HCatalog CLI
The HCatalog CLI supports these command line options:
|
Option |
Usage |
Description |
|---|---|---|
|
-g |
|
Tells HCatalog that the table which needs to be created must have group "mygroup". |
|
-p |
|
Tells HCatalog that the table which needs to be created must have permissions "rwxr-xr-x". |
|
-f |
|
Tells HCatalog that myscript.hcatalog is a file containing DDL commands to execute. |
|
-e |
|
Tells HCatalog to treat the following string as a DDL command and execute it. |
|
-D |
|
Passes the key-value pair to HCatalog as a Java System Property. |
|
hcat |
Prints a usage message. |
Note the following:
- The -g and -p options are not mandatory.
- Only one -e or -f option can be provided, not both.
- The order of options is immaterial; you can specify the options in any order.
If no option is provided, then a usage message is printed:
Usage: hcat { -e "<query>" | -f <filepath> } [-g <group>] [-p <perms>] [-D<name>=<value>]
Create/Drop/Alter Table
CREATE TABLE
If you create a table with a CLUSTERED BY clause you will not be able to write to it with Pig or MapReduce. This is because they do not understand how to partition the table, so attempting to write to it would cause data corruption.
CREATE TABLE AS SELECT
Not supported. Throws an exception with the message "Operation Not Supported".
DROP TABLE
Supported. Behavior the same as Hive.
ALTER TABLE
Supported except for the REBUILD and CONCATENATE options. Behavior the same as Hive.
Create/Drop/Alter View
Note: Pig and MapReduce cannot read from or write to views.
CREATE VIEW
Supported. Behavior same as Hive.
DROP VIEW
Supported. Behavior same as Hive.
ALTER VIEW
Supported. Behavior same as Hive.
Show/Describe
SHOW TABLES
Supported. Behavior same as Hive.
SHOW PARTITIONS
Not supported. Throws an exception with message "Operation Not Supported".
SHOW FUNCTIONS
Supported. Behavior same as Hive.
DESCRIBE
Supported. Behavior same as Hive.
Create/Drop Index
CREATE and DROP INDEX operations are supported.
Note: Pig and MapReduce cannot write to a table that has auto rebuild on, because Pig and MapReduce do not know how to rebuild the index.
Create/Drop Function
CREATE and DROP FUNCTION operations are supported, but created functions must still be registered in Pig and placed in CLASSPATH for MapReduce.
"dfs" Command and "set" Command
Supported. Behavior same as Hive.
Other Commands
Any command not listed above is NOT supported and throws an exception with the message "Operation Not Supported".