Re: [HACKERS] xReader, double-effort (was: Temporary tables under hot standby)

2012-04-27 Thread Aakash Goel
Sure Kevin, will get the wiki page ready asap, and reply back. Thanks.

On Thu, Apr 26, 2012 at 8:10 PM, Kevin Grittner kevin.gritt...@wicourts.gov
 wrote:

 [resending because of postgresql.org bounces on first try]

 Simon Riggs si...@2ndquadrant.com wrote:
  Kevin Grittner kevin.gritt...@wicourts.gov wrote:

  The GSoC xReader project is intended to be a major step toward
  that, by providing a way to translate the WAL stream to a series
  of notifications of logical events to clients which register with
  xReader.
 
  This is already nearly finished in prototype and will be published
  in May. Andres Freund is working on it, copied here.

 URL?

  It looks like there is significant overlap there.

 Hard for me to know without more information.  It sounds like there
 is at least some overlap.  I hope that can involve cooperation, with
 the efforts of Andres forming the basis of Aakash's GSoC effort.
 That might leave him more time to polish up the user filters.

 Aakash: It seems like we need that Wiki page rather sooner than
 later.  Can you get to that quickly?  I would think that just
 copying the text from your approved GSoC proposal would be a very
 good start.  If you need help figuring out how to embed the images
 from your proposal, let me know.

 -Kevin



Re: [HACKERS] xReader, double-effort (was: Temporary tables under hot standby)

2012-04-27 Thread Aakash Goel
All, the wiki page is now up at http://wiki.postgresql.org/wiki/XReader.

On Sat, Apr 28, 2012 at 1:19 AM, Aakash Goel aakash.b...@gmail.com wrote:

 Sure Kevin, will get the wiki page ready asap, and reply back. Thanks.


 On Thu, Apr 26, 2012 at 8:10 PM, Kevin Grittner 
 kevin.gritt...@wicourts.gov wrote:

 [resending because of postgresql.org bounces on first try]

 Simon Riggs si...@2ndquadrant.com wrote:
  Kevin Grittner kevin.gritt...@wicourts.gov wrote:

  The GSoC xReader project is intended to be a major step toward
  that, by providing a way to translate the WAL stream to a series
  of notifications of logical events to clients which register with
  xReader.
 
  This is already nearly finished in prototype and will be published
  in May. Andres Freund is working on it, copied here.

 URL?

  It looks like there is significant overlap there.

 Hard for me to know without more information.  It sounds like there
 is at least some overlap.  I hope that can involve cooperation, with
 the efforts of Andres forming the basis of Aakash's GSoC effort.
 That might leave him more time to polish up the user filters.

 Aakash: It seems like we need that Wiki page rather sooner than
 later.  Can you get to that quickly?  I would think that just
 copying the text from your approved GSoC proposal would be a very
 good start.  If you need help figuring out how to embed the images
 from your proposal, let me know.

 -Kevin





Re: [HACKERS] xReader, double-effort

2012-04-27 Thread Greg Smith

On 04/26/2012 12:57 PM, Robert Haas wrote:

I don't recall seeing any previous postings about the 2Q project,
either.  We should try to keep these discussions on-list.


First brought up two months ago to the list it seemed most relevant to 
at the time: 
http://archives.postgresql.org/pgsql-cluster-hackers/2012-02/msg1.php and 
the solid commentary started coming out yesterday, right near the 
approach of May as promised.  There hasn't been much posted on hackers 
about this out of respect for the extended CommitFest.


I personally suggested Aakash vent ideas out on pgsql-students (or here) 
at the beginning of the month: 
http://archives.postgresql.org/pgsql-students/2012-04/msg2.php but 
the next time I heard about the subject was the acceptance notice.


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Re: [HACKERS] xReader, double-effort

2012-04-27 Thread Kevin Grittner
Greg Smith g...@2ndquadrant.com wrote:
 On 04/26/2012 12:57 PM, Robert Haas wrote:
 I don't recall seeing any previous postings about the 2Q project,
 either.  We should try to keep these discussions on-list.
 
 First brought up two months ago to the list it seemed most
 relevant to at the time: 

http://archives.postgresql.org/pgsql-cluster-hackers/2012-02/msg1.php
 and the solid commentary started coming out yesterday, right near
 the approach of May as promised.  There hasn't been much posted on
 hackers about this out of respect for the extended CommitFest.
 
 I personally suggested Aakash vent ideas out on pgsql-students (or
 here) at the beginning of the month: 
 http://archives.postgresql.org/pgsql-students/2012-04/msg2.php
 but the next time I heard about the subject was the acceptance
 notice.
 
That's largely my fault.  Aakash's original proposal was naively
assuming that logical records were available in our xlog stream and
wanted to work on tools to do something useful with that data. 
There was some confusion among the various core team members,
committers, and other contributors who volunteered to review the
proposals about whether he was talking about analyzing the server
log or xlog.  We had a wide-ranging discussion on the freenode
#postgresql channel about it, and brainstormed to the current idea
-- at which point Aakash had about a week and a half to rewrite his
proposal along the lines discussed on irc.  A week after that the
acceptance notices came out.
 
