Name	Meaning	Typically
N	number of objects in the database	103 .. 1010
d	number of dimensions in object features	1 .. 256
P	number of bytes per disk page	512 .. 8K
V	number of bytes for d-dimensional vector	4d
O	average number of bytes per stored object (key+vector)	12+4d .. 256+4d
NO	average number of stored objects per page P/O	1 .. 512
NP	number of disk pages to hold stored objects N/NO	50 .. 1010
Topen	time to open a database file	10ms
TP	time to read a page from disk into memory	10ms
TD	time to compute distance between two objects (using vectors)	100us (?)
TK	average time to find the page address for a given object	10ms (?)

The T_K measure is related to the use of a DBMS (e.g. dbm or DB2) to look up object vectors via the object identifier/key (the file name of the image).