setColumnComment

Syntax

setColumnComment(table, columnComments)

Arguments

table is a DFS table or MVCC table.

columnComments is a dictionary. Its keys are table columns and values are comments for each column.

Details

Add comments to columns of a DFS table or an MVCC table. Use function schema to view column comments.

Examples

$ n=1000000
$ sym=rand(`A`B`C`D`E`F,n)
$ date=rand(2019.06.01..2019.06.10,n)
$ open=rand(100.0,n)
$ high=rand(200.0,n)
$ close=rand(200.0,n)
$ pre_close=rand(200.0,n)
$ change=rand(100.0,n)
$ vol=rand(10000,n)
$ amount=rand(100000.0,n)
$ t=table(sym,date,open,high,close,pre_close,change,vol,amount);

$ db1=database("",VALUE,2019.06.01..2019.06.10)
$ db2=database("",VALUE,`A`B`C`D`E`F)
$ db=database("dfs://db1",COMPO,[db1,db2])
$ pt=db.createPartitionedTable(t,`pt,`date`sym).append!(t);

$ setColumnComment(pt,{sym:"stock ticker", date:"trading date", open:"open price", high:"highest price", low:"lowest price", close:"close price", vol:"trading volume (shares)", amount:"trading volume (dollar)"})
$ schema(pt).colDefs;

name	typeString	typeInt	comment
sym	SYMBOL	17	stock ticker
date	DATE	6	trading date
open	DOUBLE	16	open price
high	DOUBLE	16	highest price
close	DOUBLE	16	close price
vol	INT	4	trading volume (shares)
amount	DOUBLE	16	trading volume (dollar)

$ id=`XOM`GS`AAPL
$ x=102.1 33.4 73.6
$ mt = mvccTable(id, x);
$ setColumnComment(mt, {id:"identifier"})
$ schema(mt).colDefs

name	typeString	typeInt	extra	comment
id	STRING	18		identifier
x	DOUBLE	16