Shulou(Shulou.com)06/01 Report--

There are two types of memory parameters in mysql. One is thread-specific memory. One is the thread-specific memory of global sharing: join_buffer_size, sort_buffer_size, read_buffer_size sequential read data buffer, read_rnd_buffer_size random read data buffer, bulk_insert_buffer_size bulk insert temporary memory, tmp_table_size internal temporary table memory, max_heap_table_size memory table memory.

Join_buffer_size:The minimum 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.When Batched Key Access is used, the value of join_buffer_size defines how large the batch of keys is in each request to the storage engine are used for normal index scans, range index scans, and the minimum size of buffers for joins that do not use indexes and thus perform full table scans. When using batch key access, the value of join_buffer_size defines the size of the batch key in each request made to the storage engine

Sort_buffer_size:Each session that must perform a sort allocates a buffer of this size allocates a buffer of this size for each session that must perform a sort

Read_buffer_size:Each thread that does a sequential scan for a MyISAM table allocates a buffer of this size (in bytes) for each table it scans each thread that sequentially scans the MyISAM table allocates a buffer of this size (in bytes) for each table it scans

Tmp_table_size:The maximum size of internal in-memory temporary tables. The maximum size of internal temporary tables in memory. There are two kinds of mysql temporary tables, one is created using create temporary table, which is called external temporary table, and the other is generated by union, order by, group by, distinct and other statements, which is called internal temporary table.

Max_heap_table_size:This variable sets the maximum size to which user-created MEMORY tables are permitted to grow this variable sets the maximum size that allows memory tables created by the user to grow

Global shared memory: key_buffer_size (MyISAM index cache), the amount of memory allocated by query_cache_size to cache query results, how many threads the thread_cache_size server should cache for reuse, the number of tables opened by all table_open_cache threads, binlog_cache_ size binary log buffer, innodb_log_buffer_size transaction log buffer, innodb_buffer_pool_size data and index buffers

The index block of the key_buffer_size:Index blocks for MyISAM tables are buffered and are shared by all threads.MyISAM table is buffered and shared by all threads.

The amount of memory allocated by query_cache_size:The amount of memory allocated for caching query results to cache query results

Thread_cache_size:How many threads the server should cache for reuse. When a client disconnects, the client's threads are put in the cache if there are fewer than thread_cache_size threads there.The default value= 8 + (max_connections/100)

In order to improve the performance of the client request to create a connection, MySQL provides a connection pool, that is, Thread_Cache pool, which places idle connection threads in the connection pool instead of destroying them immediately. The advantage is that when there is a new request, mysql will not immediately create a connection thread, but first go to Thread_Cache to find free connection thread, if there is, then directly use, do not exist to create a new connection thread.

Table_open_cache:The number of open tables for all threads. The number of tables opened for all threads.

Binlog_cache_size:The size of the cache to hold changes to the binary log during a transaction. During the transaction, the cache saves the size of the changes to the binary log.

The byte size of the buffer that innodb_log_buffer_size:The size in bytes of the buffer that InnoDB uses to write to the log files on disk.InnoDB uses to write to log files on disk.

Innodb_buffer_pool_size:The size in bytes of the buffer pool, the memory area where InnoDB caches table and index data. The default value is 134217728 bytes (128MB). The byte size of the buffer pool and the memory area of InnoDB cache table and index data. The default is 134217728 bytes (128MB)

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