PHP Oracle Web Applications by Kuassi Mensah

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PHP Oracle Web Applications:
Best Practices and Caching Strategies
Kuassi Mensah Server Technologies Oracle
Mensah, Technologies,

Agenda

• ► PHP, the OCI8 Extension and Oracle Database
• Scaling Database Connectivity
• Database Resident Connection Pool – Solving the C20K
Problem
• Logon Storm Shield
• Scaling Database Operations
• Bind Variables, Statement Caching, Row Prefetching
• Scaling Very Complex Queries
• Scaling with Stored Procedures
• Caching Strategies
• Resultset Caching
• Continuous Query Notification and Mid-tier Cache
Invalidation
• I Memory Database Cache
In M D t b C h

© 2009 Oracle Corporation

PHP and the OCI8 Extension


Three Tier Web Model


What is OCI8?

• Main Oracle Database extension for PHP
• Open source and part of PHP
• Current version is OCI8 1.3 – in PHP 5.3 and in PECL
<?php
$c = oci_connect('un', 'pw', 'localhost/orcl');
$s = oci_parse($c, 'select * from employees');
oci_execute($s);
while (($row = oci_fetch_array($s, OCI_ASSOC)) != false)
foreach ($row as $item)
( )
print $item;
?>


Get the Latest OCI8 1.3

• php.net
• PHP 5 3 Source code Windows binaries
5.3 code,
• PECL - PHP Extension Community Library
• For updating PHP 4 - 5.2 with OCI8 1.3
• htt //
http://oss.oracle.com/projects/php
l / j t / h
• RPMs for Linux with OCI8
• Unbreakable Linux Network
• Oracle's Linux Support program
• OCI8 RPM available for PHP
• Zend Se e
e d Server
• Linux, Windows, Mac
• Support from Zend


Oracle Database 11.1 and PHP

• Oracle 11.1 was released August 2007
• Connection Pooling - DRCP
• Server (database) Query Result Cache
• Client Query Result Cache
• Query Annotation
• Continuous Query Notification
• Cube Organized Materialized Views
• Total Recall
• ...


Oracle Database 11.2 and PHP

• Oracle 11.2 was released September 2009
• Many new features building on 11gR1 innovations
• Improved views for DRCP connection pooling
• Continuous Query Notification for Views
• Client Query Result Cache
• Table Annotation
• View Annotation
• Client query result cache (CQRC) supported with DRCP
• Pre-fetching supported in more places
• Edition Based Redefinition
• RAC One Node option
• ...


Agenda

• PHP, the OCI8 Extension and Oracle Database
• ►Scaling Database Connectivity
Problem
• Scaling Strategies
Invalidation
• I Memory Database Cache
In M D t b C h


Database Resident
Connection Pool - Solving
the C20K problem


Standard OCI8 connections

$c = oci_connect($un, $pw, $db);

• High CPU Overhead
• Connection establishment slow
• Frequent connect and disconnect
• Does not scale in web environments
• One database server process per PHP user
• Maxes out database server memory
• Cannot handle the Digg effect


Persistent OCI8 Connections

$c = oci_pconnect($un, $pw, $db);

• Not closable (prior to OCI8 1.3)
• Fast for subsequent connections
• Some control configurable in php.ini
oci8.max_persistent
oci8.persistent_timeout
oci8.ping_interval


Database Resident Connection Pool
Solving the C20K Problem
Dedicated servers
Connection Connection
( DB handle) Broker

Session
Session
Session
(User Handle)
1 Session
S i
(User Handle)
(User Session
Handle)
(User Handle)
Oracle Net (User Handle)

2

• Pool of dedicated servers
• (1) Server allocated/locked on Appl Connect
Appl.
• (2) Direct server access after handoff
• (3) Server released on Appl. ConnClose .
• N man-in-the-middle, l
No i th iddl low l t
latency


DRCP: System Overview


PHP DRCP Benchmark

• See PHP DRCPC
Whitepaper
• 2GB RAM
• 1 connection broker
• 100 pooled servers


Sample Sizing for 5000 Users
Dedicated DRCP Servers
Servers (Pool of 100)

