I'm having a weird problem with index organized table. I'm running Oracle 11g standard.
i have a table src_table
SQL> desc src_table;
Name Null? Type
--------------- -------- ----------------------------
ID NOT NULL NUMBER(16)
HASH NOT NULL NUMBER(3)
........
SQL> select count(*) from src_table;
COUNT(*)
----------
21108244
now let's create another table and copy 2 columns from src_table
set timing on
SQL> create table dest_table(id number(16), hash number(20), type number(1));
Table created.
Elapsed: 00:00:00.01
SQL> insert /*+ APPEND */ into dest_table (id,hash,type) select id, hash, 1 from src_table;
21108244 rows created.
Elapsed: 00:00:15.25
SQL> ALTER TABLE dest_table ADD ( CONSTRAINT dest_table_pk PRIMARY KEY (HASH, id, TYPE));
Table altered.
Elapsed: 00:01:17.35
It took Oracle < 2 min.
now same exercise but with IOT table
SQL> CREATE TABLE dest_table_iot (
id NUMBER(16) NOT NULL,
hash NUMBER(20) NOT NULL,
type NUMBER(1) NOT NULL,
CONSTRAINT dest_table_iot_PK PRIMARY KEY (HASH, id, TYPE)
) ORGANIZATION INDEX;
Table created.
Elapsed: 00:00:00.03
SQL> INSERT /*+ APPEND */ INTO dest_table_iot (HASH,id,TYPE)
SELECT HASH, id, 1
FROM src_table;
"insert" into IOT takes 18 hours !!! I have tried it on 2 different instances of Oracle running on win and linux and got same results.
What is going on here ? Why is it taking so long ?
The APPEND hint is only useful for a heap-organized table.
When you insert into an IOT, I suspect that each row has to be inserted into the real index structure separately, causing a lot of re-balancing of the index.
When you build the index on a heap table, a temp segment is used and I'm guessing that this allows it to reduce the re-balancing overhead that would otherwise take place.
I suspect that if you created an empty, heap-organized table with the primary key, and did the same insert without the APPEND hint, it would take more like the 18 hours.
You might try putting an ORDER BY on your SELECT and see how that affects the performance of the insert into the IOT. It's not guaranteed to be an improvement by any means, but it might be.
Related
I new at using PL/SQL and I want the following:
I have this table on Oracle SQLcl
create table Child (
id varchar not null,
name varchar not null,
gender varchar not null,
YearOfBirth number(4) not null,
YearsOfAge number(4) null,
CONSTRAINT Pk primary key (id)
);
And I want a PL/SQL (preferred anonymous) that update field of "YearsOfAge" by minusing 2020 from the "YearOfBirth" field. I could do that but my problem is that the table won't be updated until I insert the PL/SQL block again. So whenever I insert a new row, I have to insert my PL/SQL block again. I want to get the table updated whenever I insert/update a row, without a need to insert this block following a new row.
To be clearer, I just want to insert SL/SQL block one time after creating the table, then get the table's "YearsOfAge" updated whenever I insert/update/delete a row. So when I write "select * from Child;" I need to see the "YearsOfAge" with the new value that computed from subtracting 2020 from "YearOf Birth".
My current PL/SQL is below:
begin
IF INSERTING THEN
update Child set YearsOfAge = 2020 - YearOfBirth;
ELSIF DELETEING THEN
update Child set YearsOfAge = 2020 - YearOfBirth;
ELSE
update Child set YearsOfAge = 2020 - YearOfBirth;
END IF;
END;
/
If you really need to store the age this way, some options are virtual columns, views, and triggers.
Virtual Column
With a virtual column, Oracle will automatically perform the calculation on the fly.
SQL> create table Child
2 (
3 id number not null,
4 name varchar2(10) not null,
5 gender varchar2(10) not null,
6 YearOfBirth number(4) not null,
7 YearsOfAge number generated always as (2020 - yearOfBirth) null,
8 constraint pk_child primary key (id)
9 );
Table created.
SQL> insert into child(id, name, gender, yearOfBirth) values(1, 'A', 'female' , 1990);
1 row created.
