Os Treat

An Introduction to pl/php

by Robert Treat
http://www.brighterlamp.org/

What is pl/php
aka PL/PHP, Pl/PHP, pl/PHP
●

Database procedural language based on
●

PHP

Allows you to program inside the database
●

using PHP

Let's see an example eh?
CREATE OR REPLACE FUNCTION hello_world()
RETURNS text
LANGUAGE plphp
AS $$
$var = quot;howdy yallquot;;
RETURN $var;
$$;

RETURNS text
LANGUAGE plphp
AS $$
RETURN $var;
$$;
pagila=# select hello_world();
hello_world
----------------
howdy yall
(1 row)

RETURNS text
LANGUAGE plphp
AS $$
RETURN $var;
$$;
pagila=# select hello_world();
hello_world
----------------
howdy yall
(1 row)
Fancy huh?

Where does pl/php come from?
Originally developed by Command Prompt, Inc.
●

Currently maintained by Alvaro Herrera, Alexey
●

Klyukin (both work for Command Prompt)
Has gone through a number of re-writes
●

http://plphp.commandprompt.com/
●

Who uses pl/php?
We don't know... but it seems popular...
●

So why do people use pl/php?
Nicely integrates with PostgreSQL
●

close to data
–

easily access tables and whatnot
–

●

close to data
–

–

Save on network traffic
●

●

close to data
–

–

Save on network traffic
●

You can use PHP to write it!
●

Any reason to avoid it?
PostgreSQL specific
●

PostgreSQL specific (well, maybe that's really
●

a reason to use it)

PostgreSQL specific (well, maybe that's really
●

a reason to use it)
Adds dependencies to your database
●

Code is still green
●

Small user community
●

Installation
Pre-requisites:
●

PostgreSQL 8.1+
–

Installation
Pre-requisites:
●

PostgreSQL 8.1+
–

-bash-3.00$ pg_config --version

Installation
Pre-requisites:
●

PostgreSQL 8.1+
–

PostgreSQL 8.1.9

Installation
Pre-requisites:
●

PostgreSQL 8.1+
–

PostgreSQL 8.1.9

Also need php development package (yum install
–
php-devel)

Installation
Pre-requisites:
●

PostgreSQL 8.1+
–

PostgreSQL 8.1.9

–
php-devel)

[root@localhost html]# php-config --version

Installation
Pre-requisites:
●

PostgreSQL 8.1+
–

PostgreSQL 8.1.9

–
php-devel)

[root@localhost html]# php-config --version
5.1.2

Installation
Grab the latest release tarball, unpack it, configure
●

and make (simple eh?)

Installation
●

rob@ridley:~/devel/plphp$

Installation
●

rob@ridley:~/devel/plphp$ tar zxvf plphp-1.3.3.tar.gz

Installation
●

./plphp-1.3.3/
./plphp-1.3.3/sql/
<snip>
./plphp-1.3.3/plphp.c
rob@ridley:~/devel/plphp$

Installation
●

./plphp-1.3.3/
./plphp-1.3.3/sql/
<snip>
rob@ridley:~/devel/plphp$ cd plphp-1.3.3

Installation
●

./plphp-1.3.3/
./plphp-1.3.3/sql/
<snip>
rob@ridley:~/devel/plphp/plphp-1.3.3$

Installation
●

./plphp-1.3.3/
./plphp-1.3.3/sql/
<snip>
rob@ridley:~/devel/plphp/plphp-1.3.3$ ./configure

Installation
●

./plphp-1.3.3/
./plphp-1.3.3/sql/
<snip>
rob@ridley:~/devel/plphp/plphp-1.3.3$ ./configure
checking for gcc... gcc
<snip>
checking for pg_config... /usr/bin/pg_config
checking for existence of /usr/lib/postgresql/8.1/lib/pgxs/src/makefiles/pgxs.mk... yes
checking for PostgreSQL version... 8.1.9
checking for php-config... /usr/bin/php-config
checking for php_module_startup in -lphp5... no
checking for php_module_startup in -lphp4... no
configure: error: Cannot locate a proper php library

Installation – libphp5

no longer supports building against mod_php
●

most distributions don't ship static php library
●

don't be fooled!
●

rob@ridley:~$ locate libphp
●
/usr/lib/libphp5.so
/usr/lib/apache2/modules/libphp5.so

rob@ridley:~$ ls al /usr/lib/libphp5.so
lrwxrwxrwx 1 root root 35 20060826 20:43
/usr/lib/libphp5.so > /usr/lib/apache2/modules/libphp5.so

