Statistics on tables

Hi,
Does the analyze table command actually delete statistics before regenrating new stats ?. If a query is issued during the analyze is running, will it have any stats available to it ?
Thanks
Vissu

Vissu,
That's an interesting question. I would hope that Oracle offers the same concurrency models to meta-data queries as it does for any other query, so a session that is reading statistics should see a consistent view of the data until the statement has finished. I'd be interested in hearing other opinions...
Hi,
Does the analyze table command actually delete statistics before regenrating new stats ?. If a query is issued during the analyze is running, will it have any stats available to it ?
Thanks
Vissu

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How to check/verify running sql in lib cache is using updated statistics of table

How to check/verify running sql in lib cache is using updated statistics of table used in from clause.
one of my application table is highly busy i.e frequent update/insert/delete.
we gather table stats every 30 min.

Hello, "try dynamic sampling" = think "outside the box", maybe hit two birds with same stone.
As a matter of fact, I was just backing up your statement: "30 minutes seems pretty extreme"
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How to Gather Statistics of Tables and Indexes

Hi all,
Plz help me in Gathering Statistics of Tables and Indexes.
Thanks

for tables
exec dbms_stats.gather_table_stats('SCOTT', 'EMPLOYEES');
for indexes
exec dbms_stats.gather_index_stats('SCOTT', 'EMPLOYEES_PK');
check this link for detail
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RSRV: Oracle statistics info table for table /BIC/FCube1 may be obsolete

Hi,
I run RSRV on cube1 and got several yellow lines such as:
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Will users encounter any issues with report?
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Hi,
it is years of data but how do you decide that the data is huge to warrant creating a new cube?
You noted that
"verify if it makes sense to copy the data into a new cube "
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Is creating a new cube the only solution to this OBSOLETE problem?
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Null statistics for tables but still got optimizer problem

Hi,
We got a batch application on 10.2.0.4 Oracle database that does a lot of deletes and inserts when run it. Nightly statistics gathering was not enough so I deleted and locked the statistics for all tables. Now it has null statistics so it supposes to use dynamic sampling instead of statistics. At beginning the query executions were ok, however after the application ran for a well, it still chosen a very bad query execution plan (with cost over ten times more that it was normal).
What is happening here? Null statistics is still not good enough for the highly volatile database? Is there anything else I can do?
Thanks in advance.

Provide information like the structure of your table (including indexes), your compartibilty and optimizer settings, your SQL Statement and sample explain plan of the SQL.

Gather statistics on table slow down after partitioning + 10.2.0.4

Hi All,
Oracle 10.2.0.4
OS: Sun solaris
We have a table with 36 indexes on that and the number of columns on the table is 60. total number of rows on the table is 19 million.
The issue now is we used to collect statistics after a bulk load (insert) on the table,it will take maximum 3hrs for completing the statistics collection.
Recently we partitioned (range partition) the table based on the year column like below,
PARTITION BY RANGE (year)
(PARTITION A_2006 VALUES LESS THAN ('2007'),
PARTITION A_2007 VALUES LESS THAN ('2008'),
PARTITION A_2008 VALUES LESS THAN ('2009'),
PARTITION A_2009 VALUES LESS THAN ('2010'),
PARTITION A_MAX VALUES LESS THAN (MAXVALUE)
All the indexes are local indexes now.
Now if we collect the statistics it takes more than 6hrs to complete. Please find the gather stats code below
exec dbms_stats.gather_table_stats( 'SCHEMANAME','TABLENAME',method_opt=> 'for all indexed columns', cascade => true );
Please advice on solving the issue....
TIA,

ORCLDB wrote:
Hi All,
Any help...I won't be able to give you any valid suggestion as I have not come across many such cases.
If you don't mind, here are a few pointers
1) You may want to check (from a different session) to identify what is the stats collection routine spending time on
2) You may want to collect stats on each partition separately (and the collect global stats) to see if any particular partition is the culprit
3) You may want to collect stats on table and on its indexes separately (i.e. not use cascade=>true) to see which one is taking time.

