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how to create index on table

by wei su » Wed Dec 02, 2015 11:12 pm

recently I need to do some research on kognitio.
I trying to run the sql "CREATE COMPRESSED INDEX "A" ON " tableA"("COL")"
it always return with this kind of error "42000 [Kognitio][WX2 Driver][kognitio81a.test.tsi.lan:6550] CI2013: Expected ON at or near ", offset 26 "CREATE COMPRESSED INDEX "-->"<--"
"
but don't know why?

I have some question:
1. dose kognitio support "create index"? or does it have to like "create comressed index"?
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Re: how to create index on table

by markc » Thu Dec 03, 2015 9:18 am

If you look at the Kognitio documentation (see http://www.kognitio.com/forums/viewtopic.php?t=3), you can find the correct syntax for CREATE COMPRESSED INDEX / CREATE COMPRESSED DATA MAP (index/data map mean the same thing here).

Specifically, chapter 9 of the Kognitio Guide explains what compressed data maps are, and when they are useful.

As Kognitio is an in-memory product, normally you would load the relevant images into RAM and not use any indices from then on. So there is no "CREATE INDEX" command.
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Re: how to create index on table

by skkirkham » Thu Dec 03, 2015 10:45 am

Hi

I thought it might be also worthwhile mentioning that in order to get great performance out of Kognitio you should be looking to pin the data you are reporting off in memory. When working with Kognitio and Tableau I always look to put all the data used by the workbooks or dashboards into RAM. The basic syntax to do this is

Code: Select all

CREATE TABLE IMAGE MySchema.MyTable
or

Code: Select all

CREATE VIEW IMAGE MySchema.MyView

The use of images renders the use of compressed indexes largely unnecessary. Unless your object is too big to fit in RAM they would only be used in the creation of the images themselves.

The syntax above is good enough to get you start with memory imaging but there is much more information on syntax for creating images in the Kognitio SQL guide section 1.3. For a more detailed explanation refer to section 2 in the Kognitio Guide. Both of these are included in the latest documentation available to download in pdf format here.

Regards
Sharon
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Re: how to create index on table

by wei su » Thu Dec 03, 2015 6:02 pm

thanks guys for quick response.
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