Table description
COLUMN DATA_TYPE NULLABLE DEFAULT_VALUE
ID VARCHAR2(16) No
UPDATED_DATE TIMESTAMP(6) Yes
DETAILS CLOB Yes
TX_STATUS VARCHAR2(10) Yes
TX_USER VARCHAR2(16) Yes
PREMIUM NUMBER(10,2) Yes JSON_VALUE("DETAILS" FORMAT JSON , '$.policy.premium' RETURNING NUMBER(10,2) NULL ON ERROR)
Where,
DETAILS - JSON Document
PREMIUM - column is virtual column.
If i select virtual column with order by clause, query execution is taking too much time to run a select query.
The below query is taking 32.23secs. PREMIUM is the virtual column here
select id,tx_status,updated_date,tx_user, PREMIUM from J_MARINE_CERT j order by j.UPDATED_DATE desc
After removing PREMIUM, it is taking 0.009secs.
select id,tx_status,updated_date,tx_user from J_MARINE_CERT j order by j.UPDATED_DATE desc
Even after indexing PREMIUM, updated_date it is taking same amount of time(32.23) to execute.
I had the same issue and the only good solution was creating a Materialized View for values from json.
CREATE MATERIALIZED VIEW mv_for_query_rewrite
BUILD IMMEDIATE
REFRESH FAST ON STATEMENT WITH PRIMARY KEY
AS SELECT tbl.id, jt.*
FROM jour_table tbl,
json_table(tbl.json_document, '$' ERROR ON ERROR NULL ON EMPTY
COLUMNS (
some_number NUMBER PATH '$.PONumber',
userid VARCHAR2(10) PATH '$.User'
)) jt;
Reason for performance drop is that Oracle takes whole json in memory to select one value from it.
From Oracle documentation
Related
I am trying to partition an existing table in Oracle 12C R1 using below SQL statement.
ALTER TABLE TABLE_NAME MODIFY
PARTITION BY RANGE (DATE_COLUMN_NAME)
INTERVAL (NUMTOYMINTERVAL(1,'MONTH'))
(
PARTITION part_01 VALUES LESS THAN (TO_DATE('01-SEP-2017', 'DD-MON-RRRR'))
) ONLINE;
Getting error:
Error report -
SQL Error: ORA-14006: invalid partition name
14006. 00000 - "invalid partition name"
*Cause: a partition name of the form <identifier> is
expected but not present.
*Action: enter an appropriate partition name.
Partition needs to be done on the basis of data datatype column with the interval of one month.
Min value of Date time column in the Table is 01-SEP-2017.
You can't partition an existing table like that. That statement is modifying the partition that hasn't been created yet. I don't know the automatic way to do this operation and I am not sure that you can do it.
Although I have done this thing many times but with manual steps. Do the following if you can't find an automated solution:
Create a partitioned table named table_name_part with your clauses and all your preferences.
Insert into this partitioned table all rows from original table. Pay attention to compression. If you have some compression on table (Basic or HCC) you have to use + APPEND hint.
Create on partitioned table your constrains and indexes from the original table.
Rename the tables and drop the original table. Do not drop it until you make some counts on them.
I saw that your table has the option to auto-create partition if it does not exists. (NUMTOYMINTERVAL(1,'MONTH')) So you have to create your table with first partition only. I assume that you have here a lot of read-only data, so you won't have any problem with consistency instead of last month. Probably there is some read-write data so there you have to be more careful with the moment when you want to insert data in new table and switch tables.
Hope to help you. As far as I know there might be a package named DBMS_REDEFINITION that can help you with an automated version of my steps. If you need more details or need some help on my method, please don't hesitate.
UPDATE:
From Oracle 12c R2 you can convert a table from an unpartitioned to a partitioned one with your method. Find a link below. Now this is a challenge for me and I am trying to convert, but I think there is no way to make this conversion online in 12c R1.
