ClickHouse/src/Storages/MergeTree/TTLMergeSelector.h

#pragma once

#include <Storages/MergeTree/MergeSelector.h>


namespace DB
{

/** Merge selector, which is used to remove values with expired ttl.
  * It selects parts to merge by greedy algorithm: 
  *  1. Finds part with the most earliest expired ttl and includes it to result.
  *  2. Tries to find the longest range of parts with expired ttl, that includes part from step 1.
  */
class TTLMergeSelector : public IMergeSelector
{
public:
    explicit TTLMergeSelector(time_t current_time_, bool only_drop_parts_) : current_time(current_time_), only_drop_parts(only_drop_parts_) {}

    PartsInPartition select(
        const Partitions & partitions,
        const size_t max_total_size_to_merge) override;
private:
    time_t current_time;
    bool only_drop_parts;
};

}