If you are importing large CSV or SQL dumps to MySQL, chances are you were looking for ways to see how far the import has gone. If you know how many rows there are from the file being imported, you can do a SELECT COUNT(*) but that would take sometime for the query to finish especially on really big imports.

Using lsof, you can monitor the current file offset to which a process is reading from using the -o option. Knowing the size of the file and some snapshots of the offset, you can get a somewhat rough idea of how fast the import goes. Note though that this is only file-read-pace not actual import speed as MySQL import can vary depending on a number of conditions i.e. table growth, secondary indexes, etc.

Let’s say I am importing a 1.1G CSV file into a table.

[revin@forge msb_5_5_300]$ ls -al /wok/dta/samples/ft_history.csv 
-rw-rw-r--. 1 revin revin 1075456654 Nov 8 23:25 /wok/dta/samples/ft_history.csv …

A special extended edition of Tech Messages for 2013-03-07 through 2013-03-10:

• http://eyeseast.github.com/python-tablefu/
  Really looking forward to trying this out. Anyone interested in weighing in with their experiences?
• How to selectively kill queries in MySQL? — dba square | A resource on MySQL
  Especially helpful when you have hundreds of queries that need to die.
• Redis with an SSD swap, not what you want - Antirez weblog

Two cons against NoSQL data stores read like this: 1. It’s very hard to move data out from one NoSQL to some other system, even other NoSQL. There is a very hard lock in when it comes to NoSQL. If you ever have to move to another database, you have basically to re-implement a lot [...]

Recently, I found myself needing MariaDB 5.1.60 for Windows for some testing purposes. Therefore, I needed to build it from source. I ended up using what I’d call a “blend” of the commands listed in this “how-to” and the readme file INSTALL-WIN-SOURCE, so I thought I’d post those steps.

1. Download 5.1.60 MariaDB source from here.

2. cd C:\mariadb-5.1

3. win\configure.js

4. cmake .

5. VS: File -> Open -> Solution -> MySql.sln
6. VS: Build -> Build Solution
7. VS: Right-click “PACKAGE” -> Build (in “Solution Explorer” View)

That’s it.

Let’s fire it up:

MariaDB> select version(); …

A comma-separated values (CSV) file is a simple file format that is widely supported, so it is often used to move tabular data between different computer programs that support the format. CSV file is a text format for a database table. Each record in the table is one line of the text file. Each field value of a record is separated from the next with a comma. For example, a CSV file might be used to transfer information from a database to a spreadsheet or another database. Of course, there are more advanced formats to store data, for example, XML, but CSV does have one advantage over XML. CSV has much lower overhead, thereby using much less bandwidth and storage than XML.

Now let’s analyse how one can save data from a MySQL table to a CSV file.

The first and very likely the easiest way is to change Storage Engine to CSV and save it to some archived file …

In this article we describe benefits and shortcomings of different ways of exporting data from a MySQL table to the CSV format.

MySQL keeps many different files, some contain real data, some contain meta data. Witch ones are important? Witch can your throw away?

This is my attempt to create a quick reference of all the files used by MySQL, whats in them, what can you do if they are missing, what can you do with them.

When I was working for Dell doing Linux support my first words to a customer where “DO YOU HAVE COMPLETE AND VERIFIED BACKUP?” Make one now before you think about doing anything I suggest here.

You should always try to manage your data through a MySQL client.  If things have gone very bad this may not be possible. MySQL may not start. If your file system get corrupt you may have missing files. Sometimes people create other files in the MySQL directory (BAD).  This should help you understand what is safe to remove.

Before you try to work with one of these files make sure you have the file permissions set …

In database modeling, a m:n relationship is usually resolved by an additional table. But what if this relation is used only for archiving and the number of links in the resulting table is not too high? In that context, I got the idea to store all referring ID's as CSV string directly into a TEXT column of one of the referring tables. I came to this idea, because otherwise I would have to build complicated foreign keys and this way I also save one additional table. Certainly, this only makes sense if the data is not frequently accessed as foreign key. Nevertheless, I would like to tackle the problem, even if the implementation is very MySQL-oriented.

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If your MySQL server has hundreds of clients (applications) and tens of thousands of queries per second,  MySQL default network settings may NOT be for you.  Network performance is not often a significant factor in the performance of MySQL.  That said, there are things to consider.

If you are building new applications make these changes now.  Developer expectations are hard to change.  My example below will break your application if  developers open a database connections and then spend ten minutes playing with their play doe before making a query.  If you have working applications …

As most of MySQL users, I have often ignored what I'd like to call the minor storage engines. MYISAM, InnoDB and NDB (aka MySQL Cluster) are well covered in several articles; but what about engines like CSV or ARCHIVE? As part of some internal projects, we have been playing around with these 2 with some interesting results. On this article I'll concentrate on CSV.
ScenarioCurrently we have a few servers that are storing historical data that will eventually be migrated into Oracle. Two things need to happen until we can finally decommission them: 1) export the data to CSV so it can be imported in bulk into Oracle and 2) keep the data online so it can be queried as needed until the migration is finalized. I thought it would be interesting if we could solve both issues simultaneously and decided to try the CSV engine. Here's a description of the process.
Understanding CSV EngineThe CSV engine, as far as I can tell, was and example …