In previous releases you could partition a non-partitioned table using
EXCHANGE PARTITION or DBMS_REDEFINITION in an "almost online" manner,
but both methods require multiple steps. Oracle Database 12c Release 2
makes it easier than ever to convert a non-partitioned table to a
partitioned table, requiring only a single command and no downtime.
https://oracle-base.com/articles/12c/online-conversion-of-a-non-partitioned-table-to-a-partitioned-table-12cr2
Solution
I found a solution for you. Here you will have all of my steps that I run to convert table online. :)
1. Create regular table and populate it.
CREATE TABLE SCOTT.tab_unpartitioned
(
id NUMBER,
description VARCHAR2 ( 50 ),
created_date DATE
);
INSERT INTO tab_unpartitioned
SELECT LEVEL,
'Description for ' || LEVEL,
ADD_MONTHS ( TO_DATE ( '01-JAN-2017', 'DD-MON-YYYY' ),
-TRUNC ( DBMS_RANDOM.VALUE ( 1, 4 ) - 1 ) * 12 )
FROM DUAL
CONNECT BY LEVEL <= 10000;
COMMIT;
2. Create partitioned table with same structure.
--If you are on 11g create table with CREATE TABLE command but with different name. ex: tab_partitioned
CREATE TABLE SCOTT.tab_partitioned
(
id NUMBER,
description VARCHAR2 ( 50 ),
created_date DATE
)
PARTITION BY RANGE (created_date)
INTERVAL( NUMTOYMINTERVAL(1,'YEAR'))
(PARTITION part_2015 VALUES LESS THAN (TO_DATE ( '01-JAN-2016', 'DD-MON-YYYY' )),
PARTITION part_2016 VALUES LESS THAN (TO_DATE ( '01-JAN-2017', 'DD-MON-YYYY' )),
PARTITION part_2017 VALUES LESS THAN (TO_DATE ( '01-JAN-2018', 'DD-MON-YYYY' )));
--this is an alter command that works only in 12c.
ALTER TABLE tab_partitioned
MODIFY
PARTITION BY RANGE (created_date)
(PARTITION part_2015 VALUES LESS THAN (TO_DATE ( '01-JAN-2016', 'DD-MON-YYYY' )),
PARTITION part_2016 VALUES LESS THAN (TO_DATE ( '01-JAN-2017', 'DD-MON-YYYY' )),
PARTITION part_2017 VALUES LESS THAN (TO_DATE ( '01-JAN-2018', 'DD-MON-YYYY' )));
3. Check if the table can be converted. This procedure should run without any error.
Prerequisites: table should have an UNIQUE INDEX and a Primary Key constraint.
EXEC DBMS_REDEFINITION.CAN_REDEF_TABLE('SCOTT','TAB_UNPARTITIONED');
4. Run the following steps like I have done.
EXEC DBMS_REDEFINITION.START_REDEF_TABLE('SCOTT','TAB_UNPARTITIONED','TAB_PARTITIONED');
var num_errors varchar2(2000);
EXEC DBMS_REDEFINITION.COPY_TABLE_DEPENDENTS('SCOTT','TAB_UNPARTITIONED','TAB_PARTITIONED', 1,TRUE,TRUE,TRUE,FALSE,:NUM_ERRORS,FALSE);
SQL> PRINT NUM_ERRORS -- Should return 0
EXEC DBMS_REDEFINITION.SYNC_INTERIM_TABLE('SCOTT','TAB_UNPARTITIONED','TAB_PARTITIONED');
EXEC DBMS_REDEFINITION.FINISH_REDEF_TABLE('SCOTT','TAB_UNPARTITIONED','TAB_PARTITIONED');
At the end of the script you will see that the original table is partitioned.
