addColumn

addColumn(table, colNames, colTypes)

table can be a table of any type, including an in-memory table, a stream table, a DFS table, or a dimension table.

colNames is a STRING scalar/vector indicating the name(s) of the column(s) to be added.

colTypes is a scalar/vector indicating the data type(s) of the column(s) to be added.

Add a column or columns to a table. It is the only way to add a column to a stream table, a DFS table, or a dimension table. SQL update statement is not supported for these cases.

Note that the table should be updated by function loadTable after adding a new column into a DFS table or dimension table with addColumn.

Example 1. Add columns to a DFS table.

ID=1..6
x=1..6\5
t1=table(ID, x)
db=database("dfs://rangedb",RANGE,  1 4 7)
pt = db.createPartitionedTable(t1, `pt, `ID)
pt.append!(t1);
addColumn(pt,["price", "qty"],[DOUBLE, INT]);

After using addColumn and before data with the new schema is inserted, we can still insert data with the old schema.

t2=table(1 as ID, 1.2 as x)
pt.append!(t2)
select * from pt;

After data with the new schema is inserted, however, data with the old schema can no longer be inserted.

t3=table(1 as ID, 1.6 as x, 10.0 as price, 6 as qty)
pt.append!(t3)
select * from pt;

t4=table(2 as ID, 2.2 as x)
pt.append!(t4); // The data to append contains fewer columns than the schema.

Example 2. Add columns to a stream table.

n=10
ticker = rand(`MSFT`GOOG`FB`ORCL`IBM,n)
x=rand(1.0, n)
t=streamTable(ticker, x)
share t as st
addColumn(st,["price", "qty"],[DOUBLE, INT])
insert into st values("MSFT",12.0,25.46,256)
select * from st;