onstat -C command: Print B-tree scanner information

Use the -C command to display information about the B-tree scanner subsystem and each B-tree scanner thread.

Read syntax diagramSkip visual syntax diagram
Syntax:

>>-onstat-- -C--+-prof--+--------------------------------------><
                +-hot---+   
                +-part--+   
                +-clean-+   
                +-range-+   
                +-map---+   
                +-alice-+   
                '-all---'   

The following options are available with the onstat -C command and can be combined:
prof
Prints the profile information for the system and each B-tree scanner thread. This is the default option.
hot
Prints the hot list index key in the order to be cleaned
part
Prints all partitions with index statistics
clean
Prints information about all the partitions that were cleaned or need to be cleaned
range
Prints the savings in pages processed by using index range scanning
map
Displays the current bitmaps for each index being cleaned by the alice cleaning method
alice
Displays the efficiency of the alice cleaning method option
all
Prints all onstat -C options

Example output using the prof option

Figure 1. onstat -C command output with the prof option
Btree Cleaner Info
BT scanner profile Information
==============================
Active Threads                               1
Global Commands                        2000000   Building hot list
Number of partition scans                11003
Main Block                          0xc000000003c9dc68
BTC Admin                           0xc0000000024bc208


BTS info             id   Prio    Partnum      Key     Cmd
0xc000000003c9dee8    0   High   0x00000000     0       40  Yield N
    Number of leaves pages scanned                         77
    Number of leaves with deleted items                     6
    Time spent cleaning (sec)                               0
    Number of index compresses                              0
    Number of deleted items                               113
    Number of index range scans                             0
    Number of index leaf scans                              0
    Number of index alice scans                             2 

Output description using the prof option

Id
BTSCANNER ID
Prio
Current priority of BTSCANNER
Partnum
The partition number for the index this thread is currently working on
Cmd
Command this thread is processing currently

Example output using the hot option

Figure 2. onstat -C command output with the hot option
Btree Cleaner Info

Index Hot List
==============
    Current Item           5     List Created          15:29:47
    List Size              4     List expires in              0 sec
    Hit Threshold        500     Range Scan Threshold        -1


Partnum        Key            Hits
0x00100191       1              14 *
0x00A00022       1              13 *
0x00100191       2               8 *
0x00100150       2               7 * 

Output description using the hot option

Partnum
The partition number for an index
Key
Index Key
Hits
The current value of the Hit counter
*
Indicates that this partition has been cleaned during this hot list duration

Example output using the part option

Figure 3. onstat -C command output with the part option
Btree Cleaner Info


Index Statistics
================
 Partnum  Key     Positions   Compress      Split
0x00100002  1           146          0          0
0x00100004  1             4          0          0
0x00100004  2            13          0          0
0x00100005  1             1          0          0
0x00100005  2             0          0          0
0x00100006  1             1          0          0
0x00100006  2             0          0          0
0x00100007  2             1          0          0
0x00100008  2             1          0          0
0x0010000a  1             0          0          0
0x0010000e  3             1          0          0
0x00100011  1             1          0          0
0x00100013  2             2          0          0 

Output description using the part option

Partnum
The partition number for an index
Key
Index Key
Positions
Number of times index has been read
Compress
Number of pages which have been compressed
Split
Number of splits that have occurred
C
Indicates partition is busy being cleaned
N
Index partition no longer eligible for cleaning

Example output using the clean option

Figure 4. onstat -C command output with the clean option
Btree Cleaner Info

Index Cleaned Statistics
=========================
 Partnum  Key      Dirty Hits  Clean Time  Pg Examined  Items Del  Pages/Sec
0x00100013  2               2           0           0           0       0.00
0x0010008b  3               1           0           0           0       0.00
0x001000c7  1               2           0           0           0       0.00
0x00100150  2               7           0           0           0       0.00
0x0010016f  2               2           0           0           0       0.00
0x00100191  1              14           0           0           0       0.00
0x00100191  2               8           0           0           0       0.00
0x00a00011  2               6           0           0           0       0.00
0x00a00013  1               0           0          24           0      24.00
0x00a00019  1               0           0         470         225     470.00
0x00a00022  1              13           0           0           0       0.00
0x00a00022  2               5           0           0           0       0.00 

