEP', N'WAIT_XTP_HOST_WAIT', N'WAIT_XTP_OFFLINE_CKPT_NEW_LOG', N'WAIT_XTP_CKPT_CLOSE', N'PWAIT_ALL_COMPONENTS_INITIALIZED')), Running_Waits AS (
SELECT  W1.wait_type
    , wait_time_s
    , pct
    , SUM(pct) OVER (ORDER BY pct DESC ROWS UNBOUNDED PRECEDING) AS [running_pct] 
FROM   Waits AS W1)
SELECT     
    wait_type
    , wait_time_s
    , pct
    , running_pct
FROM      Running_Waits
WHERE     running_pct - pct = 99
ORDER BY  running_pct
OPTION (RECOMPILE);

This query I got from Paul Randal blog, his blog has a lot of information about waits. Since not all wait types are indicators of real issue, the where clause is removing unnecessary type.

The common wait types for me are in the table below, there are much more, but you can start with that list.

Wait_TypeAreaDescriptionAction
ASYNC_IO_COMPLETIONI/OUsed to indicate a worker is waiting on a asynchronous I/O operation to complete not associated with database pagesSince this is used for various reason you need to find out what query or task is associated with the wait. Two examples of where this wait type is used is to create files associated with a CREATE DATABASE and for “zeroing” out a transaction log file during log creation or growth.
CHECKPOINT_QUEUEBufferUsed by background worker that waits on events on queue to process checkpoint requests. This is an “optional” wait type see Important Notes section in blogYou should be able to safely ignore this one as it is just indicates the checkpoint background worker is waiting for work to do. I suppose if you thought you had issues with checkpoints not working or log truncation you might see if this worker ever “wakes up”. Expect higher wait times as this will only wake up when work to do
CHKPTBufferUsed to coordinate the checkpoint background worker thread with recovery of master so checkpoint won’t start accepting queue requests until master onlineYou should be able to safely ignore. You should see 1 wait of this type for the server unless the checkpoint worker crashed and had to be restarted.. If though this is technically a “sync” type of event I left its usage as Background
CXPACKETQueryUsed to synchronize threads involved in a parallel query. This wait type only means a  parallel query is executing.You may not need to take any action. If you see high wait times then it means you have a long running parallel query. I would first identify the query and determine if you need to tune it. Note sys.dm_exec_requests only shows the wait type of the request even if multiple tasks have different wait types. When you see CXPACKET here look at all tasks associated with the request. Find the task that doesn’t have this wait_type and see its status. It may be waiting on something else slowing down the query. wait_resource also has interesting details about the tasks and its parallel query operator
IO_COMPLETIONI/OUsed to indicate a wait for I/O for operation (typically synchronous)  like sorts and various situations where the engine needs to do a synchronous I/OIf wait times are high then you have a disk I/O bottleneck. The problem will be determining what type of operation and where the bottleneck exists. For sorts, it is on the storage system associated with tempdb. Note that database page I/O does not use this wait type. Instead look at PAGEIOLATCH waits.
LAZYWRITER_SLEEPBufferUsed by the Lazywriter background worker to indicate it is sleeping waiting to wake up and check for work to doYou should be able to safely ignore this one. The wait times will appear to “cycle” as LazyWriter is designed to sleep and wake-up every 1 second. Appears as LZW_SLEEP in Xevent
LOGBUFFERTransaction LogUsed to indicate a worker thread is waiting for a log buffer to write log blocks for a transactionThis is typically a symptom of I/O bottlenecks because other workers waiting on WRITELOG will hold on to log blocks. Look for WRITERLOG waiters and if found the overall problem is I/O bottleneck on the storage system associated with the transaction log
RESOURCE_SEMAPHOREQueryUsed to indicate a worker is waiting to be allowed to perform an operation requiring “query memory” such as hashes and sortsHigh wait times indicate too many queries are running concurrently that require query memory. Operations requiring query memory are hashes and sorts. Use DMVs such as dm_exec_query_resource_semaphores and dm_exec_query_memory_grants
SOS_SCHEDULER_YIELDSQLOSUsed to indicate a worker has yielded to let other workers run on a schedulerThis wait is simply an indication that a worker yielded for someone else to run. High wait counts with low wait times usually mean CPU bound queries. High wait times here could be non-yielding problems
THREADPOOLSQLOSIndicates a wait for a  task to be assigned to a worker threadLook for symptoms of high blocking or contention problems with many of the workers especially if the wait count and times are high. Don’t jump to increase max worker threads especially if you use default setting of 0. This wait type will not show up in sys.dm_exec_requests because it only occurs when the task is waiting on a worker thread. You must have a worker to become a request. Furthermore, you may not see this “live” since there may be no workers to process tasks for logins or for queries to look at DMVs.
WRITELOGI/OIndicates a worker thread is waiting for LogWriter to flush log blocks.High waits and wait times indicate an I/O bottleneck on the storage system associated with the transaction log

The next posts I will show an example for each wait in the list.

