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Tuesday, April 19, 2011

HCC compression

In my free time this week I have been playing on the exadata.  The first thing I wanted to determine is the compression ratios for my data, and the select statistics.

One of the first observations I made was how HCC saves you on selects. I took a 158g table from another system, and loaded it up in HCC query mode (I loaded it direct).. the table is now 6g in size.. WOW, but that didn't impress me as much as my select.

First I selected from the table with storage indexes off.  2.02 seconds.. 2.02 seconds ?  1.7 Billion rows that was 158g of data.  wow.

Next I select from the table with storage indexes on. it takes 9.02..  The extra 7 seconds was the exadata building the storage indexes.   Then I select again.  .30 seconds.  No indexes.

I am going to do some more testing.  but this certainly is impressive !!

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