BW Statistics - RSDDSTATWHM table

Hi all,
Does somebody know about the "Action" field in the RSDDSTATWHM table, and it's possible values ?
Some values are sometimes confusing, for example :
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- action 12 : extractor
what is the difference between these 2 actions ?
Thanks
Vincent

Field ACTION (Procedure in WHM) represents different stages of data load process to record time spent in each of these stages. For example:
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Oracle table statistics

Dear All Members,
Is there any way where we can check whether current statistics in table are outdated in oracle? In OTN i found using view "DBA_TAB_MODIFICATIONS" we can gather timestamps of statistics
But can we use this to compare the quality of statistics in DB tables?
Regards,
Shanaka.

Hi Shanaka,
As far as I know that the DBA_TAB_MODIFICATIONS table used to collect quality of statistics value by SAP, also. There's only one exception that at the first step, without paying an attention to the DBA_TAB_MODIFICATIONS records, the system creates new statistics by using "-f stats -t all" parameters. At the second and further steps, new stats will be created for the tables that are need to be collected.
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Note 588668 - FAQ: Database statistics
Note 408527 - Checking the statistics using DBA_TAB_MODIFICATIONS,
Best regards,
Orkun Gedik

Managing statistics for object collections used as table types in SQL

Hi All,
Is there a way to manage statistics for collections used as table types in SQL.
Below is my test case
Oracle Version :
SQL> select * from v$version;
BANNER
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
PL/SQL Release 11.2.0.3.0 - Production
CORE    11.2.0.3.0      Production
TNS for IBM/AIX RISC System/6000: Version 11.2.0.3.0 - Production
NLSRTL Version 11.2.0.3.0 - Production
SQL> Original Query :
SELECT
     9999,
     tbl_typ.FILE_ID,
     tf.FILE_NM ,
     tf.MIME_TYPE ,
     dbms_lob.getlength(tfd.FILE_DATA)
FROM
     TG_FILE tf,
     TG_FILE_DATA tfd,
          SELECT
          FROM
               TABLE
                    SELECT
                         CAST(TABLE_ESC_ATTACH(OBJ_ESC_ATTACH( 9999, 99991, 'file1.png', NULL, NULL, NULL),
                         OBJ_ESC_ATTACH( 9999, 99992, 'file2.png', NULL, NULL, NULL)) AS TABLE_ESC_ATTACH)
                    FROM
                         dual
     )     tbl_typ
WHERE
     tf.FILE_ID     = tfd.FILE_ID
AND tf.FILE_ID = tbl_typ.FILE_ID
AND tfd.FILE_ID = tbl_typ.FILE_ID;
Elapsed: 00:00:02.90
Execution Plan
Plan hash value: 3970072279
| Id | Operation                                | Name         | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                         |              |     1 |   194 | 4567   (2)| 00:00:55 |
|* 1 | HASH JOIN                               |              |     1 |   194 | 4567   (2)| 00:00:55 |
|* 2 |   HASH JOIN                              |              | 8168 |   287K|   695   (3)| 00:00:09 |
|   3 |    VIEW                                  |              | 8168 |   103K|    29   (0)| 00:00:01 |
|   4 |     COLLECTION ITERATOR CONSTRUCTOR FETCH|              | 8168 | 16336 |    29   (0)| 00:00:01 |
|   5 |      FAST DUAL                           |              |     1 |       |     2   (0)| 00:00:01 |
|   6 |    TABLE ACCESS FULL                     | TG_FILE      |   565K|    12M|   659   (2)| 00:00:08 |
|   7 |   TABLE ACCESS FULL                      | TG_FILE_DATA |   852K|   128M| 3863   (1)| 00:00:47 |
Predicate Information (identified by operation id):
   1 - access("TF"."FILE_ID"="TFD"."FILE_ID" AND "TFD"."FILE_ID"="TBL_TYP"."FILE_ID")
   2 - access("TF"."FILE_ID"="TBL_TYP"."FILE_ID")
Statistics
          7 recursive calls
          0 db block gets
      16783 consistent gets
