pl/sql tips and techniques webinar presentation

EMBARCADERO TECHNOLOGIESEMBARCADERO TECHNOLOGIES

PL/SQL Tips & Techniques

Scott Walz | Embarcadero Director of Software Consultants

Dan Hotka |Author & Instructor |Oracle Ace Director

EMBARCADERO TECHNOLOGIES

PL/SQL Tips and Techniques

• Rapid SQL– PL/SQL Templates

• Read my blogs

– PL/SQL Debugging

• Prior Webinar

– PL/SQL Profiling

• Read my blogs

• PL/SQL Tips– Oracle Overview

– Compiler Options

• Includes some useful performance Tips for Functions


Oracle Architecture

DefaultResult

Cache

(11g)

Oracle SGA

Dedicated

User

Processes

Listener

TNSNAMES.ORA

LISTENER.ORADatabase Files

Tablespaces

Database FilesDatabase Files

Buffer Pool

nK(Optional)

Keep(optional)

Recycle(Optional)

Library

Cache

Shared Pool

Dictionary

Cache

Shared

SQL

SQL

Source

Exe Plan

Call

Stack

PGA

UGA

Sess

Data

Cursor

Area

Sort

Area

Client

Result

Cache

(11g)

PL/SQL

EngineSQL Engine

SQ

L

Statem

ent

External Files

UTL File

External Tables

OCI/JDBC

URL


Oracle Architecture


PL/SQL Overview

• Procedure

– Does processing

– Returns a code that the work was successful or not

– May or may not be passed values

– May or may not return values

• Functions

– Similar to Procedure EXCEPT it does return a value!


PL/SQL Overview

• Packages– Grouping related procedures and functions– Can share cursors/work areas– Code inheritance– When one module is accessed…entire package is loaded

into Oracle

• Database Triggers– Assigned to tables– Executes before or after a DML to the table


Rapid SQL Templates

• IF-THEN-ELSE– Can nest 250+ Deep

– ELSE is optional

– ELSIF is indeed misspelled!

Ctrl+ Space bar


Rapid SQL Templates

IF_ENDIF IF_ELSIF


Rapid SQL Templates


Rapid SQL Templates

• Case– Alternative to IF-THEN-ELSE

– Can nest 250+ Deep

– ELSE is optional

Case + Ctrl+ Space bar


Rapid SQL Templates

CASE


Rapid SQL Templates


PL/SQL Profiling

• Profiler

– How long each routine took to execute

– How long each line of code took to execute

– RapidSQL has a nice interface• Easy to use

• Highlights performance issues

– Dan will demonstrate how it works…


Rapid SQL Profiler


PL/SQL Debugging

• Debugger:

– Oracle symbolic debugger

– Changing variable content on the fly

– Setting code breakpoints

– Stepping through code dependencies

Demo


Stored Programs Syntax

• Procedures– Optional parameters

• NOCOPY makes reference to original parameter

• Useful when passing collections

– AUTHID is Definer unless specified!

– Autonomous Transaction• Allows for DML no matter

how current transaction ends

– Accessible by (list)• Oracle12 New Feature

• Only executable by this list of routines

Create [or replace] Procedure[ (parameter IN OUT IN OUT …) [NOCOPY] ][AUTHID {DEFINER | CURRENT_USER } ][ACCESSIBLE BY (<list>)]{IS | AS}[PRAGMA AUTONOMOUS_TRANSACTION;][ local variables]BEGIN<logic flow code>[EXCEPTION]<exception code processing.END [procedure name];



• Functions– Optional parameters– Allows for Parallel DML– DETERMINISTIC

• Allows for the previous result to be used rather than rerunning the function when using the same parameters

– Accessible by (list)• Oracle12 New Feature• Only executable by this

list of routines

Create [or replace] Function[ (parameter …) ]RETURN <datatype>[AUTHID {DEFINER | CURRENT_USER } ][PARALLEL_ENABLE][ACCESSIBLE BY (<list>)][DETERMINISTIC][RESULT_CACHE] - 11g {IS | AS}[PRAGMA AUTONOMOUS_TRANSACTION;][ local variables]BEGIN<logic flow code>Must have a RETURN clause[EXCEPTION]<exception code processing.END [function name];



Functions called from SQL CANNOT:• Commit or rollback

• Update the database

• Update same table as DML SQL


Oracle 11g Query Result Cache• IF same function called with same in_vars

• SQL with /*+ RESULT_CACHE */ hint

• Function with RESULT CACHE syntax

– RELIES_ON (table1, table2, …) – optional table DML check• Depreciated in Oracle11r2

• First result cache returned instead of rerunning the function/SQL!

• Results stored in the SGA (Result Cache Memory)

• Any session running the function/SQL can benefit!

– * Enterprise Edition of Oracle

• Good for any table that is queried more than it is updated

– Result Cache is flushed with an update


11g Query Result Cache

• Query Result Cache Sizing and Monitoring– Sizing via Init.Ora settings:

• RESULT_CACHE_MAX_SIZE– 0 disables it– Size in bytes in increments of 32K [num

G | M | K ] – Initially defaults to 10% Shared Pool Size

• RESULT_CACHE_MAX_RESULT– 0 – 100 – Percentage of

RESULT_CACHE_MAX_SIZE single result can take

– Dynamic performance views:• V$RESULT_CACHE_STATISTICS• V$RESULT_CACHE_MEMORY• V$RESULT_CACHE_OBJECTS• V$RESULT_CACHE_DEPENDENCY


Oracle 11g Query Result CacheBe careful out there!

– Make sure the SQL inside the function does not have other dependencies• Such as a SYSDATE or some other variable NOT passed in as an in

variable

• Can probably fix about ANY problem by putting the dependencies as in variables!


New PL/SQL FeaturesOracle12 allows for Granting Roles to PL/SQL Programs

– A major problem in the past is a called program accesses a table…the connected user needed permissions to both the program and the underlying table

– Oracle12 allows for permissions to be granted to just the package/procedure/function so the users cannot directly access the underlying tables!

Oracle Database 12c New Features pg 246-248


Questions

23


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