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292 lines
11 KiB
C++
292 lines
11 KiB
C++
#pragma once
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#include <Core/Row.h>
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#include <Core/Block.h>
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#include <Core/Types.h>
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#include <Core/NamesAndTypes.h>
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#include <Storages/MergeTree/MergeTreeIndexes.h>
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#include <Storages/MergeTree/MergeTreePartInfo.h>
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#include <Storages/MergeTree/MergeTreePartition.h>
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#include <Storages/MergeTree/MergeTreeDataPartChecksum.h>
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#include <Storages/MergeTree/KeyCondition.h>
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#include <Columns/IColumn.h>
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#include <Poco/Path.h>
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#include <shared_mutex>
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namespace DB
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{
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class MergeTreeData;
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/// Description of the data part.
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struct MergeTreeDataPart
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{
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using Checksums = MergeTreeDataPartChecksums;
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using Checksum = MergeTreeDataPartChecksums::Checksum;
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MergeTreeDataPart(const MergeTreeData & storage_, const String & name_, const MergeTreePartInfo & info_)
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: storage(storage_), name(name_), info(info_)
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{
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}
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MergeTreeDataPart(MergeTreeData & storage_, const String & name_);
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/// Returns the name of a column with minimum compressed size (as returned by getColumnSize()).
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/// If no checksums are present returns the name of the first physically existing column.
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String getColumnNameWithMinumumCompressedSize() const;
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struct ColumnSize
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{
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size_t marks = 0;
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size_t data_compressed = 0;
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size_t data_uncompressed = 0;
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void add(const ColumnSize & other)
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{
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marks += other.marks;
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data_compressed += other.data_compressed;
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data_uncompressed += other.data_uncompressed;
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}
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};
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/// NOTE: Returns zeros if column files are not found in checksums.
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/// NOTE: You must ensure that no ALTERs are in progress when calculating ColumnSizes.
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/// (either by locking columns_lock, or by locking table structure).
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ColumnSize getColumnSize(const String & name, const IDataType & type) const;
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ColumnSize getTotalColumnsSize() const;
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/// Returns full path to part dir
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String getFullPath() const;
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/// Returns part->name with prefixes like 'tmp_<name>'
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String getNameWithPrefix() const;
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/// Generate the new name for this part according to `new_part_info` and min/max dates from the old name.
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/// This is useful when you want to change e.g. block numbers or the mutation version of the part.
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String getNewName(const MergeTreePartInfo & new_part_info) const;
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bool contains(const MergeTreeDataPart & other) const { return info.contains(other.info); }
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/// If the partition key includes date column (a common case), these functions will return min and max values for this column.
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DayNum getMinDate() const;
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DayNum getMaxDate() const;
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/// otherwise, if the partition key includes dateTime column (also a common case), these functions will return min and max values for this column.
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time_t getMinTime() const;
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time_t getMaxTime() const;
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bool isEmpty() const { return rows_count == 0; }
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const MergeTreeData & storage;
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String name;
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MergeTreePartInfo info;
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/// A directory path (relative to storage's path) where part data is actually stored
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/// Examples: 'detached/tmp_fetch_<name>', 'tmp_<name>', '<name>'
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mutable String relative_path;
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size_t rows_count = 0;
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size_t marks_count = 0;
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std::atomic<UInt64> bytes_on_disk {0}; /// 0 - if not counted;
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/// Is used from several threads without locks (it is changed with ALTER).
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/// May not contain size of checksums.txt and columns.txt
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time_t modification_time = 0;
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/// When the part is removed from the working set. Changes once.
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mutable std::atomic<time_t> remove_time { std::numeric_limits<time_t>::max() };
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/// If true, the destructor will delete the directory with the part.
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bool is_temp = false;
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/// If true it means that there are no ZooKeeper node for this part, so it should be deleted only from filesystem
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bool is_duplicate = false;
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/**
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* Part state is a stage of its lifetime. States are ordered and state of a part could be increased only.
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* Part state should be modified under data_parts mutex.
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*
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* Possible state transitions:
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* Temporary -> Precommitted: we are trying to commit a fetched, inserted or merged part to active set
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* Precommitted -> Outdated: we could not to add a part to active set and doing a rollback (for example it is duplicated part)
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* Precommitted -> Commited: we successfully committed a part to active dataset
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* Precommitted -> Outdated: a part was replaced by a covering part or DROP PARTITION
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* Outdated -> Deleting: a cleaner selected this part for deletion
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* Deleting -> Outdated: if an ZooKeeper error occurred during the deletion, we will retry deletion
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*/
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enum class State
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{
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Temporary, /// the part is generating now, it is not in data_parts list
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PreCommitted, /// the part is in data_parts, but not used for SELECTs
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Committed, /// active data part, used by current and upcoming SELECTs
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Outdated, /// not active data part, but could be used by only current SELECTs, could be deleted after SELECTs finishes
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Deleting /// not active data part with identity refcounter, it is deleting right now by a cleaner
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};
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/// Current state of the part. If the part is in working set already, it should be accessed via data_parts mutex
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mutable State state{State::Temporary};
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/// Returns name of state
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static String stateToString(State state);
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String stateString() const;
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String getNameWithState() const
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{
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return name + " (state " + stateString() + ")";
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}
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/// Returns true if state of part is one of affordable_states
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bool checkState(const std::initializer_list<State> & affordable_states) const
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{
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for (auto affordable_state : affordable_states)
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{
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if (state == affordable_state)
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return true;
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}
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return false;
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}
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/// Throws an exception if state of the part is not in affordable_states
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void assertState(const std::initializer_list<State> & affordable_states) const;
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/// In comparison with lambdas, it is move assignable and could has several overloaded operator()
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struct StatesFilter
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{
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std::initializer_list<State> affordable_states;
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StatesFilter(const std::initializer_list<State> & affordable_states) : affordable_states(affordable_states) {}
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bool operator() (const std::shared_ptr<const MergeTreeDataPart> & part) const
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{
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return part->checkState(affordable_states);
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}
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};
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/// Returns a lambda that returns true only for part with states from specified list
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static inline StatesFilter getStatesFilter(const std::initializer_list<State> & affordable_states)
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{
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return StatesFilter(affordable_states);
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}
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/// Primary key (correspond to primary.idx file).