SQL> insert into child(id, name, gender, yearOfBirth) values(2, 'B', 'male' , 2000);
1 row created.
SQL> insert into child(id, name, gender, yearOfBirth) values(3, 'C', 'non-binary', 2010);
1 row created.
SQL> select * from child;
ID NAME GENDER YEAROFBIRTH YEARSOFAGE
---------- ---------- ---------- ----------- ----------
1 A female 1990 30
2 B male 2000 20
3 C non-binary 2010 10
View
One downside of virtual columns is that they cannot use functions like SYSDATE, so the year has to be hard-coded. With a view, the expression can reference SYSDATE and will always be up-to-date:
create or replace view child_view as
select id, name, gender, yearOfBirth, extract(year from sysdate) - yearOfBirth yearsOfAge
from child;
Trigger (Warning)
You can also use a trigger to create the value when a row is inserted or updated:
create or replace trigger child_trg
before update or insert on child
for each row
begin
if updating('YEAROFBIRTH') or inserting then
:new.yearsOfAge := extract(year from sysdate) - :new.yearOfBirth;
end if;
end;
/
But in practice, triggers are a pain to maintain. Which leads to the question: why do you want to store this information in the first place?
Good database design should minimize the amount of redundant data. There are always exceptions, but you should have a good reason for those exceptions, like an especially complicated calculation that you don't want others to get wrong, you can't create a PL/SQL function because of an unusual security constraint, etc. Calculating something as trivial as the age may cause more problems than it solves.
I am trying to come up with a way to make sure that when a table is updated, that a certain condition is met. Can this be done in a trigger? I have made the following two tables, storeTable and employeeTable.
I need to make sure that when storeManager is updated in the storeTable, that the employee has a storeID that matches the store in which I am trying to update the storeManager. (employee cannot be manager of a store he does not work at)
In addition, I need to make sure that the employee exists in the employeeTable. I was thinking some sort of CASE statement would be best, but dont know how this could be enforced by a trigger.
I was thinking about morphing the "Foreign Key Trigger for Child Table" trigger example from https://docs.oracle.com/cd/B12037_01/appdev.101/b10795/adfns_tr.htm#1007172 but I could not figure out how to change this to fit my specific need. Any help is much appreciated.
For context, the current keys are:
storeTable:
storeID PRIMARY KEY
employeeTable:
empID PRIMARY KEY
storeID FOREIGN KEY REFERS TO storeTable.storeID
To me, it seems that constraints can do the job. You don't need triggers.
Here's how. First, create tables without any constraints. Then add them, both primary and foreign key ones which will be deferrable (otherwise you wouldn't be able to insert any rows as parent keys don't exist yet).
SQL> create table employee
2 (empid number,
3 fname varchar2(10),
4 storeid number
5 );
Table created.
SQL> create table store
2 (storeid number,
3 storename varchar2(20),
4 storemanager number
5 );
Table created.
SQL>
SQL> alter table employee add constraint pk_employee primary key (empid, storeid);
Table altered.
SQL> alter table store add constraint pk_store primary key (storeid);
Table altered.
SQL>
SQL> alter table store add constraint fk_store_emp foreign key (storemanager, storeid)
2 references employee (empid, storeid)
3 deferrable initially deferred;
Table altered.
SQL> alter table employee add constraint fk_emp_store foreign key (storeid)
2 references store (storeid)
3 deferrable initially deferred;
Table altered.
SQL>
Now let's add some data: initial insert into employee will be OK until I commit - then it'll fail because its store doesn't exist yet:
SQL> insert into employee values (1, 'John' , 1);
1 row created.
SQL> commit;
commit
*
ERROR at line 1:
ORA-02091: transaction rolled back
ORA-02291: integrity constraint (SCOTT.FK_EMP_STORE) violated - parent key not
found
SQL>
But, if I don't commit and pay attention to what I'm entering (i.e. that referential integrity is maintained), it'll be OK:
SQL> insert into employee values (1, 'John' , 1);
1 row created.
SQL> insert into employee values (2, 'Matt' , 2);
1 row created.
