In VFP 6, two free tables, table1 (739,068 records) and table2 (609,862 records) each has a fieldx which is a 7 byte long character representation of a number which is unique within each table. Each table has an index tag on fieldx. The following:
SELECT fieldx FROM table2 WHERE fieldx NOT IN (SELECT fieldx FROM table1)
This correctly return 31,183 records in 1002.50 seconds.
SELECT fieldx FROM table1 INTO CURSOR tab1 NOFI
SELECT fieldx FROM table2 INTO CURSOR tab2 NOFI
SELECT fieldx FROM tab2 WHERE fieldx NOT IN (SELECT fieldx FROM tab1)
This correctly return 31,183 records in 25.60 seconds.
Before each run I made sure that VFP was the only process running on the Windows 95 machine. Pretty strange.
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