Projection encoding possibilities

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Projection encoding possibilities

Post by nnani » Tue Apr 01, 2014 7:22 am

Hello All,

Had some of question regarding encoding type with respect to types of projection.

Want to know, how does Vertica behave in every of these scenarios

1. Create a table with encoding type..It creates projection with encoding type specified
2. Create a table without encoding type .. Does it create a super projection with encoding type as AUTO(if no type specified), Why does it not give encoding type on its own.
2. Create custom projection after already existing super projections. Does custom projection copy column encoding ?
3. use a CTAS query and create a new table..Does new projection copy column encoding from previous projections
4. using Like keyword with "including projections" ..Does the new projection copy column encoding from previous table

I am seeing many of my super projections having column encoding as AUTO..which I think Vertica should automatically comeup with the encoding types.

Also is there any relation of the column encoding with create type of projection (delayed creation, create table with PROJ clause)

According to previous versions Vertica would suggest the encoding type automatically if no encoding is specified, Is there some change in this behavior.
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Re: Projection encoding possibilities

Post by NorbertKrupa » Tue Apr 01, 2014 1:30 pm

When you first create a table and load data into it, Vertica will use a sample of that data to come up with a guess on the encoding. You would run database designer to get a better encodings on your projection.

By CTAS I'm guessing you mean CREATE TABLE AS. If you're using database designer for additional projections, it doesn't copy the super projection column encodings. Otherwise, the projection gets created when data is first loaded in if one has not yet been defined.
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