From pgsql-hackers-owner+M4145@postgresql.org Sat Feb 3 05:54:06 2001 Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id FAA22302 for ; Sat, 3 Feb 2001 05:54:04 -0500 (EST) Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by mail.postgresql.org (8.11.1/8.11.1) with SMTP id f13Ap4q95132; Sat, 3 Feb 2001 05:51:04 -0500 (EST) (envelope-from pgsql-hackers-owner+M4145@postgresql.org) Received: from mail.retep.org.uk ([216.126.85.184]) by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f13AnIq94863 for ; Sat, 3 Feb 2001 05:49:18 -0500 (EST) (envelope-from peter@retep.org.uk) Received: from heather.retep.org.uk ([193.113.118.193]) (authenticated) by mail.retep.org.uk (8.11.1/8.11.1) with ESMTP id f13AlnO94823; Sat, 3 Feb 2001 05:47:49 -0500 (EST) (envelope-from peter@retep.org.uk) Message-Id: <5.0.2.1.0.20010203103036.009efec0@mail.retep.org.uk> X-Sender: peter@mail.retep.org.uk X-Mailer: QUALCOMM Windows Eudora Version 5.0.2 Date: Sat, 03 Feb 2001 10:46:24 +0000 To: Alex Pilosov , tomasz konefal From: Peter Mount Subject: Re: [HACKERS] TODO list: Allow Java server-side programming Cc: pgsql-hackers@postgresql.org In-Reply-To: References: <20010202194049.38902.qmail@web12003.mail.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Status: OR At 14:57 02/02/01 -0500, Alex Pilosov wrote: >On Fri, 2 Feb 2001, tomasz konefal wrote: > > > could someone please clarify what "Allow Java > > server-side programming" actually means? what are the > > limitations of using java and jdbc with pgsql? > >It means to embed Java interpreter inside postgres, and allow writing >stored procedures and triggers in Java. Thats correct. Basically you are talking of something like PL/Java. The Java side would be simple, but its linking the JVM to the backend that's the problem. It's been a while since I delved into the backend, but unless it's changed from fork() to threading, I don't really see this happening, unless someone who knows C that well knows of a portable way of communicating between two processes - other than RMI. If that could be solved, then you could use JNI to interface the JVM. I know some people think this would slow the backend down, but it's only the instanciation of the JVM thats slow, hence the other reason fork() is holding this back. Ideally you would want the JVM to be running with PostMaster, and then each backend can then use the JVM as and when necessary. Obviously you wouldn't want a JVM in every installation, but there are a lot of good reasons to have this capability. For example, as part of the course I did this week, we used Tomcat (Servlet/JSP/Web server). Now there's no reason why Tomcat could run within the same JVM. JBoss is another good example (EJB Server). The JBoss team have actually got Tomcat to run within the same JVM. Doesn't hinder performance at all, but does reduce the memory footprint. This is a good future thing to look into (why not for 8.0 ;-) ). If we could find an _optional_ way of hooking the backend direct into the JVM, we could get PostgreSQL into a lot of new areas. It also would make things like CORBA etc a doddle. PS: I'm writing down notes of the course to go onto the JDBC web site this weekend, so there's some nice things for EJB, RMI, Corba etc. More later, Peter From pgsql-hackers-owner+M4153@postgresql.org Sat Feb 3 11:54:12 2001 Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id LAA13446 for ; Sat, 3 Feb 2001 11:54:12 -0500 (EST) Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by mail.postgresql.org (8.11.1/8.11.1) with SMTP id f13GrZq17345; Sat, 3 Feb 2001 11:53:35 -0500 (EST) (envelope-from pgsql-hackers-owner+M4153@postgresql.org) Received: from mailout04.sul.t-online.com (mailout04.sul.t-online.com [194.25.134.18]) by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f13GnZq17000 for ; Sat, 3 Feb 2001 11:49:37 -0500 (EST) (envelope-from peter_e@gmx.net) Received: from fwd06.sul.t-online.com by mailout04.sul.t-online.com with smtp id 14P5rE-0000zq-00; Sat, 03 Feb 2001 17:48:16 +0100 Received: from peter.localdomain (520083510237-0001@[212.185.245.12]) by fmrl06.sul.t-online.com with esmtp id 14P5r6-0YvD60C; Sat, 3 Feb 2001 17:48:08 +0100 Date: Sat, 3 Feb 2001 17:56:33 +0100 (CET) From: Peter Eisentraut To: Peter Mount cc: Alex Pilosov , tomasz konefal , Subject: Re: [HACKERS] TODO list: Allow Java server-side programming In-Reply-To: <5.0.2.1.0.20010203103036.009efec0@mail.retep.org.