V$segstat statistics meaning

Hi,
I am working on a project to find all the segments growth pattern in database and for that I am using V$SEGSTAT to get the stats about segments.
In my environment, for 1 LOB object, the stats in V$SEGSTAT looks like:
space used ==> 953767766114
space allocated ==> 67108864
And I want to know what is the meaning of 'space used' here? How and when it can be more that actual space allocated??
I know when it can go negative (from shrink and reorg) but in order to get my project done, I need the clear definition of 'space used' and 'space allocated' stats.
The actual LOB size here is only 25gig, so how come 'space used' can be 953 gig here?
I know that V$SEGSTAT contains cumulative stats since the instance startup but what metrics its using to calculate these values?
The only thing I can think of here is that it's counting every block being used/accessed as 'space used', thats the only way it can go that high.
Oracle document just has the definition of the view and I couldn't find any clear definition of these stats.
Oracle Version ==> 11203
OS ==> AIX
Thanks
Daljit Singh

In the answer I gave to the thread you linked to I said:
I do know that the mechanism is a little more sophisticated than a simple "if it's not in the buffer cache it's not in v$segstat"
v$segment_statistics is simply v$segstat with a couple of joins to add names.
Regards
Jonathan Lewis
@jloracle

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thanks in advance
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vinayraj wrote:
yeahh exactlyy ...
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Optimizer Statistics Concepts
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Hi SAP guru,
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Hi ,
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setTxn     N
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lastCheckpointEnd     0x6f/0x33c2d6     0xb6a/0x8c4a6b
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nCacheMiss     4583077     57469807
nLogBuffers     3     3
bufferBytes     3145728     3145728
(MB)     3.00     3.00
cacheDataBytes     563450470     370211966
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adminBytes     29880     16346272
lockBytes     1113     1113
cacheTotalBytes     566596198     373357694
(MB)     540.35     356.06
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nFSyncRequest     59     1452
nFSyncTimeouts     0     0
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nTempBufferForWrite     0     0
nRepeatIteratorReads     0     0
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Hello Linda,
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[long,String,long] --> [{long,long}, {String}}
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Its hard to believe that building of the tree for secondary database takes so much longer.
Why doesnt building the tree for primary database take so long. The data in the primary database is same as its key to be able to search on these values.
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The cache stats mentioned above relate to these .
Can you try explaining this. We are trying to figure out is it worth trying to build the secondary index later for bulk loading.

What is the column value in v$sesstat & v$sysstat

hi guys,
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What does it refering when it mention statistic value?

flaskvacuum wrote:
SID USERNAME                       STATISTIC                                                     VALUE
94 ORACLE PROC                    physical read total bytes                                          15110144
94 ORACLE PROC                    physical reads                                                      420
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This is my second iphone. My first one would not reach full charge and the usage meter never showed any statistics after a week of use.
This phone has been great with a few things wrong, one continues to be the battery meter. When charging sometimes the battery on the screen will be full, sometimes it isn't no real pattern. But the plug icon always shows up and the usage meter does reset. However I have noticed one thing.
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Mail: [email protected]

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RSQL
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hi all,
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burleson wrote:
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Hi Don
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http://richardfoote.wordpress.com/

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The cheap one has a 80 GB hard drive, the more expensive has a 120 GB hard drive.
The cheap one has a Combo Drive, the more expensive a Super Drive.
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How oracle decide whetehr to use index or full scan (statistics)

