DevHeads.net

Postings by Aleksey Tsalolikhin

6.3 installer keeps cycling in a 10 second countdown to boot

Hi. I've been running CentOS 5 for ages. (Thanks!)

I went to install 6.3 - I downloaded the 64-bit DVD 1 image, and put
it on a USB drive. Booted into a screen that said boot will start in
10.. 9... 8.. 7.. 6.. 5.. 4.. 3.. 2.. 1.. 10.. and so on, infinite
loop, the boot never starts.

I tried booting in text mode, but it doesn't boot, just goes back to the menu.

Is there some way to find out why the centos installer refuses to start?

I used to have CentOS 5 on this system.

Why do I have holes in my pages?

Why do I have holes in my pages?

Postgres 8.4.12

"select ctid from big_table" on my master shows that pages have
"holes" in them.

Here is example for page 431665:

(431665,2)
(431665,5)
(431665,8)
(431665,11)
(431665,14)
(431665,17)
(431665,20)
(431665,23)

Current DB size is 400 GB and it takes up 2.7 TB (on a 6.6 TB filesystem).

So what happened to rows 1, 3 and 4 and so on?

I have to size a database server for next year's budget, and I will
have to explain to my mgmt why we have 400 GB taking up 2.7 TB.

postgres process got stuck in "notify interrupt waiting" status

Hi.

We use LISTEN/NOTIFY quite a bit but today something unusual (bad) happened.

Number of processes waiting for a lock just started to go up up up.

I finally found the object being locked was pg_listener which
RhodiumToad on IRC kindly informed happens during LISTEN/NOTIFY. The
process that had the lock (in pg_locks it had granted = t ) was shown
by ps in status "notify interrupt waiting" and has had the lock for
over half an hour.

C locale versus en_US.UTF8. (Was: String comparision in PostgreSQL)

On Wed, Aug 29, 2012 at 9:45 AM, Merlin Moncure < ... at gmail dot com> wrote:
What is the difference between C and en_US.UTF8, please? We see that
the same query (that invokes a sort) runs 15% faster under the C
locale. The output between C and en_US.UTF8 is identical.

how to amend SQL standard to add comments?

Hi. Does anybody here know how to add comments to the SQL standard?
I believe this would benefit lots of people.

Situation: When a system administrator or database administrator looks at
a gnarly SQL query chewing up system resources, there is no way to tell
by looking at the query server-side which application it came from, what its
purpose is, and who the author or responsible party is.

Data: in ANSI SQL standard, you can put single-line comments by preceeding
the line with a double-hyphen. These comments will be thrown away by the
database client and the server will never see them.

nice'ing the postgres COPY backend process to make pg_dumps run more "softly"

Hi. When pg_dump runs, our application becomes inoperative (too
slow).

A 154 GB table swelled to 527 GB on the Slony slave. How to compact it?

We're replicating a PostgreSQL 8.4.x database using Slony1-1.2.x

The origin database "data/base" directory is 197 GB in size.

The slave database "data/base" directory is 562 GB in size and is
over 75% filesystem utilization which has set off the "disk free" siren.

My biggest table* measures 154 GB on the origin, and 533 GB on
the slave.

phantom long-running query (check_postgres.pl reports a long-running query, but the database logs don't show it)

I got an alert from check_postgres.pl today on a long-running query on
our production database, but our PostgreSQL 8.4.9 server log, which is
configured to log queries over 5 seconds long
("log_min_duration_statement = 5000") does not show the query.

check_postgres.pl showed:
Date/Time: Wed Feb 8 08:41:36 PST 2012
POSTGRES_QUERY_TIME WARNING: (host:xxx) longest query: 264s
(database:xxx PID:xxx port:xxx address:xxx username:xxx)

postgres log showed other long-running queries, but nothing over 48s.

It's really interesting why the database server log does not show this query.

Can you think o

pg_dump does not include triggers - should it?

Hi,

We are using Postgres 8.4.8 and it is a very fine database.

We just noticed our pg_dumps (generated with
"pg_dump -Fc -n public $our_db_name") does not
include triggers on tables in database $our_db_name.
Should it? (We'd like it to, we are counting on pg_dump to
backup all our data, including the triggers.)

Thanks again for a great product!

Best,
-at

Installing yesterday's CentOS (or how to install the patch/package set from 3 weeks ago)

Hello,

Let's say your operating policy is "no patch updates without testing
first in the test environment". Let's say it takes you 3 weeks to
test.

How to update CentOS 5.4 to 5.6?

Is there a way to update a CentOS 5.4 server to 5.6 (but not 5.7)?

"yum update" takes me all the way up to 5.7.

