onstat -X command: Print thread information
Use the onstat -X command to obtain precise information about the threads that are waiting for buffers.
For each buffer in use, the onstat -X command displays general buffer information that is also available with either the onstat -b or onstat -B commands. For more information, refer to the onstat -b command in onstat -b command: Print buffer information for buffers in use.
Example output
Figure 1. onstat
-X command output
Buffers (Access)
address owner flags pagenum memaddr nslots pgflgs scount waiter
Buffer pool page size: 2048
0 modified, 3000 total, 4096 hash buckets, 2048 buffer size
Buffer pool page size: 8192
0 modified, 1000 total, 1024 hash buckets, 8192 buffer size
Output description
The onstat -X command
has a waiter field to list all user threads that are waiting
for the buffer, whereas the onstat -b and onstat
-B commands contain a waitlist field that displays
the address of the first user thread that is waiting for the buffer.
The maximum number of shared buffers is specified in the buffers field
in the BUFFERPOOL configuration parameter in the ONCONFIG file.
- Buffer pool page size
- The size of the buffer pool pages in bytes
- address
- The address of the buffer header in the buffer table
- flags
- Flags identifying the current status of the buffer page:
- 0x01
- Modified Data
- 0x02
- Data
- 0x04
- LRU
- 0x08
- Error
- 0x10
- Shared lock
- 0x20
- LRU AIO write in progress
- 0x40
- Chunk write in progress
- 0x80
- Exclusive lock
- 0x100
- Cleaner assigned to LRU
- 0x200
- Buffer should avoid bf_check calls
- 0x400
- Do log flush before writing page
- 0x800
- Buffer has been 'buff' -checked
- 0x8000
- Buffer has been pinned
- 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
- scount
- Displays the number of threads that are waiting for the buffer
- waiter
- Lists the addresses of all user threads that are waiting for the buffer