https://www.cnblogs.com/abclife/p/15968628.html
根据这篇文档中的脚本，在我们自己的环境中跑了下，第一次跑的结果如下：
运行完上面跑出的split脚本后，还是存在jumbo块，第二次跑出的结果：
从上面结果可以看出，chunks的数量增加了，但jumbo chunks的数量没有减少很多。
也和阿里云后台沟通，jumbo chunk不能分裂的原因：
因为大部分jumbo chunk是相同shard key组成的，所以无法继续分割。
不知道有没有通过这种方法分割成功的案例。
具体运行脚本如下：
1、使用以下脚本找出未被检测到的Jumbo块，并生成相关命令：
var allChunkInfo = ``function``(ns){
``var chunks = db.getSiblingDB(``"config"``).chunks.find({``"ns": ns}).sort({``min``:1}).noCursorTimeout(); //this will ``returnallchunks ``forthe ns ordered ``bymin
``var totalChunks = 0;
``var totalJumbo = 0;
``var totalSize = 0;
``var totalEmpty = 0;
``chunks.forEach(
``functionprintChunkInfo(chunk) {
``var db1 = db.getSiblingDB(chunk.ns.split(``"."``)[0]) // get the ``databasewe will be running the command against later
``var ``key= db.getSiblingDB(``"config"``).collections.findOne({_id:chunk.ns}).``key``; // will need this ``forthe dataSize call
``// dataSize ``returnsthe info we need ``onthe data, but using the estimate ``optiontouse counts ``isless intensive
``var dataSizeResult = db1.runCommand({datasize:chunk.ns, keyPattern:``key``, ``min``:chunk.``min``, ``max``:chunk.``max``, estimate:``false``});
``if(dataSizeResult.``size> 67108864) {
``totalJumbo++;
``print(``'sh.splitFind("'+ chunk.ns.toString() + ``'", '+ JSON.stringify(chunk.``min``) + ``')'+ ``' // '``+ chunk.shard + ``' '+ Math.round(dataSizeResult.``size``/1024/1024) + ``' MB '+ dataSizeResult.numObjects );
``}
``totalSize += dataSizeResult.``size``;
``totalChunks++;
``if (dataSizeResult.``size== 0) { totalEmpty++ }; //``countempty chunks ``forsummary
``}
``)
``print(``"***********Summary Chunk Information***********"``);
``print(``"Total Chunks: "``+totalChunks);
``print(``"Total Jumbo Chunks: "``+totalJumbo);
``print(``"Average Chunk Size (Mbytes): "``+(totalSize/totalChunks/1024/1024));
``print(``"Empty Chunks: "``+totalEmpty);
``print(``"Average Chunk Size (non-empty): "``+(totalSize/(totalChunks-totalEmpty)/1024/1024));
}
2、脚本必须通过mongos router进行调用：
mongos> allChunkInfo(``"db.test_col"``)
3、 生成如下结果
sh.splitFind(``"db.test_col"``, {``"_id"``:``"jhxT2neuI5fB4o4KBIASK1"``}) // shard-1 222 MB 7970
sh.splitFind(``"db.test_col"``, {``"_id"``:``"zrAESqSZjnpnMI23oh5JZD"``}) // shard-2 226 MB 7988
sh.splitFind(``"db.test_col"``, {``"_id"``:``"SgkCkfSDrY789e9nD4crk9"``}) // shard-1 218 MB 7986
sh.splitFind(``"db.test_col"``, {``"_id"``:``"X5MKEH4j32OhmAhY7LGPMm"``}) // shard-1 238 MB 8338
...
***********Summary Chunk Information***********
Total Chunks: 5047
Total Jumbo Chunks: 120
Average Chunk ``Size(Mbytes): 19.29779934868946
Empty Chunks: 1107
Average Chunk ``Size(non-empty): 24.719795257064895
4、运行上一步骤的split命令
备注：阿里云分片集群介绍