jstests/core/explain2.js


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// Test calculation of the 'millis' field in explain output.

t = db.jstests_explain2;
t.drop();

t.ensureIndex({a: 1});
for (i = 1000; i < 4000; i += 1000) {
    t.save({a: i});
}

// Run a query with one $or clause per a-value, each of which sleeps for 'a' milliseconds.
function slow() {
    sleep(this.a);
    return true;
}
clauses = [];
for (i = 1000; i < 4000; i += 1000) {
    clauses.push({a: i, $where: slow});
}
explain = t.find({$or: clauses}).explain(true);
printjson(explain);

// Verify the duration of the whole query, and of each clause.
assert.gt(explain.executionStats.executionTimeMillis, 1000 - 500 + 2000 - 500 + 3000 - 500);