Recent blog entries for cbbrowne

Speaking on PostgreSQL

I’m doing a talk on Sept 13th at GTALUG GTALUG Sept 2016 where I’ll be talking on things new in PostgreSQL 9.5 (released in January 2016) and upcoming in 9.6.

Here’s a copy of the material…
PostgreSQL New Stuff

Syndicated 2016-09-06 15:37:25 from

Spamalicious times

Hmmph. Google sent me a “nastygram” indicating that one of my blog entries had something suggestive of content injection.

I poked around, and it was by no means evident that it was really so. The one suspicious posting was which legitimately has some stuff that looks like labels, as it contains a bunch of sample SQL code. I’m suspicious that they’re accounting that as being evil…

But it pointed me at a couple of mostly-irritating things…

  1. I haven’t generated a blog entry since 2013. Well, I’m not actually hugely worried about that.
  2. I reviewed proposed response posts, since, probably about 2013. Wow, oh wow, was that ever spam-filled. Literally several thousand attempts to get me to publish various and sundry advertising links. It’s seriously a pain to get rid of them all, as I could only trim out about 150 at a time. And hopefully there weren’t many “real” proposed postings; it’s almost certain I’ll have thrown those away. (Of course, proposed postings about things I said in 2013… How relevant could it still be???)

Syndicated 2016-08-15 20:44:52 from

Nexus 7 on CyanogenMod

At last…

I had been lazy, leaving all alone.

In February, I figured I was heading off for a chunk of the month on a cruise, hence wanting tablet for multimedia, but without network, so it was timely not to spend time fiddling with configuration with possible risk of mussing such up.

Alas, the OTA upgrade to JellyBean did a certain chunk of mussing…  It busted SuperUser access, thereby breaking Titanium Backup.  No backups went properly since :-( .

So, today seemed right timing.  I wanted backup, and needed root, the latter looking like a fight.  Ah well, go for gusto, see what we get without it…

I had to upgrade adb to support latest Android…   Got Clockwork Recovery in place, and zip files for CM10.1 and Google Apps…

The last backup was Feb 16, but happily the files still remained after fresh CM10.1 installation, so I could do a good chunk of recovery of apps, and in plenty of cases, this was basically network configuration, so apps would update their own data upon startup.  Sweet!

Superuser is nicely integrated into CM10, also sweet, no extra installation process.

I’ll need to reconfigure the launcher, due to the shift from ADW (I had a license) to built-in Trebuchet on CM10, but that seems like the “worst” irritation, and one I can well live with.

I’m not sure I can readily identify big differences between stock Android and CM10, but there are nice small creature comforts my CM10 phone has gotten me used to, like a quick “turn on/off WiFi” directly on notification screens.  Small but I like it.

Syndicated 2013-03-09 00:18:21 from

Mailman subscriber lists

As part of “due diligence” for some mailing lists I am involved with (for Slony, see slony-backups ), I discovered the need to dump out Mailman mailing list subscribers.

There is a script to do this, written in Python, mentioned on the Mailman wiki, accessible as

I’d kind of rather have something a bit more version-tracked, so I poked around at GitHub, and found larsks / mailman-subscribers

That was a little out of date; the last code was from a couple of years ago, so I forked, updated to the latest, and suggested that “larsks” pull it, which he did, quite quickly.

The “kudos” bit is that I noticed a bit of a blemish, in that the mailing list password was required to be on the command line, thereby making it visible to anyone with access to /usr/bin/ps on one’s system. I submitted a feature request, and Lars was so kind as to have this feature added so quickly that by the time I had the prototype of my Slony “subscriber backup” script working, I immediately needed to change it to make use of the lovely new password-in-file feature. Nice!

Syndicated 2013-02-27 18:32:42 from

Installing git-annex from Debian unstable

Installing git-annex from unstable

I happen to be a supporter of Joey Hess’ Git Annex Kickstarter project; no big bucks, but it seemed a good thing to help out.

I got in the stickers, that were my “project reward,” and figured I should start playing with the new results. I’m particularly keen on the planned Android client, but I should make some use of it before that comes available.

There’s good news, and bad news:

Good news
He has added in an assistant to provide interactive help in setting up repositories. It’s included in debian unstable, in a version released September 24th.
Bad news
I generally prefer using packages from debian testing, and it has a version released July 24th, well before any of this, and without any of Joey’s recent enhancements.

Fortunately, drawing in the September/~unstable~ version isn’t too terribly difficult. My /etc/apt/preferences.d/simple configuration has Pin-Priority values that prefer stable over testing, testing over unstable, and unstable over experimental (where enormous potential for breakage lies!).

