Emergency

Search Results for: disk write

Making “Insert Ignore” Fast, by Avoiding Disk Seeks

In my post from three weeks ago, I explained why the semantics of normal ad-hoc insertions with a primary key are expensive because they require disk seeks on large data sets. Towards the end of …


Making “Replace Into” Fast, by Avoiding Disk Seeks

In this post two weeks ago, I explained why the semantics of normal ad-hoc insertions with a primary key are expensive because they require disk seeks on large data sets. Towards the end of the …


Disk Seeks are Evil, so Let’s Avoid Them, Part 1

Disk seeks are expensive. Typically, a disk can perform no more than a few hundred seeks per second. So, any database operation that induces a disk seek is going to be slow, perhaps unacceptably slow. …


Tokyo Tyrant -The Extras Part III : Write Bottleneck

This is part 3 of my Tyrant extra’s, part 1 focused on durability, part 2 focused on the perceived performance wall. #3.  Tokyo Cabinet Can have only a single writer thread, bottlenecking performance When writing …


SSD, XFS, LVM, fsync, write cache, barrier and lost transactions

We finally managed to get Intel X25-E SSD drive into our lab. I attached it to our Dell PowerEdge R900. The story making it running is worth separate mentioning – along with Intel X25-E I …


How multiple disks can benefit for single client workload ?

Let us talk few more about disks. You might have read my previous post and Matt’s Reply and it looks like there are few more things to clarify and explain. Before I get to main …


Is disk Everything for MySQL Performance ?

I read very nice post by Matt today and it has many good insights though I can’t say I agree on all points. First there is a lot of people out where which put it …


How much overhead is caused by on disk temporary tables

As you might know while running GROUP BY and some other kinds of queries MySQL needs to create temporary tables, which can be created in memory, using MEMORY storage engine or can be created on …


MySQL net_write_timeout vs wait_timeout and protocol notes

In my previous post I mentioned you might need to increase net_write_timeout to avoid connection being aborted and now I think I should have better explained that. MySQL uses a lot of different timeout variables …


Innodb Double Write

One of very interesting techniques Innodb uses is technique called “doublewrite” It means Innodb will write data twice when it performs table space writes – writes to log files are done only once. So why …