Performance Tuning Apex Applications - · PDF filePerformance Tuning Apex Applications ......

Performance Tuning Apex Applications

Doug Gault

Copyright © 2010 Sumneva - All Rights Reserved - http://sumneva.com - [email protected]

MY BACKGROUND

• Doug Gault

• [email protected]

• Using Oracle since 1988

• Versions 5.1b, 6, 7, 8, 9, 10, 11

• Focused on Web Technologies

• OWA, ‘PSP’, Web DB, HTML-DB, APEX

• Ex-Hotsos Employee of 5 years

• Product Development Director - APEX Applications

• 2004 through 2008

• Commercial Applications written in APEX

• Joined Sumner Technologies January 2009

• Co-Founded Sumneva January 2010

2


AGENDA

• Introduction - Knowledge is Power

• Coding Best Practices ... Get Started Right

• Monitoring the Performance of Your Application

• Tools Available for Diagnosis

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Introduction:Knowledge is Power

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WHEN DEALING WITH PERFORMANCE, KNOWLEDGE IS POWER...

• Know the Architecture

• Know the Intended End User

• Know the Expectations

• Know the Application’s Purpose

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Know Your Architecture

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LOGICAL ARCHITECTURE

• APEX is a metadata-based environment

• No need to write code to instantiate an APEX component

• Rather you specify options with Wizards or the Application Builder

• “Metadata-based” does not imply limitations on complexity

• APEX’s development environment is quite extensible

• Can add calls to PL/SQL almost everywhere

• Which can in turn, call other languages

• APEX is built in APEX

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LOGICAL ARCHITECTURE

• Some benefits of a metadata-based framework:

• No code is generated

• Impossible to tune

• Not extensible

• Easy to transfer from one environment to another

• Done without leaving the browser

• Application Builder masks all complexity

• User just sees screens and provides values

• You can incorporate APEX metadata in your applications

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• APEX is comprised of three schemas:

APEX SCHEMAS

APEX_PUBLIC_USER*

FLOWS_FILES

APEX_030200All APEX metadata is

stored here

Any uploaded files end up here initially

All APEX page views connect as this schema

* When the EPG is used, ANONYMOUS will be the public APEX schema

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PHYSICAL ARCHITECTURE

• Despite its simplicity, the physical architecture of APEX can be configured a number of different ways

• Simple for development & testing

• Everything on a single box

• Sophisticated for production

• Multiple HTTP Servers with a Load Balancer

• SSL & ASO for end-to-end secure transactions

• RAC at the Database tier for performance boosts

• Data Guard for fault tolerance

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APPLICATION EXPRESS ARCHITECTURE

• 9i & 10g

• Access via HTTP Server (Apache)

• MOD_PLSQL

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• 11g +

• Can replace Oracle HTTP server with Embedded PL/SQL Gateway (EPG)

• Provides Oracle database with Web Server capability

• Runs in XML-DB HTTP SERVER

• Oracle 10g XE also uses a version of EPG

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DATABASE SESSION

Oracle DatabaseOracle Forms Client Oracle Application Server

• Similar to a Phone Call

• Both parties have to invest resources to carry on a conversation

• Even if no one is talking

• Each additional conversation puts some additional strain on the host party

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APEX SESSION

Oracle Databasewith APEX

Web Browser Oracle HTTP Server

• smlr 2 a txt msg :)

• Both parties need few resources to carry on a conversation

• Regardless of whether someone is taking or not

• Each additional conversation puts little additional strain on the host party

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SESSION STATE

• APEX sessions are logically and physically distinct from underlying database sessions

• mod_plsql on the Middle Tier will connect to the database via the APEX_PUBLIC_USER

• Multiple APEX users can share the same database connection

• Thus, there is a one-to-many relationship between APEX users and database sessions

• Main reason APEX can scale as well as it does

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• Important Things to Take Away Regarding Performance

• Your code is stored as metadata (Not Pre-Compiled Objects)

• Rendered on demand (for EACH demand)

• Application session state is maintained by APEX

• Once the HTTP request is satisfied, the Oracle session is released

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Know Your Users and Their Expectations

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USERS AND EXPECTATIONS

• Your users dictate what is acceptable

• Different target audiences will have different acceptability criteria

• Users of a PUBLIC site

• Expect sub-second response time

• Will bail out early if performance is bad

• Often won’t give you a second chance

• Users of CORPORATE “Window on Data” systems

• Tend to know more about the data they are working with

• Are more forgiving of poor response time

• May have no other choice as to where they get their data

• Still have their limits!

