执行命令

通过 JDBC 执行命令

下面的独立示例创建 books_demo 集合及索引，写入一条记录后执行搜索。在已有数据库运行时请使用新的集合名。

import java.sql.*;
import java.util.Properties;

public class MilvusJdbcExample {
    public static void main(String[] args) throws Exception {
        String url = args.length == 0
                ? "jdbc:dbvisitor:milvus://127.0.0.1:19530/default"
                : args[0];
        Properties props = new Properties();
        props.setProperty("consistencyLevel", "Strong");
        props.setProperty("connectTimeout", "10000");
        props.setProperty("maxRetry", "3");
        // If authentication is enabled:
        // props.setProperty("token", "YOUR_TOKEN");

        Class.forName("net.hasor.dbvisitor.driver.JdbcDriver");
        try (Connection conn = DriverManager.getConnection(url, props)) {
            try (Statement stmt = conn.createStatement()) {
                stmt.executeUpdate("CREATE TABLE books_demo (" +
                        "book_id INT64 PRIMARY KEY, title VARCHAR(200), " +
                        "word_count INT32 DEFAULT 0, book_intro FLOAT_VECTOR(2))");
                stmt.executeUpdate("CREATE INDEX idx_intro ON books_demo (book_intro) " +
                        "USING 'FLAT' WITH (metric_type='L2')");
                stmt.executeUpdate("LOAD TABLE books_demo");
            }

            String insert = "INSERT INTO books_demo " +
                    "(book_id, title, word_count, book_intro) VALUES (?, ?, ?, ?)";
            try (PreparedStatement ps = conn.prepareStatement(insert)) {
                ps.setLong(1, 1L);
                ps.setString(2, "A book");
                ps.setInt(3, 1000);
                ps.setObject(4, new float[] {0.1F, 0.2F});
                System.out.println("inserted=" + ps.executeUpdate());
            }

            String search = "SELECT book_id, title, score FROM books_demo " +
                    "WHERE word_count >= ? ORDER BY book_intro <-> ? LIMIT ?";
            try (PreparedStatement ps = conn.prepareStatement(search)) {
                ps.setInt(1, 100);
                ps.setObject(2, new float[] {0.1F, 0.2F});
                ps.setInt(3, 5);
                ps.setFetchSize(128);
                ps.setQueryTimeout(30);
                try (ResultSet rs = ps.executeQuery()) {
                    while (rs.next()) {
                        System.out.printf("%d %s %.4f%n", rs.getLong("book_id"),
                                rs.getString("title"), rs.getFloat("score"));
                    }
                }
            }
        }
    }
}

控制分页写入

下面片段使用已打开的连接 conn。fetchSize 控制内部每页记录数，LIMIT 控制本次选取的总量；执行失败不会回滚先前成功的页面。

try (PreparedStatement ps = conn.prepareStatement(
        "UPSERT INTO books_demo (book_id, title, word_count, book_intro) VALUES (?, ?, ?, ?)")) {
    ps.setLong(1, 1L);
    ps.setString(2, "Revised book");
    ps.setInt(3, 1200);
    ps.setObject(4, new double[] {0.1, 0.2});
    ps.executeUpdate();
}
try (PreparedStatement ps = conn.prepareStatement(
        "UPDATE books_demo SET word_count = ? WHERE book_id = ? LIMIT ?")) {
    ps.setInt(1, 1500);
    ps.setLong(2, 1L);
    ps.setInt(3, 1);
    ps.setFetchSize(128);
    System.out.println(ps.executeLargeUpdate());
}
try (PreparedStatement ps = conn.prepareStatement(
        "DELETE FROM books_demo WHERE book_id = ? LIMIT ?")) {
    ps.setLong(1, 1L);
    ps.setInt(2, 1);
    System.out.println(ps.executeLargeUpdate());
}

try (PreparedStatement ps = conn.prepareStatement(
        "SELECT book_id, title FROM books_demo WHERE word_count >= ?")) {
    ps.setInt(1, 100);
    ps.setFetchSize(256);
    ps.setMaxRows(1000);
    ps.setQueryTimeout(30);
    try (ResultSet rs = ps.executeQuery()) {
        while (rs.next()) {
            System.out.println(rs.getLong("book_id") + ": " + rs.getString("title"));
        }
    }
}

执行控制

• setFetchSize(rows)：单页记录数，不是总量上限。
• setQueryTimeout(seconds)：执行时间预算，包含重试和后续结果取页，单位秒。
• 连接与单次 RPC 超时见参数配置；命令同步等待时间见 Hint 支持。

写后立即读取

SDK 2.6.22 的 QueryIterator 使用集合默认一致性。分页查询或 DML 选取数据需要写后立即可见时，建表应设置 WITH (consistency_level=Strong)；仅配置连接参数 consistencyLevel=Strong 不够。

可绑定的参数类型见参数绑定。