Spec-Zone .ru
спецификации, руководства, описания, API
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Spec-Zone .ru
спецификации, руководства, описания, API
|
The INNODB_BUFFER_PAGE table holds information about each page
in the InnoDB buffer pool.
Table 20.16. INNODB_BUFFER_PAGE Columns
| Column name | Description |
|---|---|
POOL_ID |
Buffer Pool ID. An identifier to distinguish between multiple buffer pool instances. |
BLOCK_ID |
Buffer Pool Block ID. |
SPACE |
Tablespace ID. Uses the same value as in INNODB_SYS_TABLES.SPACE.
|
PAGE_NUMBER |
Page number. |
PAGE_TYPE |
Page type string. One of allocated (Freshly allocated page), index (B-tree node), undo_log (Undo log
page), inode (Index node), ibuf_free_list (Insert buffer free list), ibuf_bitmap
(Insert buffer bitmap), system (System page), trx_system (Transaction system data), file_space_header
(File space header), extent_descriptor (Extent descriptor page),
blob (Uncompressed BLOB page), compressed_blob
(First compressed BLOB page), compressed_blob2 (Subsequent comp
BLOB page), unknown (unknown).
|
FLUSH_TYPE |
Flush type. |
FIX_COUNT |
Number of threads using this block within the buffer pool. When zero, the block is eligible to be evicted. |
IS_HASHED |
Whether hash index has been built on this page. |
NEWEST_MODIFICATION |
Log Sequence Number of the youngest modification. |
OLDEST_MODIFICATION |
Log Sequence Number of the oldest modification. |
ACCESS_TIME |
An abstract number used to judge the first access time of the page. |
TABLE_NAME |
Name of the table the page belongs to. |
INDEX_NAME |
Name of the index the page belongs to. It can be the name of a clustered index or a secondary index. |
NUMBER_RECORDS |
Number of records within the page. |
DATA_SIZE |
Sum of the sizes of the records. |
COMPRESSED_SIZE |
Compressed page size. Null for pages that are not compressed. |
PAGE_STATE |
Page state. A page with valid data has one of the following states: FILE_PAGE
(buffers a page of data from a file), MEMORY (buffers a page from
an in-memory object), Other possible states (managed by InnoDB)
are: null, READY_FOR_USE, NOT_USED,
REMOVE_HASH.
|
IO_FIX |
Specifies whether any I/O is pending for this page: IO_NONE = no
pending I/O, IO_READ = read pending, IO_WRITE = write pending.
|
IS_OLD |
bpage->old. |
FREE_PAGE_CLOCK |
bpage->freed_page_clock. |
Notes:
This table is primarily useful for expert-level performance monitoring, or when developing performance-related extensions for MySQL.
Since the INFORMATION_SCHEMA is a general-purpose way
to monitor the MySQL server, use this table rather than the corresponding InnoDB system table for any new monitoring application you develop.
You must have the PROCESS privilege to query this
table.