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// Test the explain command on the primary and on secondaries:
//
// 1) Explain of read operations should work on the secondaries iff slaveOk is set.
//
// 2) Explain of write operations should
// --fail on secondaries, even if slaveOk is set,
// --succeed on primary without applying any writes.
var name = "explain_slaveok";
print("Start replica set with two nodes");
var replTest = new ReplSetTest({name: name, nodes: 2});
var nodes = replTest.startSet();
replTest.initiate();
var primary = replTest.getPrimary();
// Insert a document and let it sync to the secondary.
print("Initial sync");
primary.getDB("test").explain_slaveok.insert({a: 1});
replTest.awaitReplication();
// Check that the document is present on the primary.
assert.eq(1, primary.getDB("test").explain_slaveok.findOne({a: 1})["a"]);
// We shouldn't be able to read from the secondary with slaveOk off.
var secondary = replTest.getSecondary();
secondary.getDB("test").getMongo().setSlaveOk(false);
assert.throws(function() {
secondary.getDB("test").explain_slaveok.findOne({a: 1});
});
// With slaveOk on, we should be able to read from the secondary.
secondary.getDB("test").getMongo().setSlaveOk(true);
assert.eq(1, secondary.getDB("test").explain_slaveok.findOne({a: 1})["a"]);
//
// Test explains on primary.
//
// Explain a count on the primary.
var explainOut = primary.getDB("test").runCommand(
{explain: {count: "explain_slaveok", query: {a: 1}}, verbosity: "executionStats"});
assert.commandWorked(explainOut, "explain read op on primary");
// Explain an update on the primary.
explainOut = primary.getDB("test").runCommand({
explain: {update: "explain_slaveok", updates: [{q: {a: 1}, u: {$set: {a: 5}}}]},
verbosity: "executionStats"
});
assert.commandWorked(explainOut, "explain write op on primary");
// Plan should have an update stage at its root, reporting that it would
// modify a single document.
var stages = explainOut.executionStats.executionStages;
assert.eq("UPDATE", stages.stage);
assert.eq(1, stages.nWouldModify);
// Confirm that the document did not actually get modified on the primary
// or on the secondary.
assert.eq(1, primary.getDB("test").explain_slaveok.findOne({a: 1})["a"]);
secondary.getDB("test").getMongo().setSlaveOk(true);
assert.eq(1, secondary.getDB("test").explain_slaveok.findOne({a: 1})["a"]);
//
// Test explains on secondary.
//
// Explain a count on the secondary with slaveOk off. Should fail because
// slaveOk is required for explains on a secondary.
secondary.getDB("test").getMongo().setSlaveOk(false);
explainOut = secondary.getDB("test").runCommand(
{explain: {count: "explain_slaveok", query: {a: 1}}, verbosity: "executionStats"});
assert.commandFailed(explainOut, "explain read op on secondary, slaveOk false");
// Explain of count should succeed once slaveOk is true.
secondary.getDB("test").getMongo().setSlaveOk(true);
explainOut = secondary.getDB("test").runCommand(
{explain: {count: "explain_slaveok", query: {a: 1}}, verbosity: "executionStats"});
assert.commandWorked(explainOut, "explain read op on secondary, slaveOk true");
// Explain .find() on a secondary, setting slaveOk directly on the query.
secondary.getDB("test").getMongo().setSlaveOk(false);
assert.throws(function() {
secondary.getDB("test").explain_slaveok.explain("executionStats").find({a: 1}).finish();
});
secondary.getDB("test").getMongo().setSlaveOk(false);
explainOut = secondary.getDB("test")
.explain_slaveok.explain("executionStats")
.find({a: 1})
.addOption(DBQuery.Option.slaveOk)
.finish();
assert.commandWorked(explainOut, "explain read op on secondary, slaveOk set to true on query");
secondary.getDB("test").getMongo().setSlaveOk(true);
explainOut =
secondary.getDB("test").explain_slaveok.explain("executionStats").find({a: 1}).finish();
assert.commandWorked(explainOut, "explain .find() on secondary, slaveOk set to true");
// Explain .find() on a secondary, setting slaveOk to false with various read preferences.
var readPrefModes = ["secondary", "secondaryPreferred", "primaryPreferred", "nearest"];
readPrefModes.forEach(function(prefString) {
secondary.getDB("test").getMongo().setSlaveOk(false);
explainOut = secondary.getDB("test")
.explain_slaveok.explain("executionStats")
.find({a: 1})
.readPref(prefString)
.finish();
assert.commandWorked(
explainOut, "explain .find() on secondary, '" + prefString + "' read preference on query");
// Similarly should succeed if a read preference is set on the connection.
secondary.setReadPref(prefString);
explainOut =
secondary.getDB("test").explain_slaveok.explain("executionStats").find({a: 1}).finish();
assert.commandWorked(
explainOut,
"explain .find() on secondary, '" + prefString + "' read preference on connection");
// Unset read pref on the connection.
secondary.setReadPref();
});
// Fail explain find() on a secondary, setting slaveOk to false with read preference set to primary.
var prefStringPrimary = "primary";
secondary.getDB("test").getMongo().setSlaveOk(false);
explainOut = secondary.getDB("test").runCommand(
{explain: {find: "explain_slaveok", query: {a: 1}}, verbosity: "executionStats"});
assert.commandFailed(explainOut, "not master and slaveOk=false");
// Similarly should fail if a read preference is set on the connection.
secondary.setReadPref(prefStringPrimary);
explainOut = secondary.getDB("test").runCommand(
{explain: {find: "explain_slaveok", query: {a: 1}}, verbosity: "executionStats"});
assert.commandFailed(explainOut, "not master and slaveOk=false");
// Unset read pref on the connection.
secondary.setReadPref();
// Explain an update on the secondary with slaveOk off. Should fail because
// slaveOk is required for explains on a secondary.
secondary.getDB("test").getMongo().setSlaveOk(false);
explainOut = secondary.getDB("test").runCommand({
explain: {update: "explain_slaveok", updates: [{q: {a: 1}, u: {$set: {a: 5}}}]},
verbosity: "executionStats"
});
assert.commandFailed(explainOut, "explain write op on secondary, slaveOk false");
// Explain of the update should also fail with slaveOk on.
secondary.getDB("test").getMongo().setSlaveOk(true);
explainOut = secondary.getDB("test").runCommand({
explain: {update: "explain_slaveok", updates: [{q: {a: 1}, u: {$set: {a: 5}}}]},
verbosity: "executionStats"
});
assert.commandFailed(explainOut, "explain write op on secondary, slaveOk true");
replTest.stopSet();
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