Installation – libphp5

no longer supports building against mod_php
●

most distributions don't ship static php library
●

need to build your own php libs
●

make libphp5.la install
●

configure –enable-embed –prefix=your_dir;
●

make install

Installation
configure plphp
●

./configure –with-php=/home/rob/devel/plphp/embedphp/
rob@ridley:~/devel/plphp/plphp-1.3.3$
checking for gcc... gcc
<snip>
checking for pg_config... /usr/bin/pg_config
checking for existence of /usr/lib/postgresql/8.1/lib/pgxs/src/makefiles/pgxs.mk... yes
checking for PostgreSQL version... 8.1.9
checking for php-config... /home/rob/devel/plphp/embedphp//bin/php-config
checking for php_module_startup in -lphp5... yes
configure: creating ./config.status
config.status: creating Makefile
config.status: creating config.h

Installation
sudo make install
●

rob@ridley:~/devel/plphp/plphp-1.3.3$ sudo make install
<snip>
/bin/sh /usr/lib/postgresql/8.1/lib/pgxs/src/makefiles/../../config/install-sh -c -m 755
libplphp.so.0.0 /usr/lib/postgresql/8.1/lib/plphp.so

Installing pl/php into the Database
Once .so is compiled, you need to install the
●

language into your database.

●

Should be easier than compiling
●

●

Should be easier than compiling
●

Probably won't be...
●

pagila=# INSERT INTO pg_pltemplate VALUES
pagila-# ('plphpu', 'f', 'plphp_call_handler', 'plphp_validator', '$libdir/plphp', NULL);
INSERT 0 1

Creates an entry into the shared catalogs
●

Does not mean that pl/php is installed!
●

But you can now install it into any database
●

using the “Create Language” command

pagila=#

pagila=# create language plphp;

pagila=# create language plphpu;
ERROR: could not load library quot;/usr/lib/postgresql/8.1/lib/plphp.soquot;: /usr/lib/libphp5.so:
undefined symbol: ap_loaded_modules

ERROR: could not load library quot;/usr/lib/postgresql/8.1/lib/plphp.soquot;: /usr/lib/libphp5.so:
undefined symbol: ap_loaded_modules

See? Simple...

pagila=# create language plphp;
ERROR: could not load library quot;/usr/lib/pgsql/plphp.soquot;: libphp5.so: cannot open shared
object file: No such file or directory

See? Simple...

PostgreSQL can't find the php shared library
●

We need to find libphp5.so and set
●

PostgreSQL up to find it.

[root@localhost pgsql]# locate libphp5.so
/usr/lib/httpd/modules/libphp5.so

[root@localhost pgsql]# pg_config --libdir
/usr/lib

[root@localhost pgsql]# ln -sf /usr/lib/httpd/modules/libphp5.so /usr/lib/

[root@localhost pgsql]# createlang -U postgres plphp pagila
CREATE LANGUAGE

[root@localhost pgsql]# psql -U postgres pagila
Welcome to psql 8.1.1, the PostgreSQL interactive terminal.

Type: copyright for distribution terms
h for help with SQL commands
? for help with psql commands
g or terminate with semicolon to execute query
q to quit

CREATE LANGUAGE
pagila=#

pl/php vs. pl/phpu ?
PostgreSQL offers “trusted” and “untrusted”
●

languages
Untrusted means it can access the file system
●

More flexible, more useful, likely a good
●

choice when working with any complexity
Opens small security hole; be aware.
●

pl/php basics
CREATE OR REPLACE FUNCTION iheartphp(text)
RETURNS text
LANGUAGE plphpu
STRICT
AS $$
$retval = $args[0] . ' loves PHP!';
return $retval;
$$;
CREATE FUNCTION
pagila=# SELECT iheartphp('Robert');
iheartphp
-------------------
Robert loves PHP!
(1 row)

How useful!

pl/php not so basics
Need a page to show us inventory
●

An item is in stock if we have no rows in our
●

rental table, or all rows have a return date
Normally this would be two queries
●

