If we have not set parallel degree for a table then we can ( try to ) force parallel execution on a table using a parallel hint Does this 'parallelism' works on the index search in the query as well?
In which situations non-parallel non-partitioned table but parallel index (degree>2) will facilitate a query?
Is it possible to build index partition in parallel?I tried following command
alter index <index_name> rebuild partition <partition name> online parallel 5;
It executed without complaining, but want to know if index partitions can be build in parallel?
I have a huge table (about 60 gb) partition over range. The index on this table is global index created on 4 columns together. I have a query which is running very slowly. The explain plan is showing the use of this global index.Explain plan is not showing pstart and pend because the index is global.
View 6 Replies View RelatedI am inserting data into a global temporary table and then using 'parallel' hint to query from this temporary table. I remember reading that the queries on the temp table may not run in parallel as the parallel sessions may not be able to see the data in the temporary table
However the execution plan as well as px_session, v$sql indicate that the query on the temporary table in fact run in parallel mode
select * from table(dbms_xplan.display_cursor(null,null,'ALLSTATS LAST'));
PLAN_TABLE_OUTPUT
-----------------------------------------------------------------------------------------------------------------------
SQL_ID 7d68g52g0mskz, child number 0
-------------------------------------
select /*+ gather_plan_statistics parallel(t,4) */ * from dbo_gtt t order by id,object_id
Plan hash value: 5815349
--------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name | Starts | E-Rows | A-Rows | A-Time | Buffers | OMem | 1Mem | Used-Mem |Used-Tmp|
--------------------------------------------------------------------------------------------------------------------------
| 1 | PX COORDINATOR | | 1 | | 99999 |00:00:01.46 | 3 | | | |
|
| 2 | PX SEND QC (ORDER) | :TQ10001 | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
| 3 | SORT ORDER BY | | 0 | 1 | 0 |00:00:00.01 | 0 | 11M| 1311K| 424K (0)|
|
| 4 | PX RECEIVE | | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
| 5 | PX SEND RANGE | :TQ10000 | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
| 6 | PX BLOCK ITERATOR | | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
|* 7 | TABLE ACCESS FULL| DBO_GTT | 0 | 1 | 0 |00:00:00.01 | 0 | | | |
|
--------------------------------------------------------------------------------------------------------------------------
Predicate Information (identified by operation id):
---------------------------------------------------
7 - access(:Z>=:Z AND :Z<=:Z)
select px_servers_executions from v$sql where sql_text like 'select%dbo_gtt t%';
PX_SERVERS_EXECUTIONS
---------------------
0
4
select sid, qcsid, server#, degree from v$px_session where qcsid = 228;
SID QCSID SERVER# DEGREE
---------- ---------- ---------- ----------
247 228 1 4
196 228 2 4
224 228 3 4
234 228 4 4
226 228 1 4
252 228 2 4
212 228 3 4
229 228 4 4
228 228
9 rows selected.
unfortunately I do not have access to get trace (tkprof) report. What must have happened during the execution?
I am executing a sql statement which is doing FTS in parallel mode The server has 8 cpus and threads_per_cpu is 2
The v$sql shows PX_SERVERS_EXECUTIONS as 8
select PX_SERVERS_EXECUTIONS, sql_text from v$sql where sql_id='0q0nk5117yth2'
8, select /*+ full(a) parallel(a)....
however the px_sessions shows 17 sessions (16 parallel session + 1 parent session (where sid = qcsid) Now in px_sessions, these 16 parallel session are divided in 2 server sets 1 and 2 and values for degree and required degree are 8 and 16 respectively
However, all the time, only 8 sessions which belong to server set = 1, were active though its state was waiting with event "PX Deq Credit: send blkd"
The other session which belong to server set = 2 were never active and always had waint event ='PX Deq: Execution Msg'
what could be the reason that 16 parallel session could not be started though I am the only person using the server, there aren't any batch jobs, dbms_jobs,even archivelogs (not a prod system)?
Note that paralel_max_servers setting is 16
Another issue being the duing start of the query approximately 100-115 blocks were read for the query (checked from longops) however after 60-70% blocks are read the number of blocks read / seconds falls down to 10-20 blocks / second across all parallel sessions.
Does parallel hint works in cursor queries? The cursor query is something like :
cursor c is
select /*+ parallel(s,8) */
from table ref_tab s ---- >>
<where condition>;
The table ref_tab hold data for a single day at any point of time and gets truncate before loading the next days data.On average the table holds around 7 million rows and doesn't contains any index (think that's fine as all together we are loading the whole set).And, we are using bulk logic with save exceptions to open the cursor and load the data into the target table.
