CACHE TABLE
Description
CACHE TABLE
statement caches contents of a table or output of a query with the given storage level. This reduces scanning of the original files in future queries.
Syntax
Parameters
LAZY
- Only cache the table when it is first used, instead of immediately.
table_identifier
-
Specifies the table or view name to be cached. The table or view name may be optionally qualified with a database name.
Syntax:[ database_name. ] table_name
OPTIONS ( 'storageLevel' [ = ] value )
-
OPTIONS
clause withstorageLevel
key and value pair. A Warning is issued when a key other thanstorageLevel
is used. The valid options forstorageLevel
are:NONE
DISK_ONLY
DISK_ONLY_2
MEMORY_ONLY
MEMORY_ONLY_2
MEMORY_ONLY_SER
MEMORY_ONLY_SER_2
MEMORY_AND_DISK
MEMORY_AND_DISK_2
MEMORY_AND_DISK_SER
MEMORY_AND_DISK_SER_2
OFF_HEAP
storageLevel
. IfstorageLevel
is not explicitly set usingOPTIONS
clause, the defaultstorageLevel
is set toMEMORY_AND_DISK
.
query
- A query that produces the rows to be cached. It can be in one of following formats:
- a
SELECT
statement - a
TABLE
statement - a
FROM
statement
- a