Column groups
Warning
Supported only for row-oriented tables. Support for column-oriented tables is currently under development.
Columns of the same table can be grouped to set the following parameters:
DATA
: A storage device type for the data in this column group. Acceptable values:ssd
,rot
.COMPRESSION
: A data compression codec. Acceptable values:off
,lz4
.
By default, all columns are in the same group named default
. If necessary, the parameters of this group can also be redefined.
Example
In the example below, for the created table, the family_large
group of columns is added and set for the series_info
column, and the parameters for the default group, which is set by default
for all other columns, are also redefined.
CREATE TABLE series_with_families (
series_id Uint64,
title Utf8,
series_info Utf8 FAMILY family_large,
release_date Uint64,
PRIMARY KEY (series_id),
FAMILY default (
DATA = "ssd",
COMPRESSION = "off"
),
FAMILY family_large (
DATA = "rot",
COMPRESSION = "lz4"
)
);
Note
Available types of storage devices depend on the YDB cluster configuration.