Tips and Tricks to avoid common pit falls with SQL CLR deployment

  1. If you are using Visual Studio to build and deploy the SQL CLR solution ensure you have below settings

SQLCLR

SQL CLR2

SQLCLR3.jpg

2) First things first, Ensure CLR Integration is enabled at instance level.

EXEC sp_configure 'show advanced options' , '1';
reconfigure;

EXEC sp_configure 'clr enabled' , '1' ;
reconfigure;

EXEC sp_configure 'show advanced options' , '0';
reconfigure;

 

3) Ensure Appropriate CLR Integration Code Access Security levels are set when creating assembly’s in SQL Server

CREATE ASSEMBLY [SOAPSQLSPCLR]
AUTHORIZATION [dbo]
FROM 'C:\Program Files\Microsoft SQL Server\MSSQL10_50.WMVDSQL01\MSSQL\Binn\SQLCLRSoapConsumer.dll'
WITH PERMISSION_SET = [EXTERNAL_ACCESS,SAFE,UNSAFE]
GO

 

  • SAFE : Only internal computation and local data access are allowed. SAFE is the most restrictive permission set. Code executed by an assembly with SAFE permissions cannot access external system resources such as files, the network, environment variables, or the registry
  • EXTERNAL_ACCESS: These assemblies have the same permissions as SAFE assemblies, with the additional ability to access external system resources such as files, networks, environmental variables, and the registry
  • UNSAFE:  unrestricted access to resources, both within and outside SQL Server. Code executing from within an UNSAFE assembly can also call unmanaged code.

Please refer to msdn documentation here https://msdn.microsoft.com/en-us/library/ms345101.aspx

4) Ensure the database is setup correctly

If you are using assemblies with External access and Unsafe the database property TRUSTWORTHY needs to be turned on.

USE database_name
GO
EXEC sp_changedbowner 'sa'
ALTER DATABASE database_name SET TRUSTWORTHY ON 

 

Refer to MSDN documentation on TRUSTWORTHY https://msdn.microsoft.com/en-us/library/ms187861.aspx

Variable WMI not found…

When you are setting up alerts using WMI and if your intention is to capture the event data with sql agent job make sure you change below settings in SQL Server Agent Configuration.

dba_sqlagent

or

EXEC msdb.dbo.sp_set_sqlagent_properties @alert_replace_runtime_tokens = 1
GO

 

This will allow SQL Server Agent to replace the tokens with running values (what database changed, who changed it etc.). Read more about using Tokens in Job Steps here (make sure you read the security note in the article and understand the security risk).

Clone your SQL Database instantly with new DBCC command CLONEDATABASE

 

Based on MS documentation this is a quick way to create a copy of database (only Schema) including statistics and Indexes of source database this was released in SQL 14 service pack 2.

When this command is issued SQL Server creates an internal snapshot of source database just like how it creates for checkdb and drops this snapshot when the cloning process is done but during the cloning process it holds a shared lock on source database and X lock on target database and it leaves target database in read only mode although you can change the state of the target database if you intent to add data or modify.

So why do you need to clone database.

According to MS DBCC CLONEDATABASE should be used to create a schema and statistics only copy of a production database in order to investigate query performance issues.”. The original intention of the feature is to diagnose any performance issues of a production database with out needing to effect the production database. Although this is so late in the game its never to late for new feature.

Don’t confuse with Database Snapshots that’s totally different concept.
dbcc clonedatabase([AdventureWorks2014],[AdventureWorks2014_Clone])

 

dbcc clone 1

 

dbcc clone 2

https://support.microsoft.com/en-us/kb/3177838

Bottom line: Saves a lot of time when you are debugging execution plans and performance related issues.

High CPU Usage SQL Server (One Bad Query)

My colleague reported to me that one of our database server is reporting consistent high CPU usage so I looked at it I noticed CPU was at 100% from last one week when I contacted the application owner and I foundthat they implemented a new feature that polls the database for every second to ensure the data collection process is running properly as it was necessary to ensure that we are under compliance in terms of reporting and auditing. So I ran a query to pull the queries with high cpu utilization with execution count. I certainly noticed a query running more often with high cpu usage.

 

Exec stats

I know that above highlighted query is causing the high cpu usage, next I looked at query stats and noticed this query is running twice every second, so I looked at the plan

Select top 1 col1 from table order by 1

Table is clustered and col1 is not part of clustered index and does not have an index. simple enough SQL server decides to do Clustered index scan and sorts(fully blocking) col1 and selects 1 row with no predicate SQL server doesn’t think its missing an index.

PLan 1

PLan 1 properties .jpg
SQL Server Execution Times: with out non clustered index
CPU time = 2296 ms, elapsed time = 658 ms.

So I created a non clustered index on col1 in desc on the table

plan 2.jpg
SQL Server Execution Times: with non clustered index
CPU time = 0 ms, elapsed time = 0 ms.

Cpu Usage dramatically reduced

Cpu usage.jpg

Bottom line:

Its very important to understand no matter how much physical resources you might have on a  server its very important understand that one bad query can literally bring the server down to it knees.

 

Search a Column from a table in SQL Database

SELECT
SCHEMA_NAME(schema_id)+'.'+[name] as objectname
,type_desc
,referenced_schema_name AS SchemaName
,referenced_entity_name AS TableName
,referenced_minor_name  AS ColumnName
FROM [sys].[all_objects] ob cross apply sys.dm_sql_referenced_entities ( SCHEMA_NAME(schema_id)+'.'+[name], 'OBJECT') e
where is_ms_shipped = 0 and type_desc in ('AGGREGATE_FUNCTION'
,'SQL_SCALAR_FUNCTION'
,'SQL_INLINE_TABLE_VALUED_FUNCTION'
,'SQL_STORED_PROCEDURE'
,'SQL_TABLE_VALUED_FUNCTION'
,'SQL_TRIGGER'
,'VIEW')
and name !='sp_upgraddiagrams'
and referenced_entity_name  = 'table name'
and referenced_minor_name = 'columnname'

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Aurdino & Servo with Potentiometer

Servo Potentio meter Sketch_bb1

#include <Servo.h>
Servo myservo;
void setup() {
Serial.begin(9600);
myservo.attach(5);
pinMode(A0,INPUT);
}

void loop() {
// put your main code here, to run repeatedly:
int sensorValue = analogRead(A0);
myservo.write(map(sensorValue, 0, 1023, 0, 180)); // tell servo to go to position in variable ‘pos’
Serial.println(sensorValue);
delay(1);
}