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// Verifies basic sharded transaction behavior with the supported read concern levels.
//
// @tags: [
// requires_find_command,
// requires_sharding,
// uses_multi_shard_transaction,
// uses_transactions,
// ]
(function() {
"use strict";
const dbName = "test";
const collName = "foo";
const ns = dbName + "." + collName;
const st = new ShardingTest({shards: 2, config: 1});
// Set up a sharded collection with 2 chunks, one on each shard.
assert.writeOK(st.s.getDB(dbName)[collName].insert({_id: -1}, {writeConcern: {w: "majority"}}));
assert.writeOK(st.s.getDB(dbName)[collName].insert({_id: 1}, {writeConcern: {w: "majority"}}));
assert.commandWorked(st.s.adminCommand({enableSharding: dbName}));
st.ensurePrimaryShard(dbName, st.shard0.shardName);
assert.commandWorked(st.s.adminCommand({shardCollection: ns, key: {_id: 1}}));
assert.commandWorked(st.s.adminCommand({split: ns, middle: {_id: 0}}));
assert.commandWorked(st.s.adminCommand({moveChunk: ns, find: {_id: 1}, to: st.shard1.shardName}));
// Refresh second shard to avoid stale shard version error on the second transaction statement.
assert.commandWorked(st.rs1.getPrimary().adminCommand({_flushRoutingTableCacheUpdates: ns}));
function runTest(st, readConcern, sessionOptions) {
jsTestLog("Testing readConcern: " + tojson(readConcern) +
", sessionOptions: " + tojson(sessionOptions));
const session = st.s.startSession(sessionOptions);
const sessionDB = session.getDatabase(dbName);
if (readConcern) {
session.startTransaction({readConcern: readConcern});
} else {
session.startTransaction();
}
// Target only the first shard.
assert.commandWorked(sessionDB.runCommand({find: collName, filter: {_id: -1}}));
// On a separate, causally consistent session, read from the first shard then write to the
// second one. This write is guaranteed to commit at a later cluster time than that of the
// snapshot established by the transaction on the first shard.
const otherSessionDB = st.s.startSession().getDatabase(dbName);
assert.commandWorked(otherSessionDB.runCommand({find: collName}));
assert.commandWorked(otherSessionDB.runCommand({insert: collName, documents: [{_id: 5}]}));
// Depending on the transaction's read concern, the new document will or will not be visible
// to the next statement.
const numExpectedDocs = readConcern && readConcern.level === "snapshot" ? 0 : 1;
assert.eq(
numExpectedDocs,
sessionDB[collName].find({_id: 5}).itcount(),
"sharded transaction with read concern " + tojson(readConcern) +
" did not see expected number of documents, sessionOptions: " + tojson(sessionOptions));
assert.commandWorked(session.commitTransaction_forTesting());
// Clean up for the next iteration.
assert.writeOK(sessionDB[collName].remove({_id: 5}));
}
// Specifying no read concern level is allowed and should not compute a global snapshot.
runTest(st, undefined, {causalConsistency: false});
runTest(st, undefined, {causalConsistency: true});
const kAllowedReadConcernLevels = ["local", "majority", "snapshot"];
for (let readConcernLevel of kAllowedReadConcernLevels) {
runTest(st, {level: readConcernLevel}, {causalConsistency: false});
runTest(st, {level: readConcernLevel}, {causalConsistency: true});
}
st.stop();
})();
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