最近在做基于標簽的圈人，使用了開源的Roaringbitmap淹办。Greenplum安裝完Roaringbitmap插件后勇婴，可以構(gòu)建roaringbitmap焚志，不過這些操作都是在數(shù)據(jù)庫內(nèi)完成。如果在程序中構(gòu)建RoaringBitmap胆筒，如何將數(shù)據(jù)寫入GP邮破？

其實很簡單，使用官方自己到JDBC驅(qū)動仆救，將roaringbitmap序列化后抒和，就可以寫入了。
1.首先在gp數(shù)據(jù)庫中建表
create table btable(id int,userids bytea);注意 這里是bytea 二進制類型彤蔽。
2.在程序中序列化roaringbitmap摧莽，將二進制數(shù)據(jù)寫入數(shù)據(jù)庫

    public static String url = "jdbc:pivotal:greenplum://127.0.0.1:5432;DatabaseName=gpadmin";
    // 數(shù)據(jù)庫用戶名
    public static String username = "gpadmin";
    // 數(shù)據(jù)庫密碼
    public static String password = "gpadmin";
    public static Connection conn = null;

    static {
        try {
            try {
                conn = DriverManager.getConnection(url, username, password);
            } catch (SQLException e) {
                e.printStackTrace();
            }

            Class.forName("com.pivotal.jdbc.GreenplumDriver");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

  String insql = "INSERT INTO btest(id,bs) VALUES (?,?)";
        PreparedStatement addstmt = conn.prepareStatement(insql);
        RoaringBitmap mrb = RoaringBitmap.bitmapOf(1, 2, 3, 1000);
        System.out.println("starting with  bitmap " + mrb);
        mrb.runOptimize(); //to improve compression
        byte[] array = new byte[mrb.serializedSizeInBytes()];
        try {
            mrb.serialize(new java.io.DataOutputStream(new java.io.OutputStream() {
                int c = 0;

                @Override
                public void close() {
                }

                @Override
                public void flush() {
                }

                @Override
                public void write(int b) {
                    array[c++] = (byte) b;
                }

                @Override
                public void write(byte[] b) {
                    write(b, 0, b.length);
                }

                @Override
                public void write(byte[] b, int off, int l) {
                    System.arraycopy(b, off, array, c, l);
                    c += l;
                }
            }));
        } catch (IOException ioe) {
            // should never happen because we write to a byte array
            throw new RuntimeException("unexpected error while serializing to a byte array");
        }
        addstmt.setInt(1,1);
        ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(array);

        addstmt.setBinaryStream(2,byteArrayInputStream);
        addstmt.executeUpdate();

3.將二進制數(shù)據(jù)轉(zhuǎn)化成roaringbitmap,這也是最為關(guān)鍵的一步。

select cast( cast(userids as varchar) as roaringbitmap) from btale

至此顿痪，已經(jīng)可以將roaringbitmap寫入數(shù)據(jù)庫镊辕。
至于，如何從數(shù)據(jù)中讀取roaringbitmap员魏，暫時還沒有找到方法丑蛤。