There is a detail table
There is a summary table
During batch process record is entered in detail table as well as summary table.
The process first checks if record exists in summary table for same group_no and if 'yes' then "updates" the record with the newly added amount (sums it) else inserts a new record
Whereas in the detail table it inserts the record directly
detail table :
group_no doc_no amount
101 doc1 100
101 doc2 200
102 doc3 300
102 doc4 400
summary table :
group_no amount
101 300
102 700
Now if the batch process runs in parallel, (out of many) two different sessions insert same group_no; This is because while sesond session inserts a record, first session inserting the same record (group_no) has not yet committed ; So second session Not knowing that already there is same Group_no (101) inserted, again inserts another record with same group_no rather than summing it.
Can it be solved without using temp table, select for update?
select
serialnumber from product where productid in
(select /*+ full parallel(producttask 16) */productid from producttask where
startedtimestamp > to_date('2013-07-04 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
and startedtimestamp < to_date('2013-07-05 00:00:00', 'YYYY-MM-DD HH24:MI:SS')
and producttasktypeid in
[code]....
Explain plan output:
Plan hash value: 2779236890
-----------------------------------------------------------------------------------------------------------------------------------------
| Id | Operation | Name| Rows| Bytes | Cost (%CPU)| Time| Pstart| Pstop |
-----------------------------------------------------------------------------------------------------------------------------------------
| 0 | SELECT STATEMENT || 1 | 29 | 9633M (8)|999:59:59 |||
|* 1 | FILTER |||| ||||
| 2 | PARTITION RANGE ALL || 738M| 19G| 6321K (1)| 21:04:17 | 1 | 6821 |
[code]....
Predicate Information (identified by operation id):
---------------------------------------------------
1 - filter( EXISTS (<not feasible>)
4 - filter("PRODUCTID"=:B1)
5 - filter(ROWNUM<100)
12 - access("MODELID"=:B1)
[code]....
Note: - SQL profile "SYS_SQLPROF_014153616b850002" used for this statement
does parallel hint in query can create bottleneck/Slowdown/crash database..??
View 4 Replies View Relatedoracle: 10.2.0.5.7...I can get this to work, but not the way the docs seem to say. I am wondering if I am reading the docs wrong or missing something.
The docs seem to say to get a query to run in parallel using an index you use the PARALLEL_INDEX hint. This doesn't seem to work for me. I have to do one of the following
1. change the parallel degree with an alter index, then use the PARALLEL hint (parallel index hint does nothing in this case)
2. use both the parallel_index and parallel hint
I have normal tables with hugh Data and would like to increase the performace by following means:
1) Add a new column in each table. Say this column Name is IS_LIVE. This new column have only two value 1 ( LIVE ) OR 0 ( NOT LIVE ).
2) Change the normal tables to Partitioned table. There would be only two partitioned in all the table. The partitioned key column would be IS_LIVE and both partitioend recrods would be in two different tablespace.
3) Added a POLICY function to these partitioned table to Always add a Query Predicate of '1' to all queuries.
I am interested to know that what kind of Indexes ( Global Or local ) would be suitable for these kind of Design.Is there any use of having Local index on IS_LIVE.Please note that Primary Key doesnot have this new column in it.
Is it possible for the DBMS_STATS "LIST STALE" command to show a stale partition but NOT have its table show as stale?
I had a scenario where the table itself AND 1 partition showed as stale. I ran a fnd_stats gather table stats just on that 1 partition. Once it was completed it showed the partition to no longer be stale. it also showed that the table was no longer stale. so I guess I do not need to run stats on the whole table as well?
so if this is the case, when would I need to run stats on the full partitioned table if running it on the partitions themselves removes the staleness of the table?
the reason behind the below statements:
1) We cant create TABLE PARTITIONED on CLUSTER or INDEX on CLUSTER TABLE.
2) We cant create a partitioned table with the column of LONG or LONGRAW? (But how it could be possible with BLOB, CLOB?
As per Article mentioned in Oracle Base,I have converted non-partitioned table (1 million data) into range-partition table,but,I don't see performance improvement in explain .
View 9 Replies View RelatedHow to force an index if the table not using the index?
View 10 Replies View RelatedAt work we have a linux server with Oracle 10.2.0.5 g, and we have the need, to save time, to use parallel process launched in background (&) or (at now).
The table that we are going to insert is partitioned for date and subpartitioned for name of file_source, and we are having a lot of problem with this.
Our DBA staff say that is impossible to work in this way but for me, after ten year of oracle-work, sounds strange , sure may be that we don'r use really really correctly this procedure but i suppose that Oracle is able to recevie 20 ask of insert on the same table.
