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/**
* Test the autosplitter when a collection has very low cardinality
*/
(function() {
'use strict';
load('jstests/sharding/autosplit_include.js');
var st = new ShardingTest({
name: "low_cardinality",
other: {enableAutoSplit: true, chunkSize: 1},
});
assert.commandWorked(st.s.adminCommand({enablesharding: "test"}));
assert.commandWorked(st.s.adminCommand({shardcollection: "test.foo", key: {sk: 1}}));
const bigString = "X".repeat(1024 * 1024 / 4); // 250 KB
var coll = st.getDB("test").getCollection("foo");
// Insert $numDocs documents into the collection under $key.
// Each document contains a string of 250KB
// waits for any ongoing splits to finish, and then prints some information
// about the collection's chunks
function insertBigDocsWithKey(key, numDocs) {
var bulk = coll.initializeUnorderedBulkOp();
for (var i = 0; i < numDocs; i++) {
bulk.insert({sk: key, sub: i, bs: bigString});
}
assert.commandWorked(bulk.execute());
waitForOngoingChunkSplits(st);
}
function numChunks() {
return st.config.chunks.count({"ns": "test.foo"});
}
// Accumulate ~1MB of documents under -10 and +10
insertBigDocsWithKey(-10, 4);
insertBigDocsWithKey(10, 4);
waitForOngoingChunkSplits(st);
// At least one split should have been performed
assert.gte(numChunks(), 2, "Number of chunks is less then 2, no split have been perfomed");
insertBigDocsWithKey(20, 4);
waitForOngoingChunkSplits(st);
// An additional split should have been performed
assert.gte(numChunks(), 3, "Number of chunks must be at least 3");
st.stop();
})();
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