Summaries and highlighting

Using query summary and highlighting for non-nested fields

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());
    }
}

Use highlighting when you query nested fields

The following example shows how to use `NestedQuery` to query for data where the value of the `Level1_Col1_Nested` sub-field in the `Col_Nested` nested field matches `hangzhou shanghai. The search query is highlighted in the returned results.

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

HighlightParameter parameter = new HighlightParameter();
parameter.setPreTag("<em>");
parameter.setPostTag("</em>");
Highlight highlight = new Highlight();
highlight.addFieldHighlightParam("items.description", parameter);

InnerHits innerHits = new InnerHits();
innerHits.setLimit(3);
innerHits.setSort(new Sort(Arrays.asList(
        new ScoreSort(), new DocSort(SortOrder.ASC))));
innerHits.setHighlight(highlight);

NestedQuery nestedQuery = new NestedQuery();
nestedQuery.setPath("items");
nestedQuery.setQuery(matchQuery);
nestedQuery.setScoreMode(ScoreMode.None);
nestedQuery.setInnerHits(innerHits);

SearchQuery searchQuery = new SearchQuery();
searchQuery.setQuery(nestedQuery);

Assume that the multi-level nested field `Col_Nested` includes two sub-fields: `Level1_Col1_Text` (Text) and `Level1_Col2_Nested` (Nested). The `Level1_Col2_Nested` nested field includes the `Level2_Col1_Text` sub-field.

The following example shows how to add a `BoolQuery` to a `NestedQuery` to use the summary and highlighting features on both the `Level1_Col1_Text` sub-field in the `Col_Nested` field and the `Level2_Col1_Text` sub-field under `Level1_Col2_Nested`.

public static void nestedQueryWithHighlighting(SyncClient client) {
    SearchRequest searchRequest = SearchRequest.newBuilder()
            .tableName("<TABLE_NAME>")
            .indexName("<SEARCH_INDEX_NAME>")
            .returnAllColumnsFromIndex(true)
            .searchQuery(SearchQuery.newBuilder()
                    .limit(5)
                    .query(QueryBuilders.nested()
                            .path("Col_Nested")
                            .scoreMode(ScoreMode.Min)
                            .query(QueryBuilders.bool()
                                    .should(QueryBuilders.match("Col_Nested.Level1_Col1_Text", "hangzhou shanghai"))
                                    .should(QueryBuilders.nested()
                                            .path("Col_Nested.Level1_Col2_Nested")
                                            .scoreMode(ScoreMode.Min)
                                            .query(QueryBuilders.match("Col_Nested.Level1_Col2_Nested.Level2_Col1_Text", "hangzhou shanghai"))
                                            .innerHits(InnerHits.newBuilder()
                                                    .highlight(Highlight.newBuilder()
                                                            .addFieldHighlightParam("Col_Nested.Level1_Col2_Nested.Level2_Col1_Text", HighlightParameter.newBuilder().build())
                                                            .build())
                                                    .build())))
                            .innerHits(InnerHits.newBuilder()
                                    .sort(new Sort(Arrays.asList(
                                            new ScoreSort(),
                                            new DocSort()
                                    )))
                                    .highlight(Highlight.newBuilder()
                                            .addFieldHighlightParam("Col_Nested.Level1_Col1_Text", HighlightParameter.newBuilder().build())
                                            .build())
                                    .build()))
                    .build())
            .build();
    SearchResponse resp = client.search(searchRequest);
    // Print the highlighted results.
    printSearchHit(resp.getSearchHits(), "");
}

/**
 * Print the content of searchHit.
 * @param searchHits The search hits.
 * @param prefix The prefix to add when printing nested structures to show hierarchical information.
 */
private static void printSearchHit(List<SearchHit> searchHits, String prefix) {
    for (SearchHit searchHit : searchHits) {
        if (searchHit.getScore() != null) {
            System.out.printf("%s Score: %s
", prefix, searchHit.getScore());
        }

        if (searchHit.getOffset() != null) {
            System.out.printf("%s Offset: %s
", prefix, searchHit.getOffset());
        }

        if (searchHit.getRow() != null) {
            System.out.printf("%s Row: %s
", prefix, searchHit.getRow().toString());
        }

        // Print the highlighted fragments for each field.
        if (searchHit.getHighlightResultItem() != null) {
            System.out.printf("%s Highlight: 
", prefix);
            StringBuilder strBuilder = new StringBuilder();
            for (Map.Entry<String, HighlightField> entry : searchHit.getHighlightResultItem().getHighlightFields().entrySet()) {
                strBuilder.append(entry.getKey()).append(":").append("[");
                strBuilder.append(StringUtils.join(",", entry.getValue().getFragments())).append("]
");
            }
            System.out.printf("%s   %s", prefix, strBuilder);
        }

        // Highlighted results for the nested type.
        for (SearchInnerHit searchInnerHit : searchHit.getSearchInnerHits().values()) {
            System.out.printf("%s Path: %s
", prefix, searchInnerHit.getPath());
            System.out.printf("%s InnerHit: 
", prefix);
            printSearchHit(searchInnerHit.getSubSearchHits(), prefix + "    ");
        }

        System.out.println();
    }
}