Sql-server – SQL DBA data type is changed after upgrade

sql serversql server 2014sql-server-2005

We have recently upgraded our SQL Server Database from SQL 2005 to SQL 2014.
We are experiencing slowness in both SSMS and application as well while executing a SP in SQL 2014. After checking through the sql profiler.
This is the difference.

Source Server : SQL 2005
JDBC VERSION  : 4.1
Source Data type : Big Decimal
Conversion on DB side : It is converted as Numeric (Checked through sql profiler)
Execution Time : 1 Second

The below target is the server we have upgraded from 2005.

Target Server : SQL 2014
JDBC VERSION  : 6.2
SOURCE Datatype : Big Decimal
Conversion on DB Side : It is converted as Decimal
Execution Time : 25 Seconds.

Any idea what I can do to fix this?

Best Answer

You should perform the following tasks after updating :

  1. Upgrade Database Compatibility Level
    • The database compatibility level needs to be manually changed on the 2014 instance
  2. Run DBCC CHECKDB WITH DATA_PURITY
    • Checks for invalid data values based on column data type
  3. Run DBCC UPDATEUSAGE
    • Corrects page count inaccuracies to reflect accurate information when using sp_spaceused
  4. Run sp_refreshview
    • Ensures that views are up to date
  5. Update Statistics
    • Brings database statistics are up to date to allow the query optimizer to choose the best query plan
  6. Take a Full Backup of the Database
  7. Make sure you can recover the database with all of the migration efforts
  8. Monitor Performance between Cardinality Estimators

It’s important to note: SQL Server 2014 received a major overhaul of the cardinality estimator. For the vast majority of queries, performance will improve due to better row estimations. However, in some scenarios estimations could be worse which may result in performance degradation. It’s important to monitor most commonly used queries to see if any performance degradation is resulting from poor estimations. It is possible to utilize the old cardinality estimator by leveraging a database compatibility level of 110 or lower or by leveraging trace flag 9481.

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