Database
Servers 5000 * 4 MB 100 * 4 MB

Session
Memory 5000 * 400 KB 100 * 400 KB

DRCP
Connection 5000 * 35 KB
Broker
Overhead

Total Memory 21 GB 610 MB


DRCP in PHP

• DRCP support is available in OCI8 1.3
• Developer decision to use it or not
• DRCP functionality available when linked with Oracle 11g
client libraries and connected to Oracle 11g
• OCI8 1.3 is included in PHP 5.3 and PHP 6
• For PHP 4.3.9 – 5.2 use PECL OCI8 1.3


Configuring and Starting the POOL
• Install PHP OCI8 1.3 and Oracle 11g
• Configure the pool (optional)
SQL
SQL> execute dbms connection pool.configure pool(
dbms_connection_pool.configure_pool(
pool_name => 'SYS_DEFAULT_CONNECTION_POOL',
minsize => 4,
maxsize => 40,
incrsize => 2,
session_cached_cursors => 20,
inactivity_timeout => 300,
max_think_time
max think time => 600
600,
max_use_session => 500000,
max_lifetime_session => 86400);
• Sart the pool:
SQL> execute dbms_connection_pool.start_pool();
• Set oci8.connection_class in php.ini
oci8.connection_class MY_PHP_APP
oci8 connection class = MY PHP APP


Using the Pool

1/ Changing the Connect String in PHP Applications
<?php
$c = oci_pconnect("phpweb", "phpweb",
"//localhost/orcl:pooled");
$s = oci_parse($c, 'select * from employees');
oci_execute($s);
oci_fetch_all($s, $res);
var_dump($res);
var dump($res);
?>

2/ Zero Code Change
Change the TNS alias in tnsnames.ora configuration file


Some DRCP recommendations.

• Read the PHP DRCP whitepaper
http://www.oracle.com/technology/tech/php/index.html
• Make sure oci8.connection_class is set
• Have > 1 Broker, but only a few
• Close connections when doing non-DB processing
• Explicitly control commits and rollbacks
• Avoid unexpectedly open transactions when an oci_close() or end-
of-scope
of scope occurs
• Scripts coded like this can use oci_close() to take advantage of
DRCP but still be portable to older versions of the OCI8 extension
• Monitor V$CPOOL STATS view to determine best pool size
V$CPOOL_STATS


Logon Storm Shield


Logon Storm Shield

• Logon Storm
• On Mid-tier Reboot
• DoS Attack
• Logon Storm Shield: Connection Rate Limiter
g
• configured in LISTENER.ORA
LISTENER=(ADDRESS_LIST=
(ADDRESS=(PROTOCOL=tcp)(HOST=sales)(PORT=1521)(RATE_LIMIT=3))
(ADDRESS=(PROTOCOL=tcp)(HOST=lmgmt)(PORT=1522)(RATE_LIMIT=no)))

• Set the Rate Limit to a value that matches your machine
capabilities.
biliti


Agenda

• Scaling Database Connectivity
Problem
• ►Scaling Database Operations
g g
Invalidation
• In Memory Database Cache

Bind Variables


Not Binding
Literals in SQL statements disable sharing

Poor use of cache


Binding Scalars


Binding Scalars

<?php
$c = oci_connect('hr', 'hrpwd', 'localhost/orcl');
$s = oci_parse($c,'insert into employees values (:bv)');
$name = ‘Mensah';
oci_bind_by_name($s, :bv
oci bind by name($s ':bv', $name);
oci_execute($s);
?>

• Associates PHP variable $name with placeholder :bv
• Similar to JDBC PreparedStmt
• No SQL Injection worry
• Easier to write than adding quote escaping


DB Statistics Without and With Binding
From a query example by Tom Kyte:
Not Binding Binding
Parse time elapsed 485 36
Parse count (hard) 5,000 1
Latches 328,496 118,614

