千万级别mysql合并表快速去重

mysql select * from a2kw limit 10; +-----------+-----------+------+----------+ | c1 | c2 | c3 | c4 | +-----------+-----------+------+----------+ | 662164461 | 131545534 | TOM0 | 20120520 | | 226662142 | 605685564 | TOM0 | 20120516 | | 5270

mysql> select * from a2kw limit 10;

+-----------+-----------+------+----------+

| c1        | c2        | c3   | c4       |

+-----------+-----------+------+----------+

| 662164461 | 131545534 | TOM0 | 20120520 |

| 226662142 | 605685564 | TOM0 | 20120516 |

| 527008225 | 172557633 | TOM0 | 20120514 |

| 574408183 | 350897450 | TOM0 | 20120510 |

| 781619324 | 583989494 | TOM0 | 20120510 |

| 158872754 | 775676430 | TOM0 | 20120512 |

| 815875622 | 631631832 | TOM0 | 20120514 |

| 905943640 | 477433083 | TOM0 | 20120514 |

| 660790641 | 616774715 | TOM0 | 20120512 |

| 999083595 | 953186525 | TOM0 | 20120513 |

+-----------+-----------+------+----------+

10 rows in set (0.01 sec)