Allows grouping results based on the unique values of a function query (group.func parameter)

public SolrQuery::addGroupFunction(string $value): SolrQuery

Adds a group function (group.func parameter) Allows grouping results based on the unique values of a function query.

SolrQuery::setGroup() - Enable/Disable result grouping (group parameter)
SolrQuery::addGroupField() - Add a field to be used to group results
SolrQuery::addGroupQuery() - Allows grouping of documents that match the given query
SolrQuery::addGroupSortField() - Add a group sort field (group.sort parameter)
SolrQuery::setGroupFacet() - Sets group.facet parameter
SolrQuery::setGroupOffset() - Sets the group.offset parameter
SolrQuery::setGroupLimit() - Specifies the number of results to return for each group. The server default value is 1
SolrQuery::setGroupMain() - If true, the result of the first field grouping command is used as the main result list in the response, using group.format=simple
SolrQuery::setGroupNGroups() - If true, Solr includes the number of groups that have matched the query in the results
SolrQuery::setGroupTruncate() - If true, facet counts are based on the most relevant document of each group matching the query
SolrQuery::setGroupFormat() - Sets the group format, result structure (group.format parameter)
SolrQuery::setGroupCachePercent() - Enables caching for result grouping

SolrQuery::addGroupFunction