The PHRASE_SUPPORT parameter

Set this parameter only if you plan to perform phrase searches or proximity searches.

If you are unsure what phrase and proximity searches are, see Concepts.

The PHRASE_SUPPORT index parameter allows you to specify the type of phrase searches the index supports. You can set PHRASE_SUPPORT to one of the following settings:
  • NONE
  • MEDIUM
  • MAXIMUM

The NONE setting means that the index does not support phrase or proximity searches.

Setting PHRASE_SUPPORT to lower levels of phrase and proximity support can cause false matches. However, lower levels of phrase support have the following two advantages:
  • Improved performance for searches that use the index
  • Reduced disk space consumption by the index

A setting of MEDIUM results in a low accuracy of matches, while MAXIMUM results in the highest accuracy. The default setting is NONE.

Given the nature of the Excalibur search engine, a false hit from a phrase search is more likely with the lower settings of PHRASE_SUPPORT and with smaller phrases. As the size of the phrase grows, the probability of a false hit decreases.

Consider using a MEDIUM setting if one or more of the following circumstances is true:
  • Disk space is a factor.
  • You can tolerate few false hits.
  • The search phrases you plan to use are lengthy.
Consider using a MAXIMUM setting if one or more of the following circumstances is true:
  • Disk space is not a factor.
  • Accuracy is important.
  • The search phrases you plan to use are brief.