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20.30.16. The INFORMATION_SCHEMA INNODB_BUFFER_PAGE Table

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: