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DDL Statement
Last updated: 2024-08-07 17:28:21
DDL Statement
Last updated: 2024-08-07 17:28:21
Description:
The following statement descriptions are for DLC native tables, which are Iceberg tables by default. If you are using Iceberg external tables, there will be detailed differences in DDL statement. For more information, see the documentation Differences between Iceberg External and Native Table Syntax.

CREATE TABLE

Statement

CREATE TABLE [ IF NOT EXISTS ] table_identifier
( col_name[:] col_type [ COMMENT col_comment ], ... )
[ COMMENT table_comment ]
[ PARTITIONED BY ( col_name1, transform(col_name2), ... ) ]

Parameter

table_identifier

table_identifier supports a three-part format: catalog.db.name.

Schemas and Data Types

col_type
: primitive_type
| nested_type
primitive_type
: boolean
| int/integer
| long/bigint
| float
| double
| decimal(p,s), p = maximum number of digits, s = maximum number of decimal places, s <= p <= 38
| date
| timestamp, timestamp with timezone. Does not support time and without timezone.
| string, can also correspond to Iceberg uuid type.
| binary, can also correspond to Iceberg fixed type.
nested_type
: struct
| list
| map

Partition Transforms

transform
: identity, supports any type, DLC does not support this transformation.
| bucket[N], hash mod N bucketing, supports col_type: int,long, decimal, date, timestamp, string, binary
| truncate[L], L-truncation bucketing, supports col_type: int,long,decimal,string
| years, year, supports col_type: date,timestamp
| months, month, supports col_type: date,timestamp
| days/date, date, supports col_type: date,timestamp
| hours/date_hour, hour, supports col_type: timestamp

Example

CREATE TABLE dempts(
id bigint COMMENT 'id number',
num int,
eno float,
dno double,
cno decimal(9,3),
flag boolean,
data string,
ts_year timestamp,
date_month date,
bno binary,
point struct<x: double, y: double>,
points array<struct<x: double, y: double>>,
pointmaps map<struct<x: int>, struct<a: int>>
)
COMMENT 'table documentation'
PARTITIONED BY (bucket(16,id), years(ts_year), months(date_month), identity(bno), bucket(3,num),truncate(10,data));

CREATE TABLE AS SELECT

Statement

CREATE TABLE [ IF NOT EXISTS ] table_identifier
[ COMMENT table_comment ]
[ PARTITIONED BY ( col_name1, transform(col_name2), ... ) ]
[ TBLPROPERTIES ( property_name=property_value, ... ) ]
AS select_statement

Example

CREATE TABLE dempts_copy
COMMENT 'table create as select'
PARTITIONED BY (eno, dno)
AS SELECT * from dempts;

REPLACE TABLE AS SELECT

Generate a snapshot from the results of a SELECT query to update the table while retaining the table's history.

Statement

CREATE [OR REPLACE] TABLE table_identifier
[ COMMENT table_comment ]
[ PARTITIONED BY ( col_name1, transform(col_name2), ... ) ]
AS select_statement

Example

CREATE OR REPLACE TABLE dempts_replace
COMMENT 'table create as replace'
PARTITIONED BY (eno, dno)
AS SELECT * from dempts;

DROP TABLE

Statement

DROP TABLE [ IF EXISTS ] table_identifier

ALTER TABLE

Alter table statement.

ALTER TABLE ... RENAME TO

Change table name.

Statement

ALTER TABLE table_identifier RENAME TO new_table_identifier

ALTER TABLE ... SET / UNSET TBLPROPERTIES 

Update/delete data table attributes.

Statement

-- Update attribute configuration through SET.
ALTER TABLE table_identifier
SET TBLPROPERTIES (property_name=property_value, ...)

-- Delete attribute configuration through UNSET.
ALTER TABLE table_identifier
UNSET TBLPROPERTIES (property_name, ...)

Example

-- Update attribute configuration through SET.
ALTER TABLE dempts SET TBLPROPERTIES ('read.split.target-size'='268435456');

-- Delete attribute configuration through UNSET.
ALTER TABLE dempts UNSET TBLPROPERTIES ('read.split.target-size'='268435456');


ALTER TABLE ... WRITE ORDERED BY

Set the sort order of the table data during insertion.

Statement

ALTER TABLE table_identifier 
WRITE [LOCALLY] ORDERED BY 
{col_name [ASC|DESC] [NULLS FIRST|LAST]}[, ...]

