How to Sort Solr field in case insensitive manner

Question

I want to Sort string fields in Solr as case insensitive manner.

The search results are displayed as oracle sort manner, ie it first takes any special characters, numbers, upper case (AZ) then lower case (az).

The results should be special characters, numbers, upper case (A), lowercase (a) – through uppercase (Z) lowercase(z)

Current Expected

110000  110000
ATest   ATest
Btest   aTest
Ctest   BTest
Ztest   bTest
aTest   CTest
bTest   cTest
cTest   ZTest

Please help in configuring string field to Sort in Expected manner.

Answer 1

One way to achieve this would be for you to store the lower-case version of the text in a separate Solr string field when you ingest the data (eg code_for_sorting_s ) and then sort by that field.

Another way to get there would be to define a copy-field in Solr that automatically copies the value in your current field (eg code_s ) to a new field that uses the Lower Case Filter . Using the built-in types in Solr your copy-field definition could look more or less like this:

curl -X POST -H 'Content-type:application/json' --data-binary '{
  "add-copy-field":{
    "source":"code_s",
    "dest":[ "code_s_lower" ]}
}' http://your-solr-core-url/schema

In this case the value of the code_s field will be copied to a new field ( code_s_lower ). The *_s_lower suffix is defined in Solr to create a string field that uses the Lower Case Filter that I alluded to.