      16779 physical reads
          0 redo size
        916 bytes sent via SQL*Net to client
        524 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
          2 rows processed Indexes are present in both the tables ( TG_FILE, TG_FILE_DATA ) on column FILE_ID.
select
     index_name,blevel,leaf_blocks,DISTINCT_KEYS,clustering_factor,num_rows,sample_size
from
     all_indexes
where table_name in ('TG_FILE','TG_FILE_DATA');
INDEX_NAME                     BLEVEL LEAF_BLOCKS DISTINCT_KEYS CLUSTERING_FACTOR     NUM_ROWS SAMPLE_SIZE
TG_FILE_PK                          2        2160        552842             21401       552842      285428
TG_FILE_DATA_PK                     2        3544        852297             61437       852297      852297 Ideally the view should have used NESTED LOOP, to use the indexes since the no. of rows coming from object collection is only 2.
But it is taking default as 8168, leading to HASH join between the tables..leading to FULL TABLE access.
So my question is, is there any way by which I can change the statistics while using collections in SQL ?
I can use hints to use indexes but planning to avoid it as of now. Currently the time shown in explain plan is not accurate
Modified query with hints :
SELECT
    /*+ index(tf TG_FILE_PK ) index(tfd TG_FILE_DATA_PK) */
    9999,
    tbl_typ.FILE_ID,
    tf.FILE_NM ,
    tf.MIME_TYPE ,
    dbms_lob.getlength(tfd.FILE_DATA)
FROM
    TG_FILE tf,
    TG_FILE_DATA tfd,
        SELECT
        FROM
            TABLE
                    SELECT
                         CAST(TABLE_ESC_ATTACH(OBJ_ESC_ATTACH( 9999, 99991, 'file1.png', NULL, NULL, NULL),
                         OBJ_ESC_ATTACH( 9999, 99992, 'file2.png', NULL, NULL, NULL)) AS TABLE_ESC_ATTACH)
                    FROM
                         dual
    tbl_typ
WHERE
    tf.FILE_ID     = tfd.FILE_ID
AND tf.FILE_ID = tbl_typ.FILE_ID
AND tfd.FILE_ID = tbl_typ.FILE_ID;
Elapsed: 00:00:00.01
Execution Plan
Plan hash value: 1670128954
| Id | Operation                                 | Name            | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                          |                 |     1 |   194 | 29978   (1)| 00:06:00 |
|   1 | NESTED LOOPS                             |                 |       |       |            |          |
|   2 |   NESTED LOOPS                            |                 |     1 |   194 | 29978   (1)| 00:06:00 |
|   3 |    NESTED LOOPS                           |                 | 8168 | 1363K| 16379   (1)| 00:03:17 |
|   4 |     VIEW                                  |                 | 8168 |   103K|    29   (0)| 00:00:01 |
|   5 |      COLLECTION ITERATOR CONSTRUCTOR FETCH|                 | 8168 | 16336 |    29   (0)| 00:00:01 |
|   6 |       FAST DUAL                           |                 |     1 |       |     2   (0)| 00:00:01 |
|   7 |     TABLE ACCESS BY INDEX ROWID           | TG_FILE_DATA    |     1 |   158 |     2   (0)| 00:00:01 |
|* 8 |      INDEX UNIQUE SCAN                    | TG_FILE_DATA_PK |     1 |       |     1   (0)| 00:00:01 |
|* 9 |    INDEX UNIQUE SCAN                      | TG_FILE_PK      |     1 |       |     1   (0)| 00:00:01 |
| 10 |   TABLE ACCESS BY INDEX ROWID             | TG_FILE         |     1 |    23 |     2   (0)| 00:00:01 |
Predicate Information (identified by operation id):
   8 - access("TFD"."FILE_ID"="TBL_TYP"."FILE_ID")
   9 - access("TF"."FILE_ID"="TBL_TYP"."FILE_ID")
       filter("TF"."FILE_ID"="TFD"."FILE_ID")
Statistics
          0 recursive calls
          0 db block gets
         16 consistent gets
          8 physical reads
          0 redo size
        916 bytes sent via SQL*Net to client
        524 bytes received via SQL*Net from client
          2 SQL*Net roundtrips to/from client
          0 sorts (memory)
          0 sorts (disk)
          2 rows processed
Thanks,
B

