EXPLAIN SELECT p.id, s.id FROM InMemoryDIASource AS p
    INNER JOIN ZoneZone AS zz FORCE INDEX (PRIMARY) ON p.zoneId = zz.zoneId
    INNER JOIN InMemoryObject AS s FORCE INDEX (idx_zone_ra) ON zz.matchZoneId = s.zoneId
    WHERE s.ra BETWEEN p.ra - zz.deltaRa AND p.ra + zz.deltaRa
    AND s.decl BETWEEN p.decl - 0.000833 AND p.decl + 0.000833
    AND POW(p.x - s.x, 2) + POW(p.y - s.y, 2) + POW(p.z - s.z, 2) < 2.1137067679466e-10 \G

    *************************** 1. row ***************************
               id: 1
      select_type: SIMPLE
            table: s
             type: ALL
    possible_keys: idx_zone_ra
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 3044468
            Extra: 
    *************************** 2. row ***************************
               id: 1
      select_type: SIMPLE
            table: p
             type: ALL
    possible_keys: idx_zone_ra
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 30276
            Extra: Using where
    *************************** 3. row ***************************
               id: 1
      select_type: SIMPLE
            table: zz
             type: eq_ref
    possible_keys: PRIMARY
              key: PRIMARY
          key_len: 8
              ref: serge.p.zoneId,serge.s.zoneId
             rows: 1
            Extra: Using where

EXPLAIN SELECT p.id, s.id FROM InMemoryDIASource AS p
    INNER JOIN ZoneZone AS zz FORCE INDEX (PRIMARY) ON p.zoneId = zz.zoneId
    INNER JOIN InMemoryObject AS s FORCE INDEX (idx_zone_ra) ON
        zz.matchZoneId = s.zoneId AND
        s.ra BETWEEN p.ra - zz.deltaRa AND p.ra + zz.deltaRa
    WHERE s.decl BETWEEN p.decl - 0.000833 AND p.decl + 0.000833
    AND POW(p.x - s.x, 2) + POW(p.y - s.y, 2) + POW(p.z - s.z, 2) < 2.1137067679466e-10 \G

    *************************** 1. row ***************************
               id: 1
      select_type: SIMPLE
            table: s
             type: ALL
    possible_keys: idx_zone_ra
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 3044468
            Extra: 
    *************************** 2. row ***************************
               id: 1
      select_type: SIMPLE
            table: p
             type: ALL
    possible_keys: idx_zone_ra
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 30276
            Extra: Using where
    *************************** 3. row ***************************
               id: 1
      select_type: SIMPLE
            table: zz
             type: eq_ref
    possible_keys: PRIMARY
              key: PRIMARY
          key_len: 8
              ref: serge.p.zoneId,serge.s.zoneId
             rows: 1
            Extra: Using where

EXPLAIN SELECT STRAIGHT_JOIN p.id, s.id FROM InMemoryDIASource AS p
    INNER JOIN ZoneZone AS zz FORCE INDEX (PRIMARY) ON p.zoneId = zz.zoneId
    INNER JOIN InMemoryObject AS s FORCE INDEX (idx_zone_ra) ON zz.matchZoneId = s.zoneId
    WHERE s.ra BETWEEN p.ra - zz.deltaRa AND p.ra + zz.deltaRa
    AND s.decl BETWEEN p.decl - 0.000833 AND p.decl + 0.000833
    AND POW(p.x - s.x, 2) + POW(p.y - s.y, 2) + POW(p.z - s.z, 2) < 2.1137067679466e-10 \G

    *************************** 1. row ***************************
               id: 1
      select_type: SIMPLE
            table: p
             type: ALL
    possible_keys: idx_zone_ra
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 30276
            Extra: 
    *************************** 2. row ***************************
               id: 1
      select_type: SIMPLE
            table: zz
             type: ref
    possible_keys: PRIMARY
              key: PRIMARY
          key_len: 4
              ref: serge.p.zoneId
             rows: 323
            Extra: 
    *************************** 3. row ***************************
               id: 1
      select_type: SIMPLE
            table: s
             type: ref
    possible_keys: idx_zone_ra
              key: idx_zone_ra
          key_len: 4
              ref: serge.zz.matchZoneId
             rows: 30444
            Extra: Using where

EXPLAIN SELECT STRAIGHT_JOIN p.id, s.id FROM InMemoryDIASource AS p
    INNER JOIN ZoneZone AS zz FORCE INDEX (PRIMARY) ON p.zoneId = zz.zoneId
    INNER JOIN InMemoryObject AS s FORCE INDEX (idx_zone_ra) ON
        zz.matchZoneId = s.zoneId AND
        s.ra BETWEEN p.ra - zz.deltaRa AND p.ra + zz.deltaRa
    WHERE s.decl BETWEEN p.decl - 0.000833 AND p.decl + 0.000833
    AND POW(p.x - s.x, 2) + POW(p.y - s.y, 2) + POW(p.z - s.z, 2) < 2.1137067679466e-10 \G

    *************************** 1. row ***************************
               id: 1
      select_type: SIMPLE
            table: p
             type: ALL
    possible_keys: idx_zone_ra
              key: NULL
          key_len: NULL
              ref: NULL
             rows: 30276
            Extra: 
    *************************** 2. row ***************************
               id: 1
      select_type: SIMPLE
            table: zz
             type: ref
    possible_keys: PRIMARY
              key: PRIMARY
          key_len: 4
              ref: serge.p.zoneId
             rows: 323
            Extra: 
    *************************** 3. row ***************************
               id: 1
      select_type: SIMPLE
            table: s
             type: ref
    possible_keys: idx_zone_ra
              key: idx_zone_ra
          key_len: 4
              ref: serge.zz.matchZoneId
             rows: 30444
            Extra: Using where
    3 rows in set (0.00 sec)