SQL> insert into store values (1, 'Santa Clara', 1);
1 row created.
SQL> insert into store values (2, 'San Francisco', 2); --> note 2 as STOREID
1 row created.
SQL> commit;
Commit complete.
SQL> select * From employee;
EMPID FNAME STOREID
---------- ---------- ----------
1 John 1
2 Matt 2
SQL> select * From store;
STOREID STORENAME STOREMANAGER
---------- -------------------- ------------
1 Santa Clara 1
2 San Francisco 2
SQL>
See? So far so good.
Now I'll try to modify STORE table and set its manager to John who works in storeid = 1 which means that it should fail:
SQL> update store set storemanager = 1
2 where storeid = 2;
1 row updated.
SQL> commit;
commit
*
ERROR at line 1:
ORA-02091: transaction rolled back
ORA-02291: integrity constraint (SCOTT.FK_STORE_EMP) violated - parent key not
found
SQL>
As expected.
Let's now add emplyoee ID = 6, Jimmy, who works in storeid = 2 and set him to be manager in San Francisco (storeid = 2):
SQL> insert into employee values (6, 'Jimmy', 2);
1 row created.
SQL> update store set storemanager = 6
2 where storeid = 2;
1 row updated.
SQL> commit;
Commit complete.
SQL>
Yey! It works!
As you can see, no triggers needed.
Note that - if you want to drop any of those tables - you'll fail as they are referenced by each other:
SQL> drop table store;
drop table store
*
ERROR at line 1:
ORA-02449: unique/primary keys in table referenced by foreign keys
SQL> drop table employee;
drop table employee
*
ERROR at line 1:
ORA-02449: unique/primary keys in table referenced by foreign keys
SQL>
It means that you'd first have to drop foreign key constraints, then drop tables:
SQL> alter table employee drop constraint fk_emp_store;
Table altered.
SQL> alter table store drop constraint fk_store_emp;
Table altered.
SQL> drop table store;
Table dropped.
SQL> drop table employee;
Table dropped.
SQL>
That's all, I guess.
How to increment the value of the unique constraint column value in ORACLE, in the select statement.
For example, in a table 'BILLING_TABLE' - column BLNG_Sk is the unique key (Autoincremented).
So while inserting a new record into the BILLING_TABLE, for the column BLNG_SK we need to give the value (Which is the increment by 1 from the present max value.)
For example, if BLNG_SK max value is 12321.
new record should be 12322.
how to achieve this in Oracle?
Oracle has a SEQUENCE object which provides the functionality you require.
You create one using the CREATE SEQUENCE SQL statement.
The Oracle documentation provides all the required information and the documentation is available via Oracle's Web site.
Assuming you are on Oracle 12.1 or later, define it as an identity column and do not pass any value when inserting:
create table testtable
( test_id number generated always as identity
constraint testtable_pk primary key
, othercol varchar2(10) );
insert into testtable (othercol) values ('Demo');
select * from testtable;
TEST_ID OTHERCOL
---------- ----------
1 Demo
insert into testtable (othercol) values ('Demo #2');
select * from testtable;
TEST_ID OTHERCOL
---------- ----------
1 Demo
2 Demo #2
Try creating a sequence and a trigger. This is the case when you provide the value manually.
