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/**
* Testing of the query planner heuristics for determining whether a collection is eligible for
* column scan.
* @tags: [
* # Column store indexes are still under a feature flag.
* featureFlagColumnstoreIndexes,
* ]
*/
(function() {
"use strict";
load("jstests/libs/analyze_plan.js"); // For "planHasStage."
load("jstests/libs/columnstore_util.js"); // For "setUpServerForColumnStoreIndexTest."
load("jstests/noPassthrough/libs/server_parameter_helpers.js"); // For "setParameter."
if (!setUpServerForColumnStoreIndexTest(db)) {
return;
}
const coll = db.columnstore_planning_heuristics;
coll.drop();
assert.commandWorked(coll.createIndex({"$**": "columnstore"}));
// Reset the given params to values such that the related check is guaranteed NOT to pass in this
// test. Since the heuristics are OR-ed together, this allows us to isolate a single threshold for
// testing.
function resetParameters(params) {
for (const paramName of params) {
setParameter(
db, paramName, 1024 * 1024 * 1024); // any large number is enough for these tests
}
}
function assertColumnScanUsed(filter, shouldUseColumnScan, thresholdName) {
const explain = coll.find(filter, {_id: 0, a: 1}).explain();
assert(planHasStage(db, explain, "COLUMN_SCAN") == shouldUseColumnScan,
`Threshold met: ${thresholdName} but column scan was${
(shouldUseColumnScan ? " not " : " ")}used: ${tojson(explain)}`);
}
// Helper that sets the parameter to the specified value and ensures that column scan is used.
function runParameterTest(paramName, paramValue, queryFilter = {}) {
setParameter(db, paramName, paramValue);
assertColumnScanUsed(queryFilter, true, paramName);
resetParameters([paramName]);
}
// Start with all thresholds set to non-passing values.
resetParameters([
"internalQueryColumnScanMinNumColumnFilters",
"internalQueryColumnScanMinAvgDocSizeBytes",
"internalQueryColumnScanMinCollectionSizeBytes"
]);
// Test heuristics on an empty collection.
assertColumnScanUsed({}, false, "none"); // No thresholds met.
runParameterTest("internalQueryColumnScanMinNumColumnFilters", 0);
runParameterTest("internalQueryColumnScanMinAvgDocSizeBytes", 0);
runParameterTest("internalQueryColumnScanMinCollectionSizeBytes", 0);
// Test heuristics on a non-empty collection (content doesn't matter for this test).
for (let i = 0; i < 20; ++i) {
coll.insert([{a: i}]);
}
assertColumnScanUsed({}, false, "none"); // No thresholds met.
runParameterTest("internalQueryColumnScanMinNumColumnFilters", 1, {a: 1});
runParameterTest("internalQueryColumnScanMinAvgDocSizeBytes", 1);
runParameterTest("internalQueryColumnScanMinCollectionSizeBytes", 1);
// Special case - use available memory as the collection size threshold.
setParameter(db, "internalQueryColumnScanMinCollectionSizeBytes", -1);
assertColumnScanUsed({}, false, "none");
// Test that a hint will still allow us to use the index.
const explain = coll.find({}, {_id: 0, a: 1}).hint({"$**": "columnstore"}).explain();
assert(planHasStage(db, explain, "COLUMN_SCAN"),
`Hint should have overridden heuristics to use column scan: ${tojson(explain)}`);
})();
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