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/// Always loaded in RAM. Contains each index_granularity-th value of primary key tuple.
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/// Note that marks (also correspond to primary key) is not always in RAM, but cached. See MarkCache.h.
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using Index = Columns;
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Index index;
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MergeTreePartition partition;
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/// Index that for each part stores min and max values of a set of columns. This allows quickly excluding
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/// parts based on conditions on these columns imposed by a query.
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/// Currently this index is built using only columns required by partition expression, but in principle it
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/// can be built using any set of columns.
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struct MinMaxIndex
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{
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/// A direct product of ranges for each key column. See Storages/MergeTree/KeyCondition.cpp for details.
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std::vector<Range> parallelogram;
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bool initialized = false;
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public:
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MinMaxIndex() = default;
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/// For month-based partitioning.
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MinMaxIndex(DayNum min_date, DayNum max_date)
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: parallelogram(1, Range(min_date, true, max_date, true))
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, initialized(true)
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{
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}
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void load(const MergeTreeData & storage, const String & part_path);
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void store(const MergeTreeData & storage, const String & part_path, Checksums & checksums) const;
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void update(const Block & block, const Names & column_names);
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void merge(const MinMaxIndex & other);
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};
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MinMaxIndex minmax_idx;
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Checksums checksums;
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/// Columns description.
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NamesAndTypesList columns;
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using ColumnToSize = std::map<std::string, UInt64>;
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/** It is blocked for writing when changing columns, checksums or any part files.
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* Locked to read when reading columns, checksums or any part files.
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*/
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mutable std::shared_mutex columns_lock;
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/** It is taken for the whole time ALTER a part: from the beginning of the recording of the temporary files to their renaming to permanent.
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* It is taken with unlocked `columns_lock`.
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*
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* NOTE: "You can" do without this mutex if you could turn ReadRWLock into WriteRWLock without removing the lock.
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* This transformation is impossible, because it would create a deadlock, if you do it from two threads at once.
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* Taking this mutex means that we want to lock columns_lock on read with intention then, not
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* unblocking, block it for writing.
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*/
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mutable std::mutex alter_mutex;
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~MergeTreeDataPart();
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/// Calculate the total size of the entire directory with all the files
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static UInt64 calculateTotalSizeOnDisk(const String & from);
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void remove() const;
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/// Makes checks and move part to new directory
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/// Changes only relative_dir_name, you need to update other metadata (name, is_temp) explicitly
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void renameTo(const String & new_relative_path, bool remove_new_dir_if_exists = true) const;
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/// Generate unique path to detach part
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String getRelativePathForDetachedPart(const String & prefix) const;
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/// Moves a part to detached/ directory and adds prefix to its name
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void renameToDetached(const String & prefix) const;
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/// Makes clone of a part in detached/ directory via hard links
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void makeCloneInDetached(const String & prefix) const;
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/// Populates columns_to_size map (compressed size).
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void accumulateColumnSizes(ColumnToSize & column_to_size) const;
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/// Initialize columns (from columns.txt if exists, or create from column files if not).
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/// Load checksums from checksums.txt if exists. Load index if required.
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void loadColumnsChecksumsIndexes(bool require_columns_checksums, bool check_consistency);
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/// Checks that .bin and .mrk files exist
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bool hasColumnFiles(const String & column) const;
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/// For data in RAM ('index')
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UInt64 getIndexSizeInBytes() const;
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UInt64 getIndexSizeInAllocatedBytes() const;
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private:
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/// Reads columns names and types from columns.txt
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void loadColumns(bool require);
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/// If checksums.txt exists, reads files' checksums (and sizes) from it
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void loadChecksums(bool require);
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/// Loads index file. Also calculates this->marks_count if marks_count = 0
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void loadIndex();
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/// Load rows count for this part from disk (for the newer storage format version).
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/// For the older format version calculates rows count from the size of a column with a fixed size.
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void loadRowsCount();
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void loadPartitionAndMinMaxIndex();
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void checkConsistency(bool require_part_metadata);
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ColumnSize getColumnSizeImpl(const String & name, const IDataType & type, std::unordered_set<String> * processed_substreams) const;
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};
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using MergeTreeDataPartState = MergeTreeDataPart::State;
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}
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