Prost!

Execution runtime information for developers ;)

Developers should use this statistics to get more information about what they just did and pay attention to high physical or logical read values.

SQL Server provides commands that are used to return query statistics like SET STATISTICS IO, TIME.

The IO command return information about physical, logical for tables referenced in the query and also worktables, which means tables in tempdb for the duration of the query and are removed automatically when it has finished the operation.

Using statistics time will show the parse, compile time for the query and the actual execution time after the query results. It’s useful to measure the amount of time a query takes to execute from end to end.

Using SQL Operations Studio Agent

SQL Operations Studio Agent is visual way to see, edit and create SQL Server jobs and everybody was asking this feature when SQL Operations Studio appears.

To install this the agent follow the link https://docs.microsoft.com/en-us/sql/sql-operations-studio/sql-server-agent-extension?view=sql-server-2017.

sqlops01

Installing the agent 

sqlops02

With the extension installed, right-click on the instance -> Manage to see the server jobs 

sqlops03

But, not everything is working. I tried to edit a job step and didn’t work. For example, the Ola hallengren maintenace scripts after created wasn’t possible to change using the GUI differently than using SSMS.

Even trying to using the GUI to create a new step didn’t work and I changed using TSQL.

sqlops05
sqlops04

The script is available in my Git here to download. After changed the script I succeeded ran it.

With extensions we have more features available to work with SQL Operations Studio and is improving the utilization. Also you can create your own widget. In my tip on MSSQLTips.com I’m showing how to create it.

I recommend install SQL Server Agent, Profiler, Reports and certainly whoisactive

sqlops06

How to install SQL Server SQLPS Powershell module

SQLPS module to Powershell helps to do so many things on SQL Server without SSMS and the main objective is to automate tasks for your environment.

This module isn’t installed by default, so there are a couple of steps before use it. First, install the module and the simple cmdlet install-module SQLPS won’t work.

To install the module you need install a couple of things (if you have SQL Server instance there is already installed).

The installation is quite simple and isn’t necessary to restart the system. There are 3 files necessary and need to install in the sequence below.

With all installed let’s try to import the module on powershell.

2018-08-01_20-36-01

Actually that didn’t work (yet). In the error message shows it’s not allowed to run scripts in my system.

Next step is to change the execution policy to run scripts in the system. Let’s try it using the cmdlets Get-ExecutionPolicy to know the actual value and Set-ExecutionPolicy to change it.  ( more information )

2018-08-01_20-45-23

Ok, second error and this time because I’m trying to change to RemoteSigned and only as administrator I can change it.

2018-08-01_20-54-28

Running as administrator the local machine execution policy has changed and the SQLPS module can be imported and use the cmdlets.

2018-08-01_21-00-16

Troubleshooting Transactional Replication – part 1

The common way to replicate data and objects from one server to another is using transactional replication. As you know, SQL Server processes all actions within the database using Transact-SQL statements. Each completed statement is called a transaction. In transactional replication, each committed transaction is replicated to the subscriber as it occurs.

trnsact
“Sometimes” can occur a problem and the process don’t work accordingly. The fist step I like to do is run sp_whoisactive in the servers (Publisher, Distributor and Subscriber), you can see if there are any process blocking the replication.

Next, is to see the publisher and subscriber agents, if there is any issue they will show, like for example login locked.

To have more information what’s happening I like to query the system view MSrepl_Transactions in the distribution database, this view contains one row for each replicated transaction and with that information run the procedure¬†sp_browsereplcmds specifying the seqno start @xact_seqno_start = N’0x0000014F000034B0001C’ for example.

The procedure sp_browserreplcmds returns a record set with the commands stored in the distribution database. It show like a table like below.

2018-07-29_20-31-59