Comparison of WD and TEXT indexes

This table compares WD and TEXT indexes in terms of syntax and capability.

Table 2-1: WD versus TEXT index

Feature

Supported by WD index?

Supported by TEXT index?

Conjunction of terms

Yes, expressed in the form:

tbl.col
CONTAINS('great','white'
,'whale')

Yes, expressed in the form:

CONTAINS(tbl.col,'great
white whale')

General boolean expressions

Yes, expressed in the form:

tbl.col CONTAINS
('great') AND ( tbl.col
CONTAINS('white) OR
tbl.col CONTAINS('whale')
AND NOT tbl.col
CONTAINS('ship'))

Yes, expressed in the form:

CONTAINS(tbl.col,
'great AND ( white OR
whale AND NOT ship )')

Search for terms matching prefix

No

Yes, for example:

CONTAINS
(tbl.col,'whale*')

Acceleration of LIKE predicates

Yes, for example:

tbl.col LIKE 'whale%'

No

Searches for terms in proximity

No

Yes, for example:

CONTAINS(tbl.col,
'white BEFORE whale')

CONTAINS(tbl.col,
'whale NEAR white')

CONTAINS(tbl.col, '
"white whale" ')

Ordering of results based on search scoring

No

Yes

In TEXT index, searching for terms matching a prefix and searching for a LIKE expression have different semantics and may return very different results depending on the text configuration. The specification of minimum length, maximum length and a stoplist will govern the prefix processing but does not affect LIKE semantics.

NoteMeaning of boolean expressions will differ between WD index and TEXT index when term dropping occurs because, the effect of dropped terms in TEXT index processing has no equivalent in the WD index.