Impala Statement Types
Lists the SQL statement types for workloads that use Apache Impala. You can find the statement types on the Impala Queries page in the Type list. For more detailed information about these types of SQL statements, see the Impala documentation.
| Statement Type | Description |
|---|---|
| ALTER TABLE | Changes the structure or properties of an existing table. For
example, ALTER TABLE table_name ADD PARTITION
(month=1, day=1); |
| ALTER VIEW | Changes the characteristics of a view. For example,
ALTER VIEW view_name AS SELECT * FROM
table_name; |
| COMPUTE STATS | Gathers information about volume and distribution data in a
table and all associated columns and partitions. For example,
COMPUTE STATS table_name; |
| CREATE DATABASE | Creates a new database. For example, CREATE DATABASE
database_name; |
| CREATE FUNCTION | Creates a user-defined function (UDF), which you can use to
implement custom logic during SELECT or
INSERT operations. For example, CREATE
FUNCTION function_name LOCATION
'hdfs_path_to_jar' SYMBOL='class_name'; |
| CREATE ROLE | Creates a role to which privileges can be granted. After
privileges are granted to roles, then the roles can be assigned to
users. A user who has been assigned a role is only able to
exercise the privileges of that role. For example, CREATE
ROLE role_name; |
| CREATE TABLE | Creates a new table and specifies its characteristics. For
example, CREATE TABLE table_name
(column_name data_type)
PARTITIONED BY (column_name
data_type) LOCATION
'hdfs_path'; |
| CREATE TABLE AS SELECT | Creates a new table with the output from a SELECT statement.
For example, CREATE TABLE table_name AS
SELECT * FROM table_3; |
| CREATE TABLE LIKE | Creates a new table by cloning an existing table. For
example, CREATE TABLE table_name_2 LIKE
table_name_1; |
| CREATE VIEW | Creates a shorthand abbreviation (alias) for a query. A view
is a purely logical construct with no physical data
behind it. For example, CREATE VIEW
view_name AS SELECT * FROM
table_name; |
| DDL | Data Definition Language. SQL statements that define data
structures. For example, CREATE TABLE; |
| DESCRIBE DB | Displays metadata about a database. For example,
DESCRIBE database_name; |
| DESCRIBE TABLE | Displays metadata about a table. For example,
DESCRIBE table_name; |
| DML | Data Manipulation Language. SQL statements that manipulate
data structures. For example, ALTER
TABLE; |
| DROP DATABASE | Removes a database from the system. For example,
DROP database_name; |
| DROP FUNCTION | Removes a user-defined function (UDF) so that it is not
available for execution during Impala SELECT or INSERT operations.
For example, DROP FUNCTION function_name; |
| DROP STATS | Removes the specified statistics from a table or a partition.
For example, DROP STATS table_name; |
| DROP TABLE | Removes a table and its underlying HDFS data files for
internal tables, although not for external tables. For example,
DROP TABLE table_name; |
| DROP VIEW | Removes the specified view. Because a view is purely a
logical construct with no physical data behind it, DROP VIEW only
involves changes to metadata in the metastore database, not any
data files in HDFS. For example, DROP VIEW
view_name; |
| EXPLAIN | Generates a query execution plan for a
specific query. For example, EXPLAIN SELECT * FROM
table_1; |
| GRANT PRIVILEGE | Grants privileges on specified objects to groups. For
example, GRANT privilege_name ON
TABLE table_name TO
role_name; |
| GRANT ROLE | Grants roles on specified objects to groups. For example,
GRANT ROLE role_nameTO GROUP
group_name; |
| LOAD | Loads data from an external data source
into a table. For example, LOAD DATA INPATH
'hdfs_file_or_directory_path' INTO TABLE tablename; |
| N/A | These queries failed due to syntax errors and Impala is not able to identify a query type for them. |
| REFRESH | Reloads the metadata for a table from the metastore database
and does an incremental reload of the file and block metadata from
the HDFS NameNode. REFRESH is used to avoid
inconsistencies between Impala and external metadata sources,
specifically the Hive Metastore and the NameNode. For example,
REFRESH table_name; |
| REVOKE PRIVILEGE | Revokes privileges on a specified object from groups. For
example, REVOKE privilege_name ON TABLE
table_name; |
| REVOKE ROLE | Revokes roles on a specified object from groups. For example,
REVOKE ROLE role_name FROM GROUP
group_name; |
| SELECT | Requests data from a data source. For
example, SELECT * FROM table_1; |
| SET | Sets configuration properties or session
parameters. For example, SET compression_codec=snappy; |
| SHOW COLUMN STATS | Displays the column statistics for a specified table. For
example, SHOW COLUMN STATS table_name; |
| SHOW CREATE TABLE | Displays the CREATE TABLE statement used to reproduce the
current structure of a table. For example, SHOW CREATE
TABLE table_name; |
| SHOW DATABASES | Displays all available databases. For example, SHOW
DATABASES; |
| SHOW FILES | Displays the files that constitute a specified table or a
partition within a partitioned table. For example, SHOW
FILES IN table_name; |
| SHOW FUNCTIONS | Displays user-defined functions (UDFs) or user-defined
aggregate functions (UDAFs) that are associated
with a particular database. For example, SHOW FUNCTIONS IN
database_name; or SHOW
AGGREGATE FUNCTIONS IN database_name; |
| SHOW GRANT ROLE | Lists all the grants for the specified role name. For
example, SHOW GRANT ROLE role_name; |
| SHOW ROLES | Displays all available roles. For example, SHOW
ROLES; |
| SHOW TABLES | Displays the names of tables. For example, SHOW
TABLES; |
| SHOW TABLE STATS | Displays the statistics for a table. For example,
SHOW TABLE STATS table_name; |
| TRUNCATE TABLE | Removes the data from an Impala table, while leaving the
table itself. For example, TRUNCATE TABLE
table_name; |
| USE | Switches the current session to a specified database. For
example, USE database_name; |
