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6.9 InnoDB Activity Metrics

Lists the InnoDB Activity metrics and provides a brief description of each.

Table 6.9 InnoDB Activity Metrics

NameDescription
Available Undo LogsThe total number of available InnoDB undo logs. Supplements the innodb_undo_logs system variable, which reports the number of active undo logs.
Buffer Pool Bytes DataThe total number of bytes in the InnoDB buffer pool containing data. The number includes both dirty and clean pages. For more accurate memory usage calculations than with Innodb_buffer_pool_pages_data, when compressed tables cause the buffer pool to hold pages of different sizes.
Buffer Pool Bytes DirtyThe total current number of bytes held in dirty pages in the InnoDB buffer pool. For more accurate memory usage calculations than with Innodb_buffer_pool_pages_dirty, when compressed tables cause the buffer pool to hold pages of different sizes.
Buffer Pool Dump StatusThe progress of an operation to record the pages held in the InnoDB buffer pool, triggered by the setting of innodb_buffer_pool_dump_at_shutdown or innodb_buffer_pool_dump_now.
Buffer Pool Load StatusThe progress of an operation to warm up the InnoDB buffer pool by reading in a set of pages corresponding to an earlier point in time, triggered by the setting of innodb_buffer_pool_load_at_startup or innodb_buffer_pool_load_now.
Buffer Pool Pages DataThe number of pages containing data (dirty or clean).
Buffer Pool Pages DirtyThe number of pages currently dirty.
Buffer Pool Pages Flushed (Delta)The number of buffer pool page-flush requests.
Buffer Pool Pages FreeThe number of free pages.
Buffer Pool Pages LatchedThe number of latched pages in InnoDB buffer pool.
Buffer Pool Pages MiscThe number of pages that are busy because they have been allocated for administrative overhead such as row locks or the adaptive hash index.
Buffer Pool Pages TotalThe total size of the buffer pool, in pages.
Buffer Pool Read Ahead (Delta)The number of pages read into the InnoDB buffer pool by the read-ahead background thread.
Buffer Pool Read Ahead Evicted (Delta)The number of pages read into the InnoDB buffer pool by the read-ahead background thread that were subsequently evicted without having been accessed by queries.
Buffer Pool Read Requests (Delta)The number of logical read requests InnoDB has done.
Buffer Pool Reads (Delta)The number of logical reads that InnoDB could not satisfy from the buffer pool, and had to read directly from the disk.
Buffer Pool Resize StatusThe status of an operation to resize the InnoDB buffer pool dynamically, triggered by setting the innodb_buffer_pool_size parameter dynamically.
Buffer Pool Wait Free (Delta)Normally, writes to the InnoDB buffer pool happen in the background. However, if it is necessary to read or create a page and no clean pages are available, it is also necessary to wait for pages to be flushed first. This counter counts instances of these waits.
Buffer Pool Write Requests (Delta)The number writes done to the InnoDB buffer pool.
Data Fsyncs (Delta)The number of fsync() operations so far.
Data Pending FsyncsThe current number of pending fsync() operations.
Data Pending ReadsThe current number of pending reads.
Data Pending WritesThe current number of pending writes.
Data Read (Delta)The amount of data read since the server was started.
Data Reads (Delta)The total number of data reads.
Data Writes (Delta)The total number of data writes.
Data Written (Delta)The amount of data written so far, in bytes.
Dblwr Pages Written (Delta)The number of pages that have been written for doublewrite operations.
Dblwr Writes (Delta)The number of doublewrite operations that have been performed.
Have Atomic BuiltinsIndicates whether the server was built with atomic instructions.
Log Waits (Delta)The number of times that the log buffer was too small and a wait was required for it to be flushed before continuing.
Log Write Requests (Delta)The number of log write requests.
Log Writes (Delta)The number of physical writes to the log file.
Os Log Fsyncs (Delta)The number of fsync() writes done to the log file.
Os Log Pending FsyncsThe number of pending log file fsync() operations.
Os Log Pending WritesThe number of pending log file writes.
Os Log Written (Delta)The number of bytes written to the log file.
Pages Created (Delta)The number of pages created.
Page SizeThe compiled-in InnoDB page size.
Pages Read (Delta)The number of pages read.
Pages Written (Delta)The number of pages written.
Row Lock Current WaitsThe number of row locks currently being waited for.
Row Lock Time (Delta)The total time spent in acquiring row locks, in milliseconds.
Row Lock Time AvgThe average time to acquire a row lock, in milliseconds.
Row Lock Time MaxThe maximum time to acquire a row lock, in milliseconds.
Row Lock Waits (Delta)The number of times a row lock had to be waited for.
Rows Deleted (Delta)The number of rows deleted from InnoDB tables.
Rows Inserted (Delta)The number of rows inserted into InnoDB tables.
Rows Read (Delta)The number of rows read from InnoDB tables.
Rows Updated (Delta)The number of rows updated in InnoDB tables.
Truncated Status Writes (Delta)The number of times output from the SHOW ENGINE INNODB STATUS statement has been truncated.
InnoDB Buffer Cache Sub-Optimal Hit (Rate)Logical I/O is many times faster than physical I/O, and therefore a DBA should strive to keep physical I/O to a minimum. It is true that logical I/O is not free, and that the DBA should work to keep all I/O to a minimum, but it is best if most data access is performed in memory. When using InnoDB, most data access should occur in RAM, and therefore the InnoDB buffer cache hit rate should be high.
InnoDB Buffer Pool Writes Bottleneck (Rate)For optimal performance, InnoDB should not have to wait before writing pages into the InnoDB buffer pool.
InnoDB Log Waits Bottleneck (Rate)For optimal performance, InnoDB should not have to wait before writing DML activity to the InnoDB log buffer.
Buffer Pool Megabytes DataThe total number of megabytes in the InnoDB buffer pool containing data.
Buffer Pool Megabytes DirtyThe total current number of megabytes held in dirty pages in the InnoDB buffer pool.