How does the performance compare to moving these values into their
own table and JOINing on a foreign key?
Gili
On 10/12/2011 8:27 AM, Paigan Jadoth wrote:
Hi
Some two years ago, Thomas kindly answered some questions I had
briefly per mail, among them one about support for BITMAP indices.
My experience from work was back then and still is that BITMAP indices
can provide a tremendous performance boost for data with many rows but
only few distinct values (e.g. a column "month" with 10^5,6,7 rows but
values always between 1 and 12.
Here's a very nice description of the concept in the (otherwise often
fuzzy ^^) documentation of Intersystems Caché:
http://docs.intersystems.com/cache20111/csp/docbook/DocBook.UI.Page.cls?KEY=GSQL_indices#GSQL_indices_bitmap
(btw. we found that BITMAP indices are superior to "normal" indices
for most data that has to be indexed at all and later on, one of
intersys' tech consultants approved that from their point of view)
The answer two years ago was "not yet" (see original german mail
below).
I don't need it "right now", but it might be a major decision aspect
wether to use H2 in our customer projects in the future.
So all I want to ask now is: Is there an interest of putting the topic
on the roadmap for a future version of H2?
Thank you.
Re: Konkreter zu H2
Sat, 30. Jan 2010 16:24:58
[...]
- Bitmap Index: Meiner/unserer Erfahrung in der Arbeit nach ist das eine exzellente
Indexart. Aber ist soweit ich gelesen hab weder in H2 noch auf der Roadmap. Absichtlich
nicht, oder nur "noch"> nicht?
Noch nicht.
Gruss
Thomas
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