The situation is that we usede this procedure in other server and it's work but the answer of our DBA-staff is that we have less data storage and so on. In the end some times this proceduers have a low time of execution and some times no, this goes out of my ability to find out the problem.
We have a DWH with STAGING AREA, ODS Level, DDS Level and DM Level, the Staing area is paritionend for file_source, the ODS Area is partitioned by range (date) and subpartitioned for name (file_source), the DDS area is partitioned by range(date) and subpartitioned for Origin system(that include all the file_source) and the DM area is only partitioned by date.
So the most big problems that we meet are between the Staging are and ODS area, and between the Ods area and the DDS Area, the most important thing is that this table (DDS) is a monster of near 500.000.000 of rows (ITr of data) but we look only at the date to elaborate.
The solution is clear, divide this table in two, one online and one of storage as usually and correctly a normal situation require, but unfortunatly is a situation that we Erhedit from an old system and at the moment is not approoved the change request on this site.
The really strange thing is that sometimes work and some times not, without understand the cause of this. My opinion on this is that the DB is not correctly configured but the System Staff say that everything is correct and there are no problem. My first problem is to understand, if possible, wich is the limit of this way to operate, can i insert in a subpartition in the same time with twenty parallel process that write on same partition and different subpartition? Is correct to act in this way to save time about the data-load or better doing it one by one? On my experience i realized that Oracle can manage(is his work) a lot of request in the same time, but in this DB that we are using i continue to see problems that sounds like if we are usuing a tool that is not working in the correct way...
May be we went beyond some limit but in the end are less then 5.000.000 records per day that we move i think that a DWH have to support more than this...
I would like to know the following.
If multiple queries are run in parallel(at the same time) against a table or a set of tables (query referencing multiple tables), does it reduce the performance.
In other words is Oracle capable of reading (selecting from) the same table multiple times in parllel.
I have table A with size 120 Million and two more tables are of size 2 Million on Table B and less than 1 Million size on table C.I had created Partition and Parallel degree 4 on the table A. Created table B with Parallel degree 2 and Created table C with NOPARALLEL.
My query is using above tables with joins and inserting into table D using HINT /*+ APPEND NOLOGGING*/I had executed the explain on the above criteria the cost is showing 20767.
Later created Tables A,B and C with NOPARALLEL. Applied HINT on Table D /*+ APPEND NOLOGGING*/ and als applied HINT /*+ PARALLEL(A, 4) PARALLEL(B C, 2) on select query which uses to insert into Table D.
My question which is best practice on PARALLEL degree creation at table level or query level:
a) Creating table with Paralle (degree 4)
b) Applying HINT /*+ PARALLEL (TABLE A , 4) */ at query level
'Oracle fast parallel data unload into ASCII file(s)' in this blog: URL....I have compiled the code and created the objects and the directory in my DB...But when I execute :
SELECT *
FROM TABLE(
DATA_UNLOAD(
CURSOR(
SELECT /*+ PARALLEL(A, 2, 1) */
TABLE_NAME || '|' ||
COLUMN_NAME || '|' ||
DATA_TYPE
FROM MYTABLE A
[code]....
It is supposed to return 2 rows (because of parallel execution), but it just returns 1..Do I have to do something special in order to make parallel pipelined function work
I have a partioned (by row_create_date) table, lets called it TABLE_X, which has about 300 million records. This table has 7 columns including the primary key and a non-unique, locally partitioned column called trace_id; 99% of queries access this table via this column.
Lately, querying TABLE_X via the trace_id has been very very bad. Queries run for over 1 hr in some cases. So we decided to change the index for trace_id to a global index. Now queries against TABLE_X return in seconds. So far so good.
However, when the query has to join TABLE_X to another table, the query sometimes runs for over 1 hours; back to the same old problem. Here is an illustration;
SELECT COUNT(1) FROM TABLE_X WHERE TRACE_ID = 'XXXXX';
-- returns in seconds
SELECT COUNT(1)
FROM TABLE_X,
TABLE_Y
WHERE TABLE_X.TRACE_ID = 'XXXXX'
AND TABLE_X.TRACE_D = TABLE_Y.TRACE_ID;
-- runs for over 1 hr, even when TABLE_Y.TRACE_ID is a primary key.
I created table Rang pertitionned, and List subpartitionned. My table is Interval partitionning. My subpartition is template based as is :
PARTITION BY RANGE ( DINFOIDENTITE )
INTERVAL ( (NUMTOYMINTERVAL(1,'MONTH')) )
SUBPARTITION BY LIST ( AVANT_DERNIER_MATCLE )
[Code]....
i would have the same repartition with 10 differents tablespaces, one for each subpartition.
