That query only returns 114 rows...

Changed the query to return 286k rows and the IO is quite different (on the "detail" table), since CHAR always has 5 bytes....

Table 'stable_c'. Scan count 1, logical reads 1037, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

Table 'ptable_cc'. Scan count 1, logical reads 16, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

Table 'stable_vc'. Scan count 1, logical reads 639, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

Table 'ptable_vc'. Scan count 1, logical reads 23, physical reads 0, read-ahead reads 0, lob logical reads 0, lob physical reads 0, lob read-ahead reads 0.

Same CPU time...

I made the column 5 bytes long, but I inserted data from 1 to 5 bytes... that's why char has more reads than varchar...

The execution plan states that the char has a cost of 47% and varchar of 53%... The merge join on char is 37% and on varchar is 44%.

Thanks,

Pedro