IOT tables ..Analyze
I see that Oracle Index Organized Tables are not getting analyzed by itself. Is this expected? Do i need to analyze this table manually ?
We are using 10.1.0.5
Thanks
Look at the dbms_iot built-in package
http://www.psoug.org/reference/dbms_iot.html
Similar Messages
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<p>
{color:#339966}Hi,
I have a very basic question.
I want to know what exactly happens in the Database architecture when a table analyze is done by gathering the stats.
How does this analyze helps in performance of queries.
Thanks
Mns{color}
</p>hi,
Table analyze is done to get the internal details for the table like exact space used,exact blocks used,row chaining etc.
optimizer uses these details in creating execution plan for the statements for that table.
SQL> set lines 10000
SQL> select table_name,num_rows,blocks,chain_cnt,avg_row_len from user_tables where table_name='EMP';
TABLE_NAME NUM_ROWS BLOCKS CHAIN_CNT AVG_ROW_LEN
EMP
SQL> analyze table emp compute statistics;
Table analyzed.
SQL> select table_name,num_rows,blocks,chain_cnt,avg_row_len from user_tables where table_name='EMP';
TABLE_NAME NUM_ROWS BLOCKS CHAIN_CNT AVG_ROW_LEN
EMP 14 1 0 40
Regards
Edited by: NKU on Nov 5, 2008 12:28 AM -
IOT table in highly concurrent env
Hi All,
I have done some bench marking of IOT vs Heap tables and found that updates are lot faster on an IOT table. We will have select, update and inserts on the table we are considering, delete are probably rare - we will drop a partition when we want to delete rows during a maintanence window.
Does anyone see any issues using IOT table in a highly concurrent DML activity (OLTP) env? If so could you please share any experineces?
Thanks a lot,
VissuHi All,
I have done some bench marking of IOT vs Heap tables and found that updates are lot faster on an IOT table. We will have select, update and inserts on the table we are considering, delete are probably rare - we will drop a partition when we want to delete rows during a maintanence window.
Does anyone see any issues using IOT table in a highly concurrent DML activity (OLTP) env? If so could you please share any experineces?
Thanks a lot,
Vissu -
How May i verify, table analyzed or not and if yes, when it was done?
How May i verify, table analyzed or not and if yes, when it was done?
SQL> desc user_tables
Name Null? Type
TABLE_NAME NOT NULL VARCHAR2(30)
TABLESPACE_NAME VARCHAR2(30)
CLUSTER_NAME VARCHAR2(30)
IOT_NAME VARCHAR2(30)
PCT_FREE NUMBER
PCT_USED NUMBER
INI_TRANS NUMBER
MAX_TRANS NUMBER
INITIAL_EXTENT NUMBER
NEXT_EXTENT NUMBER
MIN_EXTENTS NUMBER
MAX_EXTENTS NUMBER
PCT_INCREASE NUMBER
FREELISTS NUMBER
FREELIST_GROUPS NUMBER
LOGGING VARCHAR2(3)
BACKED_UP VARCHAR2(1)
NUM_ROWS NUMBER
BLOCKS NUMBER
EMPTY_BLOCKS NUMBER
AVG_SPACE NUMBER
CHAIN_CNT NUMBER
AVG_ROW_LEN NUMBER
AVG_SPACE_FREELIST_BLOCKS NUMBER
NUM_FREELIST_BLOCKS NUMBER
DEGREE VARCHAR2(10)
INSTANCES VARCHAR2(10)
CACHE VARCHAR2(5)
TABLE_LOCK VARCHAR2(8)
SAMPLE_SIZE NUMBER
LAST_ANALYZED DATE
PARTITIONED VARCHAR2(3)
IOT_TYPE VARCHAR2(12)
TEMPORARY VARCHAR2(1)
SECONDARY VARCHAR2(1)
NESTED VARCHAR2(3)
BUFFER_POOL VARCHAR2(7)
ROW_MOVEMENT VARCHAR2(8)
GLOBAL_STATS VARCHAR2(3)
USER_STATS VARCHAR2(3)
DURATION VARCHAR2(15)
SKIP_CORRUPT VARCHAR2(8)
MONITORING VARCHAR2(3)
CLUSTER_OWNER VARCHAR2(30)
DEPENDENCIES VARCHAR2(8)
COMPRESSION VARCHAR2(8)
SQL> -
Oracle Database 10g Release 10.2.0.1.0 - Production
PL/SQL Release 10.2.0.1.0 - Production
CORE 10.2.0.1.0 Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
we have iot table which has 7.7 million record ,in production environment and i need to modify one column of this table say "T"
i planned to
create new table "copy_T" with create table as select and
truncate "T" and
modify "T"
i inserted again all records from copy_T to T with
insert into T select * from copyT
what is the best approach for this case
Message was edited by:
JAA
Message was edited by:
JAACreate a temporary table with parallel execution and Truncate the old table ( better rename the table) and
Rename the temporary table to the required table name -
When is table analyzed after mapping
The OWB 10.1 User Guide says this about the mapping configuration parameter Analyze Table Statements:
"If you set this parameter to true, Warehouse Builder generates code for analyzing the target table after the target is loaded if the resulting target table only is double or half its original size."
