Applies to
TQDB, TQDBItem, TQDBView
Declaration
property Filter : TKey;
Description
The Filter property effectively screens certain keys from the index. If Filter is null (i.e. '') navigation operations can access every key in the index but, if not, only keys which match the Filter pattern are accessible.
The algorithm for pattern-matching is governed by the setting of UseGrepMatch.
N.B.: Be aware that filtered navigation carries a much greater overhead than unfiltered, e.g., with 10 character keys and the simple matching protocol:
filter type relative time
none 20
match every key 80
match 1 in 10 240
match 1 in 100 1600
match 1 in 1000 18000
The overhead is even greater for grep-style matching.
Setting ItemIndex directly is not affected by the Filter, nor are the search methods.