Best,
-at

multi-master replication (Was: Has Pg 9.1.0 been released today?)

On Tue, Sep 13, 2011 at 6:55 PM, Joshua D. Drake < ... at commandprompt dot com> wrote:
Thank you Joshua, I just took a look at Postgres-R. FAQ states "Can I
use Postgres-R in a productive environment? Not yet, sorry." I'm a
production line sys admin so I can't touch it yet.

How did I get 8 Exclusive locks on the same table? And how many locks is too many?

Hi,

We use the fine Bucardo check_postgres Nagios plugin,
and it reported a "CRITICAL" level spike in database locks
(171 locks).

I looked closely at my database logs and found an even bigger spike
just a few minutes earlier (208 locks).

I saw 8 EXCLUSIVE locks on table X. All of these queries completed
within 5 seconds.

How to set selinux policy "allow httpd_t unconfined_t:shm { unix_read unix_write }; " using an seboolean? (How to get a new seboolean?)

Hi. I'm trying to get OTRS running on CentOS 5.5 with SELinux enabled,
and audit.log / audit2allow tell me I need to add the local policy:

#============= httpd_t ==============
allow httpd_t unconfined_t:shm { unix_read unix_write };

which I think will allow the httpd access to read and write from shared memory?
Is that right? What are the risks involved in opening this? I notice it is
denied by the default policy.

To simplify configuration management, I would prefer to make this setting
using /usr/sbin/setseebool, but I don't see an sebool that deals with shm...

How do I request one?

Why is iptables configured to accept packets on ports 50 and 51?

[root@hwdltsaloli ~]# cat /etc/sysconfig/iptables
# Firewall configuration written by system-config-securitylevel
# Manual customization of this file is not recommended.
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:RH-Firewall-1-INPUT - [0:0]
-A INPUT -j RH-Firewall-1-INPUT
-A FORWARD -j RH-Firewall-1-INPUT
-A RH-Firewall-1-INPUT -i lo -j ACCEPT
-A RH-Firewall-1-INPUT -p icmp --icmp-type any -j ACCEPT
-A RH-Firewall-1-INPUT -p 50 -j ACCEPT
-A RH-Firewall-1-INPUT -p 51 -j ACCEPT
-A RH-Firewall-1-INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A RH-Firewall-1-INP

How can you have an Exclusive Lock on nothing? please help me understand this lock monitoring query output

Hi. I use the following query (from
<a href="http://wiki.postgresql.org/wiki/Lock_Monitoring" title="http://wiki.postgresql.org/wiki/Lock_Monitoring">http://wiki.postgresql.org/wiki/Lock_Monitoring</a>)
to monitor locks; and I've got an ExlusiveLock that does not have a relation
name associated with it. What is locked with the Exclusive Lock in this case,
please?

pg_dump makes our system unusable - any way to pg_dump in the middle of the day? (postgres 8.4.4)

I read in the pg_dump man page that pg_dump does not block other users
accessing the database (readers or writers).

In practice, if I pg_dump our 100 GB database, our application, which
is half Web front end and half OLTP, at a certain point, slows to a
crawl and the Web interface becomes unresponsive. I start getting
check_postgres complaints about number of locks and query lengths. I
see locks around for over 5 minutes.

I've had to abort pg_dump as it made the system unusable.

Can I pg_dump without breaking the system?

Best,
-at

How much maximum memory will CentOS 5 support? I know it's not 16 GB!

How much maximum memory will CentOS 5 support, please?

The product info page at <a href="http://www.centos.org/product.html" title="http://www.centos.org/product.html">http://www.centos.org/product.html</a>
says 16GB, but I am running 80 GB RAM right now and seeing
80 GB in top.

I see the same 16 GB limit on the RHEL page:
<a href="http://www.redhat.com/rhel/compare/#note_4" title="http://www.redhat.com/rhel/compare/#note_4">http://www.redhat.com/rhel/compare/#note_4</a>

The server hardware is capable of 192 GB RAM and I want to
add memory, but want to be sure the OS will support it.

Is anybody running CentOS 5 or RHEL 5 with 192 GB or more, please?

Best,
-at

database is bigger after dump/restore - why? (60 GB to 109 GB)

Hi. Last week our 60 GB database (per psql \l+) was (re-)replicated to
the DR site using SlonyI, and arrived 109 GB in size which caused a
problem as it filled up the filesystem on the DR server - we expected the
DR database to be the same size.

Why does my DB size differ between Production and DR? (Postgres 8.4)

utilization (80 GB used), on DR is at 51% (56 GB used). We use
SlonyII-1.2.x to keep the DR up to date. I would like to account for
the 24 GB difference.