• Overall system is more efficient
• PHP user elapsed time directly benefits


Binding Best Practices

• Set length parameter to your upper data size for re-
executed IN binds oci_bind_by_name($s, “:b”, $b, 40);
_ _ y_ ( )
• Don't bind constants
• Let the optimizer see them
• Long running unique queries may not benefit
• Parse time is a relatively small cost
• CURSOR_SHARING parameter
• S in “
Set “session” or database init.ora
• Makes every statement appear to have bound data, but
optimizer now doesn't see constants
• For bind-unfriendly applications
bind unfriendly
• Oracle 11g has Adaptive Cursor Sharing
• Can have multiple execution plans for same statement


Statement Caching


Client (aka PHP) Statement Caching

Less traffic and DB CPU


OCI8 Uses the Statement Cache.

• No PHP code change needed
• Oracle Client library cache of statement text & meta data
• On by default in php.ini
oci8.statement_cache_size
oci8 statement cache size = 20
Unit is number of statements
• Set it big enough for working set of statements
• Reduces network traffic and context switches
ff
• Moves cache management load from DB to PHP side
• Uses memory on PHP side for cached statement handles
• Uses memory on DB for per-session cursors


Row Prefetching


Prefetching Reduces Roundtrips
• Temporary buffer cache for query duration

No DB access
for next fetch

Reduces round trips

Prefetching Improves Query Times

Your results will vary


Prefetching is Enabled by Default

• Enabled by default
• Can tune per statement:

$s = oci_parse($c, 'select city from locations');
oci_set_prefetch($s, 200)
i t f t h($ 200);
oci_execute($s);
while (($row = oci_fetch_array($s, OCI_ASSOC)) != false)
foreach ($row as $item)
print $item;

Each database “round trip” prefetches 200 rows


PHP OCI8 Row Prefetching.

• No need to change PHP application
• Rows are cached internally by Oracle client libraries
• php.ini oci8.default_prefetch = 100 rows
• Was 10 rows in OCI8 1.2
• Oracle 11.2 supports REF CURSOR prefetching too
• Tuning goal:
• R d
Reduce round t i
d trips
• For big data sets: transfer reasonable chunks, not huge sets


Scaling Very Complex Queries


Scaling Very Complex SQL Queries
Problem to Solve: Query Sales and Quantity by
Year,Department, Class and Country

The SQL Query:
SELECT SUM(s.quantity) AS quantity, SUM(s.sales) AS sales,
t.calendar_year_name, p.department_name, c.class_name,
t calendar year name p department name c class name
cu.country_name
FROM times t, products p, channels c, customers cu, sales_fact s
WHERE p.item_key = s.product AND s.day_key = t.day_key AND
s.channel = c.channel_key AND
s.customer = cu.customer_key
GROUP BY p.department_name, t.calendar_year_name, c.class_name,
cu.country_name;
cu country name;


Cube Organized Materialized Views
Transparent to SQL Queries

SQL Query Materialized Views

Region
R i Date
D t

Query
Rewrite

Product Channel
Automatic OLAP Cube
Refresh

Scaling with Stored Procedures


Scaling with Stored Procedures
Java or PL/SQL

Client
Client
Any Language
Any Language
Stored Procedure Call

Multiple Unique
SQL Calls

Java or PL/SQL

Calls

SQL SQL

Up to 10 x Faster!


Agenda

• S li
Scaling D t b
Database C Connectivity
ti it
Problem
• Scaling Database OPerations
• ►Caching Strategies
• Continuous Query Notification and Mid-Tier Cache
Invalidation
• In Memory Database Cache


Resultset Caching


Oracle 11g Client & Server Result Caches

• Results of queries can be cached
• Server and client (aka PHP) have caches
• Recommended for small lookup tables
• Client cache is per-process

• Caches automatically invalidated by server data
changes

• Feature can be configured globally or per client
• DB parameter: CLIENT_RESULT_CACHE_SIZE
Per-client i sqlnet.ora: OCI RESULT CACHE MAX SIZE
P li t in l t OCI_RESULT_CACHE_MAX_SIZE
• Has a configurable 'lag' time
• If no roundtrip within defined time, cache assumed stale