Output description using the clean option

Partnum
The partition number for an index
Key
Index Key
Dirty Hits
Number of times a dirty page has been scanned
Clean Time
Total time spent, in seconds
Pg Examined
Number of pages examined by btscanner thread
Items Del
Number of items removed form this index
Pages/Sec
Number of pages examined per second
C
Indicates partition is busy being cleaned
N
index partition is no longer eligible for cleaning

Example Output

Figure 5. onstat -C range
Btree Cleaner Info

Cleaning Range Statistics
=========================
 Partnum  Key             Low          High          Size        Saving
0x001001bc  2               36             69             96      65.6 %
0x001001be  1               16             20             48      91.7 %
0x001001cd  1                8             21             32      59.4 %
0x001001cd  2               24             25             32      96.9 %
 

Output Description

Partnum
The partition number
Key
Index Key
Low
Low boundary for range scan
High
High boundary for index scan
Size
Size of index in pages
Saving
Percentage of time saved versus a full scan
C
Indicates partition is busy being cleaned
N
Index partition is no longer eligible for cleaning

Example Output

Figure 6. onstat -C map
Btree Cleaner Info

ALICE Bitmap of Deleted Index Items
===================================
Partnum   Key        Map
0x00100013  2 0000: 80000000 00000000
0x0010008b  3 0000: 80000000 00000000
0x001000c7  1 0000: 80000000 00000000
0x00100150  2 0000: 80000000 00000000
0x0010016f  2 0000: 80000000 00000000
0x00100191  1 0000: 80000000 00000000
0x00100191  2 0000: 80000000 00000000
0x00a00011  2 0000: 80000000 00000000
0x00a00013  1 0000: 00000000 00000000
0x00a00019  1 0000: 00000000 00000000
0x00a00022  1 0000: 80000000 00000000
0x00a00022  2 0000: 80000000 00000000

Output Description

Partnum
The partition number
Key
Index Key
Map
Alice bitmap

Example Output

Figure 7. onstat -C alice
Btree Cleaner Info

ALICE Cleaning Statistics
=========================

System ALICE Info: Mode =    6, Eff =    30 %, Adj =     5

Partnum    Mode BM_Sz  Used_Pg  Examined  Dirty_Pg  # I/O  Found    Eff   Adj
0x00100013    6    64       97         0         0      0      0   0.0 %    0
0x0010008b    6    64        5         0         0      0      0   0.0 %    0
0x001000c7    6    64        2         0         0      0      0   0.0 %    0
0x00100150    6    64       91         0         0      0      0   0.0 %    0
0x0010016f    6    64       91         0         0      0      0   0.0 %    0
0x00100191    6    64       26         0         0      0      0   0.0 %    0
0x00100191    6    64       26         0         0      0      0   0.0 %    0
0x001001bc    0     0       91         0         0      0      0   0.0 %    0
0x001001cd    0     0       26         0         0      0      0   0.0 %    0
0x001001cd    0     0       26         0         0      0      0   0.0 %    0
0x00a00011    6    64       91         0         0      0      0   0.0 %    0
0x00a00013    6    64       25        24         3      3      1  33.3 %    1
0x00a00019    6    64      470       470         3      3      2  66.7 %    1
0x00a00022    6    64       26         0         0      0      0   0.0 %    0
0x00a00022    6    64       26         0         0      0      0   0.0 %    0

 

Output Description

Partnum
The partition number for an index
Mode
The alice mode for the current partition
BM_Sz
The size allocated for the bitmap
Used_Pg
The size of the index in pages (used)
Dirty_Pg
Number of dirty pages
# I/O
Number of pages read
Found
Number of dirty pages found in reads
Eff
How efficient was the bitmap
Adj
Number of times the alice efficiency level for the partition was insufficient and was adjusted

Copyright© 2019 HCL Technologies Limited