Low level function for retrieving data to an ffdf object

This is the equivalent of the querySql.ffdf function, except no error report is written when an error occurs.

lowLevelQuerySql.ffdf(connection, query = "", datesAsString = FALSE)

Arguments

connection	The connection to the database server.
query	The SQL statement to retrieve the data
datesAsString	Should dates be imported as character vectors, our should they be converted to R's date format?

Value

A ffdf object containing the data. If there are 0 rows, a regular data frame is returned instead (ffdf cannot have 0 rows)

Details

Retrieves data from the database server and stores it in an ffdf object. This allows very large data sets to be retrieved without running out of memory. Null values in the database are converted to NA values in R.