Oracle 11g Client & Server Result Caches

• With Oracle 11.2 Table or View Annotation, developer
or DBA choose tables or view to be cached:
alter table last_name result_cache
create view v2 as select /*+ result cache */ col1, coln from t1
No need to change PHP application

• With Oracle 11 1 Query Annotation need to add hint
11.1 Annotation,
to queries instead:
select /*+ result_cache */ last_name from employees

• V$RESULT_CACHE_* views show cache usage


No DB Access When Client Cache Used

SQL> select parse_calls, executions, sql_text
from v$sql where sql_text like '%cjcrc%';

PARSE_CALLS
PARSE CALLS EXECUTIONS SQL TEXT SQL_TEXT
----------- ---------- -----------------------------------
2 100 select * from cjcrc
2 2 select /*+ result_cache */ * from cjcrc


Result Caching Test.
$c = oci_pconnect('hr', 'hrpwd', 'localhost/orcl');
$tbls = array('locations', 'departments', 'countries');
foreach ($tbls as $t) {
$s = oci_parse($c, "select /*+ res lt cache */ * from $t")
oci parse($c result_cache $t");
oci_execute($s, OCI_DEFAULT);
while ($row = oci_fetch_array($s, OCI_ASSOC)) {
foreach ($row as $item) {echo $item "n";}}}
$item. n ;}}}

$ siege -c 20 -t 30S http://localhost/clientcache.php

Without result cache: select * from $t
Transaction rate: 32.02 trans/sec

With result cache cache: select /*+ result cache */ * from $t
result_cache
Transaction rate: 36.79 trans/sec

Result Caching was approx. 15% better


Continuous Query Notification
and Mid Tier Cache Invalidation
Mid-Tier


Continuous Query Notification

Problem to solve:
Be notified when changes in the database invalidates
an existing query result set
2.Upon Change
( p
(DMLImpacting g
<?php the result set)
…
Callout
4.Invalidate cache
5.repopulate cache
p p
…
?>
1. Register
3.Automatic the query
Custom cache Notification
(Java or PL/SQL database job
as noificaion callback)


Example - The Cache Depends On This
Table

$ sqlplus cj/cj
create table cjtesttab (
group_id number,
name varchar2(20)
);
insert into cjtesttab values (1, 'alison');
insert into cjtesttab values (2, 'pearly');
insert into cjtesttab values (2, 'wenji');


Example - The PHP Cache-Updating
Code

<?php
// cache.php
$g = date('Y-m-d H:i:s').": Table was: ".$_GET[tabname];
file_put_contents( /tmp/cqn.txt
file put contents('/tmp/cqn txt', $g);

// In reality query the table and update the cache:
// $s = oci_parse($c, "select * from ".$_GET[tabname]);
// . . .
// $
$memcache->set('key', ...);
?>


Example - Create 'mycallback' PL/SQL
Procedure
create or replace procedure mycallback (
ntfnds in cq_notification$_descriptor) is
req utl_http.req;
resp utl_http.resp;
begin
if (ntfnds.event_type = dbms_cq_notification.event_querychange) then
f( f f )
req := utl_http.begin_request(
'http://mycomp.us.oracle.com/~cjones/cache.php&tabname='
|| ntfnds.query_desc_array(1).table_desc_array(1).table_name);
tf d d (1) t bl d (1) t bl )
resp := utl_http.get_response(req);
utl_http.end_response(resp);
end if;
end;
/


Example - Register 'mycallback' for a
Query
y
declare
reginfo cq_notification$_reg_info;
v_cursor sys_refcursor;
y ;
regid number;
begin
reginfo := cq_notification$_reg_info (
'mycallback', -- callback function
dbms_cq_notification.qos_query, -- result-set notification flag
0, 0, 0);
regid := dbms_cq_notification.new_reg_start(reginfo);
open v_cursor for select name from cjtesttab where group_id = 2;
close v_cursor;
dbms_cq_notification.reg_end;
end;
/


