Vertica Documentation – Creating a table from other tables

Admin: Replicating a table

Mon, 01 Jan 0001 00:00:00 +0000

You can create a table from an existing one using CREATE TABLE with the LIKE clause:

CREATE TABLE [schema.]table-name LIKE [schema.]existing-table
   [ {INCLUDING | EXCLUDING} PROJECTIONS ]
   [ {INCLUDE | EXCLUDE} [SCHEMA] PRIVILEGES ]

Creating a table with LIKE replicates the source table definition and any storage policy associated with it. It does not copy table data or expressions on columns.

Copying constraints

CREATE TABLE...LIKE copies all table constraints, with the following exceptions:

Foreign key constraints.

Any column that obtains its values from a sequence, including IDENTITY columns. Vertica copies the column values into the new table, but removes the original constraint. For example, the following table definition sets an IDENTITY constraint on column ID:

CREATE TABLE public.Premium_Customer
(
    ID IDENTITY ,
    lname varchar(25),
    fname varchar(25),
    store_membership_card int
);

The following CREATE TABLE...LIKE statement replicates this table as All_Customers. Vertica removes the IDENTITY constraint from All_Customers.ID, changing it to an integer column with a NOT NULL constraint:

=> CREATE TABLE All_Customers like Premium_Customer;
CREATE TABLE
=> select export_tables('','All_Customers');
                   export_tables
---------------------------------------------------
CREATE TABLE public.All_Customers
(
    ID int NOT NULL,
    lname varchar(25),
    fname varchar(25),
    store_membership_card int
);

(1 row)

Including projections

You can qualify the LIKE clause with INCLUDING PROJECTIONS or EXCLUDING PROJECTIONS, which specify whether to copy projections from the source table:

EXCLUDING PROJECTIONS (default): Do not copy projections from the source table.
INCLUDING PROJECTIONS: Copy current projections from the source table. Vertica names the new projections according to Vertica naming conventions, to avoid name conflicts with existing objects.

Including schema privileges

You can specify default inheritance of schema privileges for the new table:

EXCLUDE [SCHEMA] PRIVILEGES (default) disables inheritance of privileges from the schema
INCLUDE [SCHEMA] PRIVILEGES grants the table the same privileges granted to its schema

For more information see Setting privilege inheritance on tables and views.

Restrictions

The following restrictions apply to the source table:

It cannot have out-of-date projections.
It cannot be a temporary table.

Example

Create the table states:


=> CREATE TABLE states (
     state char(2) NOT NULL, bird varchar(20), tree varchar (20), tax float, stateDate char (20))
     PARTITION BY state;

Populate the table with data:

INSERT INTO states VALUES ('MA', 'chickadee', 'american_elm', 5.675, '07-04-1620');
INSERT INTO states VALUES ('VT', 'Hermit_Thrasher', 'Sugar_Maple', 6.0, '07-04-1610');
INSERT INTO states VALUES ('NH', 'Purple_Finch', 'White_Birch', 0, '07-04-1615');
INSERT INTO states VALUES ('ME', 'Black_Cap_Chickadee', 'Pine_Tree', 5, '07-04-1615');
INSERT INTO states VALUES ('CT', 'American_Robin', 'White_Oak', 6.35, '07-04-1618');
INSERT INTO states VALUES ('RI', 'Rhode_Island_Red', 'Red_Maple', 5, '07-04-1619');

View the table contents:

=> SELECT * FROM states;


 state |        bird         |     tree     |  tax  |      stateDate
-------+---------------------+--------------+-------+----------------------
 VT    | Hermit_Thrasher     | Sugar_Maple  |     6 | 07-04-1610
 CT    | American_Robin      | White_Oak    |  6.35 | 07-04-1618
 RI    | Rhode_Island_Red    | Red_Maple    |     5 | 07-04-1619
 MA    | chickadee           | american_elm | 5.675 | 07-04-1620
 NH    | Purple_Finch        | White_Birch  |     0 | 07-04-1615
 ME    | Black_Cap_Chickadee | Pine_Tree    |     5 | 07-04-1615
(6 rows

Create a sample projection and refresh:

=> CREATE PROJECTION states_p AS SELECT state FROM states;

=> SELECT START_REFRESH();

Create a table like the states table and include its projections:
```
=> CREATE TABLE newstates LIKE states INCLUDING PROJECTIONS;
```

View projections for the two tables. Vertica has copied projections from states to newstates:

