mongodb/jstests/sharding/merge_chunks_test_with_md_ops.js

// Tests that merging chunks does not prevent cluster from doing other metadata ops

import {ShardingTest} from "jstests/libs/shardingtest.js";

var st = new ShardingTest({shards: 2});

var mongos = st.s0;
var admin = mongos.getDB("admin");
const kDbName = "foo";

assert.commandWorked(
    admin.runCommand({enableSharding: kDbName + "", primaryShard: st.shard0.shardName}));
var coll = mongos.getCollection(kDbName + ".bar");
assert.commandWorked(admin.runCommand({shardCollection: coll + "", key: {_id: 1}}));

st.printShardingStatus();

// Split and merge the first chunk repeatedly
jsTest.log("Splitting and merging repeatedly...");

for (var i = 0; i < 5; i++) {
    assert.commandWorked(admin.runCommand({split: coll + "", middle: {_id: i}}));
    assert.commandWorked(
        admin.runCommand({mergeChunks: coll + "", bounds: [{_id: MinKey}, {_id: MaxKey}]}));
    printjson(mongos.getDB("config").chunks.find().toArray());
}

// Move the first chunk to the other shard
jsTest.log("Moving to another shard...");

assert.commandWorked(
    admin.runCommand({moveChunk: coll + "", find: {_id: 0}, to: st.shard1.shardName}));

// Split and merge the chunk repeatedly
jsTest.log("Splitting and merging repeatedly (again)...");

for (var i = 0; i < 5; i++) {
    assert.commandWorked(admin.runCommand({split: coll + "", middle: {_id: i}}));
    assert.commandWorked(
        admin.runCommand({mergeChunks: coll + "", bounds: [{_id: MinKey}, {_id: MaxKey}]}));
    printjson(mongos.getDB("config").chunks.find().toArray());
}

// Move the chunk back to the original shard
jsTest.log("Moving to original shard...");

assert.commandWorked(
    admin.runCommand({moveChunk: coll + "", find: {_id: 0}, to: st.shard0.shardName}));

st.printShardingStatus();

st.stop();