Memory use for long conversion to sqlite operations

[andrew-MET]

It appears that when doing long conversions of vfld data to sqlite for large ensembles (IFSENS - 51 members), memory can become an issue.

See http://adv-r.had.co.nz/memory.html for profiling method.

[andrew-MET]

This is probably due to the pivoting on the parameter. Probably better to use select rather than pivoting and grouping.