@Sukisen1981 , thank you again for our reply! So let me get if I understand. This part (original from my question)
index=ABC sourcetype="perf" CLASS=PL| fields RR_ID USR_ID | dedup RR_ID
| join type=left RR_ID [search index=CAB sourcetype=CC | fields rrId| rename rrId AS RR_ID]
will bring me ALL values of the first index AND no unique values from the second, correct?
The second join that you mentioned "when your second join gets performed you get ONLY values unique to both A&B (A intersection B).", you mean with this additional part (join type=inner) after the left join?
index=ABC sourcetype="perf" CLASS=PL| fields RR_ID USR_ID | dedup RR_ID
| join type=left RR_ID [search index=CAB sourcetype=CC | fields rrId| rename rrId AS RR_ID] | join type=inner RR_ID [search index=CAB sourcetype=CC | fields rrId| rename rrId AS RR_ID]
| stats count by USR_ID
I am still in this part thinking that with this additional join I will get as you mention the A intersection B, not the final part that you mentioned with only the left (join left results).
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