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Sender: 520083510237-0001@t-dialin.net Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Status: OR Peter Mount writes: > Thats correct. Basically you are talking of something like PL/Java. The > Java side would be simple, but its linking the JVM to the backend that's > the problem. I've tried that recently, here's how it looks as far as Linux JVMs go: * Kaffe has a very polluted name space. Calls to its own functions get resolved to PostgreSQL, and vice versa. Crash and burn result. The Kaffe folks have admitted that this should be fixed but I didn't look farther yet. * The Sun/Blackdown JVM didn't work at all (not even 'java -version') until I upgraded my libc. Then a simple test run crashes with an "error external to JVM"; at first it looked like a segfault when referencing a string constant. In gdb I saw myself faced with about 10 threads running when nothing was going on yet, at which point I was too exhausted to proceed. * IBM's offering didn't work at all. I don't recall the problem anymore but I think it didn't even link correctly. So currently I don't see how this could become a mainstream project, let alone across platforms. > I know some people think this would slow the backend down, but it's only > the instanciation of the JVM thats slow, hence the other reason fork() is > holding this back. Ideally you would want the JVM to be running with > PostMaster, and then each backend can then use the JVM as and when necessary. But how do the other languages cope? Starting up a new Perl for each backend can't be so cheap either. -- Peter Eisentraut peter_e@gmx.net http://yi.org/peter-e/ From pgsql-hackers-owner+M4154@postgresql.org Sat Feb 3 12:37:02 2001 Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id MAA00813 for ; Sat, 3 Feb 2001 12:37:01 -0500 (EST) Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by mail.postgresql.org (8.11.1/8.11.1) with SMTP id f13Haiq21225; Sat, 3 Feb 2001 12:36:44 -0500 (EST) (envelope-from pgsql-hackers-owner+M4154@postgresql.org) Received: from spider.pilosoft.com (p55-222.acedsl.com [160.79.55.222]) by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f13HX9q20913 for ; Sat, 3 Feb 2001 12:33:09 -0500 (EST) (envelope-from alex@pilosoft.com) Received: from localhost (alexmail@localhost) by spider.pilosoft.com (8.9.3/8.9.3) with ESMTP id MAA09231; Sat, 3 Feb 2001 12:36:01 -0500 (EST) Date: Sat, 3 Feb 2001 12:36:01 -0500 (EST) From: Alex Pilosov To: Peter Mount cc: Alex Pilosov , tomasz konefal , pgsql-hackers@postgresql.org Subject: Re: [HACKERS] TODO list: Allow Java server-side programming In-Reply-To: <5.0.2.1.0.20010203103036.009efec0@mail.retep.org.uk> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Status: OR On Sat, 3 Feb 2001, Peter Mount wrote: > It's been a while since I delved into the backend, but unless it's > changed from fork() to threading, I don't really see this happening, > unless someone who knows C that well knows of a portable way of > communicating between two processes - other than RMI. If that could be > solved, then you could use JNI to interface the JVM. There are many ways one can do this: a) each backend will have a JVM linked in (shared object). This is the way perl/tcl/ruby is embedded, and it works pretty nice. But, Java ['s memory requirement] sucks, therefore, this may not be the optimal way. > I know some people think this would slow the backend down, but it's > only the instanciation of the JVM thats slow, hence