Write Less (code) With More (Oracle Database 12c New Features)

Write Less
Code
With More
Oracle 12c New Features
Oren Nakdimon
www.db-oriented.com
 oren@db-oriented.com
 +972-54-4393763
@DBoriented
© Oren Nakdimon

This presentation is available in http://db-oriented.com/presentations
©OrenNakdimon
WHO AM I?
A CHRONOLOGY BY “ORACLE YEARS”
Where: IAF
When: Oracle 6/7 [1991-1997]
What: Developer
Where: Golden Screens
When: Oracle 8 [1997-1998]
What: Server Group Manager
Where: TELEknowledge
When: Oracle 8i/9i [1998-2003]
What: DBA Group Manager
Where: Olista
When: Oracle 10g/11g [2004-2011]
What: VP R&D + Israel Site Manager
Where:
When: Oracle 11g/12c [2011-]
What: Freelance Consultant
Where:
When: 2015-
What: Database Expert
“An expert is a person who has made all the
mistakes that can be made in a very narrow
field” (Niels Bohr, 1885-1962)

©OrenNakdimon
@DBORIENTED

©OrenNakdimon
HTTP://DB-ORIENTED.COM

©OrenNakdimon
Read a summary of this
presentation in the
article in
Oracle Scene Issue 58
MORE “WRITE LESS WITH MORE”
Download this presentation from
db-oriented.com/presentations
Read the blog post series
db-oriented.com/category/writelesswithmore/

©OrenNakdimon
AGENDA
 Go over some common use cases
 For each one
 A pre-12c solution
 A 12c solution, that allows us to write less
 We’ll see examples for features that allow writing less…
 …configuration
 …application code
 …code in SQL statements
 …“inappropriately-located” code
6

©OrenNakdimon
THE USUAL WARNING
 Before you decide to apply any of the presented
features in production, make sure:
 to thoroughly test them for your applications and
environments
 that you have the required license to use them

©OrenNakdimon
MEET THE DEMO TABLES
8

9
1. Fill the PEOPLE table from a
text file
2. Set a unique number to
ASSIGNMENT_ID (implicitly)
for every new record
3. Delete obsolete projects (but keep
their assignment history)
4. Add a “validity period” to
PROJECT_ASSIGNMENTS
5. Write a query to get project
assignments with pagination
1/2
2/2
©OrenNakdimon

©OrenNakdimon
LOADING DATA FROM FILES
 Before 12c
 SQL*Loader
 Requires a control file
 External tables
 Require a “control file” within the CREATE TABLE
statement
 Then:
INSERT INTO <“real” table> …
SELECT FROM <external table>… ;
10

©OrenNakdimon
SQL*LOADER EXPRESS MODE
 No need to create a control file
 Defaults
 File name: <tableName>.dat, in current directory
 Record delimiter: newline
 Field delimiter: comma
 No enclosures
11
12c
@ldr

©OrenNakdimon
 Mandatory command line parameter
 TABLE
 Some optional command line parameters
 DATA (up to 6 names, wildcards supported)
 TERMINATED_BY
 CHARACTERSET
 CSV = WITH_EMBEDDED
 OPTIONALLY_ENCLOSED_BY
 DATE_FORMAT
 DEGREE_OF_PARALLELISM
 DIRECT 12
12c

©OrenNakdimon
 A log file is generated for future use, including:
 Control file
 CREATE EXTERNAL TABLE statement
 INSERT statement
 Data types of all table columns should be
numeric, string or datetime
13
12c

14
text file
PROJECT_ASSIGNMENTS
1/2
2/2
©OrenNakdimon

©OrenNakdimon
AUTO-INCREMENT COLUMNS
 Before 12c
 A sequence + a BEFORE INSERT trigger
15
CREATE SEQUENCE project_assignments_seq;
--
-- first option: ignore the input even if supplied
--
CREATE TRIGGER project_assignments_bir_tr
BEFORE INSERT ON project_assignments
FOR EACH ROW
BEGIN
:new.assignment_id := project_assignments_seq.nextval;
END;

©OrenNakdimon
AUTO-INCREMENT COLUMNS
 Before 12c
 A sequence + a BEFORE INSERT trigger
16
CREATE SEQUENCE project_assignments_seq;
--
-- second option: only if input not supplied
--
CREATE TRIGGER project_assignments_bir_tr
BEFORE INSERT ON project_assignments
FOR EACH ROW
WHEN (new.assignment_id IS NULL)
BEGIN
:new.assignment_id := project_assignments_seq.nextval;
END;

