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.

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Syntax:

>>-onstat-- -X-------------------------------------------------><

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

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