But if I look in the generated package, DBMS_STATS is performed when the number of records loaded is greater than NUM_ROWS in ALL_TABLES (so greater than when the table was analyzed last).
I'm I missing something or is this a document error?
Jaap.No, you are correct!
Thats a BIG mistake from the OWB developers if you ask me. They know about it since several people opened a TAR regarding this issue.
MB -
Table analyzed / indexes rebuilt
In data warehouse, we have a contract summarization table. The daily data feed populates this table. It didn't analyzed since 4/25/2007. But its indexes are rebuilt every day when processing data. The questions are:
1. since these indexes are built daily, should we worry about the table performance because the table itself is not analyzed for 3 months?
2. we have a script running each weekend to analyze tables in this database. For some reason, this table didn't get analyzed for 3 months. This table is a very active table and data is changed daily. Any other reasons?
I really appreciate the help if someone can shed some lights.
Jin1. Why are the indexes rebuilt every day? Are they bitmap indexes that are dropped and re-created before/after loads? There is much discussion on the topic of rebuilding indexes many arguing that it is not a necessary excercise, search asktom.oracle.com. If the stats do not reflect what data is in the table then you should gather statistics.
2. Don't know what version you are using and whether you really are using the analyze command but use DBMS_STATS instead. -
Hi all,
I have the following observation related to TEMP table. I am wondering if it is always correct.
When you query dba_tables the tablespace_name is empty if it is a temporary table. Also it has 0 records.
Also I just found one index organized table in our db (first time see this creature) based on iot_type = ‘IOT’. It also has tablespace_name column empty and 0 records in table. Based on the knowledge I got from reading the index organized table should just like regular table except that its data is sorted when saved in the database. So if it is being used it should have non zero records in the table, right?
Thanks a lot for your info.
ShirleyHi..
21:37:05 ravan >conn anand/xxxxxx
Connected.
21:37:46 ravan >21:38:01 ravan >CREATE TABLE t1 (c1 NUMBER PRIMARY KEY, c2 VARCHAR2(30)) ORGANIZATION INDEX tablespace users;
Table created.
Elapsed: 00:00:00.01
21:38:51 ravan >select OWNER,TABLE_NAME,TABLESPACE_NAME,IOT_NAME,IOT_TYPE from dba_tables where table_name='T1';
OWNER TABLE_NAME TABLESPACE_NAME IOT_NAME IOT_TYPE
ANAND T1 IOT
21:49:02 ravan >insert into t1 values (1,'a');
1 row created.
Elapsed: 00:00:00.00
21:49:21 ravan >insert into t1 values (2,'b');
1 row created.
Elapsed: 00:00:00.00
21:49:25 ravan >insert into t1 values (3,'c');
1 row created.
Elapsed: 00:00:00.00
21:49:29 ravan >insert into t1 values (4,'d');
1 row created.
Elapsed: 00:00:00.00
21:49:33 ravan >
21:49:34 ravan >commit;
Commit complete.
Elapsed: 00:00:00.00
21:49:36 ravan >
21:49:36 ravan >
21:49:36 ravan >
21:49:37 ravan >select * from t1;
C1 C2
1 a
2 b
3 c
4 d
Elapsed: 00:00:00.00
21:50:40 ravan >conn sys/xxxxxx as sysdba
Connected.
21:51:20 ravan >exec dbms_stats.gather_table_stats(ownname =>'ANAND',tabname =>'T1',cascade =>true);
PL/SQL procedure successfully completed.