As a consequence, installing the testing version is pretty easy, albeit involving an option I had to go looking for:

root@cbbrowne:~# apt-get -t unstable install git-annex
... leads to loading ...
Get:1 unstable/main git-annex amd64 3.20120924 [7,411 kB]

And, with a run of % git annex webapp, it’s up and running!

Syndicated 2012-10-12 15:06:31 from

Netboot via PXE

Netboot via PXE 2012-03-13 Tue

Some notes

To get this to work, you need…

BIOS ROM that supports PXE
True for most modern motherboards and/or NICs
DHCP server
To manage passing out configuration such as IP addresses and the next-server attribute.
TFTP server
With images
It looks for images based on most-to-least specific configuration
  • MAC address
  • IP subnet
  • Default

Some things PXE doesn’t support

It was created as a standard in 1999, and hasn’t been updated much since, so there are things that postdate it, and that are thus not supported.

Likely to be troublesome anyways, as you surely want some authentication to get onto a WIFI network
It wasn’t clear that it yet mattered in 1999…
It works with IP addresses only

DHCP discussion

  • Go look for next-server attribute
  • Some discussion of handling sharing subnets across a redundant set of DHCP servers

More worth looking at

OSS hardware testing tool that’s better than memtest
OSS bootloader
  • Supports DNS, so can forward requests broadly potentially anywhere
  • Can transfer data across additional protocols, such as HTTP, HTTPS, SAN (iSCSI, AoE)
  • Can support WIFI
  • Possibly IPv6

Syndicated 2012-03-14 19:47:00 from

Subversion “deprecation”

I was a bit tickled by the characterization I saw today in the new Subversion release, describing the deprecation of version 1.5:

The Subversion 1.5.x line is no longer supported. This doesn't mean
that your 1.5 installation is doomed; if it works well and is all you
need, that's fine. "No longer supported" just means we've stopped
accepting bug reports against 1.5.x versions, and will not make any
more 1.5.x bugfix releases.

They aren’t telling us the world will end for anyone using version 1.5, just that they don’t intend to provide support anymore.

Which seems like a fine thing. Version 1.5 is 3 years old, and, when they seem to be releasing about a version per year (1.0 in 2004, 1.7 in 2011), 3 years of backwards support doesn’t seem dramatically insufficient. Particularly if, when support goes away, you’re not inherently doomed!

Syndicated 2011-10-11 19:55:00 from

PostgreSQL 9.1 now available

Making for some reasonably good news on 9/11, the next version of PostgreSQL, version 9.1, has been released.

Major enhancements include:

Synchronous replication
continuing the enhancements to built-in WAL-based replication
Per-column collations
to support linguistically-correct sorting down to the column level
Unlogged tables
improving performance for the handling of ephemeral data (e.g. – such as caches)
K-Nearest-Neighbor Indexing
indexing on distances for geographical and text-search queries
Serialized Snapshot Isolation
implementing “true serializability”
Writable Common Table Expressions
recursive and similar queries can now update data
Security Enhanced Postgres
Similar to SE-Linux, providing Mandatory Access Controls for higher grade security
Foreign Data Wrappers
attach to other databases and data sources
managing deployment of additional database features

Many of these continue the trend of continuing to enhance features added in earlier versions (e.g. – synchronous replication, KNN, Writable CTEs)

Some introduce new kinds of functionality (e.g. – SE-Postgres, FDW, Extensions), where new seeds are sown, that we may expect to flower into further new features in future versions.

Syndicated 2011-09-12 17:00:00 from

Music Playing

My latest “musical experiment” is with Clementine, which was recently added to Debian.

I should note things that I have used in the past, and some areas of past pain:

Which has often been nice enough, but which has grown long in the tooth.
Which takes the desirable step of being a client/server system which admits the availability of a bunch of backends. I have, when using it, tended to prefer the shell backend.
An “all singing, all dancing” option…
  • It uses KDE, which I’m historically not terribly keen on
  • It has libraries that are evidently clever enough to pull music off my iPod Touch as long as it’s plugged into a USB dock
  • It has the “KDE integration” that seems to want to have widgets integrating into some “KDE-compliant” window manager. I’m running StumpWM, which is decidedly not a KDE thing, so controlling Amarok always seems like a bit of a crapshoot…
  • I have played a bit with the “playlist” functionality; it hasn’t yet agreed with me…

At any rate, I saw Clementine listed as “new in Debian,” so thought I’d take a peek. I’m liking what I see thus far:

  • Onscreen widgets for all the sorts of things that need to be controlled, including
    • Managing music library, so as to add things
  • Like Amarok, it can see my iPod whenever it’s plugged in, and can play that music through the computer
  • It easily grabbed album covers (I’m not sure what service it’s using) for most of my music
  • Onscreen controls seem pretty reasonable, though I kind of wish the volume control was larger, as that’s something one wants most frequently to fiddle with.
  • There’s a cool visualization widget (think “equalizer”)

Seems pretty likable thus far…

Syndicated 2011-06-15 21:46:00 from

What’s Up Lately With Slony?

