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Improve performance of trivial count query in presense of "distributed_aggregation_memory_efficient"

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This commit is contained in:
Alexey Milovidov 2021-02-21 23:06:31 +03:00
parent e1c4ba0169
commit 0ab14120ef
1 changed files with 5 additions and 1 deletions
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6
src/Interpreters/InterpreterSelectQuery.cpp
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@ -1285,8 +1285,11 @@ void InterpreterSelectQuery::executeFetchColumns(
const auto & desc = query_analyzer->aggregates()[0];
const auto & func = desc.function;
std::optional<UInt64> num_rows{};
if (!query.prewhere() && !query.where())
{
num_rows = storage->totalRows(settings);
}
else // It's possible to optimize count() given only partition predicates
{
SelectQueryInfo temp_query_info;
@ -1296,6 +1299,7 @@ void InterpreterSelectQuery::executeFetchColumns(
num_rows = storage->totalRowsByPartitionPredicate(temp_query_info, *context);
}
if (num_rows)
{
AggregateFunctionCount & agg_count = static_cast<AggregateFunctionCount &>(*func);
@ -1790,7 +1794,7 @@ void InterpreterSelectQuery::executeMergeAggregated(QueryPlan & query_plan, bool
auto merging_aggregated = std::make_unique<MergingAggregatedStep>(
query_plan.getCurrentDataStream(),
std::move(transform_params),
settings.distributed_aggregation_memory_efficient,
settings.distributed_aggregation_memory_efficient && storage && storage->isRemote(),
settings.max_threads,
settings.aggregation_memory_efficient_merge_threads);