=> \dj
                                                      List of projections
            Schema             |                   Name                    |  Owner  |       Node       | Comment
-------------------------------+-------------------------------------------+---------+------------------+---------
 public                        | newstates_b0                              | dbadmin |                  |
 public                        | newstates_b1                              | dbadmin |                  |
 public                        | newstates_p_b0                            | dbadmin |                  |
 public                        | newstates_p_b1                            | dbadmin |                  |
 public                        | states_b0                                 | dbadmin |                  |
 public                        | states_b1                                 | dbadmin |                  |
 public                        | states_p_b0                               | dbadmin |                  |
 public                        | states_p_b1                               | dbadmin |                  |

View the table newstates, which shows columns copied from states:


=> SELECT * FROM newstates;


 state | bird | tree | tax | stateDate
-------+------+------+-----+-----------
(0 rows)

When you use the CREATE TABLE...LIKE statement, storage policy objects associated with the table are also copied. Data added to the new table use the same labeled storage location as the source table, unless you change the storage policy. For more information, see Working With Storage Locations.

Admin: Creating a table from a query

Mon, 01 Jan 0001 00:00:00 +0000

CREATE TABLE can specify an AS clause to create a table from a query, as follows:

CREATE [TEMPORARY] TABLE [schema.]table-name
    [ ( column-name-list ) ]
    [ {INCLUDE | EXCLUDE} [SCHEMA] PRIVILEGES ]
AS  [  /*+ LABEL */ ] [ AT epoch ] query [ ENCODED BY column‑ref‑list ]

Vertica creates a table from the query results and loads the result set into it. For example:

=> CREATE TABLE cust_basic_profile AS SELECT
     customer_key, customer_gender, customer_age, marital_status, annual_income, occupation
     FROM customer_dimension WHERE customer_age>18 AND customer_gender !='';
CREATE TABLE
=> SELECT customer_age, annual_income, occupation FROM cust_basic_profile
     WHERE customer_age > 23 ORDER BY customer_age;
 customer_age | annual_income |     occupation
--------------+---------------+--------------------
           24 |        469210 | Hairdresser
           24 |        140833 | Butler
           24 |        558867 | Lumberjack
           24 |        529117 | Mechanic
           24 |        322062 | Acrobat
           24 |        213734 | Writer
           ...

AS clause options

You can qualify an AS clause with one or both of the following options:

LABEL hint that identifies a statement for profiling and debugging
AT epoch clause to specify that the query return historical data

Labeling the AS clause

You can embed a LABEL hint in an AS clause in two places:

Immediately after the keyword AS:

CREATE TABLE myTable AS /*+LABEL myLabel*/...

In the SELECT statement:

CREATE TABLE myTable AS SELECT /*+LABEL myLabel*/

If the AS clause contains a LABEL hint in both places, the first label has precedence.

Note

Labels are invalid for external tables.

Loading historical data

You can qualify a CREATE TABLE AS query with an AT epoch clause, to specify that the query return historical data, where epoch is one of the following:

EPOCH LATEST: Return data up to but not including the current epoch. The result set includes data from the latest committed DML transaction.
EPOCH integer: Return data up to and including the integer-specified epoch.
TIME 'timestamp': Return data from the timestamp-specified epoch.

Note

These options are ignored if used to query temporary or external tables.

See Epochs for additional information about how Vertica uses epochs.

For details, see Historical queries.

Zero-width column handling

If the query returns a column with zero width, Vertica automatically converts it to a VARCHAR(80) column. For example:

=> CREATE TABLE example AS SELECT '' AS X;
CREATE TABLE
=> SELECT EXPORT_TABLES ('', 'example');
                       EXPORT_TABLES
----------------------------------------------------------
CREATE TEMPORARY TABLE public.example
(
    X varchar(80)
);

Requirements and restrictions

If you create a temporary table from a query, you must specify ON COMMIT PRESERVE ROWS in order to load the result set into the table. Otherwise, Vertica creates an empty table.
If the query output has expressions other than simple columns, such as constants or functions, you must specify an alias for that expression, or list all columns in the column name list.
You cannot use CREATE TABLE AS SELECT with a SELECT that returns values of complex types. You can, however, use CREATE TABLE LIKE.

Vertica Documentation – Creating a table from other tables

Admin: Replicating a table

Copying constraints

Including projections

Including schema privileges

Restrictions

Example

See also

Admin: Creating a table from a query

AS clause options

Labeling the AS clause

Note

Loading historical data

Note

Zero-width column handling

Requirements and restrictions

See also