[cvs] [Wiki] created: Project/Rdo

Tue May 27 22:20:40 UTC 2008

chuck  Tue, 27 May 2008 18:20:40 -0400

Created page: http://wiki.horde.org/Project/Rdo

[[toc]]

+ Rdo - Rampage Data Objects

Rdo is a !DataMapper implementation for Horde, using domain/entity objects
combined with Mapper objects that handle the actual data manipulation.

++ Bugs

++ People

ChuckHagenbuch is the primary author of Rdo.

++ Description

+++ Notes on database abstraction

MDB2_Schema xslt:
http://cvs.php.net/viewvc.cgi/pear/MDB2_Schema/docs/

regarding charset support, here's a topic summary:

http://www.alberton.info/dbms_charset_settings_explained.html
http://oss.backendmedia.com/MDB2/CharacterSet
http://pear.php.net/bugs/4666

In MDB2, most drivers basically resort to a "SET NAMES" query.
The MySQL driver initially used the "SET character_set_client"
statement, but I changed it after some complaints, for it
was not effective for most setups.

Another thing that bothers me, is the fact that
there isn't a single charset naming convention.

http://www.postgresql.org/docs/8.2/interactive/multibyte.html#MULTIBYTE-CHARSET-SUPPORTED
http://dev.mysql.com/doc/refman/5.0/en/charset-charsets.html
http://www.destructor.de/firebird/charsets.htm
http://www.csee.umbc.edu/help/oracle8/server.815/a67789/appa.htm#956722

For instance, Traditional Chinese is labelled as "BIG_5",
"BIG5" or "ZHT16BIG5", Russian as "KOI8", "KOI8R" or "CL8KOI8R",
Western European as "latin1", "ISO8859_1" or "WE8ISO8859P1"...
In the end, a common setCharset() method is kind of pointless
without a standard charset naming convention...
Should the DBAL define a set of constants for the most
common charsets, and leave the mapping to the drivers?

"LIKE" case sensitivity:

> I was not thinking of SQLite. I was thinking that MySQL LIKE operator is
> case insensitive (which is what most people want) but in other databases
> LIKE is case sensitive by default.

Not sure how you did in Metabase, but in MDB2 I have the following code for
this:
            switch ($operator) {
            // case insensitive
            case 'ILIKE':
                $match = $field.'LIKE ';
                break;
            // case sensitive
            case 'LIKE':
                $match = $field.'LIKE BINARY ';
                break;

Not sure if I would use "ILIKE" again, probably I would use like with an
optional
attribute to flag case sensitivity.

+++ Logging what Rdo does

See "ror_logs.png" attachment.

+++ Paging

You hardly need a library for figuring out pagination. A very simple formula
tells you how many "pages" you have.
<code type="php">
$itemsPerPage = 10;
$totalRecords = 52; //Result of SELECT FOUND_ROWS()
$pages = ceil($totalRecords/$itemsPerPage);
</code>

Based on those numbers, you know you have 6 pages of data. You can then
create a loop to generate the links with the proper parameter(s), however
you want to format them. For example:
<code>
link.php?page=3&itemsperpage=10
</code>

Would make the following query:
<code>
SELECT * FROM table LIMIT ($_GET['page']-1)*10,10
</code>

I may be off by 1 on that. Hope that helps.

On 10/18/07, Brent Baisley <brenttech at gmail.com> wrote:

You don't need to do an extra count query. If you are using MySQL, just add
SQL_CALC_FOUND_ROWS to your select query. SELECT SQL_CALC_FOUND_ROWS * FROM
...

You can then run SELECT FOUND_ROWS() to get the total rows without any
limits. It's still 2 queries, but the second one is essentially free.

+++ Adding backup database servers

> I'm kind of of the opinion that this sort of thing (failover) belongs on
the database server, not in the app.

In our environment, the apps that we use all utilize this sort of thing for
a rudimentary failover behaviour (postfix, amavisd, etc). We modified
courier-authlib and dovecot to include this type of behaviour.  We can
handle a complete crash of our primary r/w db server and still keep our
imap/http/pop3/smtp services operational.

We have two database servers that are circular redundant -> mysql-01 and
mysql-02.  mysql-01 is the primary r/w server.  If an app cannot connecto
mysql-01, then I would like to to connec to to mysql-02 and process as
normal.  When mysql-01 comes back online, it reads the updates from -02 and
continues normal operation.  We also have a handful of r/o slave servers for
the mx servers to query for user metadata.

How would you suggest the database server handle this instead of the app? 
Obviously if the db server is down, it won't be able to process a message to
redirect the host to the next server...

Horde is the only app that we have that doesn't include some sort of
failover (on connect).  I quick whipped up a patch if you think it might be
usefull, otherwise we will just use it here.  I have tested it and it works
sufficent for our needs.  We have had to modify the framework, horde, jonah,
kronolith, and turba.  The modifications are minor to each file and I have
attached them.  All changes are off of CVS HEAD.

See "Re_ _horde_ adding backup servers to mysql db driver.zip" attachment.

++ Resources

http://ajaxian.com/archives/ext-scaffold-generator-plugin-for-rails
http://ajaxian.com/archives/lipsiadmin-rails-20-ext-admin
http://blog.stuartherbert.com/php/2008/05/08/what-should-an-orm-offer/
http://code.nytimes.com/projects/dbslayer
http://www.phpdoctrine.org/index.php/documentation/manual?chapter=migration
http://michaelkimsal.com/blog/gorm-goodness-in-php/
http://grails.org/GORM
http://jan.kneschke.de/2007/2/19/typesafe-objects-in-php
http://jeremy.zawodny.com/mysql/mysql-optimization.html
http://kore-nordmann.de/blog/why_active_record_sucks.html
http://code.google.com/p/pdorm/
http://phing.info/docs/guide/current/chapters/appendixes/AppendixC-OptionalTasks.html#DbDeployTask
http://pooteeweet.org/blog/0/918#m918
http://pooteeweet.org/blog/0/1083#m1083
http://sebastian-bergmann.de/archives/751-Testing-with-SQLite-In-Memory-Databases.html
http://www.blobstreaming.org/
http://www.ddataobjects.com/current/prog/
http://www.phpdoctrine.org/documentation/manual?chapter=migration
http://framework.zend.com/manual/en/zend.db.profiler.html

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