base on performance it is better to retrieve data from view or mention the table names directly?
I have a select statement in from clause one of my table is view (which is having data collected from four tables) my question is whether performance of querry will be improved if i use directly all tables( four tables of a view) instead of a view
I have created a materialized view and also a normal View, which has 3 tables used in both the views, when inserted new records it reflects in a normal view but when i select the materialized view i cant see the updated data.
here is the materialized view i created;
CREATE MATERIALIZED VIEW pct_sales_materialized
BUILD IMMEDIATE REFRESH ON DEMAND
ENABLE QUERY REWRITE
AS
SELECT A.DEP_NAME,B.EMP_ID,C.EMP_NAME
FROM department_head A,department_child B,emp_detail C
WHERE A.DEP_ID = B.DEP_ID
AND B.EMP_ID = C.EMP_ID
If you have 3 tables (yr09, yr10,yr11) one with 2009 data, 2010 and 2011 data respectively. And a view (vw_yr091011) with a "union all" on all three.
Question: Will the performance be same for the following two queries ?
Question: Will Oracle read all 3 tables in the view when we search for only one year ?
select count(*) from yr09
where year = 2009;
-- vs
select count(*) from vw_yr091011
where year = 2009;
The following link says yes, the performance remains the same.
Link: [URL]..........
when I tried on a volume of 14000 records. The count came out same but the view took 50 more sec. And the explain plan shows it accessed all three tables.
We have few tables in our production database which are havoc in size and will increase in size in future too so as part of the corrective measures , we have jotted down the below 3 methods to manage the size of those tables :-
1> Partitioning the table and take the export of identified partitions and after that, truncate those partition.
2> Creating history tables and remove not so current data from the original table to history table.
We are on Oracle 10.2.0.4 on Solaris 10. There is a table in my production db that has 872944 number of rows. Most of its data is now unnecessary, we need to retain, based on a date column in the table just last one month's data and delete rest of the data. So after that the table will have just 3000 rows.
However as the table was huge earlier(872k rows prior to delete) , does the delete of data release its oracle blocks and does the size of the table reduce? If not, will it rebuild the table online (online redefinition) so that the query that does a full scan on this table goes faster?
I checked using an example table that just delete of data does not remove the oracle blocks - they remain in the user_tables for that table and cost of full table scan remains same. We have a query that does the full table scan so I am thinking that after this delete I should do an online table re-definition , is that the right decision?
I have a table which contains 8,21,177 amount of data totally.Now I am trying to delete around 4,84,000 of data from this table by using just one filter i.e. my query is something like below
DELETE /*+ parallel(resource,4) */ FROM resource where created_by = 'MIGN'
This is going to delete 4,84,000 rows of data . But my current issue is this is taking lots of time to delete the data . To be precise , its almost taking 25 hours to delete this data..The created_by column is indexed .
Execution Plan
----------------------------------------------------------
Plan hash value: 2389236532
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)| Time
|
--------------------------------------------------------------------------------
| 0 | DELETE STATEMENT | | 499 | 20459 | 39 (0)| 00:00:
01 |
| 1 | DELETE | RESOURCE | | | |
[code]....
I am inserting data using a procedure for 2012 and 2013 year which is using partitioned tables includes crore of data in a partition taking lot of time or taking months. Is there any other way by which I can insert data fast from our query.
View 14 Replies View Relatedi'm working on sql developer in that i'm able to access tables if particular table name is given..
i don't understand is there any grant role problem .
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 RelatedI have a view, below, which does few left outer joins to the same V_MARKET view to get data i need. When I run SQL by itself, ut runs pretty fast, 2-5 seconds. But when I do "select * from V_DEPT_DATA where busines_date = '01-APR-10'", it takes more than 10 minutes to run. I added all needed indexes and still have problems with it .
CREATE OR REPLACE VIEW V_DEPT_DATA
AS
SELECT
v1.business_date ,
v1.division ,
v1.department ,
v1.account ,
en.trader ,
[code]........
I have an issue in materialized view which has got one of the null able column and query on this column taking approximately 2 mins where as other indexed columns takes less than 10 sec.
Here is the summary
SQL> Select Count (1), Count (VAT_NO) From Mv_customer;
COUNT(1) COUNT(VAT_NO)
---------------------------------
2893561 1516
If an index is created on VAT_NO will that improve the performance. What kind of index can be created considering very less number of records has got VAT_NO
I have a view on base tables holding historical data for previous 60 months(one table per month) with union all operators.create index on those base tables will improve performance or creating a primary key with disabled novalidate will improve for retrieving data?
