You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
125 lines
4.9 KiB
125 lines
4.9 KiB
#ifndef SQL_HASH_JOIN_CHUNK_H_
|
|
#define SQL_HASH_JOIN_CHUNK_H_
|
|
|
|
/* Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.
|
|
|
|
This program is free software; you can redistribute it and/or modify
|
|
it under the terms of the GNU General Public License, version 2.0,
|
|
as published by the Free Software Foundation.
|
|
|
|
This program is also distributed with certain software (including
|
|
but not limited to OpenSSL) that is licensed under separate terms,
|
|
as designated in a particular file or component or in included license
|
|
documentation. The authors of MySQL hereby grant you an additional
|
|
permission to link the program and your derivative works with the
|
|
separately licensed software that they have included with MySQL.
|
|
|
|
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
|
|
GNU General Public License, version 2.0, for more details.
|
|
|
|
You should have received a copy of the GNU General Public License
|
|
along with this program; if not, write to the Free Software
|
|
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
|
|
|
|
#include <stddef.h>
|
|
|
|
#include "my_alloc.h"
|
|
#include "my_base.h"
|
|
#include "my_inttypes.h"
|
|
#include "my_sys.h"
|
|
#include "sql/hash_join_buffer.h"
|
|
|
|
class String;
|
|
|
|
// A HashJoinChunk is a file located on disk that can be used to store rows.
|
|
// It is used in on-disk hash join when a table is to be partitioned out to
|
|
// several smaller files, a.k.a. HashJoinChunks.
|
|
//
|
|
// When writing a column to a HashJoinChunk, we use StoreFromTableBuffers for
|
|
// converting the necessary columns into a format suitable for storage on disk.
|
|
// Conveniently, StoreFromTableBuffers creates a contiguous range of bytes and a
|
|
// corresponding length that easily and efficiently can be written out to the
|
|
// file. When reading rows back from a file, LoadIntoTableBuffers() is used to
|
|
// put the row back into the table record buffers.
|
|
//
|
|
// The basic usage goes like this:
|
|
//
|
|
// HashJoinChunk chunk;
|
|
// chunk.Init(tables); // Initialize a chunk to hold data from the given
|
|
// // tables.
|
|
// String buffer; // A buffer that is used when copying data between tables
|
|
// // and the chunk file, and vica versa.
|
|
// while (iterator->Read() == 0) {
|
|
// chunk.WriteRowToChunk(&buffer); // Write the row that lies in the record
|
|
// // buffers of "tables" to this chunk,
|
|
// // using the provided buffer.
|
|
// };
|
|
//
|
|
// chunk.Rewind(); // Prepare to read the first row in this chunk.
|
|
// chunk.LoadRowFromChunk(&buffer); // Put the row from the chunk to the
|
|
// // record buffers of "tables", using the
|
|
// // provided buffer.
|
|
class HashJoinChunk {
|
|
public:
|
|
HashJoinChunk() = default; // Constructible.
|
|
|
|
HashJoinChunk(HashJoinChunk &&other); // Movable.
|
|
|
|
HashJoinChunk(const HashJoinChunk &obj) = delete;
|
|
|
|
~HashJoinChunk();
|
|
|
|
/// Initialize this HashJoinChunk.
|
|
///
|
|
/// @returns true if the initialization failed.
|
|
bool Init(const hash_join_buffer::TableCollection &tables);
|
|
|
|
/// @returns the number of rows in this HashJoinChunk
|
|
ha_rows num_rows() const { return m_num_rows; }
|
|
|
|
/// Write a row to the HashJoinChunk.
|
|
///
|
|
/// Read the row that lies in the record buffer (record[0]) of the given
|
|
/// tables and write it out to the underlying file. If the QEP_TAB signals
|
|
/// that the row ID should be kept, it is also written out. Note that
|
|
/// TABLE::read_set is used to signal which columns that should be written to
|
|
/// the chunk.
|
|
///
|
|
/// @param buffer a buffer that is used when copying data from the tables to
|
|
/// the chunk file. Note that any existing data in "buffer" is overwritten.
|
|
///
|
|
/// @retval true on error.
|
|
bool WriteRowToChunk(String *buffer);
|
|
|
|
/// Read a row from the HashJoinChunk and put it in the record buffer.
|
|
///
|
|
/// The function will read a row from file on disk and put it in the record
|
|
/// buffers (table->record[0]) in the provided tables. The file on disk should
|
|
/// already be pointing to the start of a row.
|
|
///
|
|
/// @param buffer a buffer that is used when copying data from the chunk file
|
|
/// to the tables. Note that any existing data in "buffer" is overwritten.
|
|
///
|
|
/// @retval true on error.
|
|
bool LoadRowFromChunk(String *buffer);
|
|
|
|
/// Flush the file buffer, and prepare the file for reading.
|
|
///
|
|
/// @retval true on error
|
|
bool Rewind();
|
|
|
|
private:
|
|
// A collection of which tables the chunk file holds data from. Used to
|
|
// determine where to read data from, and where to put the data back.
|
|
hash_join_buffer::TableCollection m_tables;
|
|
|
|
// The number of rows in this chunk file.
|
|
ha_rows m_num_rows{0};
|
|
|
|
// The underlying file that is used when reading data to and from disk.
|
|
IO_CACHE m_file;
|
|
};
|
|
|
|
#endif // SQL_HASH_JOIN_CHUNK_H_
|
|
|