Understanding the Solr Result Set - fl parameter

In this first of a series of blogs about Solr result sets I'd like to talk about returned fields, both static and dynamic.

Stored Fields

Any field that is stored in Solr can be returned in the result set. The following table shows all available stored fields:

Name	Description	Type	Indexed

Name	Description	Type	Indexed
ab_*	all abstracts	mixed: alexandria_text, alexandria_asian_text	true
ad	filing date	tint	true
an	application number (tokenized)	alexandria_token	true
anorig	original, patent office format application number	alexandria_token	true
anseries	US application series code	alexandria_string	true
anucid	standardized filing identifier	string	true
ecla	ECLA classification	alexandria_string	true
fam	family identifier	string	true
fterm	F-Terms	alexandria_string	true
icl,cpcl,uscl,ficl	classifications suitable for display	string	false
ifi_name_current_id	current assignee identifier	string	true
ifi_name_original_id	original assignee identifier	string	true
ifi_pa	IFI assignees	alexandria_token	true
inv	inventors	alexandria_token	true
loadid	meta load identifier	tint	true
nclms	number of claims	tint	true
nindepclms	number of independent claims	tint	true
pa	applicants/assignees (all formats)	alexandria_token	true
pd	publication date	tint	true
pn	patent number (tokenized)	alexandria_token	true
pri	priority filing number (tokenized)	alexandria_string	true
prid	earliest priority filing date	tint	true
priorig	original, patent office format priority number	alexandria_string	true
timestamp	last modification stamp	tdate	true
ttl_*	all titles	mixed: alexandria_text, alexandria_asian_text	true
ucid	unique character identifier	string	true

The shorthand to return all static fields is the asterisk fl=*

/search/query?q=ucid:US-20160054444-A1&fl=*&rows=1

As with all examples, we discuss results in JSON format.

         "docs" : [
            {
               "timestamp" : "2016-02-27T08:29:31.936Z",
               "ucid" : "US-20160054444-A1",
               "loadid" : 229946,
               "nclms" : 19,
               "nindepclms" : 2,
               "fam" : "-1",
               "pn" : "US-20160054444-A1 US20160054444A1",
               "pd" : 20160225,
               "an" : "US-201514833357-A"
               "anseries" : "14",
               "anorig" : "US-14833357",
               "ad" : 20150824,
               "pri" : [
                  "FR-1457951"
               ],
               "prid" : 20140825,
               "priorig" : [
                  "FR-1457951"
               ],
               "cpcl" : [
                  "G01S  15/588       20130101 LI20160225BHUS        ",
                  "G01S  15/60        20130101 FI20160225BHUS        "
               ],
               "icl" : [
                  "G01S  15/58        20060101ALI20160225BHUS        ",
                  "G01S  15/60        20060101AFI20160225BHUS        "
               ],
               "ifi_pa" : [
                  "ECA ROBOTICS",
                  "ECA ROBOTICS"
               ],
               "inv" : [
                  "Pinto, Marc"
               ],
               "pa" : [
                  "ECA ROBOTICS",
                  "ECA ROBOTICS"
               ],
               "ttl_en" : [
                  "METHOD AND SONAR DEVICE FOR DETERMINING THE SPEED OF MOVEMENT OF A NAVAL VEHICLE IN RELATION TO THE SEA BED"
               ],
               "ab_en" : [
                  "<abstract mxw-id=\"PA168904151\" lang=\"EN\" load-source=\"patent-office\">\n    <p id=\"p-0001\" num=\"0000\">Sonar intended to be carried by a naval vehicle including at least one element for transmitting an acoustic signal, at least one element for receiving the acoustic signal transmitted and reflected on the sea bed and at least two phase centres (PC<sub>1</sub>, PC<sub>2</sub>) that are disposed along a first and a second axis (v<sub>1</sub>, v<sub>2</sub>), respectively, forming an interferometric antenna. The sonar includes elements for determining the speed of movement of the vehicle as a function of the computed value of the relative trim angle (β) formed between a straight line (d<sub>1</sub>) that is perpendicular to the axes (v<sub>1</sub>, v<sub>2</sub>) of the phase centres and a straight line (d<sub>2</sub>) that is perpendicular to the sea bed (F) and of the value determined for the angle of sight.</p>\n  </abstract>"
               ],
            }
         ],

Some things to notice: Multi-valued fields are returned as JSON arrays. Also, as inv, pa and ifi_pa are copyFields containing multiple values, duplicate entries may appear.

Dynamic Fields

Dynamic fields are fields that are generated either internally, like the relevance score or fields that can be generated by computing values using function queries. Dynamic fields must be listed explicitly in the fl parameter, e.g., fl=score. Below, we request the static ucid field together with the relevance score for 5 results.

/search/query?q=ab_en:sonar&fl=ucid,score&rows=5

         "docs" : [
            {
               "ucid" : "US-20160054444-A1",
               "score" : 1.1746656
            },
            {
               "ucid" : "US-9268020-B2",
               "score" : 2.8773313
            },
            {
               "ucid" : "US-20160047906-A1",
               "score" : 1.1735018
            },
            {
               "ucid" : "US-20160049143-A1",
               "score" : 0.99574935
            },
            {
               "ucid" : "US-20160047891-A1",
               "score" : 1.1675186
            }
         ],

Another type of dynamic field makes use of function queries. A simple, yet contrived, example would be to return the number of dependent claims. CLAIMS Direct stores the total number of claims in nclms as well as the number of independent claims in nindepclms, both as tint. Simple subtraction yields the desired result.

/search/query?q=ab_en:sonar&fl=ucid,nclms,nindepclms,sub(nclms,nindepclms)&rows=2

         "docs" : [
            {
               "ucid" : "US-20160054444-A1",
               "nclms" : 19,
               "nindepclms" : 2,
               "sub(nclms,nindepclms)" : 17
            },
            {
               "ucid" : "US-9268020-B2",
               "nclms" : 74,
               "nindepclms" : 3,
               "sub(nclms,nindepclms)" : 71
            }
         ],

Field Aliases

Field aliasing allows individual fields in the result set to be renamed. This functionality is particularly useful to give meaningful names to pseudo fields created by function queries as in the example above. Any field can be renamed using aliases. The syntax is: alias-field-name:original-field-name

Note

ucid is the only exception. When trying to alias the ucid, an HTTP 500 will be returned.

/search/query?q=ab_en:sonar&fl=ucid,total:nclms,independent:nindepclms,dependent:sub(nclms,nindepclms)&rows=1

         "docs" : [
            {
               "ucid" : "US-20160054444-A1",
               "total" : 19,
               "independent" : 2,
               "dependent" : 17
            }
         ],