# Characteristics of Vertica projections based on 9.1 and 9.2 version?

Select three characteristics of Vertica projections.

A

Each projection contains all rows from the anchor table.

A projection can contain a subset of columns from the anchor table.

A projection can contain data from one or more anchor tables.

B

A projection can contain a subset of rows from the anchor table.

Each projection contains all columns from the anchor table.

A projection can contain data from one or more anchor tables.

C

Each projection contains all columns from the anchor table.

A projection can contain data from one or more anchor tables.

Each projection contains all rows from the anchor table.

D

A projection can contain a subset of columns from the anchor table.

A projection can contain data from only one anchor table.

Each projection contains all rows from the anchor table.

## Answers

Looks like a question off of the Vertica Certification Exam!

This question is available in Vertica academy > Projections course.

The answer is D in this case.. i.e.

1. A projection can contain a subset of columns from the anchor table.

2. A projection can contain data from only one anchor table.

3. Each projection contains all rows from the anchor table.

No question about first point.

From 9.2 onwards perspective pre-Join projections are not supported so good with second point as well.

The third point talks about all rows from the anchor table, but Top K projection does not contain all the rows from the table.

@ersaurabhex - Per you comments (in which I agree) the answer to the question is:

E. None of the above

I remember taking the exam back in 2011 and I questioned these types of questions. I found out the exam at that time was written by a non-technical person and that lead to the inconsistencies.