21:55:34 ravan >select table_name,owner,tablespace_name,num_rows,last_analyzed,avg_row_len,blocks FROM dba_tables WHERE table_name like UPPER('%&table_name%');
Enter value for table_name: t1
TABLE_NAME OWNER TABLESPACE_NAME NUM_ROWS LAST_ANAL AVG_ROW_LEN BLOCKS
T1 ANAND 4 05-MAR-09 5
21:56:50 ravan >select table_owner,table_name,owner AS index_owner,index_name,tablespace_name,num_rows,status,index_type FROM dba_indexes WHERE table_owner = UPPER('&owner') AND table_name = UPPER('&table_name') ORDER BY table_owner, table_name, index_owner, index_name;
Enter value for owner: anand
Enter value for table_name: t1
TABLE_OWNER TABLE_NAME INDEX_OWNER INDEX_NAME TABLESPACE_NAME NUM_ROWS STATUS INDEX_TYPE
ANAND T1 ANAND SYS_IOT_TOP_28811 USERS 4 VALID IOT - TOP
Elapsed: 00:00:00.00HTH
Anand -
Hi,
My database in 10g Linux envirnoment, I have found that some of the tables in database are analyze autometically.
Is it possible in 10g that oracle will analyze the tables autometically at perticular time.
Please help.
AnandBy default, 10g ships with a DBMS_SCHEDULER job that automatically gathers statistics when Oracle considers the statistics stale. If you did not disable this job, it would be expected that Oracle would gather statistics automatically during the nightly maintenance window.
Justin -
Hi:
I need to figure out if a table has been analyzed, does anyone know how to do it.
If a table has been analyzed, will the CBO always be used, can I not use hints then?
Thanks,
ThomasIn 7.3.4 the data dictionary does not record the last analysis date for tables and/or indexes.
You can tell which tables were analyzed by this query:
select owner, table_name from dba_tables
where num_rows is not null ;for indexes the query would be
select owner, index_name from dba_indexes
where leaf_blocks is not null ;But you cannot tell when they were analyzed. -
It seems that rowid in IOT is
created by function involving primary key.
is there any built in function or package
that we use to simulate that ?
nullThink about what a ROWID actually is and it will become clear.
"The rowid of a row specifies the datafile and data block containing the row and the location of the row in that block." -
Hi All,
We had a database using IOT but now because of the performance reasons
we want to elimnate IOT table and using the Parititioned Tables.
Have you ever using the partitioned tables for ORACLE with your database?
If you have done that please share your experiences or refer me some
documents related to Partitioned tables for ORACLE to make my job more
easier.
Thanks in advance,
JPHi,
You will get good information from this Oracle site,
http://www.oracle.com/technology/documentation/index.html.
Thanks -
DataPump imp: Re-organization a Heap table to IOT compressed table
Hello,
I'd like to re-organize a heap table to IOT TABLE the heap table has a size of 25GB.
After do the expdp table I drop the heap table and create the table as IOT using the compress 2 option. Because this table has a 9 PK columns the compress prefix optimal is 2.
After, I run the impdp with the option accesss_method=direct_path (to avoid UNDO generation). The IOT index is not compressed. I doing a alter table TAB_IOT move compress, the compress work becasuse the segment reduction.
The question is exists any way to force the compression at import phase to reduce steps and storage resources.
My env is Oracle 11.1.0.7 on LInux-x64.
Many thanks
ArturoDBMS_REDEFINITION
http://www.morganslibrary.org/reference/pkgs/dbms_redefinition.html
It is not going to happen in any respect with DataPump. -
What happens when an analyze table is terminated/killed?
Just curious if a rollback occurs to the old statistics, are they corrupted, removed completely, or other?
ThanksI think the operation will get reversed (rollback) if a table analyze was interrupted and the status of previous statistics may become stale.
Why don't you try it and let us know what happens? If you can't let me know, I will try it tomorrow and let you know :) -
Analyze table taking lot of time
HI,
I am analyzing fact table. its taking almost 1 hour to. is there any solution for the same?
i am using compute statistics.
regards,
sandeepHi,
Why not DBMS_STATS which collects stats in parallel so much faster then analyze command.I strongly recommand use DBMS_STATS in case of partition tables.Much faster, collects local and global stats both.
Analyze cmd for partitioned table:--
analyze table <schema>.<table> partition (<partition_name>) estimate statistics sample 5 percent;
Use GATHER_SCHEMA_STATS for whole schema analysis .
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