Question

I have a SQL Query that comprise of two level sub-select. This is taking too much time.

The Query goes like:

   select * from DALDBO.V_COUNTRY_DERIV_SUMMARY_XREF
    where calculation_context_key = 130205268077
    and DERIV_POSITION_KEY in 
          (select ctry_risk_derivs_psn_key 
            from DALDBO.V_COUNTRY_DERIV_PSN
            where calculation_context_key = 130111216755 
            --and ctry_risk_derivs_psn_key = 76296412
            and CREDIT_PRODUCT_TYPE = 'SWP OP'
            and CALC_OBLIGOR_COUNTRY_OF_ASSETS in 
                (select ctry_cd 
                 from DALDBO.V_PSN_COUNTRY
                 where calculation_context_key = 130134216755 
                --and ctry_risk_derivs_psn_key = 76296412
                )
           )

These tables are huge! Is there any optimizations available?

Answer 1

Without knowing anything about your table or view definitions, indexing, etc. I would start by looking at the sub-selects and ensuring that they are performing optimally. I would also want to know how many values are being returned by each sub-select as this can impact performance.

How is calculation_context_key used to retrieve rows from V_COUNTRY_DERIV_PSN and V_PSN_COUNTRY? Is it an optimal execution plan?

How is DERIV_POSITION_KEY and CALC_OBLIGOR_COUNTRY_OF_ASSETS used in V_COUNTRY_DERIV_SUMMARY_XREF to retrieve rows? Again, look at the explain plan.