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AND REMEMBER...

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Performance = User Experience


THE PERFORMANCE FORMULA

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R

E)( *

iNP =

P = PerformanceR = Real Response TimeE = Expected Response Timei = Importance of the Task N = Number of Times the User Must Perform the Task


Know The Intended Purpose of the Application

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INTENDED PURPOSE

• Application Type

• Transactional (Data Entry, E-Commerce, ...)

• End User Reporting (Dynamic Reports, D/W Reporting, ...)

• Administrative (User Admin, Time Sheet Systems, ...)

• Application Volume

• Number of users accessing the system

• Size of data in the database

• Volume of data being returned by the average query

• Utilization Profile

• Even usage throughout the day

• A few peak usage times

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If not...

FIND OUT!

KNOWLEDGE IS POWER

• Chances are if you’ve been involved in the development of an APEX application, you have a good understanding of these factors for your specific application.


Things you can do to help insure good performance, and make poor performance easier to diagnose.

Performance Best Practices

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FIRST OF ALL...

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IT’S PRETTY SIMPLE REALLY!

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• It all starts with the install

• Understand how APEX works

• Be Smart about how you build your applications

• Take advantage of what APEX gives you


It All Starts With The Install

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PAY ATTENTION TO THE REQUIREMENTS

• shared_pool_size >= 100MB

• Disk Space

• APEX Tablespace

• 125 MB for standard install

• 34 MB for each additional language install

• System Tablespace

• 85MB Free

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THIS BRINGS UP THE TOPIC OF TABLESPACES

• DON’T

• Install APEX into SYSAUX

• The example in the documentation is just that

• Other things use SYSAUX

• Limited Control over Sizing and Growth

• DO

• Create specific tablespaces for both APEX_XXXXXX and FLOWS_FILES

• Ability to correctly size and control growth of APEX tablespaces

• Easier for DBA to manage tablespace placement

• Lessens opportunity for contention in the SYSAUX tablespace

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* Apologies to John Scott for my blatant plagiarism.


Understand How APEX Works

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MORE KNOWLEDGE, MORE POWER

• RENDER - Presenting the page to the user

• Computations

• Processes

• Rendering the Page Items

• PROCESS - Processing the user’s input

• Computations

• Validations

• Processes

• Branching

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MULTIPLE VIEWS OF YOUR PAGE

• In the VIEW drop-down select “Events”

• Shows both Page Rendering and Page processing events

• Shows in order of execution

• Links to definition of items for direct editing

• Show All

• Shows every possible item/action even if they are not used

• Show Used

• Shows only those items/actions that are used by the page

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EVENTS VIEW IN THE PAGE BUILDER

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Be Smart About How You Build Your Applications

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MVC - SEPARATE UI FROM LOGIC

• Try not to use HTML in your SQL Queries

• Hinders re-use

• Forces you to edit SQL to change the presentation

• Potentially forces oracle to ‘Hard Parse’ when it shouldn’t

• Impacts scalability

• Instead move display logic to APEX

• Templates

• CSS

• Item Formatting

• Report Columns

• Form Items

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MOVE ANONYMOUS PL/SQL INTO THE DATABASE

• Stored code is compiles (P-Code)

• Doesn’t need to be compiled for every run

• Easier to test individually

• Easier to isolate problem code

• Enables re-use of code

• Enables use of Interactive Debugging with SQL-Developer

• Enables PL/SQL Profiling*

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* More on this later


AVOID USE OF APEX SPECIFIC VARIABLES IN STORED PL/SQL

• In any procedure that does a significant amount of work, and may become a performance bottleneck, avoid use of:

• v(‘VARIABLE’)

• :APP_USER, :APP_ID, :SESSION_ID

• Pass values into PL/SQL as parameters

• Helps with performance & security implications

• Only incur overhead of obtaining the value once

• Ability to run/test/debug PL/SQL outside of APEX

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INSTRUMENT YOUR CODE

• A large part of easy diagnosis is knowing what is going on in your code

• Where it IS slow

• Where it is NOT slow

• Many ways to implement “Instrumentation”

