我目前正在使用GeoIPCity-Location表处理Maxmind数据库，并意识到数十万个数据是重复的。例如，我搜索过泰恩河畔纽卡斯尔：
SELECT * FROM MAXMIND
WHERE city='Newcastle Upon Tyne';
结果是：
369137 GB I7 Newcastle Upon Tyne NE20 54.9881 -1.6194
369332 GB I7 Newcastle Upon Tyne NE6 54.9881 -1.6194
369345 GB I7 Newcastle Upon Tyne NE13 54.9881 -1.6194
369355 GB I7 Newcastle Upon Tyne NE3 54.9881 -1.6194
369356 GB I7 Newcastle Upon Tyne NE5 54.9881 -1.6194
369645 GB I7 Newcastle Upon Tyne NE4 54.9881 -1.6194
369706 GB I7 Newcastle Upon Tyne NE15 54.9881 -1.6194
369959 GB I7 Newcastle Upon Tyne NE12 54.9881 -1.6194
370114 GB I7 Newcastle Upon Tyne NE27 54.9881 -1.6194
如果我只是搜索“纽卡斯尔”，那就更糟了：
382 ZA 2 Newcastle -27.758 29.9318
2279 US OK Newcastle 73065 35.2323 -97.6008
26459 US CA Newcastle 95658 38.873 -121.1543
22382 CA ON Newcastle l1b1j9 43.9167 -78.5833
38995 AU 2 Newcastle -32.9278 151.7845
40025 US ME Newcastle 4553 44.0438 -69.5675
47937 GB I7 Newcastle 54.9881 -1.6194
119830 US ME Newcastle 4553 44.0438 -69.5675
119982 US NE Newcastle 68757 42.6475 -96.9232
115052 US CA Newcastle 95658 38.873 -121.1543
120603 US NE Newcastle 68757 42.6475 -96.9232
127931 US OK Newcastle 73065 35.2323 -97.6008
136726 CA ON Newcastle 43.9167 -78.5833
136915 US TX Newcastle 76372 33.245 -98.9103
137128 US WY Newcastle 82701 43.8396 -104.5681
137130 US WY Newcastle 82701 43.8396 -104.5681
144799 IE 16 Newcastle 52.4492 -9.0611
207626 US UT Newcastle 84756 37.6924 -113.6272
213128 US UT Newcastle 84756 37.6924 -113.6272
221968 KN 5 Newcastle 17.2 -62.5833
229237 CA ON Newcastle l1b1l4 43.9167 -78.5833
232235 GB M9 Newcastle 54.9881 -1.6194
229005 CA ON Newcastle l1b1g1 43.9167 -78.5833
228722 CA ON Newcastle l1b1k9 43.9167 -78.5833
242102 CA NB Newcastle 46.9833 -65.5667
252530 IE 7 Newcastle 53.3011 -6.5022
267662 CA ON Newcastle l1b1h5 43.9167 -78.5833
266263 IE 31 Newcastle 53.0683 -6.0658
313271 CA ON Newcastle l1b1h8 43.9167 -78.5833
306632 IE 10 Newcastle 53.3408 -8.6783
320151 CA ON Newcastle l1b1l2 43.9167 -78.5833
336868 GB L6 Newcastle 52.4333 -3.1167
353050 GB R9 Newcastle 54.2 -5.8833
349314 GB Q7 Newcastle 54.3833 -5.4667
377107 ZA 2 Newcastle 2940 -27.758 29.9318
369587 GB I7 Newcastle ST5 54.9881 -1.6194
387865 AU 2 Newcastle 2297 -32.9278 151.7845
387889 AU 2 Newcastle 2300 -32.9278 151.7845
387978 AU 2 Newcastle 2306 -32.9278 151.7845
388098 AU 2 Newcastle 2302 -32.9278 151.7845
392595 AU 2 Newcastle 2296 -32.9278 151.7845
388376 AU 2 Newcastle 2899 -32.9278 151.7845
有没有办法删除重复项？我怎么知道要删除哪些副本以及要保留哪些副本？
由于