I search on Oracle documentation this morning, but the only thing i've found is that this option is possible with the STORE IN clause, but only for HASH partitionning.
Is there a way to specify STORAGE clause with a template for my indexes ?
I have created an non unique index lk_fein on lookup_fein( code,map_id,trash). When I check the explain plan it does a full table scan on lookup_fein. if I force it to use index by it does and the cost also decreases.
SQL> SELECT WORK_FEIN,
2 NON_FEIN ,
3 FI_FEIN ,
4 MFEIN ,
5 TOTAL_FEIN ,
[code]...
16:28:32 SQL> create bitmap index bp_idx_ag_id on transactions(type);
create bitmap index bp_idx_ag_id on transactions(type)
*
ERROR at line 1:ORA-25122: Only LOCAL bitmap indexes are permitted on partitioned tables
how to create bitmap index on partitiioned tables
I have a query which had a join:
a.c1=b.c1 and a.c2=@var
where @var is user supplied input at runtime...We had a index on a.c2 . The CBO would use this index to generate an opitimised query plan.We found some records from table "b" were dropping due to inner join. So we made a change in join. It'd be like
a.c1(+)=b.c1 and nvl(a.c2,@var)=@var
This query is no longer using the index, instead its doing a full table scan causing the query to slowdown.I have tried creating index on nvl(a.c2,'31-dec-9999')
But the CBO won't use it.Anyway to create index on this col so that full table scan can be avoided?
How the length of column width effects index performance?
For example if i had IOT table emp_iot with columns:
(id number,
job varchar2(20),
time date,
plan number)
Table key consist of(id, job, time)
Column JOB has fixed list of distinct values ('ANALYST', 'NIGHT_WORKED', etc...).
What performance increase i could expect if in column "job" i would store not names but concrete numbers identifying job names.
For e.g. i would store "1" instead 'ANALYST' and "2" instead 'NIGHT_WORKED'.
Facts:
Oracle 10.1.0.5
AIX 5.3
My table, HMTX have 10 partitions each of one have 6 millions of rows (average). We have 7 partitioned LOCAL indexes in that table.
Every month we load data into a new partition (6 million of rows aprox) and drop the oldest partition in table HMTX.
In order to do that we have a script that contain the next statements:
drop of all indexes
drop index n1;
drop index n...;
drop index n7;
[Code]...
create indexes again with tha same storage and degree parameters
CREATE INDEX hmtx_TST_N1 ON hmtx (campo1, campo2, campo3 .... campo8)
TABLESPACE xxxx
PCTFREE 0
INITRANS 2
[Code]....
My problem is in rhe index creation section, despite use parallel with degree 8 and nologging the index was created in :
Elapsed: 02:43:50.85.
In past months that index was created in :
Elapsed: 01:43:36.94
Elapsed: 04:48:31.24
Elapsed: 00:57:16.28
there are another way in order speed the index creation ?? o another way to disable ths index ??
I have table with 4 partition by range partition. I am loading the table in bulk mode to latest partition. Before I load , I dropped the index and after Load I will be creating index. So when I am dropping index, it is dropping index from all the partitions and when creating the index, I am creating the index for all partitions. When I am creating index using local, it is telling you have to create local index for all partitions at the same time. because of that I have to drop and recreate all indexes again. Again I have to gather stats for whole table .
I was thinking we can build index for one partition and index should remain as is for old partitions If this is not the case, how do I plan my load for a partitioned table using bulk mode to latest partition.
I have a query which has 5 unions, each clause of the union takes 1 hr to run and query results come back in 5 hrs, Is there any way I can make these clause to run in parallel?
View 13 Replies View Relatedwe have many tables in Cursor For Loop :
CREATE OR REPLACE PROCEDURE EBILL_BULK_UPDATE_SERVICE(in_cycle VARCHAR2)
AS
v_cnt NUMBER; -----Variable used for checking table is partitioned or not partitioned
CURSOR cur_update -----Cursor defined for Updating EBILL tables for service_id
is
SELECT table_name
, cycle_name
FROM NNP_EBILL_UPDATE
[code]....
As our requirement that Execute Immediate should work for 5 or more tables updation parallely at a time.If one table get completed then it should take next table from loop and then start the code till completion of all tables.
On a tab page should be displayed the result of four indifferent queries, each based on a stored procedure.At the moment, the queries are processed serially, by the statements:
GO_BLOCK('one');
CLEAR_BLOCK(No_Validate);
EXECUTE_QUERY;
GO_BLOCK('two');
CLEAR_BLOCK(No_Validate);
EXECUTE_QUERY;
Is there a way to processes the queries parallel ?