SOLR-8998,SOLR-12490: Polishing reference guide.

solr/solr-ref-guide/src/indexing-nested-documents.adoc

@@ -38,7 +38,7 @@ With the exception of in-place updates, the whole block must be updated or delet
  * The schema must include an indexed field `\_root_`. Solr automatically populates this with the value of the top/parent ID. +
  `<field name="\_root_" type="string" indexed="true" stored="false" docValues="false" />`
  ** `\_root_` must be set either as stored (stored="true") or doc values (docValues="true") to enable
-    <<updating-parts-of-documents#updating-child-documents, atomic updates of nested documents>>.
+    <<updating-parts-of-documents#updating-child-documents, atomic updates of nested documents>>. Also, beware of `uniqueBlock(\_root_)` <<json-facet-api#stat-facet-functions,field type limitation>>, if you plan to use one.
  * `\_nest_path_` is populated by Solr automatically with the path of the document in the hierarchy for non-root documents. This field is optional. +
  `<fieldType name="\_nest_path_" class="solr.NestPathField" />
   <field name="\_nest_path_" type="_nest_path_" />`

solr/solr-ref-guide/src/json-facet-api.adoc

@@ -572,7 +572,7 @@ Unlike all the facets discussed so far, Aggregation functions (also called *face
 |missing |`missing(author)` |number of documents which do not have value for given field or function
 |countvals |`countvals(author)` |number of values for a given field or function
 |unique |`unique(author)` |number of unique values of the given field. Beyond 100 values it yields not exact estimate
-|uniqueBlock |`uniqueBlock(\_root_)` or `uniqueBlock($fldref)` where `fldref=_root_` |same as above with smaller footprint strictly for <<json-faceting-domain-changes.adoc#block-join-domain-changes,counting the number of Block Join blocks>>. The given field must be unique across blocks, and only singlevalued string fields are supported, docValues are recommended.
+|uniqueBlock |`uniqueBlock(\_root_)` or `uniqueBlock($fldref)` where `fldref=\_root_` |same as above with smaller footprint strictly for <<json-faceting-domain-changes.adoc#block-join-domain-changes,counting the number of Block Join blocks>>. The given field must be unique across blocks, and only singlevalued string fields are supported, docValues are recommended.
 | |`uniqueBlock({!v=type:parent})` or `uniqueBlock({!v=$qryref})` where `qryref=type:parent` |same as above, but using bitset of the given query to aggregate hits.
 |hll |`hll(author)` |distributed cardinality estimate via hyper-log-log algorithm
 |percentile |`percentile(salary,50,75,99,99.9)` |Percentile estimates via t-digest algorithm. When sorting by this metric, the first percentile listed is used as the sort value.

solr/solr-ref-guide/src/json-query-dsl.adoc

@@ -358,7 +358,7 @@ curl -X POST http://localhost:8983/solr/techproducts/query -d '
 }'
 ----
 
-Overall this example doesn't make much sense, but just demonstrates the syntax. This feature is useful in <<json-faceting-domain-changes.adoc#adding-domain-filters,filtering domain>> in JSON Facet API <<json-facet-api.adoc#changing-the-domain,domain changes>>.
+Overall this example doesn't make much sense, but just demonstrates the syntax. This feature is useful in <<json-faceting-domain-changes.adoc#adding-domain-filters,filtering domain>> in JSON Facet API <<json-facet-api.adoc#changing-the-domain,domain changes>>. Note that these declarations add request parameters underneath, so using same names with other parameters might cause unexpected behavior. 
 
 == Tagging in JSON Query DSL
 Query and filter clauses can also be individually "tagged".  Tags serve as handles for query clauses, allowing them to be referenced from elsewhere in the request.  This is most commonly used by the filter-exclusion functionality offered by both <<faceting.adoc#tagging-and-excluding-filters,traditional>> and <<json-faceting-domain-changes.adoc#filter-exclusions,JSON>> faceting.