dbanalyzer output/optimization

Hi all, 

We have a database instance that has recently grown to around 9Gb in size. We 
recently encountered some performance issues. This mail is about suitable 
strategies to address this issue. 
*We have started adding indexes, but are not quite sure how to optimize them in 
terms of using UNIQUE, multitable indices. Does anyone have a link to a 
suitable tutorial?
*Is there a recommended size for each data volume file? For us each data volume 
is 200Mb. Ram is 1Gb.
*what should the 'data cache' be set to? The default is 10000. I increased it 
to 15000 and performance increased dramatically! Very impressive! Any general 
tips?


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Your documentation page about 'Tips on database design' 
(http://dev.mysql.com/doc/maxdb/en/45/f31c53e95511d5995d00508b5d5211/content.htm)
 covering amongst other things indexing and sql statements mentions:
'Before you define your tables, examine the structures and use the results in 
your table definitions.  When you define the key columns, ensure that any 
especially selective columns, and any columns for which search conditions are 
specified particularly often, are placed at the "beginning of the key". This 
gives the system the option of considering only a very small part of the table 
when processing a SELECT statement.'

In this paragraph, what does 'beginning of the key' mean? Could anyone 
exemplify this?

Similarly in paragraph:
'Only columns with as high a selectivity as possible "should be inverted". Do 
not choose columns such as gender or marital status as index keys, due to their 
low number of different values. These columns can only be used very rarely for 
a non-sequential search, since these searches would usually be more costly than 
a sequential search.'

In this paragraph, what does a column 'being inverted' mean? Could anyone 
exemplify this?

Many thanks for your help.
Regards
Jon Loken




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