Hi Guys,
Let say i have a index on a column.
The table and index statistics has been gathered. (without histograms).
Let say i perform a select * from table where a=5;
Oracle will perform a full scan.
But from which statistics it will be able to know indeed most of the column = 5? (histograms not used)
After analyzing, we get the below:
Table Statistics :
(NUM_ROWS)
(BLOCKS)
(EMPTY_BLOCKS)
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(CHAIN_COUNT)
(AVG_ROW_LEN)
Index Statistics :
(BLEVEL)
(LEAF_BLOCKS)
(DISTINCT_KEYS)
(AVG_LEAF_BLOCKS_PER_KEY)
(AVG_DATA_BLOCKS_PER_KEY)
(CLUSTERING_FACTOR)
thanks
Index Column (A)
======
1
1
2
2
5
5
5
5
5
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I have prepared some explanation and have not noticed that the topic has been marked as answered.
This my sentence is not completely true.
A column "without histograms" means that the column has only one bucket. More correct: even without histograms there are data in dba_tab_histograms which we can consider as one bucket for whole column. In fact these data are retrieved from hist_head$, not from histgrm$ as usual buckets.
Technically there is no any buckets without gathered histograms.
Let's create a table with skewed data distribution.
SQL> create table t as
2 select least(rownum,3) as val, '*' as pad
3    from dual
4 connect by level <= 1000000;
Table created
SQL> create index idx on t(val);
Index created
SQL> select val, count(*)
2    from t
3   group by val;
       VAL   COUNT(*)
         1          1
         2          1
         3     999998So, we have table with very skewed data distribution.
Let's gather statistics without histograms.
SQL> exec dbms_stats.gather_table_stats( user, 'T', estimate_percent => 100, method_opt => 'for all columns size 1', cascade => true);
PL/SQL procedure successfully completed
SQL> select blocks, num_rows from dba_tab_statistics
2   where table_name = 'T';
    BLOCKS   NUM_ROWS
      3106    1000000
SQL> select blevel, leaf_blocks, clustering_factor
2    from dba_ind_statistics t
3   where table_name = 'T'
4     and index_name = 'IDX';
    BLEVEL LEAF_BLOCKS CLUSTERING_FACTOR
         2        4017              3107
SQL> select column_name,
2         num_distinct,
3         density,
4         num_nulls,
5         low_value,
6         high_value
7    from dba_tab_col_statistics
8   where table_name = 'T'
9     and column_name = 'VAL';
COLUMN_NAME NUM_DISTINCT    DENSITY NUM_NULLS      LOW_VALUE      HIGH_VALUE
VAL                     3 0,33333333          0           C102            C104So, Oracle suggests that values between 1 and 3 (raw C102 and C104) are distributed uniform and the density of the distribution is 0.33.
Let's try to explain plan
SQL> explain plan for
2 select --+ no_cpu_costing
3         *
4    from t
5   where val = 1
6 ;
Explained
SQL> @plan
| Id | Operation         | Name | Rows | Cost |
|   0 | SELECT STATEMENT |      |   333K|   300 |
|* 1 | TABLE ACCESS FULL| T    |   333K|   300 |
Predicate Information (identified by operation id):
   1 - filter("VAL"=1)
Note
   - cpu costing is off (consider enabling it)Below is an excerpt from trace 10053
BASE STATISTICAL INFORMATION
Table Stats::
Table: T Alias: T
    #Rows: 1000000 #Blks: 3106 AvgRowLen: 5.00
Index Stats::
Index: IDX Col#: 1
    LVLS: 2 #LB: 4017 #DK: 3 LB/K: 1339.00 DB/K: 1035.00 CLUF: 3107.00
SINGLE TABLE ACCESS PATH
BEGIN Single Table Cardinality Estimation
Column (#1): VAL(NUMBER)
    AvgLen: 3.00 NDV: 3 Nulls: 0 Density: 0.33333 Min: 1 Max: 3
Table: T Alias: T
    Card: Original: 1000000 Rounded: 333333 Computed: 333333.33 Non Adjusted: 333333.33
END   Single Table Cardinality Estimation
Access Path: TableScan
    Cost: 300.00 Resp: 300.00 Degree: 0
      Cost_io: 300.00 Cost_cpu: 0
      Resp_io: 300.00 Resp_cpu: 0
Access Path: index (AllEqRange)
    Index: IDX
    resc_io: 2377.00 resc_cpu: 0
    ix_sel: 0.33333 ix_sel_with_filters: 0.33333
    Cost: 2377.00 Resp: 2377.00 Degree: 1
Best:: AccessPath: TableScan
         Cost: 300.00 Degree: 1 Resp: 300.00 Card: 333333.33 Bytes: 0Cost of FTS here is 300 and cost of Index Range Scan here is 2377.
I have disabled cpu costing, so selectivity does not affect the cost of FTS.
cost of Index Range Scan is calculated as
blevel + (leaf_blocks * selectivity + clustering_factor * selecivity) = 2 + (4017*0.33333 + 3107*0.33333) = 2377.
Oracle considers that it has to read 2 root/branch blocks of the index, 1339 leaf blocks of the index and 1036 blocks of the table.
Pay attention that selectivity is the major component of the cost of the Index Range Scan.
Let's try to gather histograms:
SQL> exec dbms_stats.gather_table_stats( user, 'T', estimate_percent => 100, method_opt => 'for columns val size 3', cascade => true);
PL/SQL procedure successfully completedIf you look at dba_tab_histograms you will see following
SQL> select endpoint_value,
2         endpoint_number
3    from dba_tab_histograms
4   where table_name = 'T'
5     and column_name = 'VAL'
6 ;
ENDPOINT_VALUE ENDPOINT_NUMBER
             1               1
             2               2
             3         1000000ENDPOINT_VALUE is the column value (in number for any type of data) and ENDPOINT_NUMBER is cumulative number of rows.
Number of rows for any ENDPOINT_VALUE = ENDPOINT_NUMBER for this ENDPOINT_VALUE - ENDPOINT_NUMBER for the previous ENDPOINT_VALUE.
explain plan and 10053 trace of the same query:
| Id | Operation                   | Name | Rows | Cost |
|   0 | SELECT STATEMENT            |      |     1 |     4 |
|   1 | TABLE ACCESS BY INDEX ROWID| T    |     1 |     4 |
|* 2 |   INDEX RANGE SCAN          | IDX |     1 |     3 |
Predicate Information (identified by operation id):
   2 - access("VAL"=1)
Note
   - cpu costing is off (consider enabling it)
BASE STATISTICAL INFORMATION
Table Stats::
Table: T Alias: T
    #Rows: 1000000 #Blks: 3106 AvgRowLen: 5.00
Index Stats::
Index: IDX Col#: 1
    LVLS: 2 #LB: 4017 #DK: 3 LB/K: 1339.00 DB/K: 1035.00 CLUF: 3107.00
SINGLE TABLE ACCESS PATH
BEGIN Single Table Cardinality Estimation
Column (#1): VAL(NUMBER)
    AvgLen: 3.00 NDV: 3 Nulls: 0 Density: 5.0000e-07 Min: 1 Max: 3
    Histogram: Freq #Bkts: 3 UncompBkts: 1000000 EndPtVals: 3
Table: T Alias: T
    Card: Original: 1000000 Rounded: 1 Computed: 1.00 Non Adjusted: 1.00
END   Single Table Cardinality Estimation
Access Path: TableScan
    Cost: 300.00 Resp: 300.00 Degree: 0
      Cost_io: 300.00 Cost_cpu: 0
      Resp_io: 300.00 Resp_cpu: 0
Access Path: index (AllEqRange)
    Index: IDX
    resc_io: 4.00 resc_cpu: 0
    ix_sel: 1.0000e-06 ix_sel_with_filters: 1.0000e-06
    Cost: 4.00 Resp: 4.00 Degree: 1
Best:: AccessPath: IndexRange Index: IDX
         Cost: 4.00 Degree: 1 Resp: 4.00 Card: 1.00 Bytes: 0Pay attention on selectivity, ix_sel: 1.0000e-06
Cost of the FTS is still the same = 300,
but cost of the Index Range Scan is 4 now: 2 root/branch blocks + 1 leaf block + 1 table block.
Thus, conclusion: histograms allows to calculate selectivity more accurate. The aim is to have more efficient execution plans.
Alexander Anokhin
http://alexanderanokhin.wordpress.com/

