Mongodb 分片 手动维护chunk
--显示collection的chunk分布信息db.collection.getShardDistribution()
显示chunk信息脚本：
AllChunkInfo = function(ns, est){
var chunks = db.getSiblingDB("config").chunks.find({"ns" : ns}).sort({min:1}); //this will return all chunks for the ns ordered by min
//some counters for overall stats at the end
var totalChunks = 0;
var totalSize = 0;
var totalEmpty = 0;
print("ChunkID,Shard,ChunkSize,ObjectsInChunk"); // header row
// iterate over all the chunks, print out info for each
chunks.forEach(
function printChunkInfo(chunk) {
var db1 = db.getSiblingDB(chunk.ns.split(".")); // get the database we will be running the command against later
var key = db.getSiblingDB("config").collections.findOne({_id:chunk.ns}).key; // will need this for the dataSize call
// dataSize returns the info we need on the data, but using the estimate option to use counts is less intensive
var dataSizeResult = db1.runCommand({datasize:chunk.ns, keyPattern:key, min:chunk.min, max:chunk.max, estimate:est});
// printjson(dataSizeResult); // uncomment to see how long it takes to run and status
print(chunk._id+","+chunk.shard+","+dataSizeResult.size+","+dataSizeResult.numObjects);
totalSize += dataSizeResult.size;
totalChunks++;
if (dataSizeResult.size == 0) { totalEmpty++ }; //count empty chunks for summary
}
)
print("***********Summary Chunk Information***********");
print("Total Chunks: "+totalChunks);
print("Average Chunk Size (bytes): "+(totalSize/totalChunks));
print("Empty Chunks: "+totalEmpty);
print("Average Chunk Size (non-empty): "+(totalSize/(totalChunks-totalEmpty)));
}
使用示例：
mongos> AllChunkInfo("test1.users001", true);
ChunkID,Shard,ChunkSize,ObjectsInChunk
test1.users001-_id_MinKey,shard3,11347710,171935
test1.users001-_id_-6148914691236517204,shard1,11293458,171113
test1.users001-_id_-3074457345618258602,shard1,11320716,171526
test1.users001-_id_0,shard3,11349096,171956
test1.users001-_id_3074457345618258602,shard2,11340054,171819
test1.users001-_id_6148914691236517204,shard2,11328966,171651
***********Summary Chunk Information***********
Total Chunks: 6
Average Chunk Size (bytes): 11330000
Empty Chunks: 0
Average Chunk Size (non-empty): 11330000
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