addColumn

Syntax

addColumn(table, colNames, colTypes)

Arguments

table can be 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.

Details

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.

Please note that the new column should be updated by function loadTable after adding a new column into the distributed table or dimension table by using the command addColumn.

Examples

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;

ID	x	price	qty
1	0.2
2	0.4
3	0.6
1	1.2
4	0.8
5	1
6	1.2

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;

ID	x	price	qty
1	0.2
2	0.4
3	0.6
1	1.2
1	1.6	10	6
4	0.8
5	1
6	1.2

$ 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;

ticker	x	price	qty
MSFT	0.743241031421349
FB	0.254624255700037
FB	0.947473830310628
FB	0.904140035156161
MSFT	0.193251194199547
MSFT	0.416090324753895
MSFT	0.479371337918565
ORCL	0.69910929678008
GOOG	0.131539688445628
MSFT	0.472390263108537
MSFT	12	25.46	256