• DBMS_OUTPUT

• Insert into a table

• Client identifier & Module/Action

• Hotsos ILO

• Log4PLSQL

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INSTRUMENT YOUR CODE

• Instrumentation Guidelines

• Instrumentation should exist in DEV & PROD

• Must be easy to perform

• Must be light weight

• Always “on” - Shouldn’t need to re-compiled code to access

• Take advantage of built-in functionality

• Set CLIENT_IDENTIFIER & CLIENT INFO

• set MODULE & ACTION

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GATHER STATISTICS

• Your application is made up of PL/SQL & SQL

• Your application runs in the database

• The cost-based optimizer will use more accurate query plans if you have up to date statistics

• Your application’s performance will benefit

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Gather Statistics for your application schemas!


GATHER STATISTICS

• APEX is made up of PL/SQL & SQL

• APEX runs in the database

• The cost-based optimizer will use more accurate query plans if you have up to date statistics

• APEX performance will benefit

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Gather Statistics for your APEX schemas!


Take Advantage of What APEX

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USE DECLARATIVE LOGIC WHERE APPROPRIATE

• APEX gives you many places where you can code logic

• Conditional Rendering of items, regions, etc.

• Conditional Processes

• Validation Logic

• Make use of “built-in” logic where possible

• “ITEM = VALUE will be faster than PL/SQL condition “:ITEM = VALUE”

• “Is Numeric” validation will be faster than hand coded PL/SQL

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BE SMART ABOUT PAGINATION

• In a data-set of 5,000 rows

• Any pagination scheme using X to Y

• Only needs to fetch Y+1 records

• Any pagination scheme using X to Y of Z

• Must retrieve all rows to determine the value of Z

• Row Ranges X to Y (with next & previous links) is recommended for large datasets

• Also, set Maximum Row Count to 1000 or less

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BE SMART ABOUT USING PAGE ZERO

• Items on Page Zero get rendered for every page

• Even if they are not rendered the conditional logic must be executed

• Make sure you’re using Page Zero for truly global purposes

• Don’t forget to optimize Page Zero process logic

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BE SMART ABOUT PAGE AND APPLICATION PROCESSES

• Page and Application level processes can be set to run for each page or once per session

• Very important to tune PER-PAGE-VIEW processes

• Page level processes effect performance of only their page

• Application level processes potentially effect performance for every page

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BE SMART ABOUT PAGE & REGION

• Page and Region Caching

• Exist in 3.0+

• NOT browser base - APEX caches the HTML rendered by the region in a cache table and serves up the Cached HTML from the table

• Developer Specifies

• whether or not to cache

• Timeout

• Condition for whether content is pulled from cache

• Pages can be cached “Per User”

• Best used for pages or regions that don’t change often.

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BE SMART ABOUT USING IMAGES

• Where to store Images:• “Template Images” belong in the Filesystem

• Images that appear on every or almost every page

• Logos, tabs, etc.

• “Transactional Images” can be stored in the database or the filesystem

• Images which are part of a row of data

• For Example: Image of a Product

• File System based images used on every page will be cached by the browser, making for less queries executed per page view

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Monitoring the Performance of Your

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MONITORING PERFORMANCE

• Don’t wait for users to call and tell you it’s slow

• Make it part of your daily routine to review the facts

• Remember

• Users dictate what constitutes “acceptable”

• Know your target audience

• Know your application’s purpose

• Help your users understand when their expectations aren’t realistic

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MONITORING PERFORMANCE

• In APEX

• In SQL-DEVELOPER

• Using Firefox & FireBug

• Actually better suited to diagnosis than monitoring

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IN APEX - APEX REPORTS

• Home > Administration > Monitor Activity

• Many different & interesting reports

• 4 most significant in terms of performance

• Recent Page Views

• Pave Views by Application

• Application Errors

• By Weighted Page Performance *

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* Probably the most important

D E M O N S T R A T I O N


APEX Performance Reports

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SQL-DEVELOPER REPORTS

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• Many built-in reports

• Applications

• Pages

• Schemas

• Workspaces

• Applications

• Access Log

• Activity Log

• Activity Summary

• User Summary

• Schema

• Files


SQL-DEVELOPER REPORTS

• Only work with APEX 3.0+

• Only “Activity Log” really gives any useful diagnostic information

• Doesn’t give weighted report like APEX reports do.

