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/**
* Copyright (C) 2021-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#include "mongo/platform/basic.h"
#include "mongo/base/string_data_comparator_interface.h"
#include "mongo/db/exec/sbe/accumulator_sum_value_enum.h"
#include "mongo/db/pipeline/accumulator.h"
#include "mongo/db/pipeline/accumulator_for_window_functions.h"
#include "mongo/db/pipeline/accumulator_js_reduce.h"
#include "mongo/db/query/sbe_stage_builder.h"
#include "mongo/db/query/sbe_stage_builder_accumulator.h"
#include "mongo/db/query/sbe_stage_builder_expression.h"
#include "mongo/db/query/sbe_stage_builder_helpers.h"
namespace mongo::stage_builder {
namespace {
std::unique_ptr<sbe::EExpression> wrapMinMaxArg(StageBuilderState& state,
std::unique_ptr<sbe::EExpression> arg) {
return makeLocalBind(state.frameIdGenerator,
[](sbe::EVariable input) {
return sbe::makeE<sbe::EIf>(
generateNullOrMissing(input),
makeConstant(sbe::value::TypeTags::Nothing, 0),
input.clone());
},
std::move(arg));
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorMin(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
auto collatorSlot = state.data->env->getSlotIfExists("collator"_sd);
if (collatorSlot) {
aggs.push_back(makeFunction("collMin"_sd,
sbe::makeE<sbe::EVariable>(*collatorSlot),
wrapMinMaxArg(state, std::move(arg))));
} else {
aggs.push_back(makeFunction("min"_sd, wrapMinMaxArg(state, std::move(arg))));
}
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeMin(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& minSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
// We can get away with not building a project stage since there's no finalize step but we
// will stick the slot into an EVariable in case a $min is one of many group clauses and it
// can be combined into a final project stage.
tassert(5754702,
str::stream() << "Expected one input slot for finalization of min, got: "
<< minSlots.size(),
minSlots.size() == 1);
return {makeFillEmptyNull(makeVariable(minSlots[0])), std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorMax(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
auto collatorSlot = state.data->env->getSlotIfExists("collator"_sd);
if (collatorSlot) {
aggs.push_back(makeFunction("collMax"_sd,
sbe::makeE<sbe::EVariable>(*collatorSlot),
wrapMinMaxArg(state, std::move(arg))));
} else {
aggs.push_back(makeFunction("max"_sd, wrapMinMaxArg(state, std::move(arg))));
}
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeMax(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& maxSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
tassert(5755100,
str::stream() << "Expected one input slot for finalization of max, got: "
<< maxSlots.size(),
maxSlots.size() == 1);
return {makeFillEmptyNull(makeVariable(maxSlots[0])), std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorFirst(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
aggs.push_back(makeFunction("first", makeFillEmptyNull(std::move(arg))));
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorLast(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
aggs.push_back(makeFunction("last", makeFillEmptyNull(std::move(arg))));
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorAvg(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
// 'aggDoubleDoubleSum' will ignore non-numeric values automatically.
aggs.push_back(makeFunction("aggDoubleDoubleSum", arg->clone()));
// For the counter we need to skip non-numeric values ourselves.
auto addend = makeLocalBind(state.frameIdGenerator,
[](sbe::EVariable input) {
return sbe::makeE<sbe::EIf>(
makeBinaryOp(sbe::EPrimBinary::logicOr,
generateNullOrMissing(input),
generateNonNumericCheck(input)),
makeConstant(sbe::value::TypeTags::NumberInt64, 0),
makeConstant(sbe::value::TypeTags::NumberInt64, 1));
},
std::move(arg));
auto counterExpr = makeFunction("sum", std::move(addend));
aggs.push_back(std::move(counterExpr));
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeAvg(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& aggSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
// Slot 0 contains the accumulated sum, and slot 1 contains the count of summed items.
tassert(5754703,
str::stream() << "Expected two slots to finalize avg, got: " << aggSlots.size(),
aggSlots.size() == 2);
if (state.needsMerge) {
// To support the sharding behavior, the mongos splits $group into two separate $group
// stages one at the mongos-side and the other at the shard-side. This stage builder builds
// the shard-side plan. The shard-side $avg accumulator is responsible to return the partial
// avg in the form of {count: val, ps: array_val}.
auto sumResult = makeVariable(aggSlots[0]);
auto countResult = makeVariable(aggSlots[1]);
auto partialSumExpr = makeFunction("doubleDoublePartialSumFinalize", sumResult->clone());
// Returns {count: val, ps: array_val}.
auto partialAvgFinalize =
makeNewObjFunction(FieldPair{countName, countResult->clone()},
FieldPair{partialSumName, partialSumExpr->clone()});
return {std::move(partialAvgFinalize), std::move(inputStage)};
} else {
// If we've encountered any numeric input, the counter would contain a positive integer.
