Fix by doing the following:

ntpdate ntp.nasa.gov > /dev/null

Kristian Koehntopp gives a good example:

Kristian Koehntopp writes:

TDS: Time delayed SQL_THREAD (Have a replication slave that is always
lagging 30 minutes behind).

Currently, replication is a rolling recovery: To set up replication you
restore from a full dump with a binlog position. You then continously
download binlog and roll forward. In case of a master crash a slave is a
readily recovered instance (as opposed to a backup, which still has to be
restored).

This protects against crashes, but not against oopses.

A time delayed slave (TDS) is a nice protection against oopses.

Sugar on top addendum: With the binlog being a table, any table type,
it will be very easy to delete an oopsing statement out of the
unapplied binlog queue. Currently, a simple time delayed slave will
protect you against oopses, but it will be very hard to extract the
relevant binlog portion out of the TDS replication log skipping the
oopsing statement.

With a MyISAM binlog table, it is just a matter of DELETE FROM
REPLICATION.BINLOG WHERE STATEMENT_ID = 1717;

Definately a cool idea. Instead of having to restore from a backup, you just take down your master, pull out the busted query, let the server catch up, and bring the slave up as the new master. Doing a restore from our current database backups takes about 3-4 hours, and we’re not even huge. It seems like your downtime here would be limited to however long it takes your slave to catch up. Additionally, once you take down your master and remove your bogus query (truncate table perhaps?) you can allow the slave to replicate everything and catch up (no longer limited to 30 min behind, ideally). Depending on your traffic, this could limit your downtime in the case of a catastrophic loss to 20 minutes or so instead of hours, and your data loss would be far less.

find . -name ‘*.php’ -exec wc -l {} \; | awk ‘{ SUM += $1 } END {print SUM}’

The downside to this is that it includes whitespace and braces as lines, as well as comments. Oh well. It’s a good approximation.

Edit: There are 172,189 lines of code in phpbb3.

Then I discovered ctags. I set up a cron on my PHP dev site to rescan my dev folder once an hour. BBEdit automatically discovered my ctags file and gave me the definitions right a right click.

Ctags is available through yum (yum install ctags).

ctags –languages=php –recurse=yes

It looks like the load balancer will automatically pull slaves out if they fall behind, and route connections to the ones that are the most up to date. It is based on MySQL Proxy, which is currently in Alpha.

MySQL Load Balancer

Edit: this is actually a reoccurring bug we’re seeing with the memcache 2.2.3 stable build on 2 different boxes
2nd Edit: Actually it was a bug in my code. I wasn’t setting the server and ip correctly, there was a typo in my configuration

php> echo urlencode(”test@str!ngw!th0u7\n”);
test%40str%21ngw%21th0u7%0A
php> echo urlencode(”test@str!ngw!th0u7″);
test%40str%21ngw%21th0u7

Basically, I’d recommend calling a trim() on any results you get back, unless you love newlines at the end for some reason.

My favorite awk tutorial ever.

Bruno Rodrigues Silva wrote:
> Dear all.
>
> The MySQL Manual inform that Decimal Data Type is used
> for represent exact-number, but like Float Point Data
> Type, Decimal use rounding case the fractional part is
> not sufficient. Therefore, what the difference?

Hi Bruno,

FLOAT rounds as floating point and DECIMAL rounds as you would expect it
to. Floating point arithmetic is not exact and that’s why they’ve called
DECIMAL an “exact packed decimal number” because apparently you can rely
on it’s roundings.

The primary use for DECIMAL is money, where floating point would fail
miserably and produce lots of errors (money leak) at the end of the month.

As floating point arithmetic has it’s own separated section on your
processor (unless you have a 386 or older computer) it would be *much*
faster than DECIMAL, so use it only if you are absolutely sure you need it.

cheers,
–renato

Not exactly breaking news, but I had never looked at decimal very closely. Good to know.

/usr/bin/ld: cannot find -lexpat

Now, while I can do some things on that a sys admin can, I am by no means a sys admin. I have only installed svn a handful of times, and I didn’t know what this was.

First I installed expat from source. It didn’t help.

I then installed apr and apr-util. Didn’t help. I probably needed to follow these instructions.. but I didn’t.

Libraries have been installed in:
/usr/local/apr/lib

If you ever happen to want to link against installed libraries
in a given directory, LIBDIR, you must either use libtool, and
specify the full pathname of the library, or use the `-LLIBDIR’
flag during linking and do at least one of the following:
- add LIBDIR to the `LD_LIBRARY_PATH’ environment variable
during execution
- add LIBDIR to the `LD_RUN_PATH’ environment variable
during linking
- use the `-Wl,–rpath -Wl,LIBDIR’ linker flag
- have your system administrator add LIBDIR to `/etc/ld.so.conf’

Decided I don’t care anymore about trying to figure out why it wasn’t working and just got the subversion dependencies from their site, untarred them into the svn folder as recommended. Everything compiled without issue.

On the make install, I got this:

/usr/local/src/subversion-1.4.6/subversion/svnversion/.libs/lt-svnversion: error while loading shared libraries: /usr/local/src/subversion-1.4.6/subversion/libsvn_delta/.libs/libsvn_delta-1.so.0: cannot restore segment prot after reloc: Permission denied
make: *** [revision-install] Error 127

Googling that error got me to this site, where it suggested SELinux might be breaking it. I disabled it and rebooted the machine. The install proceeded without issue at this point.