iMac (fast) id |select_type |table |type |possible_keys |key |key_len |ref |rows |Extra | ---|----------------|-----------|-------|------------------------------------------|---------------------|--------|----------------------------------------------|-------|------------| 1 |PRIMARY |a |ALL | | | | |335880 | | 1 |PRIMARY | |ref |key0 |key0 |123 |prod_welu_pdm.a.persistence_object_identifier |10 | | 2 |LATERAL DERIVED |b |ref |IDX_3062FD0DA4375C33,IDX_3062FD0DAEA34913 |IDX_3062FD0DA4375C33 |123 |prod_welu_pdm.a.persistence_object_identifier |1 |Using where | 2 |LATERAL DERIVED |c |eq_ref |PRIMARY |PRIMARY |122 |prod_welu_pdm.b.reference |1 | | 2. RHEL 7.4 Database Server (slow) id |select_type |table |type |possible_keys |key |key_len |ref |rows |Extra | ---|------------|-----------|------|------------------------------------------|----------------------|--------|---------------------------------------------|-------|---------------------------------------------| 1 |PRIMARY |a |ALL | | | | |384192 | | 1 |PRIMARY | |ref |key0 |key0 |123 |dev_welu_pdm.a.persistence_object_identifier |10 | | 2 |DERIVED |c |index |PRIMARY |UNIQ_586EC305AEA34913 |6 | |339 |Using index; Using temporary; Using filesort | 2 |DERIVED |b |ref |IDX_3062FD0DA4375C33,IDX_3062FD0DAEA34913 |IDX_3062FD0DAEA34913 |123 |dev_welu_pdm.c.persistence_object_identifier |422 | |