CREATE SEQUENCE dept_seq START WITH 12322;
Trigger definition:
CREATE OR REPLACE TRIGGER dept_bir
BEFORE INSERT ON BILLING_TABLE
FOR EACH ROW
BEGIN
SELECT dept_seq.NEXTVAL
INTO :new.id
FROM dual;
END;
/
I have 3 tables in my database namely employees,students and Images
create table employees(id number primary key,name varchar2(100), address varchar2(100));
create table students(id number primary key,name varchar2(100),address varchar2(100));
create table Images (image_id number primary key,employee_id number,student_id number,image_name varchar2(100));
Insert into employees values (1,'asdfasd','asdfasdf');
Insert into employees values (2,'asdfasd','asdfasdf');
Insert into employees values (3,'asdfasd','asdfasdf');
Insert into employees values (4,'asdfasd','asdfasdf');
Insert into employees values (5,'asdfasd','asdfasdf');
Insert into students values (1,'asdfasd','asdfasdf');
Insert into students values (2,'asdfasd','asdfasdf');
Insert into students values (3,'asdfasd','asdfasdf');
Insert into students values (4,'asdfasd','asdfasdf');
Insert into students values (5,'asdfasd','asdfasdf');
Insert into students values (49,'asdfasd','asdfasdf');
Insert into Images(image_id,employee_id,image_name) values (1,5,'adsfasdfasdf');
Insert into Images(image_id,student_id,image_name) values (2,49,'asfasdfasdf');
Now, when Inserting a row into the Images table I should check whether the employee_id / Student_id is existed in the employees table/student table, If a match found then only I have to Insert else it should not.
I thought of adding two foreign keys on the images table as follows:
alter table images add constraint fk_employeeid foreign key(employee_id)
references employees(id);
alter table images add constraint fk_studentsid foreign key(student_id)
references students(id);
But, If I do so. It will not allow me to insert null values. How can I modify my design so that whenever I insert a row in images table either it should be an employee_id or an student_id.
If I created any confusion, here is the link for the sql fiddle,http://www.sqlfiddle.com/#!4/92d24/1/0
I thought of adding two foreign keys on the images table.
But, If I do so. It will not allow me to insert null values.
You are wrong when you say the foreign key constraint won't allow NULL values. It will definitely allow the NULL values.
Test case
Let's add the foreign key constraint on the IMAGES table for the employee_id and student_id.
ALTER TABLE images ADD CONSTRAINT fk_emp FOREIGN KEY(employee_id) REFERENCES employees(ID);
ALTER TABLE images ADD CONSTRAINT fk_stu FOREIGN KEY(student_id) REFERENCES students(ID);
Let's check the INSERT with NULL values:
SQL> INSERT INTO Images(image_id,employee_id,image_name) VALUES (1,5,'adsfasdfasdf');
1 row created.
SQL> INSERT INTO Images(image_id,student_id,image_name) VALUES (2,49,'asfasdfasdf');
1 row created.
SQL> INSERT INTO Images(image_id,employee_id,image_name) VALUES (3,null,'adsfasdfasdf');
1 row created.
SQL> INSERT INTO Images(image_id,student_id,image_name) VALUES (4,null,'asfasdfasdf');
1 row created.
SQL>
SQL> COMMIT;
Commit complete.
SQL>
SQL> SELECT * FROM images;
IMAGE_ID EMPLOYEE_ID STUDENT_ID IMAGE_NAME
---------- ----------- ---------- ---------------
1 5 adsfasdfasdf
2 49 asfasdfasdf
3 adsfasdfasdf
4 asfasdfasdf
SQL>
Let's check the foreign key constraint validation:
SQL> INSERT INTO Images(image_id,employee_id,image_name) VALUES (1,10,'adsfasdfasdf');
INSERT INTO Images(image_id,employee_id,image_name) VALUES (1,10,'adsfasdfasdf')
*
ERROR at line 1:
ORA-00001: unique constraint (LALIT.SYS_C0010739) violated
SQL> INSERT INTO Images(image_id,student_id,image_name) VALUES (2,20,'asfasdfasdf');
INSERT INTO Images(image_id,student_id,image_name) VALUES (2,20,'asfasdfasdf')
*
ERROR at line 1:
ORA-00001: unique constraint (LALIT.SYS_C0010739) violated
SQL>
So, everything works as per the design.
Add constraints to images like you did. Add one more constraint:
alter table images add constraint chk_nulls
check (
(employee_id is not null and student_id is null)
or (employee_id is null and student_id is not null)
);
This way you cannot insert both nulls nor both not nulls for employee_id and student_id. And foreign keys are also checked.
Test:
insert into images values (1, 1, null, 'not important'); -- OK
insert into images values (2, null, null, 'not important'); -- error
insert into images values (3, 1, 1, 'not important'); -- error
insert into images values (4, null, 1, 'not important'); -- OK
I would keep the foreign keys, that is the correct approach.
