Hi there ,
I read your thread discussion Jan and it is certainly very interesting to
me.
There are though a couple of areas where I would (oh shit you wrote this
email in 1999, I hope you are still there anyway ..) be rather skeptical,
and these are:
Facts:
- An average DW will contain an average of 500Gb this could be in turn
around 7000.000.000 rows
- An average fact table will contain around 30Gb --> 400.000.000 rows
- There will be cases where a DW will go above 1Tb = 1000Gb
The way traditional RDBMS systems deal with this is:
1) Partitioning
There are systems like Teradata whose architecture is designed to be
able to hold as much data as needed without degradation, based on
multiprocessors and multidisks
and parallel IO/ parallel processing
In other databases like Oracle you have database level partitioning
where a big table of 30Gb could be partition by month in chunks of up to
500Mb, each one of these chunks is got associated a different data file
Note that partitioning will be fundamental for performance on the
loading, querying, backing up and archiving data
what is the support for Partitioning in mySql if any?
2) Indexing
MySql supports indexing but it just supports a class of indexing
(B-tree indexign), what about hash and bitmaps, those are very useful in
certain type of queries
3) What is the performance on loading and backup procedures in mySql?
I see mySql with very good potential to grow in the Dw arena, where no
referential integrity is needed ... (why should we need triggeres and so on
, they will slow down the queries), but there is key lack - support for
partitioning
Cheers
Oscar
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