Received: from maia.hub.org (maia-3.hub.org [200.46.204.243])
	by mail.postgresql.org (Postfix) with ESMTP id 1EAD4B5DBD9
	for <pgsql-general-postgresql.org@mail.postgresql.org>;
	Thu, 18 Aug 2011 08:33:12 -0300 (ADT)
Received: from mail.postgresql.org ([200.46.204.86])
	by maia.hub.org (mx1.hub.org [200.46.204.243]) (amavisd-maia,
	port 10024) with ESMTP id 07907-04
	for <pgsql-general-postgresql.org@mail.postgresql.org>;
	Thu, 18 Aug 2011 11:33:05 +0000 (UTC)
X-Greylist: from auto-whitelisted by SQLgrey-1.7.6
Received: from softlayer.compulab.co.il
	(50.23.254.54-static.reverse.softlayer.com [50.23.254.54])
	by mail.postgresql.org (Postfix) with ESMTP id 105E0B5DBC4
	for <pgsql-general@postgresql.org>;
	Thu, 18 Aug 2011 08:33:04 -0300 (ADT)
Received: from [62.90.235.247] (port=34028 helo=zimbra-mta.compulab.co.il)
	by softlayer.compulab.co.il with esmtp (Exim 4.69)
	(envelope-from <sim@compulab.co.il>) id 1Qu0qN-0000K5-D9
	for pgsql-general@postgresql.org; Thu, 18 Aug 2011 14:33:04 +0300
Received: from localhost (localhost.localdomain [127.0.0.1])
	by zimbra-mta.compulab.co.il (Postfix) with ESMTP id B7EAF7E954C
	for <pgsql-general@postgresql.org>;
	Thu, 18 Aug 2011 14:33:01 +0300 (IDT)
X-Virus-Scanned: amavisd-new at compulab.co.il
Received: from zimbra-mta.compulab.co.il ([127.0.0.1])
	by localhost (zimbra-mta.compulab.co.il [127.0.0.1]) (amavisd-new,
	port 10024)
	with ESMTP id Ta46NvNFUL+p for <pgsql-general@postgresql.org>;
	Thu, 18 Aug 2011 14:33:01 +0300 (IDT)
Received: from [10.1.1.27] (sim-pc.compulab.local [10.1.1.27])
	by zimbra-mta.compulab.co.il (Postfix) with ESMTP id 29C5A7E952B
	for <pgsql-general@postgresql.org>;
	Thu, 18 Aug 2011 14:33:01 +0300 (IDT)
Message-ID: <4E4CF84E.1030707@compulab.co.il>
Date: Thu, 18 Aug 2011 14:32:30 +0300
From: Sim Zacks <sim@compulab.co.il>
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US;
	rv:1.9.2.18) Gecko/20110617 Lightning/1.0b2 Thunderbird/3.1.11
MIME-Version: 1.0
To: PostgreSQL general <pgsql-general@postgresql.org>
Subject: Re: Using Postgresql as application server
References: 
 <CAN2Y=uPjF14F5A9JXj02_vaPw4TMR0WGQid_w80xt4sC8o4qGg@mail.gmail.com>
	<4E498536.9080109@darrenduncan.net>
	<008301cc5b95$e287b120$a7971360$@yahoo.com>
	<4E49A208.5070604@darrenduncan.net>
	<CAKt_ZftgpuGNbyxvQ_Bf0QrjahY5=HbxcoUUuxUYCdKbY=rp0g@mail.gmail.com>
	<4E49EC4D.1090707@darrenduncan.net>	<4E4B6828.1050506@compulab.co.il>
	<46EC79AF-3685-484E-AABE-E25969C23D56@elevated-dev.com>
	<4E4C9744.4060407@compulab.co.il>
	<CAKt_Zfs7392g+xyS-6_RBkFsmmUooftL=SZOefONH9=d8Ef+BA@mail.gmail.com>
In-Reply-To: 
 <CAKt_Zfs7392g+xyS-6_RBkFsmmUooftL=SZOefONH9=d8Ef+BA@mail.gmail.com>
Content-Type: text/html; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
X-AntiAbuse: This header was added to track abuse,
	please include it with any abuse report
X-AntiAbuse: Primary Hostname - softlayer.compulab.co.il
X-AntiAbuse: Original Domain - postgresql.org
X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12]
X-AntiAbuse: Sender Address Domain - compulab.co.il
X-Virus-Scanned: Maia Mailguard 1.0.1
X-Spam-Status: No, hits=-0.379 tagged_above=-5 required=5 tests=BAYES_00=-1.9,
	HTML_MESSAGE=0.001, KHOP_DYNAMIC=0.797, MIME_HTML_ONLY=0.723
X-Spam-Level: 
X-Archive-Number: 201108/593
X-Sequence-Number: 178875