// Unlike $sum, when there is no numeric input, $avg should return null.
auto finalizingExpression = sbe::makeE<sbe::EIf>(
makeBinaryOp(sbe::EPrimBinary::eq,
makeVariable(aggSlots[1]),
makeConstant(sbe::value::TypeTags::NumberInt64, 0)),
makeConstant(sbe::value::TypeTags::Null, 0),
makeBinaryOp(sbe::EPrimBinary::div,
makeFunction("doubleDoubleSumFinalize", makeVariable(aggSlots[0])),
makeVariable(aggSlots[1])));
return {std::move(finalizingExpression), std::move(inputStage)};
}
}
namespace {
std::tuple<bool, boost::optional<sbe::value::TypeTags>, boost::optional<sbe::value::Value>>
getCountAddend(const AccumulationExpression& expr) {
auto constArg = dynamic_cast<ExpressionConstant*>(expr.argument.get());
if (!constArg) {
return {false, boost::none, boost::none};
}
auto value = constArg->getValue();
switch (value.getType()) {
case BSONType::NumberInt:
return {true,
sbe::value::TypeTags::NumberInt32,
sbe::value::bitcastFrom<int>(value.getInt())};
case BSONType::NumberLong:
return {true,
sbe::value::TypeTags::NumberInt64,
sbe::value::bitcastFrom<long long>(value.getLong())};
case BSONType::NumberDouble:
return {true,
sbe::value::TypeTags::NumberDouble,
sbe::value::bitcastFrom<double>(value.getDouble())};
default:
// 'value' is NumberDecimal type in which case, 'sum' function may not be efficient
// due to decimal data copying which involves memory allocation. To avoid such
// inefficiency, does not support NumberDecimal type for this optimization.
return {false, boost::none, boost::none};
}
}
} // namespace
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorSum(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
// Optimize for a count-like accumulator like {$sum: 1}.
if (auto [isCount, addendTag, addendVal] = getCountAddend(expr); isCount) {
aggs.push_back(makeFunction("sum", makeConstant(*addendTag, *addendVal)));
return {std::move(aggs), std::move(inputStage)};
}
aggs.push_back(makeFunction("aggDoubleDoubleSum", std::move(arg)));
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeSum(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& sumSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
tassert(5755300,
str::stream() << "Expected one input slot for finalization of sum, got: "
<< sumSlots.size(),
sumSlots.size() == 1);
if (state.needsMerge) {
// Serialize the full state of the partial sum result to avoid incorrect results for certain
// data set which are composed of 'NumberDecimal' values which cancel each other when being
// summed and other numeric type values which contribute mostly to sum result and a partial
// sum of some of 'NumberDecimal' values and other numeric type values happen to lose
// precision because 'NumberDecimal' can't represent the partial sum precisely, or the other
// way around.
//
// For example, [{n: 1e+34}, {n: NumberDecimal("0,1")}, {n: NumberDecimal("0.11")}, {n:
// -1e+34}].
//
// More fundamentally, addition is neither commutative nor associative on computer. So, it's
// desirable to keep the full state of the partial sum along the way to maintain the result
// as close to the real truth as possible until all additions are done.
return {makeFunction("doubleDoublePartialSumFinalize", makeVariable(sumSlots[0])),
std::move(inputStage)};
}
if (auto [isCount, tag, val] = getCountAddend(expr); isCount) {
// The accumulation result is a scalar value. So, the final project is not necessary.
return {nullptr, std::move(inputStage)};
}
return {makeFunction("doubleDoubleSumFinalize", makeVariable(sumSlots[0])),
std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorAddToSet(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
const int cap = internalQueryMaxAddToSetBytes.load();
auto collatorSlot = state.data->env->getSlotIfExists("collator"_sd);
if (collatorSlot) {
aggs.push_back(makeFunction(
"collAddToSetCapped"_sd,
sbe::makeE<sbe::EVariable>(*collatorSlot),
std::move(arg),
makeConstant(sbe::value::TypeTags::NumberInt32, sbe::value::bitcastFrom<int>(cap))));
} else {
aggs.push_back(makeFunction(
"addToSetCapped",
std::move(arg),
makeConstant(sbe::value::TypeTags::NumberInt32, sbe::value::bitcastFrom<int>(cap))));
}
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeCappedAccumulator(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& accSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
tassert(6526500,
str::stream() << "Expected one input slot for finalization of capped accumulator, got: "
<< accSlots.size(),
accSlots.size() == 1);
// 'accSlots[0]' should contain an array of size two, where the front element is the accumulated
// values and the back element is their cumulative size in bytes. We just ignore the size
// because if it exceeded the size cap, we should have thrown an error during accumulation.