Try Oracle Live SQL I used to use Oracle 11g EE and got the same error message. So I tried Oracle live SQL and it perfectly worked. It has very simple and easy to understand interface,
For example, I'm creating a sales table and inserting some dummy data and partition it using range partitioning method,
CREATE TABLE sales
(product VARCHAR(300),
country VARCHAR(100),
sales_year DATE);
INSERT INTO sales (product, country, sales_year )
VALUES ('Computer','Kazakhstan',TO_DATE('01/02/2018','DD/MM/YYYY'));
INSERT INTO sales (product, country, sales_year )
VALUES ('Mobile Phone','China',TO_DATE('23/12/2019','DD/MM/YYYY'));
INSERT INTO sales (product, country, sales_year )
VALUES ('Camara','USA',TO_DATE('20/11/2020','DD/MM/YYYY'));
INSERT INTO sales (product, country, sales_year )
VALUES ('Watch','Bangladesh',TO_DATE('19/03/2020','DD/MM/YYYY'));
INSERT INTO sales (product, country, sales_year )
VALUES ('Cake','Sri Lanka',TO_DATE('13/04/2021','DD/MM/YYYY'));
ALTER TABLE sales MODIFY
PARTITION BY RANGE(sales_year)
INTERVAL(INTERVAL '1' YEAR)
(
PARTITION sales_2018 VALUES LESS THAN(TO_DATE('01/01/2019','DD/MM/YYYY')),
PARTITION sales_2019 VALUES LESS THAN(TO_DATE('01/01/2020','DD/MM/YYYY')),
PARTITION sales_2020 VALUES LESS THAN(TO_DATE('01/01/2021','DD/MM/YYYY')),
PARTITION sales_2021 VALUES LESS THAN(TO_DATE('01/01/2022','DD/MM/YYYY'))
)ONLINE;
Finally, I can write SELECT query for partitions to confirm that the partitions are created successfully.
SELECT *
FROM sales PARTITION (sales_2020);
And it gives the expected output,
I have a table named masterregistry and it contains all the info and business logic in it and the data type of the colum is clob
desc master_registy:
id number not null,
name varchar2(100),
value clob
select value from master_registry where name='REG_DATE';
o/p
11-10-17
This date is common across all the business logic, I need to query my tables which has ,
desc get_employee
====================
id number not null,
first_name varchar2(100),
last_name varchar2(100),
last_mod_dt timestamp
Now I need to get all the values from the get_employee whose last_mod_dt should be greater than the value of master_registry where name='REG_DATE'.The value in the latter table is clob data, how to fetch and compare the date of a clob data against the timestamp from another table. Please help.
Maybe you need something like this.
SELECT *
FROM get_employee e
WHERE last_mod_dt > (SELECT TO_TIMESTAMP (TO_CHAR (VALUE), 'DD-MM-YY')
FROM master_registy m
WHERE m.id = e.id);
DEMO
Note that i have used the column value directly in TO_CHAR. You may have to use TRIM,SUBSTR or whatever required to get ONLY the date component.
Need help query performance.
I have a table A joining to a view and it is taking 7 seconds to get the results. But when i do select query on view i get the results in 1 seconds.
I have created the indexes on the table A. But there is no improvements in the query.
SELECT
ITEM_ID, BARCODE, CONTENT_TYPE_CODE, DEPARTMENT, DESCRIPTION, ITEM_NUMBER, FROM_DATE,
TO_DATE, CONTACT_NAME, FILE_LOCATION, FILE_LOCATION_UPPER, SOURCE_LOCATION,
DESTRUCTION_DATE, SOURCE, LABEL_NAME, ARTIST_NAME, TITLE, SELECTION_NUM, REP_IDENTIFIER,
CHECKED_OUT
FROM View B,
table A
where B.item_id=A.itemid
and status='VALID'
AND session_id IN ('naveen13122016095800')
ORDER BY item_id,barcode;
CREATE TABLE A
(
ITEMID NUMBER,
USER_NAME VARCHAR2(25 BYTE),
CREATE_DATE DATE,
SESSION_ID VARCHAR2(240 BYTE),
STATUS VARCHAR2(20 BYTE)
)
CREATE UNIQUE INDEX A_IDX1 ON A(ITEMID);
CREATE INDEX A_IDX2 ON A(SESSION_ID);
CREATE INDEX A_IDX3 ON A(STATUS);'
So querying the view joined to a table is slower than querying the view alone? This is not surprising, is it?
Anyway, it doesn't make much sense to create separate indexes on the fields. The DBMS will pick one index (if any) to access the table. You can try a composed index:
CREATE UNIQUE INDEX A_IDX4 ON A(status, session_id, itemid);
But the DBMS will still only use this index when it sees an advantage in this over simply reading the full table. That means, if the DBMS expects to have to read a big amount of records anyway, it won't indirectly access them via the index.
At last two remarks concerning your query:
Don't use those out-dated comma-separated joins. They are less readable and more prone to errors than explicit ANSI joins (FROM View B JOIN table A ON B.item_id = A.itemid).
