New list from two workbooks

[Dave Eade]

I have a worksheet with 34000 rows, and another which has 923 rows - which
are in the 34k.
How do I filter the 34k sheet with just the 923 ?

 

[Max]

Assume 34k data in Sheet1's col A, 923 data in Sheet2's col A, from row2 down
In Sheet1,
In B2:
=IF(A2="","",--ISNUMBER(MATCH(A2,Sheet2!$A$2:$A$924,0)))
Copy down all 34k rows. Kill formulas. Apply autofilter on col B.
Col B returns: 1 for items in col A found in Sheet2's col A, 0 for items not
found, and blanks: "" for any empty cells in col A.