• Custom Reports to solve the problems

• Works with APEX 2+

• Versions for all versions of SQL-DEV 1.2, 1.5, 2.x +

• “Custom Reports” Now Included in SQL-DEV 2.1

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SQL-Developer Performance Reports

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Tools Available for Diagnosis

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TOOLS AVAILABLE FOR DIAGNOSIS

• Debug Mode

• #TIMING# Substitution Variable

• FireBug - Network Stats

• Isolating Page Items (Condition set to NEVER)

• &P_TRACE=YES

• MODULE & ACTION Reporting

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DEBUG MODE

• Great example of instrumented code!

• Activation

• Development Mode - Select DEBUG from Developer Toolbar

• From URL - Place ‘YES’ in DEBUG position

• f?p=App:Page:Session:Request:Debug:ClearCache:ItemNames:ItemValues

• Shows Step-by-Step execution and time accounting

• Shows Session Values as they are set/saved

• Show calling page processing as well as current page rendering

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0.00:0.00: S H O W: application="500201" page="21000" workspace="" request="" session="2200174147850707"0.00: Language derived from: FLOW_PRIMARY_LANGUAGE, current browser language: en-us0.00: alter session set nls_language="AMERICAN"0.00: alter session set nls_territory="AMERICA"0.00: NLS: CSV charset=WE8MSWIN12520.00: ...NLS: Set Decimal separator="."0.00: ...NLS: Set NLS Group separator=","0.00: ...NLS: Set date format="DD-MON-RR"0.00: ...Setting session time_zone to dbtimezone0.00: NLS: Language=en-us0.00: Application 500201, Authentication: CUSTOM2, Page Template: 469305264493658500.01: ...Supplied session ID can be used0.01: ...Application session: 2200174147850707, user=ADMIN0.01: Session: Fetch session header information0.01: ...Metadata: Fetch page attributes for application 500201, page 21000…


DEBUG MODE

• You can issue DEBUG information too

• Using the v(‘DEBUG’) = ‘YES’ function

• Most often used in a condition to hide/display debug regions

• Can be used in PL/SQL for conditional debug logic

• Using wwv_flow.debug(‘Foo’) procedure

• Programmer doesn’t have to worry about when debug is “on”

• Works in PL/SQL anonymous blocks and in PL/SQL Stored Objects

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DEBUG MODE - CAUTION

• There are situations where DEBUG can lie to you

• Specifically when using AJAX

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• Example

• Single page with 4 HTML regions

• Using AJAX to “Screen Scrape” report regions from other pages

• Full Screen takes over 2 minutes to render all data

• DEBUG mode reports about 0.14 seconds

• Where did the time go?


DEBUG MODE - CAUTION

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#TIMING# SUBSTITUTION VARIABLE

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• Allows you to include CPU time in the footer of a region

• Must be in the footer

• Doesn’t work in the header


#TIMING# SUBSTITUTION VARIABLE

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FIREBUG - NET TIMINGS

• Plug-in to FireFox

• Most people use it to

• Debug JavaScript

• Troubleshoot CSS

• View generated HTML code

• NET TAB

• Shows HTTP calls the browser makes to retrieve data

• Initial HTML call (f?p...)

• Images (wwv_flow_file_mgr.get_file or /i/ )

• Javascript AJAX CALLS (wwv_flow.show)

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• CAUTION (again...)

• FireBug is not perfect either.

• It can report files took longer than they did if their “display” is gated on something that is actually slow.

• FireBug does not report calls made back to the server from within a FLASH component.