Symptoms:

1. Database size reported by psql c '\l+'

Production: 52 GB

DR: 30 GB

Difference: 22 GB

2.

How to strip out the title bar from xterm windows on CentOS 5 GNOME?

Hi. Running CentOS 5 with the default GNOME desktop.

feature request: log bytes out for each request

Hi. Could you please consider logging size of reply, like Apache
httpd does with its logfile?

We've started having intermittent spikes in network usage (the network
interface on the
DB server is getting maxed out) and I suspect there is a single very
large query (just a
working hypothesis at this point).

Logging of answer sizes would help track down an issue like this; plus
you could track
on an ongoing basis how much work you're doing, which may be useful for capacity
planning.

Thanks for a great database server!

Kind regards,
Aleksey

can't install mono-devel because mono-basic requires mono-core. But I have mono-core! What to do? I need gmcs.

Hi. I'm trying to install gmcs so that I can build gbrainy, a mental exerciser.

I am not sure what package provides, maybe mono-devel? however mono-devel
fails to install because, it says, mono-basic requires mono-core. I
have mono-core
installed.

pdflush kernel thread pops up every 10 seconds or so and video decoding grinds to a halt for 1/2 a second

Hi. A friend of mine was doing real-time video decoding on
Fedora Core 13 and he had a performance glitch (1/2 a second
freeze) every 5-10 seconds. "top" showed flush-253:0
process at the moment of the freeze.

Major device number 253 corresponds to device-mapper. I advised my
friend to re-install his FC13 without LVM, to see if the glitch
is related to LVM.

After re-installing FC13 without LVM, he is seeing the glitch
every 10 seconds, and it shows flush-8:16 where before it said
flush-253:0. 8 is scsi disk driver.

flush kernel thread pops up every 10 seconds or so on FC13 and video decoding grinds to a halt for 1/2 a second

Hi. A friend of mine was doing real-time video decoding on
Fedora Core 13 and he had a performance glitch (1/2 a second
freeze) every 5-10 seconds. "top" showed flush-253:0
process at the moment of the freeze.

Major device number 253 corresponds to device-mapper. I advised my
friend to re-install his FC13 without LVM, to see if the glitch
is related to LVM.

After re-installing FC13 without LVM, he is seeing the glitch
every 10 seconds, and it shows flush-8:16 where before it said
flush-253:0. 8 is scsi disk driver.

Who maintains php-pgsql package? I want to ask about using PostgreSQL 8.4 library instead of PostgreSQL 8.1.

How do I find out who is the maintainer of the php-pgsql package, please?
I want to request upgrade from underlying postgresql-libs-8.1.21
(/usr/lib64/libpq.so.4) to postgresql84-libs-8.4.4 (/usr/lib64/libpq.so.5.2).

Background on this request: Apache httpd's php's php-pgsql uses
PostgreSQL 8.1 library (/usr/lib64/libpq.so.4), which leaks memory.
PostgreSQL 8.4 library does not leak.

Apache HTTP Server: httpd-2.2.3-43.el5.centos.3

mod_php: php-5.1.6-27.el5

PHP PostgreSQL interface is provided by: php-pgsql-5.1.6-27.el5,
which uses postgresql-libs-8.1.21-1.el5_5.1 which provide

system "stuck" with 2.6.18-128 kernel. how to move to 2.6.18-194.17?

Hi. I just noticed I had a CentOS 5.3 system that I updated to CentOS
5.5 a few days ago,
and I just ran "yum -y update" again to get the latest kernel, and I
just noticed it still has the old 2.6.18-128 kernel instead of the new
2.6.18-194.17.

How to see what SQL queries are associated with pg_locks?

How to see what SQL queries are associated with pg_locks, please?

Could somebody help with the query? I can then add it to
<a href="http://wiki.postgresql.org/wiki/Lock_Monitoring" title="http://wiki.postgresql.org/wiki/Lock_Monitoring">http://wiki.postgresql.org/wiki/Lock_Monitoring</a>

Best,
-at

ERROR: cache lookup failed for type 14237017

Yesterday, I had twelve thousand "cache lookup failed for type N"
messages, like this:

2010-09-20 00:00:00 PDT ERROR: cache lookup failed for type 14237017
2010-09-20 00:00:00 PDT CONTEXT: SQL statement "INSERT INTO
mycluster.sl_log_2 (log_origin, log_xid, log_tableid, log_actionseq,
log_cmdtype, log_cmddata) VALUES (1, $1, $2,
nextval('mycluster.sl_action_seq'), $3, $4);"

The context is always Slony sl_log_2 table. All twelve thousand
errors occurred within 40 minutes. This did happen right after a
Slony cluster set drop and recreate.

What does "type 14237017" mean?