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.

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Syntax:

>>-onstat-- -B-------------------------------------------------><

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.


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