©OrenNakdimon
IDENTITY COLUMNS
 A column can be defined as “identity”
 Implicit sequence
 Implicit NOT NULL
 GENERATED…
 [always] as identity
 by default as identity
 by default on null as identity
 You need the CREATE SEQUENCE privilege
17
@idn1
12c

©OrenNakdimon
IDENTITY COLUMNS
 Configuring the implicit sequence
 Like in CREATE SEQUENCE
 START WITH LIMIT VALUE
 Restrictions
 Only for numeric data types
 Maximum one identity column per table
 Non-identity column cannot be modified to identity
column
 CTAS ignores the identity definition
18
@idn2
12c

19
text file
PROJECT_ASSIGNMENTS
1/2
2/2
©OrenNakdimon

©OrenNakdimon
LOGICAL DELETION OF RECORDS
20

©OrenNakdimon
LOGICAL DELETION OF RECORDS
 Before 12c
 Add an IS_DELETED column
 Use a view to hide “deleted” records
21
ALTER TABLE projects ADD
is_deleted NUMBER(1) DEFAULT 0 NOT NULL
CHECK (is_deleted IN (0,1));
CREATE VIEW projects AS
SELECT *
FROM all_projects
WHERE is_deleted=0;
RENAME projects TO all_projects;

©OrenNakdimon
In-Database Archiving
 Enables to archive rows within a table by
marking them as “inactive”
 Inactive rows are still there, but are not visible
to the application (or visible, when we want)
22
@idar
12c

©OrenNakdimon
In-Database Archiving
 The table should be defined as ROW ARCHIVAL
 A hidden column is created:
ORA_ARCHIVE_STATE
 The session level parameter ROW ARCHIVAL
VISIBILITY controls if archived rows are visible
(ALL) or not (ACTIVE)
23
12c

24
text file
PROJECT_ASSIGNMENTS
1/2
2/2
©OrenNakdimon

©OrenNakdimon
VALIDITY PERIODS
 Before 12c
 Add PERIOD_START and PERIOD_END columns
 Add conditions to queries to filter only valid periods
25

©OrenNakdimon
TEMPORAL VALIDITY
 Enables to track time periods for real world
validity or effectivity
 Valid times can be set by users/application for
data
 Data can be selected by a specific valid time (or
range)
26
12c

©OrenNakdimon
TEMPORAL VALIDITY
 A valid time period consists of two date/time
columns (start/end)
 The columns can be created explicitly or
implicitly
 The table is defined with PERIOD FOR
27
12c
@vld

©OrenNakdimon
TEMPORAL VALIDITY
 Statement level visibility control
 SELECT … AS OF PERIOD FOR
 SELECT … VERSIONS PERIOD FOR
 Session level visibility control
 DBMS_FLASHBACK_ARCHIVE.enable_at_valid_time
 ALL
 CURRENT
 ASOF
28
12c

©OrenNakdimon
THERE ARE TWO SIDES TO EVERY COIN
 Hidden columns
 Hidden predicates
 “Hidden” =“Easy to Forget”
 “Hidden” ≠“Can be Ignored”
 And session-level control is session-level control
In Database
Archiving
Temporal
Validity
SELECT * FROM PROJECTS;
where most of the rows are “archived”
DELETE
PROJECT_ASSIGNMENTS;
where
enable_at_valid_time
is on

30
text file
PROJECT_ASSIGNMENTS
1/2
2/2
©OrenNakdimon

©OrenNakdimon
TOP-N AND PAGINATION QUERIES
 Before 12c
 Use inline views and ROWNUM or ROW_NUMBER( )
 Queries become quite cumbersome
31

©OrenNakdimon
TOP-N AND PAGINATION QUERIES
 All the records
 Top 8 records
 Records 5-8
32
SELECT project_id,
person_id,
assignment_id,
validity_period_start,
validity_period_end
FROM (
SELECT x.*
,rownum row_num
FROM (
SELECT project_id,
person_id,
assignment_id,
validity_period_start,
validity_period_end
FROM project_assignments
ORDER BY project_id, person_id
) x WHERE rownum <= 8
) WHERE row_num > 4;

©OrenNakdimon
ROW LIMITING
 The Row Limiting clause is added to the end of
SELECT statement
 FETCH FIRST n ROWS WITH TIES
 FETCH FIRST n ROWS ONLY
 FETCH FIRST p PERCENT ROWS
 OFFSET m ROWS FETCH NEXT n ROWS
33
12c
@topn

1/2
34
6. Write a procedure to update the
status of multiple projects
7. Write a query that shows the
number of assignments per
project in the last days
2/2
8. Write a query that shows all the
people with a valid date in their
GENERAL_INFO column
©OrenNakdimon

