truncate
Syntax
truncate(dbUrl, tableName)
Arguments
dbUrl is a string indicating the DFS path of a database.
tableName is a string indicating the table name.
Details
Remove all rows from a DFS table but keep its schema. Command truncate
is faster than the delete statement and the dropPartition function.
It is suggested to call function dropTable if you want to delete the schema of the table.
Example
$ n=1000000
$ ID=rand(150, n)
$ dates=2017.08.07..2017.08.11
$ date=rand(dates, n)
$ x=rand(10.0, n)
$ t=table(ID, date, x)
$ dbDate = database(, VALUE, 2017.08.07..2017.08.11)
$ dbID = database(, RANGE, 0 50 100 150)
$ dbName="dfs://compoDB"
$ if(existsDatabase(dbName)){
dropDatabase(dbName)
$ }
$ db = database(dbName, COMPO, [dbDate, dbID])
$ pt = db.createPartitionedTable(t, `pt, `date`ID)
$ pt.append!(t);
$ truncate(dbName, `pt)