|
|
|
Key type 8 is for variable-length keys for which not much leading character duplication is expected. Trailing padding compression enables variable length keys to be stored in the index without incurring the wasted storage of fixed length keys (with the key length set to the maximum possible length). Assuming a maximum key length of 15 bytes, then the fixed length representation of the following key values require 30 bytes:
"ABCDEF"
"DEFGHIJK"
The compressed form below would save 14 bytes:
"ABCDEF"9
"DEFGHIJK"7
Only the last segment is compressed on compound (multi-segment) keys.
Note: Key compression imposes a significant performance impact, especially when deleting records. Use this feature only when absolutely necessary to keep index space requirements to a minimum.
