| Variable | Value | Description | Range |
|---|---|---|---|
| Serwer wide memory | |||
| tmp_table_size | The maximum size of internal in-memory temporary tables. | 1024-4294967295 | |
| max_heap_table_size | This variable sets the maximum size to which MEMORY tables are allowed to grow. | 16384-4294967295 | |
| key_buffer_size | Index blocks for MyISAM tables are buffered and are shared by all threads. | 8-4294967295 (32bit) 8-OS_PER_PROCESS_LIMIT (64bit) | |
| innodb_buffer_pool_size | The size in bytes of the memory buffer InnoDB uses to cache data and indexes of its tables. | 1048576-4294967295 | |
| innodb_additional_mem_pool_size | The size in bytes of a memory pool InnoDB uses to store data dictionary information and other internal data structures. | 524288-4294967295 | |
| innodb_log_buffer_size | The size in bytes of the buffer that InnoDB uses to write to the log files on disk. | 1048576-4294967295 | |
| query_cache_size | The amount of memory allocated for caching query results. | 0-18446744073709547520 | |
| Per thread memory | |||
| max_connections | The number of simultaneous client connections allowed. | 1-100000 | |
| read_buffer_size | Each thread that does a sequential scan allocates a buffer of this size (in bytes) for each table it scans. | 8200-2147479552 | |
| read_rnd_buffer_size | When reading rows in sorted order following a key-sorting operation, the rows are read through this buffer to avoid disk seeks. | 8200-4294967295 | |
| sort_buffer_size | Each thread that needs to do a sort allocates a buffer of this size. | 0-4294967295 (32bit) 0-18446744073709547520 (64bit) | |
| thread_stack | The stack size for each thread. | 131072-4294967295 (32bit) 131072-18446744073709547520 (64bit) | |
| join_buffer_size | The size of the buffer that is used for plain index scans, range index scans, and joins that do not use indexes and thus perform full table scans. | 32bit <4GB | |