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hello,
We have just migrated a call center to UCCE 8.5.3 that runs roggers and ICM call flow scripts that contain very basic flows. In each flow there is basically a one-to-one ratio of call type elements to select skill group elements.
Generally you would expect the call volume (as our scripts are written) to have almost the same call volume in the call type interval table and the skill group interval table, with allowable differences because of RONAs, etc. But basically somewhat close.
In general this does work but after a reboot of the roggers (A and B sides) (logger down first, then router and reversed to start), the skill group interval data lags greatly from the call type interval data, meaning maybe 10% of the call type interval volume. We have learned that completely shutting down both A and B side and then briinging it back up in order from scratch seems to alleviate the problem (until the next restart). We cannot just leave the servers alone though due to company security patching policies.
Cisco TAC had recommended patching to UCCE 8.5.4 which we have recently done, but the probelm persists.
I was wondering if this data discrepancy has ever been seen by anyone else or if possibly some system config issue might be self-deating us? Rebooting the roggers leaves the phone system itself working just fine for the call centers, but the recording of statistics to the skill group interval table is greatly impacted with almost no recording of volume in relation to the call type interval (and for comparison, the call type skill group interval table as well).
We would generally not worry about it, but the workforce management vendor that takes its feed from UCCE only uses the skill group interval, which is basically reporting almost no volume in the mentioned scenarios.
If anyone can provide any information it would be most appreciated/
Thanks.
Greg

Thank you for the response. The time source check is a great idea. We ran into problems before when internal web service servers did not match the PGs (CTIOS service) and CTI provideed stats did not match.
We will continue to work through TAC, but I was just wondering if anyone else had seen this (as 8.5.4 sid not fix it) and if maybe it could have been something self-defeating in our system configuration or scripting. We did not immediately know this was happening until our 3rd party workforce management vendor made us aware.
Thanks,
Greg

How to remove the ALV Statistics option from Accounts user's userids

Dear Sir/Madam,
In our Accounts department each time one extra page is comming out. When the ALV Statistics option is make Unchecked, then it funtioninng normally that is, single page is comming out.
Is there any way to make this option permanently Unchecked ? If possible please advice and also whether there will be any unwanted implications of it ?
Please advice.
Thanks and Regards,
Pranab

Option 1 - Use SAP Report RSPRIPARADMIN you can set this for all users
Option 2 - user parameter SP01_FROM 0000000002 - This means print job will start from page 2
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Edited by: Savo on Jul 1, 2011 4:06 PM

V$segstat statistics meaning

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