I've been working with grep to try to filter a file by strings contained in another file. The problem is that I'm working with millions on records and some one grep is not getting all of the lines.

I've export the results with to two files:

1. contains the lines that match those strings
2. contains the lines that doesn't match those strings

The sum of both outputs is not the original amount of lines

```
[ ]$ grep -vwF -f functions.csv whole-data-slice_statement2.csv > output1.csv$
[ ]$ grep -wF -f functions.csv whole-data-slice_statement2.csv > output2.csv$
[ ]$ wc -l whole-data-slice_statement2.csv$
4278709 whole-data-slice_statement2.csv
[ ]$ wc -l output1.csv$
106692 output1.csv
[ ]$ wc -l output2.csv$
2326396 output2.csv

```

Could some one help me to understand if I'm doing something wrong?