Sudden performance issue in SQL Server (MSSQL)

Products

• Clarity PPM On Premise
• Clarity PPM SaaS

Issue/Introduction

• After updating SQL Server database settings, certain actions or queries that previously took seconds, now take much longer delays, minutes and the performance is very slow.
• We reverted the parameter change and still it's slow.
• Other environments are working well.
• Or sometimes the same slowness have also been seen there, but went away on its own after a couple of days.

Resolution

• Ask the DBA to flush SQL Server cache for Clarity schema by running: 
  • DBCC FLUSHPROCINDB(10)
• This will clear the database plan cache. 
• More information on this command: Microsoft Documentation