The Vertica Database Forums

Posted: **Tue Apr 01, 2014 4:08 pm**

Hi,

My question is kind of related to another topic:

viewtopic.php?f=4&t=1782

My database has ALOT of projection columns with the encoding type AUTO. Is this something I need to be concerned about?

See:

Code: Select all

dbadmin=> select encoding_type, count(*) from projection_columns group by encoding_type order by 2 desc;
  encoding_type   | count 
------------------+-------
 AUTO             | 25475
 RLE              |  1066
 COMMONDELTA_COMP |   308
 DELTAVAL         |    39
 BLOCKDICT_COMP   |    38
 DELTARANGE_COMP  |    36
(6 rows)

Posted: **Tue Apr 01, 2014 4:24 pm**

Not necessarily. With AUTO encoded columns:

For CHAR/VARCHAR, BOOLEAN, BINARY/VARBINARY, and FLOAT columns, Lempel-Ziv-Oberhumer-based (LZO) compression is used.

For INTEGER, DATE/TIME/TIMESTAMP, and INTERVAL types, the compression scheme is based on the delta between consecutive column values.

AUTO encoding is ideal for sorted, many-valued columns such as primary keys. It is also suitable for general purpose applications for which no other encoding or compression scheme is applicable. Therefore, it serves as the default if no encoding/compression is specified.

The CPU requirements for this type are relatively small. In the worst case, data might expand by eight percent (8%) for LZO and twenty percent (20%) for integer data.

However, I would go through the columns with an AUTO encoding type and see if they can possibly be improved to RLE.

See all the encoding types.

The Vertica Database Forums

Is it ok to have a lot of columns that are AUTO encoded?

Is it ok to have a lot of columns that are AUTO encoded?

Re: Is it ok to have a lot of columns that are AUTO encoded?