INSERT INTO rep_kw_osrcevents2 (sessid, eventdate, reventdataid, mdata2, sdata2, rdata2) SELECT distinct base.sessid AS sessid, base.eventdate AS eventdate, MAX(rev.eventdataid) AS reventdataid, MAX(mev.data2) AS mdata2, MAX(sev.data2) AS sdata2, MAX(rev.data2) AS rdata2 FROM temp_kw_ofirstevents AS base LEFT JOIN rep_kw_oreferevents AS rev force index (sessid) ON base.sessid=rev.sessid AND ABS(base.eventdate-rev.eventdate)<4 LEFT JOIN rep_kw_omarketingevents AS mev ON base.sessid=mev.sessid AND ABS(base.eventdate-mev.eventdate)<4 LEFT JOIN rep_kw_osubmcevents AS sev ON base.sessid=sev.sessid AND ABS(base.eventdate-sev.eventdate)<4 GROUP BY sessid,eventdate ORDER BY sessid,eventdate;


+----+-------------+-------+------+---------------+--------+---------+---------------------+---------+---------------------------------+
| id | select_type | table | type | possible_keys | key    | key_len | ref                 | rows    | Extra                           |
+----+-------------+-------+------+---------------+--------+---------+---------------------+---------+---------------------------------+
|  1 | SIMPLE      | base  | ALL  | NULL          | NULL   | NULL    | NULL                | 3975052 | Using temporary; Using filesort | 
|  1 | SIMPLE      | rev   | ref  | sessid        | sessid | 5       | reports.base.sessid |       8 |                                 | 
|  1 | SIMPLE      | mev   | ref  | sessid        | sessid | 5       | reports.base.sessid |       4 |                                 | 
|  1 | SIMPLE      | sev   | ref  | sessid        | sessid | 5       | reports.base.sessid |       3 |                                 | 
+----+-------------+-------+------+---------------+--------+---------+---------------------+---------+---------------------------------+
4 rows in set (0.00 sec)