• Great walkthrough of Firebug’s NET panel

• http://www.softwareishard.com/blog/firebug/introduction-to-firebug-net-panel/


ISOLATING PAGE ITEMS

• Once you believe you have the culprit

• Adjust its conditional rendering to “NEVER”

• Rerun the page

• Validate that the page runs more quickly

• Tune the slow element

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ISOLATING PAGE ITEMS


&P_TRACE=YES

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• Add to end of URL• f?p=App:Page:Session:Request:Debug:ClearCach:ItemNames:ItemValues&P_TRACE=YES

• Allows developers to generate 10046 level trace

• Trace file goes to database’s UDUMP directory

• Full accounting of time for the SQL Session used to render the page

• Another great example of instrumented code

• Other ways of obtaining Trace Data

• alter session set events ‘10046 trace name context forever, level 12’

• dbms_support.start_trace(waits=>true, binds=>true)

• dbms_session.session_trace_enable(waits=>true, binds=>true)


WHAT TO DO WITH THE TRACE FILE

• TKPROF / SQL-DEVELOPER 1.5+ Trace Analyzer

• Looks at trace data by SQL statement

• Dubious attribution of time (Inclusive vs. Exclusive)

• Forces you into detail before giving you the overall picture

• Hotsos / Method-R Profiler

• Full Profile of where the time went

• Accounts for ALL time (including so called NULL events)

• Starts with an overview of the situation

• 3 clicks to the heart of the problem

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Trace File Analysis Tools

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PL/SQL PROFILING

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• If your logic has been moved into the database you can take advantage of PL/SQL Profiling tools

• DBMS_PROFILER

• DBMS_HPROF

• DBMS_TRACE


DBMS_PROFILER

• Available since 8.1.7

• Computes the time that your PL/SQL program spends at each line in each subprogram

• You must have CREATE privileges on the units being profiled

• Saves statistics in database tables

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set serverout on enabled

declare run_id number;begin run_id := dbms_profiler.start_profiler(comment => to_char(sysdate,'DD-MM-YYYY HH24:MI:SS')); .. call pl/sql to be profiled .. /* Clear data from memory and store it in profiler tables.*/ dbms_profiler.flush_data; dbms_profiler.stop_profiler;end;


DBMS_HPROF

• New to 11g

• Reports PL/SQL execution profile, organized by subprogram call

• Accounts for PL/SQL and SQL execution time separately

• Do NOT need CREATE privileges on the units being profiled

• Save statistics in database tables, generates HTML, .trc files

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BEGIN /* Start profiling. Write raw profiler output to file test.trc in a directorythat is mapped to directory object PLSHPROF_DIR */

DBMS_HPROF.START_PROFILING('PLSHPROF_DIR', 'test.trc');END;/-- Execute procedure to be profiledBEGIN test;END;/BEGIN -- Stop profiling DBMS_HPROF.STOP_PROFILING;END;/


DBMS_TRACE

• Available 8.1.7+

• Traces the order in which subprograms are called

• Can specify subprograms to trace and to what level

• Compile subprograms with DEBUG to enable tracing

• Saves statistics in database tables

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DBMS_TRACE.SET_PLSQL_TRACE(trace_level INTEGER);

…PL/SQL TO TRACE…

DBMS_TRACE.CLEAR_PLSQL_TRACE;


WATCHING LONG RUNNING PAGES

• APEX is instrumented to set

• MODULE = “APEX:APPLICATION AppID”

• ACTION = “PAGE PageID”

• CLIENT INFO = “User”

• CLIENT IDENTIFIER = “User:SessionID:”

• You can query against V$ tables to see long running queries

• Custom SQL-Developer Report

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V$ QUERY

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WHAT WE’VE COVERED

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• Knowlege is Power

• Coding Best Practices ... Get Started Right

• Monitoring the Performance of Your Applications

• Tools Available for Diagnosis


PERFORMANCE RELATED READING

• Chapter 14 of Pro Oracle Application Express – John Scott & Scott Spendolini

• Sizing Up Performance – Mike Hichwa

• http://www.oracle.com/technology/oramag/oracle/07-jan/o17browser.html

• Managing Oracle Application Express – Joel Kallman

• http://www.oracle.com/technology/products/database/application_express/ppt/ODTUG2007_Managing_APEX.ppt

• Designing Application for Performance and Scalability - Bjørn Engsig

• http://www.oracle.com/technology/deploy/performance/pdf/designing_applications_for_performance_and_scalability.pdf

• Hotsos Webinars: http://portal.hotsos.com/events/webinars

• Simple Strategies for Writing and Maintaining More Efficient SQL

• Oracle Code Instrumentation or How I Learned to Stop Worrying and Love Properly Scoped Trace Files

• Using Oracle's PL/SQL Profiler Tool DBMS_PROFILER

• How to tune SQL with Extended Trace Data

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