the other reason > fork() is holding this back. Ideally you would want the JVM to be > running with PostMaster, and then each backend can then use the JVM as > and when necessary. b) since JVM is threaded, it may be more efficient to have a dedicated process running JVM, and accepting some sort of IPC connections from postgres processes. The biggest problem here is SPI, there aren't a good way for that JVM to talk back to database. c) temporarily, to have quick working code, you can reach java using hacks using programming languages already built into postgres. Both TCL (tcl blend) and Perl (JPL and another hack which name escapes me) are able to execute java code. SPI is possible, I think both of these bindings are two-way (you can go perl-java-perl-java). Might be worth a quick try? -alex From pgsql-hackers-owner+M4164@postgresql.org Sun Feb 4 04:23:42 2001 Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id EAA04260 for ; Sun, 4 Feb 2001 04:23:41 -0500 (EST) Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by mail.postgresql.org (8.11.1/8.11.1) with SMTP id f149Nhx75443; Sun, 4 Feb 2001 04:23:43 -0500 (EST) (envelope-from pgsql-hackers-owner+M4164@postgresql.org) Received: from me.tm.ee (adsl895.estpak.ee [213.168.23.133]) by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f149Mgx75338 for ; Sun, 4 Feb 2001 04:22:42 -0500 (EST) (envelope-from hannu@tm.ee) Received: from tm.ee (IDENT:hannu@localhost.localdomain [127.0.0.1]) by me.tm.ee (8.9.3/8.9.3) with ESMTP id LAA01488; Sun, 4 Feb 2001 11:18:09 +0200 Message-ID: <3A7D1E51.E383AB7F@tm.ee> Date: Sun, 04 Feb 2001 11:18:09 +0200 From: Hannu Krosing X-Mailer: Mozilla 4.72 [en] (X11; U; Linux 2.2.17 i686) X-Accept-Language: en MIME-Version: 1.0 To: Peter Mount CC: Alex Pilosov , tomasz konefal , pgsql-hackers@postgresql.org Subject: Re: [HACKERS] TODO list: Allow Java server-side programming References: <20010202194049.38902.qmail@web12003.mail.yahoo.com> <5.0.2.1.0.20010203103036.009efec0@mail.retep.org.uk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Status: OR Peter Mount wrote: > > At 14:57 02/02/01 -0500, Alex Pilosov wrote: > >On Fri, 2 Feb 2001, tomasz konefal wrote: > > > > > could someone please clarify what "Allow Java > > > server-side programming" actually means? what are the > > > limitations of using java and jdbc with pgsql? > > > >It means to embed Java interpreter inside postgres, and allow writing > >stored procedures and triggers in Java. > > Thats correct. Basically you are talking of something like PL/Java. The > Java side would be simple, but its linking the JVM to the backend that's > the problem. > > It's been a while since I delved into the backend, but unless it's changed > from fork() to threading, Someone posted here recently his port/tweaks of backend so that it used threads instead of fork(). IIRC it was done to be used inside a java client in an embedded system. ---------------- Hannu From pgsql-hackers-owner+M4168@postgresql.org Sun Feb 4 06:54:27 2001 Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id GAA19741 for ; Sun, 4 Feb 2001 06:54:26 -0500 (EST) Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by mail.postgresql.org (8.11.1/8.11.1) with SMTP id f14BsOx83329; Sun, 4 Feb 2001 06:54:24 -0500 (EST) (envelope-from pgsql-hackers-owner+M4168@postgresql.org) Received: from mail.retep.org.uk ([216.126.85.184]) by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f14Bs9x83240 for ; Sun, 4 Feb 2001 06:54:09 -0500 (EST) (envelope-from peter@retep.org.uk) Received: from heather.retep.org.uk ([193.113.241.180]) (authenticated) by mail.retep.org.uk (8.11.1/8.11.1) with ESMTP id f14BqkR83161; Sun, 4 Feb 2001 06:52:46 -0500 (EST) (envelope-from peter@retep.org.uk) Message-Id: <5.0.2.1.0.20010204114942.00a0c8d0@mail.retep.org.uk> X-Sender: peter@mail.retep.org.uk X-Mailer: QUALCOMM Windows Eudora Version 5.0.2 Date: Sun, 04 Feb 2001 11:51:21 +0000 To: Peter Eisentraut From: Peter Mount Subject: Re: [HACKERS] TODO list: Allow Java server-side programming Cc: Alex Pilosov , tomasz konefal , In-Reply-To: References: <5.0.2.1.0.20010203103036.009efec0@mail.retep.