Making it a function will consolidate logic and
●

save round trips

CREATE OR REPLACE FUNCTION movie_in_stock(integer)
RETURNS Boolean
LANGUAGE plphpu
AS $$
$sql = quot;SELECT count(*) FROM rental WHERE inventory_id = quot;.$args[0];
$res = spi_exec($sql);
$row = spi_fetch_row($res);
if ($row['count'] == 0)
return 1;
$sql = quot;SELECT count(rental_id) FROM inventory LEFT JOIN rental USING (inventory_id)
WHERE inventory.inventory_id = quot;.$args[0].quot; AND rental.return_date IS NULLquot;;

$res = spi_exec($sql);
$row = spi_fetch_row($res);
if ($row['count'] > 0)
{
return 0 ;
}
else
{
return 1;
};
$$;

spi functions?
Internal functions for interacting with the db
●

spi_exec :: execute a query with optional limit.
–

spi_status :: return status of a previous query.
–

spi_fetch_row :: return associative array of the
–
row's results.
spi_processed :: return the number of tuples in a
–
result.
spi_rewind :: put the row cursor at the beginning
–
of the result.

PHP Functions
Most PHP functions can be used inside
●

pl/php functions
CREATE OR REPLACE FUNCTION simplefunc(text,text)
RETURNS text
LANGUAGE plphpu
AS $$
return 'Did you know '. ucwords(strrev($args[0])) .' is '. strtolower($args[1]) .' backwards?';
$$;

pagila=# select simplefunc('inside out','outside in');
simplefunc
------------------------------------------------------
Did you know Tuo Edisni is outside in backwards?
(1 row)

PHP Functions
CREATE OR REPLACE FUNCTION notsimplefunc()
RETURNS text
LANGUAGE plphpu
AS $$
$sql = quot;select version()quot;;
$c = pg_connect(quot;host=10.225.105.53 dbname=template1 user=postgresquot;);
$r = pg_query($c,$sql);
$v = pg_fetch_result($r,0,0);
return $v;
$$;

PHP Functions
pagila=# SELECT notsimplefunc();
nosimplefunc
-----------------------------------------------------------------------------------------------------------
PostgreSQL 8.1.1 on i686-redhat-linux-gnu, compiled by GCC gcc (GCC) 3.4.2 20041017
(Red Hat 3.4.2-6.fc3)
(1 row)

pagila=# SELECT version();
version
-------------------------------------------------------------------------------------------------------
PostgreSQL 8.1.1 on i686-redhat-linux-gnu, compiled by GCC gcc (GCC) 4.0.1 20050727
(Red Hat 4.0.1-5)
(1 row)

Connect to external database Does have scary implications
● ●

Normally not recommended But this kind of flexibility can be cool
● ●

PHP Functions
CREATE OR REPLACE FUNCTION wickedfunc()
RETURNS text
LANGUAGE plphpu
as $$
$c = mysql_connect(quot;10.225.105.94quot;,quot;sakilaquot;);
$v = mysql_get_server_info();

return $v;
$$;

PHP Functions
CREATE OR REPLACE FUNCTION wickedfunc()
RETURNS text
LANGUAGE plphpu
as $$
$c = mysql_connect(quot;10.225.105.94quot;,quot;sakilaquot;);
$v = mysql_get_server_info();

return $v;
$$;

pagila=# SELECT wickedfunc();
wickedfunc
--------------
5.1.9-beta
(1 row)

the PEAR example
Can use PEAR modules inside functions
●

Walk through example for validating email
●

Pagila database
●

(http://pgfoundry.org/projects/dbsamples/)
Validate package
●

(http://pear.php.net/package/Validate)

the Pear example

CREATE OR REPLACE FUNCTION valid_email(text)
RETURNS boolean
IMMUTABLE
LANGUAGE plphpu
AS $$
require_once 'Validate.php';

$validate = new Validate();

return $validate->email(quot;$args[0]quot;,array(“check_domain”=>false,”use_rfc822”=>true)) ? 1 : 0;
$$;

the Pear example
pagila=# SELECT valid_email('xzilla@users.sourceforge.net');
valid_email
--------------------

t
(1 row)
pagila=# SELECT valid_email ('Robert Treat <xzilla@ users . sf . net>');
valid_email
---------------------

t
(1 row)
pagila=# SELECT valid_email('www.brighterlamp.org');
valid_email
---------------------

f
(1 row)

the Pear example
Functions may inter-operate with any other
●

part of the database system

CREATE DOMAIN validemail AS text
NOT NULL
CHECK ( valid_email(VALUE) );

the Pear example
pagila=# ALTER TABLE customer ALTER email TYPE validemail ;
ALTER TABLE

