partition

Syntax

partition(partitionCol, keys)

Arguments

partitionCol is a STRING indicating the partitioning column. For COMPO partitions, specify either of the partitioning columns.

keys is a scalar or vector without NULL values, indicating the partition(s) to select. Please refer to the following table about how to specify keys for each partition scheme:

Partition Scheme	How to Specify keys
VALUE	The associated element(s) in the partitioning vector
RANGE	The index of the associated partition(s), starting from 0
HASH	Hash modulus(moduli) of the partitioning column
LIST	The index of the associated partition(s), starting from 0

Note: The partitions specified by keys must be within the partition range of the partitioned table, otherwise an error would occur indicating the specified keys are out of range.

Details

Select one or more partitions from a partitioned table. It can only be used in the where clause of a SQL statement. This function makes it convenient to select specific partitions for HASH, LIST and RANGE partitions.

Examples

$ dbName="dfs://test_topic_partition"
$ if(existsDatabase(dbName)){
$       dropDatabase(dbName)
$ }
$ db=database(dbName, LIST, ["A"+string(1..10), "A"+string(11..20), "A"+string(21..30)])
$ n=20
$ date=rand(2012.01.01..2012.01.10, n)
$ sym=rand("A"+string(1..30), n)
$ qty=rand(100, n)
$ t=table(date, sym, qty)
$ pt=db.createPartitionedTable(t, `pt, `sym).append!(t)
$ select * from pt where partition(sym, 0 1)

date	sym	qty
2012.01.06	A4	32
2012.01.03	A10	34
2012.01.03	A17	51
2012.01.04	A14	47
2012.01.06	A16	50
2012.01.04	A15	56
2012.01.04	A16	80
2012.01.02	A11	69
2012.01.01	A14	68

$ dbName="dfs://test_topic_partition"
$ if(existsDatabase(dbName)){
$        dropDatabase(dbName)
$ }
$ db1=database("", HASH, [SYMBOL, 10])
$ db2=database("", LIST, ["A"+string(1..10), "B"+string(1..10), "C"+string(1..10)])
$ db=database(dbName, COMPO, [db1, db2])
$ n=20
$ id=symbol(string(rand(uuid(), n)))
$ sym=rand(["A"+string(1..10), "B"+string(1..10), "C"+string(1..10)].flatten(), n)
$ qty=rand(100, n)
$ t=table(id, sym, qty)
$ pt=db.createPartitionedTable(t, `pt, `id`sym).append!(t)
$ select * from pt where partition(id, 2 3), partition(sym, 1 2) order by id, sym, qty

id	sym	vqty
19e8591f-8b7c-c611-bd3e-582d00a414430	C6	69
2db9074a-0502-27ad-06d5-8d1bf3270245	B4	2
73c1ae86-51c9-3e04-c1dd-6c4b62d8a129	B9	65
99d78d5e-14bb-dc7e-7210-7bc5ad0cda5d	C10	11