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This graphic is explained in the accompanying text Examples: Search Conditions for Indexed Columns Locate the document in the library structure

The following examples show search conditions for indexed columns of the example table, as well as the corresponding search strategies that are used.

Excerpt from SQL Statement

Search Strategy

... WHERE firstkey >= 123

The table is searched sequentially from the row with the key ‘123’.

... WHERE invcolumn1 = 'Miller' AND firstkey >= 123

The whole inversion list with the value ‘Miller’ is searched from the key ‘123’ to the end of the list.

... WHERE invcolumn1 = 'Miller' AND invcolumn2 < 'C'

The system creates a logical inversion list that contains all inversion lists of invcolumn2 that begin with a value smaller than 'C' (' ', 'A', 'B').

The intersection of the logical inversion list and the inversion list with the value ‘Miller’ is determined and this intersection is processed in full.

... WHERE invcolumn1 IN ('Miller', 'Smith', 'Hawk')

The three inversion lists are processed in full.

... WHERE invcolumn2 > 8965 AND firstkey = 34 AND secondkey BETWEEN 12 AND 18

All inversion lists of invcolumn2 whose values are greater than 8965 are processed. However, they are only considered within the key limits ‘34, 12’ and ‘34, 18’.

... WHERE
multinvcolumn1 = 'Boston' AND
multinvcolumn2 = '40223' AND
multinvcolumn3 = 10000

The entire inversion list of the named ind index with the values ‘Boston’, ‘40223’ and 10000 is processed.

... WHERE
multinvcolumn1 = 'Boston' AND
multinvcolumn2 BETWEEN '40221' AND'40238'

The inversion lists within and including the values ‘Boston', ‘40221’ (binary zeros), and ‘Boston’, ‘40238’ (binary ones) are processed.

 

 

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