Example

ALTER TABLE dempts WRITE ORDERED BY category, id;

-- use optional ASC/DEC keyword to specify sort order of each field (default ASC)
ALTER TABLE dempts WRITE ORDERED BY category ASC, id DESC;

-- use optional NULLS FIRST/NULLS LAST keyword to specify null order of each field (default FIRST)
ALTER TABLE dempts WRITE ORDERED BY category ASC NULLS LAST, id DESC NULLS FIRST;

-- To order within each task, not across tasks
ALTER TABLE dempts WRITE LOCALLY ORDERED BY category, id;

ALTER TABLE ... WRITE DISTRIBUTED BY PARTITION

Modify the data distribution policy of partitioned tables.

Statement

ALTER TABLE table_identifier 
WRITE DISTRIBUTED BY PARTITION 
[ LOCALLY ORDERED BY 
{col_name [ASC|DESC] [NULLS FIRST|LAST]}[, ...]] 

Example

ALTER TABLE dempts WRITE DISTRIBUTED BY PARTITION;
ALTER TABLE dempts WRITE DISTRIBUTED BY PARTITION LOCALLY ORDERED BY id;

ALTER TABLE COLUMNS

Change field statement.

ALTER TABLE ... ADD COLUMNS

Add multiple fields.

Statement

-- Add multiple fields.
ALTER TABLE table_identifier 
ADD COLUMNS (col_name col_type [COMMENT col_comment], ...)

-- Add a single field.
ALTER TABLE table_identifier 
ADD COLUMN col_name col_type [COMMENT col_comment] 
[FIRST | AFTER target_col_name]

Example

-- Add multiple fields.
ALTER TABLE dempts
ADD COLUMNS (
new_column_1 string comment 'new_column_1 docs',
new_column_2 int comment 'new_column_2 docs'
);

-- Add a single field.
ALTER TABLE dempts 
ADD COLUMN new_column_3 string comment 'new_column docs';

ALTER TABLE ... RENAME COLUMN 

Change field name.

Statement

ALTER TABLE table_identifier 
RENAME COLUMN old_column_name TO new_column_name

ALTER TABLE ... ALTER COLUMN

Change field type/remarks.

Statement

ALTER TABLE table_identifier 
ALTER COLUMN col_name 
{TYPE new_col_type | COMMENT col_comment}
Currently, Iceberg TYPE changes only support type-safe field extensions:
int/integer -> long/bigint
float -> double
decimal(P,S) -> decimal(P2,S), where P2 > P, indicating increased precision.

Example

ALTER TABLE dempts ALTER COLUMN new_column_2 TYPE bigint;
ALTER TABLE dempts ALTER COLUMN new_column_2 comment 'alter docs';

ALTER TABLE ... DROP COLUMN

Delete a table field.

Statement

ALTER TABLE table_identifier DROP COLUMN column_name

ALTER TABLE PARTITIONS

ALTER TABLE ... ADD PARTITION FIELD

Add a single partition field.

Statement

ALTER TABLE table_identifier 
ADD PARTITION FIELD col_name|transform (col_name) [AS alias]
For transform, see the <1>CREATE TABLE< 1>.

Example

ALTER TABLE dempts ADD PARTITION FIELD new_column_1;
ALTER TABLE dempts ADD PARTITION FIELD bucket(3,new_column_2);

ALTER TABLE ... REPLACE PARTITION FIELD

Replace a single partition field.

Statement

ALTER TABLE table_identifier REPLACE PARTITION FIELD col_name|transform (col_name) [AS alias]

ALTER TABLE ... DROP PARTITION FIELD

Delete a single partition field.

Statement

ALTER TABLE table_identifier 
DROP PARTITION FIELD col_name|transform (col_name);
For transform, see the CREATE TABLE documentation.

Example

ALTER TABLE dempts DROP PARTITION FIELD new_column_1;
ALTER TABLE dempts DROP PARTITION FIELD bucket(3,new_column_2);

ALTER TABLE ... SET IDENTIFIER FIELDS 

Add identifier fields attribute.

Statement

ALTER TABLE dempts SET IDENTIFIER FIELDS empno, name

ALTER TABLE .. DROP IDENTIFIER FIELDS

Add identifier fields attribute.

Statement


ALTER TABLE dempts DROP IDENTIFIER FIELDS empno, name


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