All data must pass through our function
●

Validates all data in table
●

Validates all data inserts and updates
●

the Pear example
pagila=# INSERT INTO customer (store_id, first_name, last_name, email, address_id, active)
pagila-# VALUES (2,'pete','hache-pee','l33t@aol',40,1);
ERROR: value for domain validemail violates check constraint quot;validemail_checkquot;

No special syntax needed
●

Error messages reference function
●

We can tweak rules by modifying the function
●

pl/php triggers
pl/php functions can be used as triggers too
●

Can access new and old data in the table
●

PostgreSQL gives us access to special trigger
●

specific information

pl/php triggers
pl/php functions can be used as triggers too
●

Can access new and old data in the table
●

PostgreSQL gives us access to special trigger
●

specific information
Example: Log overdue rental returns for
●

customers automatically through functions

pl/php triggers
pagila=# d customer
Table quot;public.customerquot;
Column | Type | Modifiers
-------------+-----------------------------+----------------------------------------------------------------
customer_id | integer | not null default nextval('customer_customer_id_seq'::regclass)
store_id | smallint | not null
first_name | character varying(45) | not null
last_name | character varying(45) | not null
email | character varying(50) |
address_id | smallint | not null
activebool | boolean | not null default true
create_date | date | not null default ('now'::text)::date
last_update | timestamp without time zone | default now()
active | integer |
Indexes:
quot;customer_pkeyquot; PRIMARY KEY, btree (customer_id)
quot;idx_fk_address_idquot; btree (address_id)
quot;idx_fk_store_idquot; btree (store_id)
quot;idx_last_namequot; btree (last_name)
Foreign-key constraints:
quot;customer_address_id_fkeyquot; FOREIGN KEY (address_id) REFERENCES address(address_id) ON UPDATE CASCADE ON DELETE RESTRICT
quot;customer_store_id_fkeyquot; FOREIGN KEY (store_id) REFERENCES store(store_id) ON UPDATE CASCADE ON DELETE RESTRICT
Triggers:
last_updated BEFORE UPDATE ON customer FOR EACH ROW EXECUTE PROCEDURE last_updated()

pl/php triggers
pagila=# d rental
Table quot;public.rentalquot;
Column | Type | Modifiers
--------------+-----------------------------+------------------------------------------------------------
rental_id | integer | not null default nextval('rental_rental_id_seq'::regclass)
rental_date | timestamp without time zone | not null
inventory_id | integer | not null
customer_id | smallint | not null
return_date | timestamp without time zone |
staff_id | smallint | not null
last_update | timestamp without time zone | not null default now()
Indexes:
quot;rental_pkeyquot; PRIMARY KEY, btree (rental_id)
quot;idx_unq_rental_rental_date_inventory_id_customer_idquot; UNIQUE, btree (rental_date, inventory_id, customer_id)
quot;idx_fk_inventory_idquot; btree (inventory_id)
Foreign-key constraints:
quot;rental_customer_id_fkeyquot; FOREIGN KEY (customer_id) REFERENCES customer(customer_id) ON UPDATE CASCADE ON DELETE RESTRICT
quot;rental_inventory_id_fkeyquot; FOREIGN KEY (inventory_id) REFERENCES inventory(inventory_id) ON UPDATE CASCADE ON DELETE RESTRICT
quot;rental_staff_id_fkeyquot; FOREIGN KEY (staff_id) REFERENCES staff(staff_id) ON UPDATE CASCADE ON DELETE RESTRICT
Triggers:
last_updated BEFORE UPDATE ON rental FOR EACH ROW EXECUTE PROCEDURE last_updated()

pl/php triggers
CREATE TABLE overdue_log
(
overdue_log_id serial,
customer_id integer,
days_overdue integer
);

Each record gets a logical primary key
●

Store the customer id and the number of days
●

rental was overdue

pl/php triggers
CREATE TABLE overdue_log
(
overdue_log_id serial,
customer_id integer,
days_overdue integer
);

Each record gets a logical primary key
●

Store the customer id and the number of days
●

rental was overdue
Yes, this table is fake... no FK's, no
●

timestamps, etc...

pl/php triggers – special variables
$_TD[“old”] - Old data being removed from
●

table
$_TD[“new”] - New data being written to table
●

Associative arrays, indexed by field names
●

Null values not included
●

Other special variables
●

trigger name, trigger action, table name, etc...
–

pl/php trigger function
CREATE OR REPLACE FUNCTION watch_overdue()
RETURNS trigger
LANGUAGE plphpu
AS $$
$new =& $_TD['new'];

