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/**
* Test aggregation explain of $merge and $out pipelines.
*
* The $out stage is not allowed with a sharded output collection. Explain of $out or $merge does
* not accept writeConcern.
* @tags: [assumes_unsharded_collection, assumes_write_concern_unchanged]
*/
(function() {
"use strict";
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.isMongos().
load("jstests/libs/analyze_plan.js"); // For getAggPlanStage().
load("jstests/aggregation/extras/merge_helpers.js"); // For withEachMergeMode().
let sourceColl = db.explain_writing_aggs_source;
let targetColl = db.explain_writing_aggs_target;
sourceColl.drop();
targetColl.drop();
assert.writeOK(sourceColl.insert({_id: 1}));
// Test that $out can be explained with 'queryPlanner' explain verbosity and does not perform
// any writes.
let explain = sourceColl.explain("queryPlanner").aggregate([{$out: targetColl.getName()}]);
let outExplain = getAggPlanStage(explain, "$out");
assert.neq(outExplain, null, explain);
assert.eq(outExplain.$out, targetColl.getName(), explain);
assert.eq(targetColl.find().itcount(), 0, explain);
// Test each $merge mode with 'queryPlanner' explain verbosity.
withEachMergeMode(function({whenMatchedMode, whenNotMatchedMode}) {
const mergeStage = {
$merge: {
into: targetColl.getName(),
whenMatched: whenMatchedMode,
whenNotMatched: whenNotMatchedMode
}
};
const explain = sourceColl.explain("queryPlanner").aggregate([mergeStage]);
const mergeExplain = getAggPlanStage(explain, "$merge");
assert.neq(mergeExplain, null, explain);
assert(mergeExplain.hasOwnProperty("$merge"), explain);
assert.eq(mergeExplain.$merge.whenMatched, whenMatchedMode, mergeExplain);
assert.eq(mergeExplain.$merge.whenNotMatched, whenNotMatchedMode, mergeExplain);
assert.eq(mergeExplain.$merge.on, "_id", mergeExplain);
assert.eq(targetColl.find().itcount(), 0, explain);
});
function assertExecutionExplainFails(writingStage, verbosity) {
assert.commandFailedWithCode(db.runCommand({
explain: {aggregate: sourceColl.getName(), pipeline: [writingStage], cursor: {}},
verbosity: verbosity
}),
[51029, 51184]);
assert.eq(targetColl.find().itcount(), 0);
}
// Test that 'executionStats' and 'allPlansExec' level explain fail with each $merge mode. These
// explain modes must fail, since they would attempt to do writes. Explain must always be
// read-only (including explain of update and delete, which describe what writes they _would_ do
// if exected for real).
withEachMergeMode(function({whenMatchedMode, whenNotMatchedMode}) {
const mergeStage = {
$merge: {
into: targetColl.getName(),
whenMatched: whenMatchedMode,
whenNotMatched: whenNotMatchedMode
}
};
assertExecutionExplainFails(mergeStage, "executionStats");
assertExecutionExplainFails(mergeStage, "allPlansExecution");
});
// Also test the $out stage since it also performs writes.
assertExecutionExplainFails({$out: targetColl.getName()}, "executionStats");
assertExecutionExplainFails({$out: targetColl.getName()}, "allPlansExecution");
// Execution explain should fail even if the source collection does not exist.
sourceColl.drop();
withEachMergeMode(function({whenMatchedMode, whenNotMatchedMode}) {
const mergeStage = {
$merge: {
into: targetColl.getName(),
whenMatched: whenMatchedMode,
whenNotMatched: whenNotMatchedMode
}
};
assertExecutionExplainFails(mergeStage, "executionStats");
assertExecutionExplainFails(mergeStage, "allPlansExecution");
});
// Also test the $out stage since it also performs writes.
assertExecutionExplainFails({$out: targetColl.getName()}, "executionStats");
assertExecutionExplainFails({$out: targetColl.getName()}, "allPlansExecution");
}());
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