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https://issues.apache.org/jira/browse/SOLR-9510?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15600214#comment-15600214
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Yonik Seeley commented on SOLR-9510:
------------------------------------
Multi-select faceting (see http://yonik.com/multi-select-faceting/ for those
new to the concept) works off of tagging top-level filters (fq parameters) and
then excluding certain filters by-tag before calculating the facets.
One issue we face with parent/child facets is that the original filters used to
select the child documents (book reviews in our examples) are not top-level
filters and hence tagging doesn't work.
For example, if our root domain consisted of child documents rather than parent
documents, then we could have used top-level filters and tagged them:
{code}
fq={!tag=USER}user_s:yonik
fq={!tag=RATING}rating_i:5
{code}
Instead, those "filters" are part of the \{!parent} query and can't currently
be listed as separate filters, or tagged.
{code}
q={!parent which=type_s:book}user_s:yonik AND rating_i:5
{code}
h3. Minimum Requirements
It appears that the minimum functionality needed to do multi-select faceting
with child documents is the *filter* functionality specified in the previous
post.
Since we're starting with the set of all child documents, the domain need not
be recomputed... straight filtering will do.
Example: From the books we've already selected (books I've reviewed with a 5
star rating), we want to show who submitted the most 5 star reviews. This
requires that we ignore/exclude the user filter (or alternatively, only include
the review filter).
{code}
json.facet={
top_reviewers : {
type : terms,
field : user_s,
domain: { blockChild : "type_s:book" },
filter : { "rating_i:5" }
}
{code}
h4. Avoid Repitition
If one doesn't want to repeat the filters everywhere, there needs to be a
mechanism to name/tag them so they may be used later by name/tag.
\{!tag=mytag} provides some generic support, but it's less-than friendly when
it's not used at the top level.
Rather than use generic support, Mikhail gave a specific extension *filter* to
specify filters as parameter names:
{code}
q={!parent which=type_s:book filter=$review_filter}
review_filter=user_s:yonik
review_filter=rating_i:5
{code}
And given that these are individual queries, it becomes less onerous to tag
them if desired:
{code}
q={!parent which=type_s:book filter=$review_filter}
review_filter={!tag=USER}user_s:yonik
review_filter={!tag=RATING}rating_i:5
{code}
Then the set of things we would want *filter* to support in the JSON Facet API
would be:
- including filters by parameter
- including filters by tag
- excluding filters by tag
Example: start with all review filters, but exclude any that restrict rating.
{code}
filter : {
queryParam : review_filter, // a query that is retrieved by parameter name
excludeTags : RATING
}
{code}
Example: start with all review filters, but exclude any filters that restrict
rating.
{code}
filter : {
queryParam : review_filter, // a query that is retrieved by parameter name
excludeTags : RATING
}
{code}
Example: only apply filters that restrict by user
{code}
filter : {
includeTags : USER
}
{code}
Important note: this "excludeTags" in the filter block is very different than
"excludeTags" in the domain block (which actually recomputes the domain
starting with all documents, but excluding the named filter).
The *\{!filters}* query type Mikhail lays out does the same thing as a generic
query type and thus would be useful outside of JSON Facets.
> child level facet exclusions
> ----------------------------
>
> Key: SOLR-9510
> URL: https://issues.apache.org/jira/browse/SOLR-9510
> Project: Solr
> Issue Type: Improvement
> Security Level: Public(Default Security Level. Issues are Public)
> Components: Facet Module, faceting, query parsers
> Reporter: Mikhail Khludnev
>
> h2. Challenge
> * Since SOLR-5743 achieved block join child level facets with counts roll-up
> to parents, there is a demand for filter exclusions.
> h2. Context
> * Then, it's worth to consider JSON Facets as an engine for this
> functionality rather than support a separate component.
> * During a discussion in SOLR-8998 [a solution for block join with child
> level
> exclusion|https://issues.apache.org/jira/browse/SOLR-8998?focusedCommentId=15487095&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-15487095]
> has been found.
>
> h2. Proposal
> It's proposed to provide a bit of syntax sugar to make it user friendly,
> believe it or not.
> h2. List of improvements
> * introducing a local parameter {{filters}} for {{\{!parent}} query parser
> referring to _multiple_ filters queries via parameter name: {{\{!parent
> filters=$child.fq ..}..&child.fq=color:Red&child.fq=size:XL}}
> these _filters_ are intersected with a child query supplied as a subordinate
> clause.
> * introducing {{\{!filters params=$child.fq excludeTags=color
> v=$subq}&subq=text:word&child.fq={!tag=color}color:Red&child.fq=size:XL}} it
> intersects a subordinate clause (here it's {{subq}} param, and the trick is
> to refer to the same query from {{\{!parent}}}), with multiple filters
> supplied via parameter name {{params=$child.fq}}, it also supports
> {{excludeTags}}.
> h2. Notes
> Regarding the latter parser, the alternative approach might be to move into
> {{domain:\{..}}} instruction of json facet. From the implementation
> perspective, it's desired to optimize with bitset processing, however I
> suppose it's might be deferred until some initial level of maturity.
> h2. Example
> {code}
> q={!parent which=type_s:book filters=$child.fq
> v=$childquery}&childquery=comment_t:good&child.fq={!tag=author}author_s:yonik&child.fq={!tag=stars}stars_i:(5
> 3)&wt=json&indent=on&json.facet={
> comments_for_author:{
> type:query,
> q:"{!filters params=$child.fq excludeTags=author v=$childquery}",
> "//note":"author filter is excluded",
> domain:{
> blockChildren:"type_s:book",
> "//":"applying filters here might be more promising"
> }, facet:{
> authors:{
> type:terms,
> field:author_s,
> facet: {
> in_books: "unique(_root_)"
> }
> }
> }
> } ,
> comments_for_stars:{
> type:query,
> q:"{!filters params=$child.fq excludeTags=stars v=$childquery}",
> "//note":"stars_i filter is excluded",
> domain:{
> blockChildren:"type_s:book"
> }, facet:{
> stars:{
> type:terms,
> field:stars_i,
> facet: {
> in_books: "unique(_root_)"
> }
> }
> }
> }
> }
> {code}
> Votes? Opinions?
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