Microsoft R Server Row by Row Insert - sql-server

Question

I have a for loop that usually writes to a flat file. This way, if anything breaks, I can start where I left off. I want to convert this process to read and write from a SQL table directly using the new RevoScaleR functions in a SQL Server 2016 stored procedure that executes my R code.
Here is a simple SPROC:
USE [master]
GO
/****** Object: StoredProcedure [dbo].[Rscript_geocodeUSACities_TEST] Script Date: 8/8/2017 11:40:40 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE PROCEDURE [dbo].[Rscript_geocodeUSACities_TEST]
#usrOutputFilePath varchar(150)
,#usrOutputFileName varchar(150)
AS
BEGIN
SET NOCOUNT ON;
DECLARE #rScript nvarchar(max) = N'
#### USER INPUTS ####
usrOutputFile <- "' + #usrOutputFilePath + #usrOutputFileName + '"
#### ESTABLISH ENVIRONMENT ####
library(data.table)
library(foreach)
library(XML)
library(RCurl)
library(RJSONIO)
##turn off scientific notation
options(scipen=999)
##establish compute context
sqlServerConnString <- "Server=.;Database=External;Trusted_Connection=true"
sqlServerCC <- RxInSqlServer(connectionString=sqlServerConnString)
rxSetComputeContext(sqlServerCC)
print(rxGetComputeContext())
#### GEOCODE ####
print(dfInputData)
rxDataStep(data=dfInputData,outFile=imp.USA_Cities_Map,append="rows")
'
EXECUTE sp_execute_external_script
#language = N'R'
, #script = #rScript
,#input_data_1 =N'select 5 as test_insert'
,#input_data_1_name =N'dfInputData'
;
END
Error ouput:
Error in rxDataStep(data = dfInputData, outFile = imp.USA_Cities_Map, :
object 'imp.USA_Cities_Map' not found

Answer 1

Here you go. You don't need to set the compute context to SQL Server. But you do have to grant login permissions to the local users running the R external processes. They are all added to a local group called SqlRUserGroup, you just need to replace 'dbrownebook' with your server name.
Note that you don't add a database user for the sqlrusergroup, but only add a login. SQL R Services will impersonate the user calling sp_execute_external_script. This is explained in: https://learn.microsoft.com/en-us/sql/advanced-analytics/r/security-considerations-for-the-r-runtime-in-sql-server
use master
go
create login [dbrownebook\sqlrusergroup] from windows
create database [External]
go
use [External]
go
create schema imp
go
create table imp.USA_Cities_Map(test_insert int)
go
/****** Object: StoredProcedure [dbo].[Rscript_geocodeUSACities_TEST] Script Date: 8/8/2017 11:40:40 AM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE OR ALTER PROCEDURE [dbo].[Rscript_geocodeUSACities_TEST]
#usrOutputFilePath varchar(150)
,#usrOutputFileName varchar(150)
AS
BEGIN
SET NOCOUNT ON;
DECLARE #rScript nvarchar(max) = N'
sqlServerConnString <- "Server=.;Database=External;Trusted_Connection=true"
sqlTable <- RxSqlServerData(table = "imp.USA_Cities_Map", connectionString = sqlServerConnString)
rxDataStep(data=dfInputData,outFile=sqlTable,append="rows")
rxDataStep(data=dfInputData,outFile=sqlTable,append="rows")
rxDataStep(data=dfInputData,outFile=sqlTable,append="rows")
'
EXECUTE sp_execute_external_script
#language = N'R'
, #script = #rScript
,#input_data_1 =N'select 5 as test_insert'
,#input_data_1_name =N'dfInputData'
;
END
GO
exec [Rscript_geocodeUSACities_TEST] '',''
go
select * from imp.USA_Cities_Map