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Changes between Initial Version and Version 1 of Ticket #2917, comment 8

initial	v1
5	5	The row cache is contiguous, but limited to 8 rows. So it's used if the range of offsets (maximum row offset minus the minimum row offset plus one) is between 2 and 8 inclusive.
6	6
7		So if an expression contained e.g. map[-10] and map[10], the cache wouldn't be used (because it would need to hold 21 rows, which is more than the maximum of 8 rows). In that case, each row would be read multiple times rather than being cached.
	7	So if an expression contained e.g. map[-10] and map![10], the cache wouldn't be used (because it would need to hold 21 rows, which is more than the maximum of 8 rows). In that case, each row would be read multiple times rather than being cached.
8	8
9	9	Any expression using two or more distinct row offsets for a map (no offset is equivalent to an offset of zero) "might" trigger it. Scripts which use fixed offsets typically use small offsets, so the range being less than or equal to 8 is likely. Scripts which use larger row offsets typically do so by way of using variable row offsets, so it's likely that the cache will be used "sometimes".