Thanks Tubby,
While searching I had found out that we can use CARDINALITY hint to set statistics for TABLE funtion.
But I preferred not to say, as it is currently undocumented hint. I now think I should have mentioned it while posting for the first time
http://www.oracle-developer.net/display.php?id=427
If we go across the document, it has mentioned in total 3 hints to set statistics :
1) CARDINALITY (Undocumented)
2) OPT_ESTIMATE ( Undocumented )
3) DYNAMIC_SAMPLING ( Documented )
4) Extensible Optimiser
Tried it out with different hints and it is working as expected.
i.e. cardinality and opt_estimate are taking the default set value
But using dynamic_sampling hint provides the most correct estimate of the rows ( which is 2 in this particular case )
With CARDINALITY hint
SELECT
    /*+ cardinality( e, 5) */*
FROM
     TABLE
          SELECT
               CAST(TABLE_ESC_ATTACH(OBJ_ESC_ATTACH( 9999, 99991, 'file1.png', NULL, NULL, NULL),
               OBJ_ESC_ATTACH( 9999, 99992, 'file2.png', NULL, NULL, NULL)) AS TABLE_ESC_ATTACH)
          FROM
               dual
     ) e ;
Elapsed: 00:00:00.00
Execution Plan
Plan hash value: 1467416936
| Id | Operation                             | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                      |      |     5 |    10 |    29   (0)| 00:00:01 |
|   1 | COLLECTION ITERATOR CONSTRUCTOR FETCH|      |     5 |    10 |    29   (0)| 00:00:01 |
|   2 |   FAST DUAL                           |      |     1 |       |     2   (0)| 00:00:01 |
With OPT_ESTIMATE hint
SELECT
     /*+ opt_estimate(table, e, scale_rows=0.0006) */*
FROM
     TABLE
          SELECT
               CAST(TABLE_ESC_ATTACH(OBJ_ESC_ATTACH( 9999, 99991, 'file1.png', NULL, NULL, NULL),
               OBJ_ESC_ATTACH( 9999, 99992, 'file2.png', NULL, NULL, NULL)) AS TABLE_ESC_ATTACH)
          FROM
               dual
     ) e ;
Execution Plan
Plan hash value: 4043204977
| Id | Operation                              | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                       |      |     5 |   485 |    29   (0)| 00:00:01 |
|   1 | VIEW                                  |      |     5 |   485 |    29   (0)| 00:00:01 |
|   2 |   COLLECTION ITERATOR CONSTRUCTOR FETCH|      |     5 |    10 |    29   (0)| 00:00:01 |
|   3 |    FAST DUAL                           |      |     1 |       |     2   (0)| 00:00:01 |
With DYNAMIC_SAMPLING hint
SELECT
    /*+ dynamic_sampling( e, 5) */*
FROM
     TABLE
          SELECT
               CAST(TABLE_ESC_ATTACH(OBJ_ESC_ATTACH( 9999, 99991, 'file1.png', NULL, NULL, NULL),
               OBJ_ESC_ATTACH( 9999, 99992, 'file2.png', NULL, NULL, NULL)) AS TABLE_ESC_ATTACH)
          FROM
               dual
     ) e ;
Elapsed: 00:00:00.00
Execution Plan
Plan hash value: 1467416936
| Id | Operation                             | Name | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                      |      |     2 |     4 |    11   (0)| 00:00:01 |
|   1 | COLLECTION ITERATOR CONSTRUCTOR FETCH|      |     2 |     4 |    11   (0)| 00:00:01 |
|   2 |   FAST DUAL                           |      |     1 |       |     2   (0)| 00:00:01 |
Note
   - dynamic sampling used for this statement (level=2)I will be testing the last option "Extensible Optimizer" and put my findings here .
I hope oracle in future releases, improve the statistics gathering for collections which can be used in DML and not just use the default block size.
By the way, are you aware why it uses the default block size ? Is it because it is the smallest granular unit which oracle provides ?
Regards,
B

How table statistics going to affect insert statements

I have 2 DB's.I have a process in both DB's which will load records in to tab1 using sql loader.Tab1 in DB1 is not analyzed since 2005 while tab1 in DB2 is recently analyzed.My SQL ldr process is slow in DB1 when compared to DB2.
I am wondering how sqlloader insert is goign to relate with statistics of table.Please suggest me
Thanks

Hi,
are You speaking about to identical instances, where the only difference are the statistics?
There are severa aspects that can impact, the instance configuration, the session configuration, the storage parameters, DB workload and so on.
Have You first checked what it is constant in both instances? Thios can be a good starting point..

Gather statistics or analyze table

What is the difference between gather statistics for table and analyze table?
Regards
Arpit

Analyzing a table is gathering statistics (whether you're using the old ANALYZE statement or the preferred dbms_stats package).