Example Recap

• Table cjtesttab
• PHP script http://.../cache.php to update the cache
• PL/SQL callback procedure mycallback()
• Registered query
select name f
l t from cjtesttab where group_id = 2;
jt tt b h id 2
• Aim: refresh mid-tier cache when this query results change


Example - In Action

• Let's update the table:
update cjtesttab set name = 'c' where group_id = 2;
p j g p_ ;
commit;
• Output in /tmp/cqn.txt is:
2009-09-23
2009 09 23 13:11:39: Table was: CJ.CJTESTTAB
CJ CJTESTTAB
• Update a different group_id:
update cjtesttab set name = 'x' where group_id = 1;
commit;
• No change notification is generated


The following is intended to outline our general
product direction. It is intended for information
purposes only, and may not be incorporated into any
contract. It is not a commitment to deliver any
t t i t it t t d li
material, code, or functionality, and should not be
relied upon in making purchasing decisions.
The development, release, and timing of any
features or functionality described for Oracle’s
products remain at the sole discretion of Oracle.


Challenges with Current Caching
Mechanisms
• Cache Currency
• Content can get stale over time – invalidate or refresh cache
• R d O l vs. Updatable C h
Read-Only U d bl Cache
• Updates require synchronization with Oracle database
• Query Capability
y p y
• Persistence in the Application Tier
• Availability
• Should access to data be available if back end database is not
back-end
available?
• Significant Development effort


Oracle Database and PHP Roadmap

• PHP OCI8 integration with
g
• TimesTen In Memory Database
• A fast in memory, persistent DB
• TimesTen In Memory Database Cache
• Cache for Oracle Database
• No need for separate caching logic


Extra Slides and Free Stuff


DBMS_XA: Transactions Across Requests
• Oracle 11gR1 Feature
• Can we use it on the web? Upgrading thick client applications?
• E
Example f
l from htt //ti
http://tinyurl.com/dbmsxaex
l /db
HTTP Request #1:
rc := DBMS_XA.XA_START(DBMS_XA_XID(123), DBMS_XA.TMNOFLAGS);
UPDATE employees SET salary=salary*1.1 WHERE employee_id = 100
l l l *1 1 l id 100;
rc := DBMS_XA.XA_END(DBMS_XA_XID(123), DBMS_XA.TMSUSPEND);

HTTP Request #2:
rc := DBMS_XA.XA_START(DBMS_XA_XID(123), DBMS_XA.TMRESUME);
SELECT salary INTO s FROM employees WHERE employee_id = 100;
rc := DBMS_XA.XA_END(DBMS_XA_XID(123), DBMS_XA.TMSUCCESS);
_ _ ( _ _ ( ) _ )

HTTP Request #3:
rc := DBMS_XA.XA_COMMIT(DBMS_XA_XID(123), TRUE);


Hey Look! Free Stuff

• Oracle Instant Client
• Easy to install
• Client libraries for C, C++, Java, .Net access to a remote DB
• Oracle Database Express Edition (aka “XE”) XE )
• Same code base as full database
• Windows & Linux 32 bit
• SQL Developer
• Thick client SQL and PL/SQL development tool
• Connects to MySQL too
• Application Express ( Apex )
(“Apex”)
• Web based Application Development tool
• Try it at http://apex.oracle.com/


Some PHP & Oracle Books


Oracle Resources

• Free Oracle Techology Network (OTN)
PHP Developer Center: otn.oracle.com/php
• Free book: Underground PHP and Oracle Manual
• Whitepapers, Articles, FAQs, links to blogs, JDeveloper
PHP Extension, PHP RPMs
• Information
kuassi.mensah@oracle.com
db360.blogspot.com
christopher.jones@oracle.com
blogs.oracle.com/opal
• SQL and PL/SQL Questions
asktom.oracle.com
• ISVs and hardware vendors
oraclepartnernetwork.oracle.com
oraclepartnernetwork oracle com


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