What’s up Lately? 2011-04-12 Tue

Git Changeover

In July 2010, we switched over to use Git, which has been working out quite fine so far. The official repository is at; note that some developers are publishing their repositories publicly at GitHub:

You can find details at those “private” repositories of branches that the developers have opened to work on various bug fixes and features.

The next big version

We have been working on what seems most likely to be called the “2.1 release.”

  • There are quite a lot of fixes and enhancements already in place. We have been quite faithful about integrating release notes in as changes are made, so Master RELEASE notes should be quite accurate in representing what has changed. Some highlights include:
    • Changes to queries against sl_log_* tables improve performance when undergoing large backlog
    • Slonik now supports commands to bulk-add tables and sequences
    • Integration of clustertest framework that does rather more sophisticated tests, obsolescing previous “ducttape” and shell script tests.
    • Cleanup of a bunch of things
      • Use named parameters in all functions.
      • Dropped SNMP support that doesn’t seem to run anymore, and which was never part of any regression tests.
  • It is unlikely that it will get dubbed “version 3,” as there aren’t the sorts of deep changes that would warrant such.
    • The database schema has not materially changed in any way that would warrant re-initializing clusters, as was the case between version 1.2 and 2.0.
    • The changes generally aren’t really huge, with the exceptions of a couple features that aren’t quite ready yet (which deserves its own separate discussion)

Still Outstanding

There are two features being worked on, which we hoped would be ready around the time of PGCon 2011:

This feature causes most Slonik commands to wait for whatever event responses should be received before they may be considered properly finished. For instance SUBSCRIBE SET would wait until the subscription has been completed before proceeding.
Multinode FAIL OVER
For clusters where there are multiple origins for different sets, this allows reshaping the entire cluster properly, which has historically been rather more troublesome than people usually were able to recognize.

Unfortunately, neither of these are quite ready yet. It is conceivable that the automatic waiting may be mostly ready, but complications and interruptions have gotten in the way of completion of multinode failover.

When will 2.1 be ready?

Three possibilities seem to present themselves:

  1. Release what we’ve got as 2.1, let the outstanding items arrive in a future version.Unfortunately, this would seem to dictate that we support a “version 2.1″ for an extended period of time, complete with the trouble and effort of backpatching. It’s not very attractive.
  2. Draw in Implicit WAIT FOR EVENT, which would make for a substantially more featureful 2.1, and let multinode FAIL OVER come along later.We had been hoping that there would be common functionality between these two features, so had imagined it a bad idea to do one without the other. But perhaps that’s wrong, and Implicit WAIT FOR EVENT doesn’t need multinode failover to be meaningful. That does seem like it may be true.

    There is still the same issue as with 1. above, that this would mean having an extra version of Slony to support, which isn’t something anyone is too keen on.

  3. Wait until it’s all ready.This gets rid of the version proliferation problem, but means that it’s going to be a while (several months, perhaps quite a few) before users may benefit from any of these enhancements.

    Development of the failover facility seems like it will be bottlenecked for a while on Jan, so this suggests that it may be timely to solicit features that Steve and I might work on concurrently in the interim.

So, what might still go into 2.1?

  • We periodically get bug reports from people about this and that, and minor things will certainly get drawn in, particularly if they represent incorrect behaviour.
  • ABORT scriptI plan to send a note out soon describing my thoughts thus far.
  • Cluster Analysis ToolingI think it would be pretty neat to connect to a Slony cluster, pull out some data, and generate some web pages and GraphViz diagrams to characterize the status and health of the cluster.
  • There was evidently discussion at PGEast about trying to get the altperl scripts improved/cleaned up.My personal opinion (cbbrowne) is that they’re not quite general enough, and that making them so would be more trouble than it’s worth, so my “vote” would be to deprecate them.

    But that is certainly not the only opinion out there – there are apparently others that regularly use them.

    While I’m not keen on putting effort into them, if there is some consensus on what to do, I’d go along with it. That might include:

    • Adding scripts to address slonik features that have not thus far been included in altperl.
    • Integrating tests into the set of tests run using the clustertest framework, so that we have some verification that this stuff works properly.
  • Insert Your Pet Feature Here?Maybe there’s some low hanging fruit that we’re not aware of that’s worth poking at.

Syndicated 2011-04-12 19:26:00 from

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