How do I get a distinct value count from two fields?

[twh1]

I have two different fields (DB_INSTANCE_NAME & INSTANCE_NAME ) in two source types. These fields contain a similar value. I want distinct counts after combining both pieces of field data.

DB_INSTANCE_NAME= ansrp, flexp, sunopt, vlprod, buybprod, FDPOSPRD, aasprod, dcpscp, hydra, cidprod,  gcdprd, pspprod, HDMPRD
INSTANCE_NAME= obieep, cnavprd, gcdprd, pspprod, svdprod, tumss2, fepauth, rulesu, ecmsprod, HDMPRD, csprod, RFEP1, pcip, vlprod

I want the count of ansrp, flexp, sunopt, vlprod, buybprod, FDPOSPRD, aasprod, dcpscp, hydra, cidprod, gcdprd, pspprod, HDMPRD, obieep, cnavprd, svdprod, tumss2, fepauth, rulesu, ecmsprod, HDMPRD, csprod, RFEP1, pcip

[nick405060]

Credit goes to @micahkemp:

| stats dc(eval(mvappend(field1, field2, field3)))

[richgalloway · Accepted solution]

What you do is combine them then count them.

index=foo (sourcetype=st1 OR sourcetype=st2) | eval combinedField=coalesce(DB_INSTANCE_NAME, INSTANCE_NAME) | stats dc(combinedField) as Count