onstat -B command: Prints information about used buffers
Use the onstat -B option to display information about buffers that are not on the free-list.
Both onstat -B and onstat -b display the similar information, except that the onstat -b command only displays buffers that are currently being accessed by a user thread. The onstat -B command displays information for all the buffers that are not on the free-list.
For information about running the onstat -B command on a dump file created without the buffer pool, see Running onstat Commands on a Shared Memory Dump File.
Example output
Output description
- Buffer pool page size
- the size of the buffer pool pages in bytes
- address
- the address of the buffer header in the buffer table
- userthread
- the address of the most recent user thread to access the buffer table. Many user threads might be reading the same buffer concurrently.
- flgs
- Uses the following flag bits to describe the buffer:
- 0x01
- Modified data
- 0x02
- Data
- 0x04
- LRU
- 0x08
- Error
- pagenum
- the physical page number on the disk
- memaddr
- the buffer memory address
- nslots
- the number of slot-table entries in the page
This field indicates the number of rows (or portions of a row) that are stored on the page.
- pgflgs
- Uses the following values, alone or in combination, to describe
the page type:
- 1
- Data page
- 2
- Tblspace page
- 4
- Free-list page
- 8
- Chunk free-list page
- 9
- Remainder data page
- b
- Partition resident blobpage
- c
- Blobspace resident blobpage
- d
- Blob chunk free-list bit page
- e
- Blob chunk blob map page
- 10
- B-tree node page
- 20
- B-tree root-node page
- 40
- B-tree branch-node page
- 80
- B-tree leaf-node page
- 100
- Logical-log page
- 200
- Last page of logical log
- 400
- Sync page of logical log
- 800
- Physical log
- 1000
- Reserved root page
- 2000
- No physical log required
- 8000
- B-tree leaf with default flags
- xflgs
- Uses the following flag bits to describe buffer access:
- 0x10
- share lock
- 0x80
- exclusive lock
- owner
- the user thread that set the xflgs buffer flag
- waitlist
- the address of the first user thread that is waiting for access
to this buffer
For a complete list of all threads waiting for the buffer, refer to onstat -X command: Print thread information.