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Status: OR At 17:56 03/02/01 +0100, Peter Eisentraut wrote: >Peter Mount writes: > > > Thats correct. Basically you are talking of something like PL/Java. The > > Java side would be simple, but its linking the JVM to the backend that's > > the problem. > >I've tried that recently, here's how it looks as far as Linux JVMs go: [snip] >So currently I don't see how this could become a mainstream project, let >alone across platforms. I don't think it would be, but it would be a good side-project. Over time the various JVM's should become better to interface with. > > I know some people think this would slow the backend down, but it's only > > the instanciation of the JVM thats slow, hence the other reason fork() is > > holding this back. Ideally you would want the JVM to be running with > > PostMaster, and then each backend can then use the JVM as and when > necessary. > >But how do the other languages cope? Starting up a new Perl for each >backend can't be so cheap either. But a lot cheaper than Java. Peter From pgsql-hackers-owner+M4169@postgresql.org Sun Feb 4 06:57:24 2001 Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by candle.pha.pa.us (8.9.0/8.9.0) with ESMTP id GAA19817 for ; Sun, 4 Feb 2001 06:57:23 -0500 (EST) Received: from mail.postgresql.org (webmail.postgresql.org [216.126.85.28]) by mail.postgresql.org (8.11.1/8.11.1) with SMTP id f14BvLx83711; Sun, 4 Feb 2001 06:57:21 -0500 (EST) (envelope-from pgsql-hackers-owner+M4169@postgresql.org) Received: from mail.retep.org.uk ([216.126.85.184]) by mail.postgresql.org (8.11.1/8.11.1) with ESMTP id f14Bv7x83611 for ; Sun, 4 Feb 2001 06:57:07 -0500 (EST) (envelope-from peter@retep.org.uk) Received: from heather.retep.org.uk ([193.113.241.180]) (authenticated) by mail.retep.org.uk (8.11.1/8.11.1) with ESMTP id f14BtjR83557; Sun, 4 Feb 2001 06:55:45 -0500 (EST) (envelope-from peter@retep.org.uk) Message-Id: <5.0.2.1.0.20010204115139.009f1c50@mail.retep.org.uk> X-Sender: peter@mail.retep.org.uk X-Mailer: QUALCOMM Windows Eudora Version 5.0.2 Date: Sun, 04 Feb 2001 11:54:20 +0000 To: Alex Pilosov From: Peter Mount Subject: Re: [HACKERS] TODO list: Allow Java server-side programming Cc: Alex Pilosov , tomasz konefal , pgsql-hackers@postgresql.org In-Reply-To: References: <5.0.2.1.0.20010203103036.009efec0@mail.retep.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Precedence: bulk Sender: pgsql-hackers-owner@postgresql.org Status: OR At 12:36 03/02/01 -0500, Alex Pilosov wrote: >On Sat, 3 Feb 2001, Peter Mount wrote: [snip] > > I know some people think this would slow the backend down, but it's > > only the instanciation of the JVM thats slow, hence the other reason > > fork() is holding this back. Ideally you would want the JVM to be > > running with PostMaster, and then each backend can then use the JVM as > > and when necessary. >b) since JVM is threaded, it may be more efficient to have a dedicated >process running JVM, and accepting some sort of IPC connections from >postgres processes. The biggest problem here is SPI, there aren't a good >way for that JVM to talk back to database. That was my other idea, but it is the IPC thats problematical. You would still need to do some native api to implement some messaging system between the two. However, at the other extreme there is RPC, which is possible now, but would be a lot slower. >c) temporarily, to have quick working code, you can reach java using hacks >using programming languages already built into postgres. Both TCL (tcl >blend) and Perl (JPL and another hack which name escapes me) are able to >execute java code. SPI is possible, I think both of these bindings are >two-way (you can go perl-java-perl-java). Might be worth a quick try? Might be one way to go... Peter >-alex >