Try one of these 2:
index=ndx sourcetype=srctp data=*
| stats dc(data) as unique_data
Or
index=ndx sourcetype=srctp data=*
| stats values(data) as data_vals
from User warren – Stack Overflow https://stackoverflow.com/questions/65997187/how-to-count-the-number-of-event-based-on-json-field-structure-in-splunk/66036420#66036420
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