The view has around 8 million data and used as a fact table with 4 dimension tables.A DTS package from MSSql side refreshes OLAP cube by retrieving data from these tables in oracle.
In search queries generally we select 10-25 columns (more can't be displayed on the screen) from 5-10 tables
Say in case of insurance related application, the search might be on policy number, policy holder's first name, policy holder's last name, region, policy type etc.
And not to many columns we are displaying on the screen, say, 4 tables have collectively 4 * 20 = 80 columns, then we are displaying say 12-15 columns with 2-3 columns have aggregates on it.
since the search criteria (e.g. first name, last name, policy number etc.) is not known till last moment it will be a generic dynamic query
Is it possible that instead we create a Materialized view with query with only joining conditions but no filter conditions and selecting only columns to be displayed on the screen and then we will refresh the materialized view (to take care of recent business transactions) and fire refined query with filter criteria on this materialized view
Select col1,col2,col3,col4,col5
From tab1,tab2,tab3,tab4
Where tab1.col1=tab2.col1
And tab2.col2=tab3.col2
And tab2.col2=tab4.col2;
Will it improve performance of the search functionality
I need to create a Materialized View, which should refresh every Tuesday and Friday at 5am.
CREATE MATERIALIZED VIEW DUAL_MV
TABLESPACE USERS_SMALL
REFRESH NEXT NEXT_DAY(TRUNC(SYSDATE), 'TUESDAY') + 05/24
AS SELECT * FROM DUAL;
I can do it for single day like above, but how to refresh on multiple days, using create materialized view syntax .
I have a base table with ~20 mio. records with two FAST REFRESH Materialized Views based on that table using various aggregate functions in their view definition.
The problem is, when e.g. one record changes in the base table, I see two records in the MV log table MLOG$, but invoking the fast refresh mechanism by using using:
dbms_snapshot.refresh('mv1', 'f');
dbms_snapshot.refresh('mv2', 'f');
Is still running after ~20 minutes now.
I have two tables with 113M records in DWH_BILL_DET & 103M in prd_rerate_chg_que and Im running following merge query, which is running for 13 hrs to update records, which is quiet longer time.
SQL> explain plan for MERGE /*+ parallel (rq, 16) */
INTO DWH_BILL_DET rq
USING (SELECT rated_que_rowid,
detail_rerate_flag_code,
rerate_sel_key,
[code].....
I am new to Oracle. I want to retrieve a list of employee names from a given empID. How to create a stored procedure for this query statement
example:
select name from employee table
where empID = 10
order by name;
what the principal things to look at when we have for the same query different performance results are?I have 2 different bases: the plan and data are the same but performance results are very differents.
View 10 Replies View RelatedI am trying to join column names from a table with data from a different table. I think i should be able to pass the parameter to a 'select list' in a query. Look at my sample data below. And the data in sales table can grow till 15 rows and similarly corresponding columns in saleshist.
CREATE TABLE SALESHIST
(
PRODUCT VARCHAR2(30 BYTE),
Q1 VARCHAR2(30),
Q2 VARCHAR2(30),
Q3 VARCHAR2(30),
Q4 VARCHAR2(30)
)
[code]......
What I am trying to do is print out page that displays all of the column titles and the data under them for a query given by the user. It is then going to be put into an excel spreadsheet.
I've done this before with Java, simply by using the getMetaData function, but I can't seem to find an alternative for PL/SQL. It seems at the very least I need to know the number of columns in a query, but that would defeat the purpose of this.
Is what I am trying to do even possible or is knowing the column names an absolute necessity when printing table data?
I have a schema DEF and I have a column_name CREATE_DATE.
I wanted to write a procedure which will give me list of tables whose CREATE_DATE data is prior to year 2009.
DB Used : Oracle 10g.
A table X : NUM, INST are column names
NUM ----- INST
1234 ----- 23,22,21,78
2235 ----- 20,7,2,1
1298 ----- 23,22,21,65,98
9087 ----- 20,7,2,1
-- Based upon requirement :
1) Split values from "INST" Column : suppose 23
2) Find all values from "NUM" column for above splitted value i.e 23 ,
Eg:
For Inst : 23 ,
It's corresponding "NUM" values are : 1234,1298
3) Save these values into
A table Y : INST, NUM are column names.
