A long time ago, in the early 1980's, I decided to change jobs. I was a young guy, with no real experience of commercial software or anything like that, rather I was a self-taught sysadmin for an ancient UNix system. The company I worked for was in the Telco business, so I looked for another job where I could develop myself and at the same to use my telco knowledge.

I found a Telco startup, privately held. I must say that the fact that it was privately held meant nothing to me at the time. Nothing. They were building a system, the servers were VAXes running VMS, and again a became a sysadmin.

Having been sysadmin at this company for a while, building up the central datacenter (to be honest, in todays words, that was what I was doing, but at the time, I had no real clue. I was mosr enthusiastic and ready to take on any task than I was smart or intelligent or knew what I was doing, really). But I wanted to develop myself, …

In MySQL, even though the name read_buffer_size implies that the variable controls only read buffering, but it actually does dual purpose by providing  sequential IO buffering for both reads and[...]

A couple of question I get a lot from MySQL customers is “how will this hardware upgrade improve my transactions per second (TPS)” and “what level of TPS will MySQL perform on this hardware if I’m running ACID settings?” Running sysbench against MySQL with different values for per-thread and global memory buffer sizes, ACID settings, and other settings gives me concrete values to bring to the customer to show the impact that more RAM, faster CPUs, faster disks, or cnf changes have on the server. Here are some examples for a common question: “If I’m using full ACID settings vs non-ACID settings what performance am I going to get from this server?”

Let’s find out by running sysbench with the following settings (most are self explanatory – if not the man page can explain them):

• sysbench –test=oltp –db-driver=mysql –oltp-table-size=1000000 –mysql-engine-trx=yes –oltp-test-mode=complex …

The need: Often there is a requirement where data in a particular table has to be processed, and the data processing might be slow, while the table might be a one that is used by your application extensively. For example, a logging table that logs page hits. Or there might be an archiving operation that has to be performed on a particular table. Archiving / processing / aggregating records, all these operations are slow and can really blog down a website, combine that with the added overhead if the table that needs to have these operations performed is one that...

Does having small data-sets really help? Of course it does! Are memory lookups faster that disk lookups. Of course ! So many times I have seen people complain about queries taking too long now, while they were not taking that long earlier. There is one big reason for this, earlier the size of data-set was small so it could fit into memory. Now that the data-set has grown large enough that it cannot fit entirely into memory, the disk seeks really have slowed down the queries significantly. What to do now? Vertical partitioning. Divide the data-set into separate data-sets vertically....

If you have any open transaction(s); and if there is any statement that causes implicit commit, especially DDL statements; then the current active transaction will be committed and transaction will[...]

With the exception of Windows InnoDB has used ’simulated AIO’ on all other platforms to perform certain IO operations. The IO requests that have been performed in a ’simulated AIO’ way are the write requests and the readahead requests for the datafile pages. Let us first look at what does ’simulated AIO’ mean in this context.

We call it ’simulated AIO’ because it appears asynchronous from the

Today morning, we had a weird issue in one of the staging OLAP server (ETL); where all the InnoDB threads were locked and waiting on a signal condition for about[...]

Everybody working on Unix or in the database world stumbles over Oracle Berkeley DB every now and then. DB is an Open Source embedded database used by applications like OpenLDAP or Postfix. Traditionally it followed mostly a key-value access pattern. Now what caught my attention was the fact that the recently released DB 5.0 provides an SQLite-like C API with the promise of providing better concurrency and performance than regular SQLite. Time to give it a shot.

So I grabbed the source distribution, checked the documentation and saw that I shall use the …

Prologue: Long back there were golden days of post graduation in the “great” DDIT (Now Dharamsinh Desai University), Nadiad. Assignments, termwork and journals or everything similar was in demand – I attempted a java code as my termwork on Monday, October 03, 2005. [That’s created date of .java file, I don’t remember anything.] A “variable […]