But instead of inserting NULL's, you should define an "unknown record" in your EMPLOYEES and STUDENTS tables (maybe with an id=-1, name='UNKNOWN'), and insert -1 into your IMAGES table.
I recommend you to change the primary key in table images, and have as PK three columns (image_id, employee_id and student_id).
Edit 1: Based on comment
I think you planned in a wrong way the problem. If the images are for both, employees and students, you should have two tables, images_employees and images_students, with respectively foreign keys employee_id and student_id and of course an id for the image.
But is there any sense to have a row like this?
id: 1 student_id: null image_name: 'something'
I don't think so... please explain more about the purpose of images table.
This question already has answers here:
How to create id with AUTO_INCREMENT on Oracle?
(18 answers)
Closed 8 years ago.
I am facing issue while inserting multiple row in one go into table because column id has primary key and its created based on sequence.
for ex:
create table test (
iD number primary key,
name varchar2(10)
);
insert into test values (123, 'xxx');
insert into test values (124, 'yyy');
insert into test values (125, 'xxx');
insert into test values (126, 'xxx');
The following statement creates a constraint violoation error:
insert into test
(
select (SELECT MAX (id) + 1 FROM test) as id,
name from test
where name='xxx'
);
This query should insert 3 rows in table test (having name=xxx).
You're saying that your query inserts rows with primary key ID based on a sequence. Yet, in your insert/select there is select (SELECT MAX (id) + 1 FROM test) as id, which clearly is not based on sequence. It may be the case that you are not using the term "sequence" in the usual, Oracle way.
Anyway, there are two options for you ...
Create a sequence, e.g. seq_test_id with the starting value of select max(id) from test and use it (i.e. seq_test_id.nextval) in your query instead of the select max(id)+1 from test.
Fix the actual subselect to nvl((select max(id) from test),0)+rownum instead of (select max(id)+1 from test).
Please note, however, that the option 2 (as well as your original solution) will cause you huge troubles whenever your code runs in multiple concurrent database sessions. So, option 1 is strongly recommended.
Use
insert into test (
select (SELECT MAX (id) FROM test) + rownum as id,
name from test
where name='xxx'
);
as a workaround.
Of course, you should be using sequences for integer-primary keys.
If you want to insert an ID/Primary Key value generated by a sequence you should use the sequence instead of selecting the max(ID)+1.
Usually this is done using a trigger on your table wich is executed for each row. See sample below:
CREATE TABLE "MY_TABLE"
(
"MY_ID" NUMBER(10,0) CONSTRAINT PK_MY_TABLE PRIMARY KEY ,
"MY_COLUMN" VARCHAR2(100)
);
/
CREATE SEQUENCE "S_MY_TABLE"
MINVALUE 1 MAXVALUE 999999999999999999999999999
INCREMENT BY 1 START WITH 10 NOCACHE ORDER NOCYCLE NOPARTITION ;
/
CREATE OR REPLACE TRIGGER "T_MY_TABLE"
BEFORE INSERT
ON
MY_TABLE
REFERENCING OLD AS OLDEST NEW AS NEWEST
FOR EACH ROW
WHEN (NEWEST.MY_ID IS NULL)
DECLARE
IDNOW NUMBER;
BEGIN
SELECT S_MY_TABLE.NEXTVAL INTO IDNOW FROM DUAL;
:NEWEST.MY_ID := IDNOW;
END;
/
ALTER TRIGGER "T_MY_TABLE" ENABLE;
/
insert into MY_TABLE (MY_COLUMN) values ('DATA1');
insert into MY_TABLE (MY_COLUMN) values ('DATA2');
insert into MY_TABLE (MY_ID, MY_COLUMN) values (S_MY_TABLE.NEXTVAL, 'DATA3');
insert into MY_TABLE (MY_ID, MY_COLUMN) values (S_MY_TABLE.NEXTVAL, 'DATA4');
insert into MY_TABLE (MY_COLUMN) values ('DATA5');
/
select * from MY_TABLE;