CREATE FLEXIBLE TABLE

Creates a flexible (flex) table in the logical schema.

Creates a flexible (flex) table in the logical schema.

When you create a flex table, Vertica automatically creates two dependent objects:

  • Keys table that is named flex-table-name_keys

  • View that is named flex-table-name_view

The flex table requires the keys table and view. Neither of these objects can exist independently of the flex table.

Syntax

Create with column definitions:

CREATE [[ scope ] TEMP[ORARY]] FLEX[IBLE] TABLE [ IF NOT EXISTS ]
   [[database.]schema.]table-name
   ( [ column-definition[,...] [, table-constraint ][,...] ] )
   [ ORDER BY column[,...] ]
   [ segmentation-spec ]
   [ KSAFE [k-num] ]
   [ partition-clause]
   [ {INCLUDE | EXCLUDE} [SCHEMA] PRIVILEGES ]
   [ DISK_QUOTA quota ]

Create from another table:

CREATE FLEX[IBLE] TABLE [[database.]schema.] table-name
   [ ( column-name-list ) ]
   [ {INCLUDE | EXCLUDE} [SCHEMA] PRIVILEGES ]
   AS  query [ ENCODED BY column-ref-list ]
   [ DISK_QUOTA quota ]

Parameters

For general parameter descriptions, see CREATE TABLE; for parameters specific to temporary flex tables, see CREATE TEMPORARY TABLE and Creating flex tables.

You cannot partition a flex table on any virtual column (key).

Privileges

Non-superuser: CREATE privilege on table schema

Default columns

The CREATE statement can omit specifying any column definitions. CREATE FLEXIBLE TABLE always creates two columns automatically:

__raw__
LONG VARBINARY type column to store unstructured data that you load. By default, this column has a NOT NULL constraint.
__identity__
IDENTITY column that is used for segmentation and sorting when no other column is defined.

Default projections

Vertica automatically creates superprojections for both the flex table and keys tables when you create them.

If you create a flex table with one or more of the ORDER BY, ENCODED BY, SEGMENTED BY, or KSAFE clauses, the clause information is used to create projections. If no clauses are in use, Vertica uses the following defaults:

Table Sort order Encoding Segmentation K-safety
Flexible table ORDER BY *.__identity__ none SEGMENTED BY hash *.__identity__ ALL NODES OFFSET 0 1
Keys table ORDER BY *._keys_frequency none UNSEGMENTED ALL NODES 1

Examples

The following example creates a flex table named darkdata without specifying any column information. Vertica creates a default superprojection and buddy projection as part of creating the table:

=> CREATE FLEXIBLE TABLE darkdata();
CREATE TABLE
=> \dj darkdata1*
                         List of projections
 Schema |         Name         |  Owner  |       Node       | Comment
--------+----------------------+---------+------------------+---------
 public | darkdata1_b0         | dbadmin |                  |
 public | darkdata1_b1         | dbadmin |                  |
 public | darkdata1_keys_super | dbadmin | v_vmart_node0001 |
 public | darkdata1_keys_super | dbadmin | v_vmart_node0002 |
 public | darkdata1_keys_super | dbadmin | v_vmart_node0003 |
(5 rows)

=> SELECT export_objects('','darkdata1_b0');
CREATE PROJECTION public.darkdata1_b0 /*+basename(darkdata1),createtype(P)*/
(
 __identity__,
 __raw__
)
AS
 SELECT darkdata1.__identity__,
        darkdata1.__raw__
 FROM public.darkdata1
 ORDER BY darkdata1.__identity__
SEGMENTED BY hash(darkdata1.__identity__) ALL NODES OFFSET 0;

SELECT MARK_DESIGN_KSAFE(1);
(1 row)

=> select export_objects('','darkdata1_keys_super');
CREATE PROJECTION public.darkdata1_keys_super /*+basename(darkdata1_keys),createtype(P)*/
(
 key_name,
 frequency,
 data_type_guess
)
AS
 SELECT darkdata1_keys.key_name,
        darkdata1_keys.frequency,
        darkdata1_keys.data_type_guess
 FROM public.darkdata1_keys
 ORDER BY darkdata1_keys.frequency
UNSEGMENTED ALL NODES;

SELECT MARK_DESIGN_KSAFE(1);
(1 row)

The following example creates a table called darkdata1 with one column definition (date_col). The statement specifies the partition by clause to partition the data by year. Vertica creates a default superprojection and buddy projections as part of creating the table:

=> CREATE FLEX TABLE darkdata1 (date_col date NOT NULL) partition by
  extract('year' from date_col);
CREATE TABLE

See also