Skip to main content

10 Million records manipulation in Oracle DB

Say you are given a task to manipulate a set of 10 million records from a couple of tables.
What would you do? Sit and think???!!!!

See if the following helps you..

Replicate the tables data into temporary tables
Create indexes on the columns you want to manipulate the data
Write your query..

Dont ask me what language you are talking!!!!
Look at the examples

Select count(1) from hugeTable1;--7999900 records
Select count(1) from hugeTable2; --9893990

Create table tmp1
as
Select *
from hugeTable1
where 1=2;

insert /*+append*/ into tmp1
select * from hugeTable1;

Create table tmp2
as
Select *
from hugeTable2
Where 1=2;

insert /*+append*/ into tmp2
select * from hugeTable2;

create index indTmp1 on tmp1(column1,column2);
create index indTmp2 on tmp2(column1,column2);

Select *
from tmp1,tmp2
where tmp1.column1=tmp2.column1 and
          tmp1.column2=tmp2.column2;
   

Should you face any issues, please write to me ( susilaarya@gmail.com )

Comments

Post a Comment

Popular posts from this blog

Design and Operations ( Employee- Model )

-- DB design drop table emp_Salary; drop table emp_Designation; drop table emp; drop table Designations; drop table Departments; drop table Salary_Bands; drop table Addresses; Create table emp( emp_id number, emp_Name varchar2(20), emp_address_id varchar2(10), emp_created_date date, emp_created_by varchar2(20), constraint e_pk primary key(emp_id) ); Create table Departments( dept_id number, dept_name Varchar2(20), constraints dept_pk primary key(dept_id) ); Create table Designations( dept_id number references Departments(dept_id), desg_id number, desg_description varchar2(20), constraints desg_pk primary key(dept_id,desg_id) ); Create table emp_Designation( emp_id number references emp(emp_id), emp_des_dept_id number references departments(dept_...
Post a Comment
Read more

How to remove duplicate rows without using DISTINCT or ROWID or GROUP BY methods in Oracle?

Make use of SET operators and CTAS (Create Table AS) method.. Example: Create table tmp_tb1 as Select * from table1 intersect Select * from table1; truncate table table1; insert into table1 select * from tmp_tb1; -- This will now have removed all duplicates in the table... commit; *** You can use UNION operator in place of INTERSECT
2 comments
Read more

Identify current and prev details of a customer

  create table customer_rating( id char, name char, irrating char, jcrrating char, procDate date, flag char ); insert into customer_rating values('A','D','X','Y','28-Jul-21','M'); insert into customer_rating values('A','D','M','L','27-Jul-21','M'); Select cr.id, cr.name, cr_prev.irrating pcob_rating, cr.irrating cob_rating, cr_prev.jcrrating pcob_jcr_rating, cr.jcrrating cob_jcr_rating From Customer_Rating cr join Customer_Rating cr_Prev  ON cr.procdate = '28-Jul-21' AND cr_prev.id = cr.id AND cr_prev.procdate = (  Select max(procdate) from Customer_Rating  Where id=cr.id and procdate < cr.procdate ) ;
Post a Comment
Read more