Elasticsearch vector and full-text search in 10 minutes

var response = es.indices().exists(e -> e.index("books"));
System.out.println(response.value());
		

var response = es.count(c -> c.index("books"));
System.out.println(response.count());
		

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.StringReader;
import java.util.List;

import co.elastic.clients.elasticsearch.ElasticsearchClient;
import co.elastic.clients.elasticsearch._types.Refresh;
import co.elastic.clients.elasticsearch.core.BulkRequest;
import co.elastic.clients.elasticsearch.core.SearchResponse;
import co.elastic.clients.elasticsearch.core.search.Hit;
import co.elastic.clients.elasticsearch.esql.EsqlFormat;
import co.elastic.clients.transport.endpoints.BinaryResponse;

public class Main {
    record Book(
        String title,
        String author,
        int release_year,
        String description
    ) {}

    public static void main(String[] args) throws Exception {
        ElasticsearchClient es = ElasticsearchClient.of(b -> b
            .host(System.getenv("ES_URL"))
            .apiKey(System.getenv("ES_API_KEY"))
        );

        es.indices().create(c -> c
            .index("books")
            .withJson(new StringReader("""
                {
                  "mappings": {
                    "properties": {
                      "description": {
                        "type": "semantic_text"
                      }
                    }
                  }
                }
                """))
        );

        List<Book> books = List.of(
            new Book(
                "The Left Hand of Darkness",
                "Ursula K. Le Guin",
                1969,
                "An envoy visits an icy planet whose people have no fixed gender, feeling out politics and friendship across a deep cultural gap."
            ),
            new Book(
                "Project Hail Mary",
                "Andy Weir",
                2021,
                "A lone astronaut wakes with amnesia on a spaceship and has to stop a disaster that threatens all life on Earth."
            ),
            new Book(
                "The Name of the Wind",
                "Patrick Rothfuss",
                2007,
                "A gifted young musician and magician tells the story of his rise from orphan to legend."
            ),
            new Book(
                "Klara and the Sun",
                "Kazuo Ishiguro",
                2021,
                "An artificial friend watches human love and loneliness while hoping a child will pick her."
            ),
            new Book(
                "Dune",
                "Frank Herbert",
                1965,
                "On a desert planet prized for a rare spice, a young heir is pulled into a war over ecology, religion, and power."
            )
        );

        BulkRequest.Builder bulk = new BulkRequest.Builder()
            .refresh(Refresh.WaitFor);
        for (Book book : books) {
            bulk.operations(op -> op
                .index(idx -> idx
                    .index("books")
                    .document(book)
                )
            );
        }
        es.bulk(bulk.build());

        String semanticQuery = """
            {
              "query": {
                "semantic": {
                  "field": "description",
                  "query": "surviving alone in space"
                }
              }
            }
            """;
        SearchResponse<Book> response = es.search(s -> s
                .index("books")
                .withJson(new StringReader(semanticQuery)),
            Book.class
        );
        System.out.println("Semantic:");
        for (Hit<Book> hit : response.hits().hits()) {
            System.out.println("  " + hit.score() + " " + hit.source().title());
        }

        String hybridQuery = """
            {
              "query": {
                "bool": {
                  "should": [
                    {
                      "match": {
                        "title": "wind"
                      }
                    },
                    {
                      "semantic": {
                        "field": "description",
                        "query": "young magician coming of age"
                      }
                    }
                  ]
                }
              }
            }
            """;
        response = es.search(s -> s
                .index("books")
                .withJson(new StringReader(hybridQuery)),
            Book.class
        );
        System.out.println("\nHybrid:");
        for (Hit<Book> hit : response.hits().hits()) {
            System.out.println("  " + hit.score() + " " + hit.source().title());
        }

        String esql = """
            FROM books
            | STATS books = COUNT(*) BY decade = release_year - (release_year % 10)
            | KEEP decade, books
            | SORT decade ASC
            """;
        BinaryResponse aggregation = es.esql().query(q -> q
            .query(esql)
            .format(EsqlFormat.Csv)
        );
        System.out.println("\nBy decade:");
        try (BufferedReader reader = new BufferedReader(
            new InputStreamReader(aggregation.content())
        )) {
            reader.lines().skip(1).forEach(line -> {
                String[] values = line.split(",", -1);
                System.out.println("  " + values[0] + "s: " + values[1]);
            });
        }

        es.close();
    }
}