Tablestore:Summary and highlighting

Prerequisites

Install the Tablestore SDK for Java and initialize a client.

Feature description

Summary and highlighting extracts text fragments around terms matched by a query and encloses the matched terms in pre-tags and post-tags. You can use the fragments to display the context of query matches. This feature supports only Text fields.

Before you use summary and highlighting, set enableHighlighting to true for the field when you create a search index. In a query, use SearchQuery.highlight to specify the fields whose fragments you want to return and the fragment settings. A field must be used in a query condition that supports summary and highlighting. Otherwise, no highlighted fragments are returned for the field.

The following query types can return summary and highlighting results: TermQuery, TermsQuery, MatchQuery, MatchPhraseQuery, PrefixQuery, WildcardQuery, RangeQuery, BoolQuery, ConstScoreQuery, and NestedQuery.

For a BoolQuery or ConstScoreQuery, you can configure summary and highlighting for fields used by child queries of the preceding seven query types. For a NestedQuery, configure InnerHits.highlight to return summary and highlighting results for matched child rows. For more information, see Nested query.

The following example uses a match query to retrieve rows in which the description field contains the tablestore term. The example encloses matched terms in the returned fragments with <b> and </b>. The description field is a Text field for which summary and highlighting is enabled.

String tableName = "example_table";
String indexName = "example_index";

MatchQuery matchQuery = new MatchQuery();
matchQuery.setFieldName("description");
matchQuery.setText("tablestore");

HighlightParameter highlightParameter = new HighlightParameter();
highlightParameter.setPreTag("<b>");
highlightParameter.setPostTag("</b>");

Highlight highlight = new Highlight();
highlight.addFieldHighlightParam("description", highlightParameter);

SearchQuery searchQuery = new SearchQuery();
searchQuery.setQuery(matchQuery);
searchQuery.setHighlight(highlight);
searchQuery.setLimit(10);

SearchRequest request = new SearchRequest(tableName, indexName, searchQuery);
SearchResponse response = client.search(request);
for (SearchHit hit : response.getSearchHits()) {
    HighlightResultItem resultItem = hit.getHighlightResultItem();
    if (resultItem == null) {
        continue;
    }
    HighlightField field = resultItem.getHighlightFieldByName("description");
    if (field != null) {
        System.out.println(field.getFragments());
    }
}

Parameters

request.searchQuery.highlight is of the Highlight type. The values in fieldHighlightParams are HighlightParameter objects that configure the fragment behavior for individual fields.

The following table uses full parameter paths to describe the two configuration levels: Highlight and HighlightParameter.

Response