Run optimizer statistics for one table

dear all,
i noticed an error in DB16 , that is <b>Missing Statistics for a table </b> SAPGRP.MC03BF0SETUP.
How to run/ generate the stats. for this table

Dear Somckit
here is the error msg. from DB16.
                                                                                Description         Table: SAPGRP.MC03BF0SETUP # Table or index has no optimizer
Correction Type     D
Corrective Action   Collect optimizer statistics
Check Log           /oracle/GRP/sapcheck/cdwqhqnz.chk
Single Messages
No.   Description
1     Table: SAPGRP.MC03BF0SETUP # Table or index has no optimizer statistics
2     Table: SAPGRP.MC03BX0SETUP # Table or index has no optimizer statistics
3     Table: SAPGRP.MC03UM0SETUP # Table or index has no optimizer statistics
4     Index: SAPGRP.MC03BF0SETUP~0 # Table or index has no optimizer statistics
5     Index: SAPGRP.MC03BX0SETUP~0 # Table or index has no optimizer statistics
6     Index: SAPGRP.MC03UM0SETUP~0 # Table or index has no optimizer statistics
Thank u.

Analize table ... estimate statistics

I have read in this discussion group that it was a good idea to analyze the spatial index table to optimize performance.
Should this be done:
- only once?
- after loading the layer?
- each time it is massively updated?
BTW what does "sample 32 percent" mean?
Thanks,
Jean-Pierre

Hi Jean-Pierre,
I've never had to run this more than once (after the spatial index was created on an initial data set), but I don't do a lot of updates usually.
There are two ways to analyze a table:
analyze table table_name compute statistics;
analyze table table_name estimate statistics sample N percent; --- where N is an integer
Sometimes I have index tables with millions and millions of rows. If I run compute statistics is can take an hour or more. If I say estimate statistics sample 1 percent it completes in seconds/minutes and all of the right things happen with respect to performance. I use sample so I can work with data faster. BTW - this is only for quadtree indexes. It doesn't hurt to gather stats on an rtree index table, but it doesn't help either.
The procedure I posted happens to sample about 32 percent of the rows, but there is nothing magical about this number.

Index Statistics Update - Problem

We had performance problem yesterday with FI report FAGLL03, it timed out in online execution and in background mode it took 5000+ sec to execute. Result was no more than 100 records.
Later with some investigation problem drill down to index usage of table FAGLFLEXA. We then updated the index statistics of table from DB02. After that report worked fine with execution time of 10-15 sec for same set of input.
However user, in morning , was complaining again about performance problem with same report FAGLL03. We did that update index statistics again and as it was the case yesterday it fixed the problem.
Later today I checked SQL server the job SAP CCMS_xxx_xxx_Update_Tabstats, which I guess is updating index statistics daily at 0400 hours, is working fine. I can't see any error log there. Daily job to check database consistency is also not reporting anything.
Anyidea what could be going wrong.
Basis Consultants are looking into problem however I am putting this case here if anyone of you had same problem and fixed it.
Thanks,
Pawan.
Edited by: Pawan Kesari on Dec 11, 2009 4:05 PM

Hi,
Appears the stats are dropped eveytime the job runs @04:00
Have a look at the table DBSTATC in trx: DB21 to see if it's setup to dropped the stats..
Mark

DB02 view is empty on Table and Index analyses DB2 9.7 after system copy

Dear All,
I did the Quality refresh by System copy export/import method. ECC6 on HP-UX DB29.7.
After Import Runstats status n Db02 for Table and Index analysis was empty and all value showing '-1'. Eventhough
a) all standard backgrnd job scheduled in sm36
b) Automatic runstats are enabled in db2 parameters
c) Reorgchk all scheduled periodically from db13 and already ran twice.
4) 'reorgchk update statistics on table all' was also ran on db2 level.
but Run stats staus in db02 was not getting updated. Its empty.
Please suggest.
Regards
Vinay

Hi Deepak,
Yes, that is possible (but only offline backup). But for the new features like reclaimable tablespace (to lower the high watermark)
it's better to export/import with systemcopy.
Also with systemcopy you can use index compression.
After backup and restore you can have also reclaimable tablespace, but you have to create new tablespaces
and then work with db6conv and online table move to move one tablespace online to the new one.
Best regards,
Joachim

Statistics on tables

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