$sql = quot;SELECT
rental_date + (rental_duration * '1 day'::interval) as due_date
FROM
rental
INNER JOIN inventory USING (inventory_id)
INNER JOIN film USING (film_id)
WHERE
rental_id =quot;. $new['rental_id'];

$rs = spi_exec($sql);
$r = spi_fetch_row($rs);

continued...

pl/php trigger function
continued...

pg_raise('notice',$r['due_date']);
pg_raise('notice',$new['return_date']);
if ($new['return_date'] > $r['due_date'])
{
/* rental is overdue, we need to convert our dates to php time values,
find the difference between them, and then convert that to days */

$dayo = (strtotime($new['return_date']) - strtotime($r['due_date']))/60/60/24;
pg_raise('notice',$dayo);

$sql = quot;INSERT INTO overdue_log (customer_id,days_overdue)
VALUES (quot;.$new['customer_id'].quot;,quot;.$dayo.quot;)quot;;

$rs = spi_exec($sql);
};

return null;
$$;

pl/php triggers (the trigger)
CREATE TRIGGER watch_overdue
AFTER insert or update
ON rental
FOR EACH row
EXECUTE PROCEDURE watch_overdue();

No special syntax needed
–

Trigger fires on any insert or update
–

We can tweak rules by modifying the function
–

pl/php triggers

pagila=# INSERT INTO rental
pagila-# VALUES (DEFAULT,now() - '1 month'::interval,2792,549,now(),1);

pl/php triggers

NOTICE: plphp: 2006-07-30 11:27:56.854139
NOTICE: plphp: 2006-08-25 11:27:56.854139
NOTICE: plphp: 26
INSERT 0 1
pagila=#

pl/php triggers

NOTICE: plphp: 2006-07-30 11:27:56.854139
NOTICE: plphp: 2006-08-25 11:27:56.854139
NOTICE: plphp: 26
INSERT 0 1
pagila=# SELECT * FROM overdue_log;

pl/php triggers

NOTICE: plphp: 2006-07-30 11:27:56.854139
NOTICE: plphp: 2006-08-25 11:27:56.854139
NOTICE: plphp: 26
INSERT 0 1
pagila=# SELECT * FROM overdue_log;
overdue_log_id | customer_id | days_overdue
----------------------+-----------------+----------------
1| 549 | 26

pl/php – one more example
CREATE OR REPLACE FUNCTION text_array_to_result(text[])
RETURNS setof text
LANGUAGE plphpu
AS $$

// TRICKY!! $args[0] refers to the first argument of the function
// so $args[0][0] refers to the first value of the array passed into the first argument!

$i=0;
while ($args[0][$i])
{
$ret = $args[0][$i];
return_next($ret);
$i++;
}

#pg_raise('notice',$args[0]);
$$;

pagila=# SELECT * FROM text_array_to_result('{txt arg 1,txt arg 2}');
text_array_to_result
----------------------
txt arg 1
txt arg 2
(2 rows)

Works with arrays
●

Works for set returning functions
●

pagila=# SELECT * FROM text_array_to_result('{txt arg 1,txt arg 2}');
text_array_to_result
----------------------
txt arg 1
txt arg 2
(2 rows)

Works with arrays
●

Works for set returning functions
●

Oh yeah... no special syntax :-)
●

but wait, there's more!
Composite data types
●

Working with array types
●

Global shared variables
●

Polymorphic Arguments
●

Polymorphic Return Types
●

Composite Types
●

pl/php - caveats
Rough around the edges
●

sometimes uncover segfaults
–

lots of warnings / notices from php
–

no in / out parameters (8.1)
–

pl/php - caveats
●

–

–

–

Can't call other pl/php functions directly
●

pl/php - caveats
●

–

–

–

●

Not fully tested against all PHP functions
●

pl/php - caveats
●

–

–

–

●

Not fully tested against all PHP functions
●

Needs some C developers to contribute
●

Thanks!
Command Prompt, Inc.
Alvarro Herrera
Alexey Klyukin
Greg Sabino-Mullane
OmniTI
The PHP & PostgreSQL Communities
:-)

Os Treat

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Andere mochten auch

Andere mochten auch (9)

Ähnlich wie Os Treat

Ähnlich wie Os Treat (20)

Mehr von oscon2007

Mehr von oscon2007 (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Os Treat