These attribute types are recognized regardless of attribute set. Some are recognized for search, others for scan.

Type Name Version 7 Embedded Sort 1.1 8 Term Set 1.1 9 Rank weight 1.1 9 Approx Limit 1.4 10 Term Ref 1.4

The embedded sort is a way to specify sort within a query - thus removing the need to send a Sort Request separately. It is both faster and does not require clients that deal with the Sort Facility.

The value after attribute type 7 is 1=ascending, 2=descending.. The attributes+term (APT) node is separate from the rest and must be @or'ed. The term associated with APT is the level .. 0=primary sort, 1=secondary sort etc..

Example:

Search for water, sort by title (ascending):

@or @attr 1=1016 water @attr 7=1 @attr 1=4 0

Search for water, sort by title ascending, then date descending:

@or @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 @attr 7=2 @attr 1=30 1

The Term Set feature is a facility that allows a search to store hitting terms in a “pseudo” resultset; thus a search (as usual) + a scan-like facility. Requires a client that can do named result sets since the search generates two result sets. The value for attribute 8 is the name of a result set (string). The terms in term set are returned as SUTRS records.

Seach for u in title, right truncated.. Store result in result set named uset.

@attr 5=1 @attr 1=4 @attr 8=uset u

The model as one serious flaw.. We don't know the size of term set.

Rank weight is a way to pass a value to a ranking algorithm - so that one APT has one value - while another as a different one.

Search for utah in title with weight 30 as well as any with weight 20.

@attr 2=102 @or @attr 9=30 @attr 1=4 utah @attr 9=20 utah

Newer Zebra versions normally estemiates hit count for every APT (leaf) in the query tree. These hit counts are returned as part of the searchResult-1 facility.

By setting a limit for the APT we can make Zebra turn into approximate hit count when a certain hit count limit is reached. A value of zero means exact hit count.

We are intersted in exact hit count for a, but for b we allow estimates for 1000 and higher..

@and a @attr 9=1000 b

This facility clashes with rank weight! Fortunately this is a Zebra 1.4 thing so we can change this without upsetting anybody!

Zebra supports the searchResult-1 facility.

If attribute 10 is given, that specifies a subqueryId value returned as part of the search result. It is a way for a client to name an APT part of a query.

Scan

Type Name Version 8 Result set narrow 1.3 9 Approx Limit 1.4

If attribute 8 is given for scan, the value is the name of a result set. Each hit count in scan is @and'ed with the result set given.

The approx (as for search) is a way to enable approx hit counts for scan hit counts. However, it does NOT appear to work at the moment.