©OrenNakdimon
 Write a stored procedure that
 Gets a collection parameter of “project updates”,
each one with:
 PROJECT_ID
 UPDATE_TIME
 STATUS
 Updates the PROJECTS table with the latest status of
each project
35
PROJECT_ID STATUS
1 2
2 3
3 4
4 2
3
2
4
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2
PROJECT
ID
UPDATE
TIME STATUS
1 10:00 2
1 14:00 3
2 09:00 1
3 09:00 4
2 08:00 3
3 08:00 2
2 10:00 2

©OrenNakdimon
36
CREATE OR REPLACE PACKAGE projects_dl AS
TYPE proj_update_t IS RECORD(
project_id projects.project_id%TYPE,
update_time DATE,
status projects.status%TYPE);
TYPE proj_update_tt IS TABLE OF proj_update_t;
PROCEDURE update_status(
i_proj_update_list IN proj_update_tt
);
END projects_dl;

©OrenNakdimon
37
CREATE OR REPLACE PACKAGE BODY projects_dl AS
i_proj_update_list IN proj_update_tt) IS
BEGIN
MERGE INTO projects p
USING (
SELECT project_id,
MAX(status) keep(dense_rank LAST
ORDER BY update_time) latest_status
FROM TABLE(i_proj_update_list)
GROUP BY project_id
) i
ON (p.project_id = i.project_id)
WHEN MATCHED THEN UPDATE
SET p.status = i.latest_status;
END update_status;
END projects_dl;

©OrenNakdimon
SELECT FROM COLLECTION VARIABLES
 Before 12c
 Impossible to SELECT FROM package-level collections
38
PL/SQL: SQL Statement ignored
ORA-22905:
cannot access rows from a non-nested table item
PLS-00642:
local collection types not allowed in SQL statements

©OrenNakdimon
 Before 12c
 Schema-level collection types must be created and used,
even if needed only in the scope of a single package
39
CREATE OR REPLACE TYPE proj_update_t AS OBJECT (
project_id INTEGER,
update_time DATE,
status INTEGER)
CREATE TYPE proj_update_tt AS TABLE OF proj_update_t
CREATE OR REPLACE PACKAGE projects_dl AS
i_proj_update_list IN proj_update_tt
);
END projects_dl;

©OrenNakdimon
PROJECT
NAME
LAST DAYS TO SHOW
IN REPORTS
Project A 2
Project B 3
Project C 4
PROJECT
NAME DATE
NUM OF
ASSIGNMENTS
Project A 02/03/2016 3
Project A 03/03/2016 3
Project B 01/03/2016 5
Project B 02/03/2016 4
Project B 03/03/2016 2
Project C 29/02/2016 1
Project C 01/03/2016 0
Project C 02/03/2016 0
Project C 03/03/2016 1
@ltrl

©OrenNakdimon
LATERAL INLINE VIEWS
 An inline view in a query can be defined as
LATERAL
 It allows it to refer to other tables that appear to
its left in the FROM clause
43
12c

©OrenNakdimon
CALLING PL/SQL FROM SQL
 Before 12c
 A PL/SQL function must be stored in the database
 And it must be public (either standalone or exposed
in a package spec)
45

©OrenNakdimon
CALLING PL/SQL FROM SQL
 Before 12c
46
CREATE OR REPLACE FUNCTION is_date(i_info IN VARCHAR2)
RETURN NUMBER AS
l_date DATE;
BEGIN
IF i_info IS NULL THEN
RETURN 0;
ELSE
l_date := to_date(i_info, 'dd/mm/yyyy');
RETURN 1;
END IF;
EXCEPTION
WHEN OTHERS THEN
RETURN 0;
END;
SELECT * FROM people WHERE is_date(general_info) = 1;

©OrenNakdimon
PL/SQL in the WITH Clause
 Before 12c, the WITH clause included only
subquery factoring
 In 12c, it can include also PL/SQL declarations
 Functions, that can be used in the query
 Procedures, that can be used in the functions
 Name resolution
 statement-level function names have precedence
over schema-level stored functions
47
12c
@with

©OrenNakdimon
PL/SQL in the WITH Clause
 Not yet supported in static SQL in PL/SQL
 If used as subquery, the top-level statement
must be hinted with WITH_PLSQL (or be itself a
SELECT with PL/SQL declaration)
 Considerations for statement-level vs. schema-
level functions
 Ad-hoc vs. common functionality
 Performance
 Consider also PRAGMA UDF
48
12c

Write Less (code) With More (Oracle Database 12c New Features)

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