auto pushFinalize =
makeFunction("getElement",
makeVariable(accSlots[0]),
makeConstant(sbe::value::TypeTags::NumberInt32,
static_cast<int>(sbe::vm::AggArrayWithSize::kValues)));
return {std::move(pushFinalize), std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorPush(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
const int cap = internalQueryMaxPushBytes.load();
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
aggs.push_back(makeFunction(
"addToArrayCapped"_sd,
std::move(arg),
makeConstant(sbe::value::TypeTags::NumberInt32, sbe::value::bitcastFrom<int>(cap))));
return {std::move(aggs), std::move(inputStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorStdDev(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
aggs.push_back(makeFunction("aggStdDev", std::move(arg)));
return {std::move(aggs), std::move(inputStage)};
}
std::unique_ptr<sbe::EExpression> buildFinalizePartialStdDev(sbe::value::SlotId stdDevSlot) {
// To support the sharding behavior, the mongos splits $group into two separate $group
// stages one at the mongos-side and the other at the shard-side. This stage builder builds
// the shard-side plan. The shard-side $stdDevSamp and $stdDevPop accumulators are responsible
// to return the partial stddev in the form of {m2: val1, mean: val2, count: val3}.
auto stdDevResult = makeVariable(stdDevSlot);
return makeNewObjFunction(
FieldPair{
"m2"_sd,
makeFunction("getElement",
stdDevResult->clone(),
makeConstant(sbe::value::TypeTags::NumberInt32,
static_cast<int>(sbe::vm::AggStdDevValueElems::kRunningM2)))},
FieldPair{"mean"_sd,
makeFunction(
"getElement",
stdDevResult->clone(),
makeConstant(sbe::value::TypeTags::NumberInt32,
static_cast<int>(sbe::vm::AggStdDevValueElems::kRunningMean)))},
FieldPair{
"count"_sd,
makeFunction("getElement",
stdDevResult->clone(),
makeConstant(sbe::value::TypeTags::NumberInt32,
static_cast<int>(sbe::vm::AggStdDevValueElems::kCount)))});
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeStdDevPop(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& stdDevSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
tassert(5755204,
str::stream() << "Expected one input slot for finalization of stdDevPop, got: "
<< stdDevSlots.size(),
stdDevSlots.size() == 1);
if (state.needsMerge) {
return {buildFinalizePartialStdDev(stdDevSlots[0]), std::move(inputStage)};
} else {
auto stdDevPopFinalize = makeFunction("stdDevPopFinalize", makeVariable(stdDevSlots[0]));
return {std::move(stdDevPopFinalize), std::move(inputStage)};
}
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalizeStdDevSamp(
StageBuilderState& state,
const AccumulationExpression& expr,
const sbe::value::SlotVector& stdDevSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
tassert(5755209,
str::stream() << "Expected one input slot for finalization of stdDevSamp, got: "
<< stdDevSlots.size(),
stdDevSlots.size() == 1);
if (state.needsMerge) {
return {buildFinalizePartialStdDev(stdDevSlots[0]), std::move(inputStage)};
} else {
auto stdDevSampFinalize = makeFunction("stdDevSampFinalize", makeVariable(stdDevSlots[0]));
return {std::move(stdDevSampFinalize), std::move(inputStage)};
}
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulatorMergeObjects(
StageBuilderState& state,
const AccumulationExpression& expr,
std::unique_ptr<sbe::EExpression> arg,
EvalStage inputStage,
PlanNodeId planNodeId) {
std::vector<std::unique_ptr<sbe::EExpression>> aggs;
auto filterExpr = makeLocalBind(
state.frameIdGenerator,
[](sbe::EVariable input) {
return makeBinaryOp(
sbe::EPrimBinary::logicOr,
generateNullOrMissing(input),
makeBinaryOp(sbe::EPrimBinary::logicOr,
makeFunction("isObject", input.clone()),
sbe::makeE<sbe::EFail>(ErrorCodes::Error{5911200},
