DolphinDB 中使用 TSDB 引擎创建分区表失败：必须为 TSDB 引擎指定排序键

Question

I wrote this script to create a partitioned table using a TSDB storage engine in DolphinDB.

dbName = "dfs://tsdb_value_int"
n = 10000
t = table(n:n, [`int,`long,`short,`float,`double,`string,`char,`bool,`timestamp], [INT, LONG, SHORT,FLOAT, DOUBLE, STRING, CHAR, BOOL, TIMESTAMP])
pt1 = db.createPartitionedTable(table=t, tableName=`pt1, partitionColumns=`int,compressMethods=dict(`timestamp`long,`delta`delta),keepDuplicates=ALL)

It raises an exception:

The sort keys must be specified for TSDB engine.

How can I create a partitioned table in DolphinDB?

Answer 1

To use the TSDB storage engine, you must specify sortColumns of function createPartitionedTable . The TSDB engine maintains an index based on the order of sort columns, so you can specify those frequently-queried columns as sort columns.

dbName = "dfs://tsdb_value_int"
if(existsDatabase(dbName)){
dropDatabase(dbName)
}
db = database(directory=dbName, partitionType=VALUE, partitionScheme=1..10,engine="TSDB")
n = 10000
t = table(n:n, [`int,`long,`short,`float,`double,`string,`char,`bool,`timestamp], [INT, LONG, SHORT,FLOAT, DOUBLE, STRING, CHAR, BOOL, TIMESTAMP])
pt1 = db.createPartitionedTable(table=t, tableName=`pt1, partitionColumns=`int,compressMethods=dict(`timestamp`long,`delta`delta),sortColumns=`short`int, keepDuplicates=ALL)
t[`int] = rand(100,n)
t[`long] = rand(100000l,n)
t[`short] = rand(10h,n)
t[`float] = rand(100.0f,n)
t[`double] = rand(100.0,n)
t[`string] = rand("A"+string(1..1000),n)
t[`char] = rand(100,n)
t[`bool] = rand([true,false],n)
tem = 2012.06.13T13:30:10.000
ts = array(timestamp,0,n)
for(i in 1..n){
tem=temporalAdd(tem, 1, `s)
ts.append!(tem)
 }
t[`timestamp] = ts
pt1.append!(t)

See createPartitionedTable — DolphinDB 2.0 documentation for details.