Migrate from Oracle to Microsoft (Views) – Part III

Continued from Migrate from Oracle to Microsoft (Views) – Part II here part III with the main focus on very interesting topic testing ;-).

Testing

When I implemented all about 20 views from Oracle to SQL Server, I had to test the performance and not least important, the content of the views if their still contain the same. And how do you do that the easiest way?

Measure performance

For measuring the performance you simply select alls Views with a SELECT COUNT(*) on both databases. Don’t forget to clear the cache before each run.
To generate all the COUNT-Statements I created a little script, just to make life easier right ;-):

 --Generate Queries - Performance Test...
SELECT  v.TABLE_NAME,
		--stuff(c.list,1,1,'') as cols,
		'PRINT ''' + v.Table_name + '''    ' +
		'SELECT '''+v.Table_name+''' as Tbl_name, NULL as cnt UNION ALL ' +
		'SELECT '''+v.Table_name+''' as Tbl_name, count(*) as cnt FROM [dbo].['+v.Table_name +'] '--WHERE 1=2 '
		+ CHAR(13)+CHAR(10)
		
  FROM INFORMATION_SCHEMA.VIEWS v  
  --where v.TABLE_NAME LIKE '%What you like%'
 ORDER BY v.TABLE_NAME
 

--To the generated output you just add below in front and you're ready to go:
 
SET STATISTICS TIME ON 

PRINT 'My_View'    SELECT 'My_View' as Tbl_name, NULL as cnt UNION ALL SELECT 'My_View' as Tbl_name, count(*) as cnt FROM [dbo].[My_View]   
...

Compare content

1. First you create a database linked server on your SQL Server database. If you don’t know how to do this, please read the following How-to.
2. If you have only a few comparison you easily create EXCEPT-SELECT-Query and compare your Oracle Views over the database link (linked-Server) to your Microsoft Views.
   1. If you have many views, I created a query to generate these queries including the fields names and most important in the same order which is important if you do an EXCEPT-Query.

--Generate Queries - MINUS-Query...
SELECT  v.TABLE_NAME,
		--stuff(c.list,1,1,'') as cols,
		'SELECT '''+v.Table_name+''' as Tbl_name, NULL as cnt, ' + stuff(c_null.list,1,1,'') +
		' UNION ALL ' +																					
		'SELECT '''+v.Table_name+''' as Tbl_name, count(*) as cnt, '+ stuff(c_null.list,1,1,'') +  ' FROM [LinkedServerName]..[SchemaName].['+v.Table_name +'] ' + --' WHERE 1=2 '+ 
		' EXCEPT ' +
		'SELECT '''+v.Table_name+''' as Tbl_name, count(*) as cnt, '+ stuff(c_null.list,1,1,'') + ' FROM [dbo].['+v.Table_name +'] ' + --' WHERE 1=2 ' +
		' UNION ALL ' +
		'SELECT '''+v.Table_name+''' as Tbl_name, null as cnt, '+ stuff(c.list,1,1,'') + ' FROM OPENQUERY(LinkedServerName,''SELECT * FROM SchemaName.'+v.Table_name +''') ' + --' WHERE 1=2 '+ 
		'EXCEPT ' +
		'SELECT '''+v.Table_name+''' as Tbl_name, null as cnt, '+ stuff(c.list,1,1,'') + ' FROM [dbo].['+v.Table_name +'] ' + --' WHERE 1=2 '
		+ CHAR(13)+CHAR(10)
		, stuff(c.list,1,1,'') as cols
  FROM INFORMATION_SCHEMA.VIEWS v cross apply
	   (
		SELECT 
          --',CAST(['+cast(c.COLUMN_NAME as varchar)+'] AS VARCHAR(3000)) AS ' +cast(c.COLUMN_NAME as varchar)+' ' as [text()]
          ',['+cast(c.COLUMN_NAME as varchar)+'] ' as [text()]
          FROM INFORMATION_SCHEMA.COLUMNS c
         WHERE c.DATA_TYPE != 'ntext'
           AND c.TABLE_NAME = v.table_name
--         GROUP BY c.TABLE_NAME
         ORDER BY ORDINAL_POSITION
           FOR XML PATH('')
       ) as c(list)
       CROSS APPLY
	   (
		SELECT 
          ',NULL AS ['+cast(c.COLUMN_NAME as varchar)+']' as [text()]
          FROM INFORMATION_SCHEMA.COLUMNS c
         WHERE c.DATA_TYPE != 'ntext'
           AND c.TABLE_NAME = v.table_name-
--         GROUP BY c.TABLE_NAME
         ORDER BY ORDINAL_POSITION
           FOR XML PATH('')
       ) as c_null(list)
       
       --WHERE v.TABLE_NAME LIKE '%blabla%'
        
 
 ORDER BY v.TABLE_NAME

Have fun, let me know if you have questions or comment to add notes or annotations.

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