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html style="direction: ltr;">
  <head>
    <meta content="text/html; charset=ISO-8859-1"
      http-equiv="Content-Type">
    <style>body p { margin-bottom: 0cm; margin-top: 0pt; } </style>
  </head>
  <body style="direction: ltr;"
    bidimailui-detected-decoding-type="latin-charset" bgcolor="#ffffff"
    text="#000000">
    On 08/18/2011 07:57 AM, Chris Travers wrote:
    <blockquote
cite="mid:CAKt_Zfs7392g+xyS-6_RBkFsmmUooftL=SZOefONH9=d8Ef+BA@mail.gmail.com"
      type="cite">
      <pre wrap="">On Wed, Aug 17, 2011 at 9:38 PM, Sim Zacks <a class="moz-txt-link-rfc2396E" href="mailto:sim@compulab.co.il">&lt;sim@compulab.co.il&gt;</a> wrote:

</pre>
      <blockquote type="cite">
        <pre wrap="">The point was not whether I have a bug in an external application, the point
is that I need an external application which creates more overhead and
another point of failure in the application stack.

</pre>
      </blockquote>
      <pre wrap="">1)  Not sure how an external python script is different from a
PL/Python sproc except that the former exists external to transaction
control.
</pre>
    </blockquote>
    There are many differences. <br>
    1) If I have a database function and I copy my database to another
    server, the function still works. <br>
    If I have an external daemon application, I not only have to copy my
    database, I also have to copy the daemon application. Then I have to
    build an init script and make sure it runs at startup. My
    LISTEN/NOTIFY daemon is a c application, so when I move my database
    to a server on a different platform, I have to recompile it.&nbsp; <br>
    <blockquote
cite="mid:CAKt_Zfs7392g+xyS-6_RBkFsmmUooftL=SZOefONH9=d8Ef+BA@mail.gmail.com"
      type="cite">
      <pre wrap="">2) there is absolutely no reason you can't build redundancy into this system.
</pre>
    </blockquote>
    Its not a question of whether I can or cannot build redundancy, it
    is a question of whether I have to build an entire system in order
    to call a database function from another database function. The only
    reason this is complicated is because it needs to be in its own
    session. That simple issue shouldn't force me to build: a) a daemon
    application, b) include redundancy to ensure that it is running, c)
    not be included in my database backup/restore.<br>
    Remember, I don't want to build a _system_, I basically want an
    asynchronous trigger. On specific event call a database function in
    its own transaction space and allow the existing transaction to end.
    <br>
    <blockquote
cite="mid:CAKt_Zfs7392g+xyS-6_RBkFsmmUooftL=SZOefONH9=d8Ef+BA@mail.gmail.com"
      type="cite">
      <pre wrap="">3)  The overhead really shouldn't be bad, and if your parts are
well-modularized, and carefully designed overhead really should be
minimal.
</pre>
    </blockquote>
    Any overhead that is not necessary should not be added in. It is the
    minor level of frustration that something didn't work when I
    migrated servers until the "Oh Yeah" kicked in. Then looking through
    all my notes to find the compilation instructions for my daemon
    because we moved from a 32 bit server to a 64 bit. Then trying to
    figure out the syntax for the init script, because we moved from
    Gentoo to Debian and it is slightly different. It isn't a lot of
    overhead but it is completely unneccessary in our situation. <br>
    I will agree that this is entirely necessary if your application
    actually uses an external system and the database communicates
    through Listen/Notify. You have 2 systems to deal with in any case,
    but for me the only external component is having the daemon listen
    so it can call another function in the database. IOW, I don't
    generally deal with anything else on the server.<br>
    <br>
    <blockquote
cite="mid:CAKt_Zfs7392g+xyS-6_RBkFsmmUooftL=SZOefONH9=d8Ef+BA@mail.gmail.com"
      type="cite">
      <pre wrap="">Best Wishes,
Chris Travers
</pre>
    </blockquote>
    <p>Sim<br>
    </p>
  </body>
</html>