Use qualifiers for all columns when working with more than one table or view in your query (and A.status='VALID' ...).
UPDATE: I see now, that you are not selecting any columns from the table, so why join it at all? It seems you are merely looking up whether a record exists in the table, so use EXISTS or IN accordingly. (This may not make it faster, but a lot more readable at least.)
SELECT
ITEM_ID, BARCODE, CONTENT_TYPE_CODE, DEPARTMENT, DESCRIPTION, ITEM_NUMBER, FROM_DATE,
TO_DATE, CONTACT_NAME, FILE_LOCATION, FILE_LOCATION_UPPER, SOURCE_LOCATION,
DESTRUCTION_DATE, SOURCE, LABEL_NAME, ARTIST_NAME, TITLE, SELECTION_NUM, REP_IDENTIFIER,
CHECKED_OUT
FROM View
WHERE itemid IN
(
SELECT itemid
FROM A
WHERE status = 'VALID'
AND session_id IN ('naveen13122016095800')
)
ORDER BY item_id, barcode;
Table creation query:
create table students(
student_no number,
student_name varchar2(20),
student_addres varchar2(25),
student_dob date
joining_time date
)
Insert query:
insert into students
values (1,'ram','chittoor',to_date('02/04/2012','dd/mm/yyyy'),to_date('01:21:45','hh:mi:ss))
result:1 row inserted
Query to check insert:
select * from students
Result:
student_no student_name student_address student_dob joining_date
.......... ............ ............... ........... ............
1 ram chittoor 2-apr-2012 1-jul-2012
Qhy are the time values not getting inserted properly?
Your date is inserted properly, the tool you're using just seems to show the date without the time potion, check your tool settings;
Oracle has no support for Time only format, only date and time. Here is an excerpt from Oracle type documentation:
In a time-only entry, the date portion defaults to the first day of
the current month
Which is the case, you you get 1-July.
Based on this info, you'll need to rethink your queries.
Here is working example
If you want to get the Time from joining_time column then your,
Select query should be
SELECT student_no,
student_name,
student_addres,
student_dob,
TO_CHAR (joining_time, 'hh:mi:ss') AS joining_time
FROM students
I am trying to use the "Create Table As Select" feature from Oracle to do a fast update. The problem I am seeing is that the "Null" field is not being preserved.
I defined the following table:
create table mytable(
accountname varchar2(40) not null,
username varchar2(40)
);
When I do a raw CTAS, the NOT NULL on account is preserved:
create table ctamytable as select * from mytable;
describe ctamytable;
Name Null Type
----------- -------- ------------
ACCOUNTNAME NOT NULL VARCHAR2(40)
USERNAME VARCHAR2(40)
However, when I do a replace on accountname, the NOT NULL is not preserved.
create table ctamytable as
select replace(accountname, 'foo', 'foo2') accountname,
username
from mytable;
describe ctamytable;
Name Null Type
----------- ---- -------------
ACCOUNTNAME VARCHAR2(160)
USERNAME VARCHAR2(40)
Notice that the accountname field no longer has a null, and the varchar2 field went from 40 to 160 characters. Has anyone seen this before?
This is because you are no longer selecting ACCOUNTNAME, which has a column definition and meta-data. Rather you are selecting a STRING, the result of the replace function, which doesn't have any meta-data. This is a different data type entirely.
A (potentially) better way that might work is to create the table using a query with the original columns, but with a WHERE clause that guarantees 0 rows.
Then you can insert in to the table normally with your actual SELECT.
By having query of 0 rows, you'll still get the column meta-data, so the table should be created, but no rows will be inserted. Make sure you make your WHERE clause something fast, like WHERE primary_key = -999999, some number you know would never exist.
Another option here is to define the columns when you call the CREATE TABLE AS SELECT. It is possible to list the column names and include constraints while excluding the data types.
An example is shown below:
create table ctamytable (
accountname not null,
username
)
as
select
replace(accountname, 'foo', 'foo2') accountname,
username
from mytable;
Be aware that although this syntax is valid, you cannot include the data type. Also, explicitly declaring all the columns somewhat defeats the purpose of using CREATE TABLE AS SELECT.