VoltDB on Windows 10@Docker

VoltDB on Windows 10@Docker
If you look for a truly in-memory open source database then VoltDB might be the only choice available at the moment. Unfortunately, for me, there are no binaries for Windows available as big part of the code was written in C/C++ which is hard to port from Linux to Windows. But there is a way ...

CPU vs GPU in OLAP

Databases on GPGPU are still in a very early stage of development. I would even say that, unless it is top secret, it is rather only a field for academic research at the moment – and that is where we can find the most information about it. Recently I got back to looking for something ...

On Column Sizes

If you just started your adventure with databases you may not pay too much attention do data types. Often reading in the data from a flat file will be so troublesome that you just define column types to be VARCHAR(100) just to have everything read in. Maybe after having the data read you convert some ...

Courses in Databases

I was preparing a post about what can slow down a query, but when I was reading a lot of different stuff online to make sure I am writing truth I encountered several interesting papers, and presentations that I think are worth reading. First of them is a series of presentations regarding Data Processing on ...

Know your database – a complex query

I have seen in my life many people learning SQL without prior understanding how databases work. But there are many crucial things that can make writing queries more fun, if it is not fun enough. Optimization in terms of memory use and execution is one of them. I would even say that is the most ...

In-Memory Bitmap Index in Postgres

I have written twice already that bitmap indexes are not implemented in Postgres. But somebody may as why then explain writes that it used Bitmap Index Scan? However, that is not on-disk index I wrote about. One of the most interesting analysis of performance I found is at Depesz.com, which is a blog of a Polish database ...

FiFO with SQL

I am going to create small system/website that will allow me to manage my stocks, and monitor the portfolio. I do not have much of it, but I cannot access the data from wherever I want and it is not so dynamic. Beside the design itself I came across a problem of recreating a FIFO ...

PGOpenCL – PostgreSQL and GPU

I wanted to play a bit with PostgreSQL and CUDA, but to make it work it would be worth to have both PostgreSQL and sample CUDA program compiled. There are many sources online about integrating PostgreSQL with CUDA, but most of them use outdated CUDA features and are copies one of another. Probably it is ...

BigData (R)evolution

I want to learn some more about the scale, but not scale in general but scaling data storing and processing. Nowadays if you hear about the big data, it often implies hadoop based distributed system. As Yahoo is one of the biggest contributors to Hadoop at the moment, the best tutorial is also on their ...

PostgreSQL 9.3

I did not realize that on my brithday PostgreSQL hit 9.3 mark (see a news). With this release there is a new join type that I first hear about. It is named LATERAL JOIN. There is no need for me to copy the documentation, so if you want to know what that is head to ...

B-tree or Bitmap

Recently I read a lot about databases, mostly theory but also from the design point of view. I have to admit that until recently I had no idea what a B-tree is. I mean beside that it is a kind of a data structure, but how it is build and why on average there is ...

No Duplicates in Subset

Yesterday I was helping a friend of mine with an interesting problem. There is a big table ~4MLN rows, it is wide (has many columns, lets say 30). We are interested in getting rows, which contain duplicates in 5 columns, we do not care what data are in other columns, at least not with regard ...

Adding DSN with VBA

Access is a popular choice for a database GUI. There is no need to know how to connect with a specific database from Access as long as we know how to use an ODBC connection. To make everything fully automated it is even possible to add such a connection with a simple VBA script, maybe ...

Paste Faster into Excel

Excel and Access often do come along. When you have make them work combining one database with dozens of Excel sheets it is necessary to be able to read and write data fast, otherwise it becomes annoying pretty fast. There are several ways to apporach this problem. Reading Excel sheet into Access can be easily ...

Few Words About Indexes

Writing the previous post it came to my mind, that many people may not be aware that using custom functions in WHERE clauses may be the reason why the index is not used. There are several facts about indexes you should keep in mind: index is most often a b-tree, see one of the Princeton’s lectures ...