The HP Performance Support and news forum has stated the following:

''The limit is memory based. Although not technically a 'limit', as in terms of number of rows or size of file, there IS a limit.
It would be unwise to just fill up lots of dat files with row upon row of data, trust me, you do this too much and you'll run into problems.
Every Vuser you run has it's own copy of the data assigned to it in memory, if you have lots of vusers and your data files are huge then that = huge * lots of vusers which eventually equals resource problems and an invalid test.''

For this case, you may want to consider using Virtual Table Server (VTS). to accomplish your goal.

HP LoadRunner Virtual Table Server - or VTS for short - is a web-based application that is built to work with LoadRunner Vuser scripts.
VTS offers an alternative to standard LoadRunner parameterization. VTS includes a table that contains parameter values that can be used
by your Vuser scripts. The VTS table is composed of columns and rows. Each column represents a set of values that can be used by a specific
parameter in your Vuser scripts. The cells within a column contain the actual values of the parameter.