"$mergeObjects only supports objects")));
},
arg->clone());
inputStage = makeFilter<false>(std::move(inputStage), std::move(filterExpr), planNodeId);
aggs.push_back(makeFunction("mergeObjects", std::move(arg)));
return {std::move(aggs), std::move(inputStage)};
}
}; // namespace
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildArgument(
StageBuilderState& state,
const AccumulationStatement& acc,
EvalStage stage,
boost::optional<sbe::value::SlotId> optionalRootSlot,
PlanNodeId planNodeId) {
auto [argExpr, outStage] = generateExpression(
state, acc.expr.argument.get(), std::move(stage), optionalRootSlot, planNodeId);
return {argExpr.extractExpr(), std::move(outStage)};
}
std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage> buildAccumulator(
StageBuilderState& state,
const AccumulationStatement& acc,
EvalStage inputStage,
std::unique_ptr<sbe::EExpression> inputExpr,
PlanNodeId planNodeId) {
using BuildAccumulatorFn =
std::function<std::pair<std::vector<std::unique_ptr<sbe::EExpression>>, EvalStage>(
StageBuilderState&,
const AccumulationExpression&,
std::unique_ptr<sbe::EExpression>,
EvalStage,
PlanNodeId)>;
static const StringDataMap<BuildAccumulatorFn> kAccumulatorBuilders = {
{AccumulatorMin::kName, &buildAccumulatorMin},
{AccumulatorMax::kName, &buildAccumulatorMax},
{AccumulatorFirst::kName, &buildAccumulatorFirst},
{AccumulatorLast::kName, &buildAccumulatorLast},
{AccumulatorAvg::kName, &buildAccumulatorAvg},
{AccumulatorAddToSet::kName, &buildAccumulatorAddToSet},
{AccumulatorSum::kName, &buildAccumulatorSum},
{AccumulatorPush::kName, &buildAccumulatorPush},
{AccumulatorMergeObjects::kName, &buildAccumulatorMergeObjects},
{AccumulatorStdDevPop::kName, &buildAccumulatorStdDev},
{AccumulatorStdDevSamp::kName, &buildAccumulatorStdDev},
};
auto accExprName = acc.expr.name;
uassert(5754701,
str::stream() << "Unsupported Accumulator in SBE accumulator builder: " << accExprName,
kAccumulatorBuilders.find(accExprName) != kAccumulatorBuilders.end());
return std::invoke(kAccumulatorBuilders.at(accExprName),
state,
acc.expr,
std::move(inputExpr),
std::move(inputStage),
planNodeId);
}
std::pair<std::unique_ptr<sbe::EExpression>, EvalStage> buildFinalize(
StageBuilderState& state,
const AccumulationStatement& acc,
const sbe::value::SlotVector& aggSlots,
EvalStage inputStage,
PlanNodeId planNodeId) {
using BuildFinalizeFn = std::function<std::pair<std::unique_ptr<sbe::EExpression>, EvalStage>(
StageBuilderState&,
const AccumulationExpression&,
sbe::value::SlotVector,
EvalStage,
PlanNodeId)>;
static const StringDataMap<BuildFinalizeFn> kAccumulatorBuilders = {
{AccumulatorMin::kName, &buildFinalizeMin},
{AccumulatorMax::kName, &buildFinalizeMax},
{AccumulatorFirst::kName, nullptr},
{AccumulatorLast::kName, nullptr},
{AccumulatorAvg::kName, &buildFinalizeAvg},
{AccumulatorAddToSet::kName, &buildFinalizeCappedAccumulator},
{AccumulatorSum::kName, &buildFinalizeSum},
{AccumulatorPush::kName, &buildFinalizeCappedAccumulator},
{AccumulatorMergeObjects::kName, nullptr},
{AccumulatorStdDevPop::kName, &buildFinalizeStdDevPop},
{AccumulatorStdDevSamp::kName, &buildFinalizeStdDevSamp},
};
auto accExprName = acc.expr.name;
uassert(5754700,
str::stream() << "Unsupported Accumulator in SBE accumulator builder: " << accExprName,
kAccumulatorBuilders.find(accExprName) != kAccumulatorBuilders.end());
if (auto fn = kAccumulatorBuilders.at(accExprName); fn) {
return std::invoke(fn, state, acc.expr, aggSlots, std::move(inputStage), planNodeId);
} else {
// nullptr for 'EExpression' signifies that no final project is necessary.
return {nullptr, std::move(inputStage)};
}
}
} // namespace mongo::stage_builder
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