INST NUM
23 1234,1298
1) I have a thousand records in Table X , and for all of those records i need to split and save data into Table Y.Hence, I need to do this task with best possible performance.
2) After this whenever a new data comes in Table X, above 'split & save' operation should automatically be called and append corresponding data wherever possible..
I am writing a SQL inside an application to retrieve data from a table for certain IDs or for All employees based on the user's input. I create a variable :SELECTION for the where clause. When I run the SQL, I receive the error of missing right parenthesis. There is no error if I hard code the IDs.
If the input is 'All' -> the variable :SELECTION is blank so if the SQL :
select name, address, ID from employee :SELECTION
will be
select name, address, ID from employee
If the input of users ID as '1234','9999' - > the :SELECTION = ' where ID in (:VARIABLEID)'
:VARIABLEID = '1234','9999'
so the SQL:
select name, address, ID from employee :SELECTION
should be
select name, address, ID from employee where ID in ('1234','9999')
However, I got the missing right parenthesis error. I suspect it is something with the single quote, so I tried different ways, but it is still not working.
Look into the below table:
TABLE :- EMPLOYEE
________________________
| ID | SUPERVISOR |
|_______________________|
| A101 | B102 |
|________|______________|
| | |
| B102 | C104 |
|________|______________|
| | |
| C104 | D108 |
|________|______________|
| | |
| D108 | E104 |
|________|______________|
Here B102 is supervisor of A101 and C104 is supervisor of B102 and so on. I want to get this data into new table in below format
TABLE :- Hierarchy
________________________________________________________________
| ID |SUPERVISOR_1 |SUPERVISOR_2 |SUPERVISOR_3 |SUPERVISOR_4|
|______________________|_____________|_____________|____________|
| A101 | B102 | C104 | D108 | E104 |
|________|_____________|_____________|_____________|____________|
| | | | | |
| B102 | C104 | D108 | E104 | NULL |
|________|_____________|_____________|_____________|____________|
| | | | | |
| C104 | D108 | E104 | NULL | NULL |
|________|_____________|_____________|_____________|____________|
| | | | | |
| D108 | E104 | NULL | NULL | NULL |
|________|_____________|_____________|_____________|____________|
| | |
| E104 | NULL | NULL NULL NULL
|________|_____________|_____________|_____________|____________|
I want to insert 1st two rows into Hierarchy table, then I would like to update Supervisor_2 to Supervisor_4. Here I don't want to use 'CONNECT BY PRIOR', as it take more time to execute (there are millions of records).SQL code for same.
I have the following table with the some sample data:
|| Filename || receiving_site || originating_site ||
| fileA | siteA | HQ |
| fileA | siteA | siteA |
| fileB | siteA | HQ |
| fileA | siteB | HQ |
| fileA | siteB | siteB |
| fileB | siteB | HQ |
| fileB | siteB | siteB |
The table works in such way:
1. For each of the Filename, if originating_site is not the same as receiving_site, it means that the file has been sent to receiving_site but has not been acknowledged received yet.
2. For each of the Filename, if originating_site is the same as receiving_site, it means the file has been sent and received by the receiving_site.
My task is to list out all the Filename per receiving_site that has been sent, but not received yet by the receiving_site. For example from the sample data above, I am expecting to see that siteA, fileB has not been received yet.
How can I do that? I had tried MINUS and NOT EXISTS command, but I am just not able to get the result that I want.
How to retrieve first hundred records from a table ?
FYI
---
The table size is 5 GB
The table count is 127922653
Table has 14 columns
Table is partitioned as well.
The table has 10 partitions.
I have a "select ... into" in my PL/SQL and it doesn't retreive any data(I suppose just certain columns because if it doesn't retreive a row then the PL/SQL should throw an error) when there are many users accessing this table. It shouldn't be some table locking right? Because if it is, it should wait until the table is available then it will retreive data. Currently it just proceeds with the PL/SQL and selecting nothing in that query. what details should I look at to trace the cause of this problem.
View 4 Replies View RelatedI am using oracle 11g database.
unforunatly i delete the data from main table. and i operated alter stmt.
now how do i retrieve the data..??
I am having only select_catalog_role in database. Can I take complete AWR report data from awr views without using DBMS_WORKLOAD_REPOSITORY package?
View 6 Replies View Relatedsometimes when I re-run a query a few times, the speed after the first run become much faster. this is a problem for me when I'm trying to optimize a query. is there some sort of cache? can it be disabled?
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