If we had had any idea that 2Q was working on something along these
lines, we would have coordinated or guided him in another direction.
The post you cite from a couple months ago was way too vague to
have even an inkling that it had anything to do with providing feeds
of the logical interpretation of the WAL stream.  I don't recall
having heard the idea even mentioned before.
 
The timing in regard to the release process seems to have had an
effect on both groups here, since I suggested he read up on
walsender and walreceiver and a few other areas, put together a Wiki
page with the plan, and *then* describe the preliminary plan to the
community (a month or so before starting to code), so that details
could be hashed out in public before time was spent coding.  Had
there not been so many people heads-down trying to get the release
out, I might have advised him to post a hand-wavy description of the
effort before he got the Wiki page set up and reviewed the relevant
code.
 
As Josh points out, his first choice was to write utilities to *do*
something with the logical xlog information, and he only switched
over to working on *producing* it when he heard that no such thing
was currently available.  I think there's a lot of room to
coordinate these efforts so that there *isn't* a waste of effort as
long as communication is open enough.
 
-Kevin

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Re: [HACKERS] xReader, double-effort

2012-04-27 Thread Greg Smith

On 04/27/2012 06:48 PM, Kevin Grittner wrote:

That's largely my fault.


It may not have come out that way, but I was trying more to point out 
the complexity of the story rather than assign blame.  I find it hard to 
point at any obvious don't do that again target here.


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Re: [HACKERS] xReader, double-effort (was: Temporary tables under hot standby)

2012-04-26 Thread Simon Riggs
On Thu, Apr 26, 2012 at 3:40 PM, Kevin Grittner
kevin.gritt...@wicourts.gov wrote:
 [resending because of postgresql.org bounces on first try]

 Simon Riggs si...@2ndquadrant.com wrote:
 Kevin Grittner kevin.gritt...@wicourts.gov wrote:

 The GSoC xReader project is intended to be a major step toward
 that, by providing a way to translate the WAL stream to a series
 of notifications of logical events to clients which register with
 xReader.

sigh Yes, it appears very similar. I didn't know about this.

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 PostgreSQL Development, 24x7 Support, Training  Services

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Re: [HACKERS] xReader, double-effort (was: Temporary tables under hot standby)

2012-04-26 Thread Robert Haas
On Thu, Apr 26, 2012 at 11:02 AM, Simon Riggs si...@2ndquadrant.com wrote:
 On Thu, Apr 26, 2012 at 3:40 PM, Kevin Grittner
 kevin.gritt...@wicourts.gov wrote:
 [resending because of postgresql.org bounces on first try]

 Simon Riggs si...@2ndquadrant.com wrote:
 Kevin Grittner kevin.gritt...@wicourts.gov wrote:

 The GSoC xReader project is intended to be a major step toward
 that, by providing a way to translate the WAL stream to a series
 of notifications of logical events to clients which register with
 xReader.

 sigh Yes, it appears very similar. I didn't know about this.

I don't recall seeing any previous postings about the 2Q project,
either.  We should try to keep these discussions on-list.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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Re: [HACKERS] xReader, double-effort (was: Temporary tables under hot standby)

2012-04-26 Thread Simon Riggs
On Thu, Apr 26, 2012 at 5:57 PM, Robert Haas robertmh...@gmail.com wrote:
 On Thu, Apr 26, 2012 at 11:02 AM, Simon Riggs si...@2ndquadrant.com wrote:
 On Thu, Apr 26, 2012 at 3:40 PM, Kevin Grittner
 kevin.gritt...@wicourts.gov wrote:
 [resending because of postgresql.org bounces on first try]

 Simon Riggs si...@2ndquadrant.com wrote:
 Kevin Grittner kevin.gritt...@wicourts.gov wrote:

 The GSoC xReader project is intended to be a major step toward
 that, by providing a way to translate the WAL stream to a series
 of notifications of logical events to clients which register with
 xReader.

 sigh Yes, it appears very similar. I didn't know about this.

 I don't recall seeing any previous postings about the 2Q project,
 either.  We should try to keep these discussions on-list.

While that's true, it wasn't much of a stretch to think that I might
be planning to do more work on replication since I've done that for
years and years now. Also, I do keep requesting GSOC doesn't put such
major tasks out there, but not much heed taken.

Beautiful illustration of a multi-master conflict case though.

Not sure just yet what the resolution is, and it will probably take a
few weeks to resolve that happily.

Glad we're all facing in the same direction, which is the most important thing.

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Re: [HACKERS] xReader, double-effort

2012-04-26 Thread Josh Berkus

 The GSoC xReader project is intended to be a major step toward
 that, by providing a way to translate the WAL stream to a series
 of notifications of logical events to clients which register with
 xReader.

 sigh Yes, it appears very similar. I didn't know about this.

This isn't a problem. In fact, it's the *exact opposite* of a problem.

The student wanted to do more advanced things with the xlog stream, and
we convinced him to narrow the scope in order to make the project
achievable.

With 2Q having done some/most of the basic work, the student can focus
on more advanced applications of the data again.  Win!

However, it would be great if someone from 2Q co-mentored him.

--Josh


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