sequnce module

Summary

• ddal-sequence is a module which can provide distributed primary key. It doesn't dependency on the other modules of ddal,so you can include this module independently.

• ddal-sequence privid a default id rangeg getting strategy: DatabaseIdRangeGetter. you can use it to quickly implement a distributed primary key function.

 from: org.hellojavaer.ddal.sequence.DatabaseIdRangeGetter
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
 *
 *  |                     --------------
 *                        | 700 ~ NULL |
 * Master                 |            |
 *                        |            |
 *  |                     --------------
 * _ _ _ _ _ _ _ _ _ _ _ _ _/ _ _ _  _\ _ _ _ _ _ _ _ _ _ _ _ _
 *                         /           \
 *  |            -------------        -------------
 *               | 120 ~ 200 |        | 201 ~ 300 |
 * Follower      | 301 ~ 400 |        | 501 ~ 600 |
 *               | 401 ~ 500 |        | 601 ~ 700 |
 *  |            -------------        -------------
 * _ _ _ _ _ _ _ _/_ _ _ _ _ \_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
 *               /            \
 *  |      ------------      -------------
 *         |  1  ~ 20 |      | 21  ~ 40  |
 *         |  41 ~ 60 |      | 81  ~ 100 |
 * Client  |  61 ~ 80 |      | 101 ~ 120 |
 *         ------------      -------------
 *           /    |   \        /    |   \
 *  |      [id] [id]  [id]   [id]  [id] [id]
 * _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Useage

• add dependency

<dependency>
    <groupId>org.hellojavaer.ddal</groupId>
    <artifactId>ddal-sequence</artifactId>
    <version>x.x.x</version><!-- goto https://github.com/hellojavaer/ddal get the last release version -->
</dependency>

• init sequence table

CREATE TABLE sequence (
        id bigint(20) NOT NULL AUTO_INCREMENT,
        schema_name varchar(32) NOT NULL,
        table_name varchar(64) NOT NULL,
        begin_value bigint(20) NOT NULL,
        next_value bigint(20) NOT NULL,
        end_value bigint(20) DEFAULT NULL,
        step int(11),
        skip_n_steps int(11),
        select_order int(11) NOT NULL,
        version bigint(20) NOT NULL DEFAULT '0',
        deleted tinyint(1) NOT NULL DEFAULT '0',
        PRIMARY KEY (id),
        KEY idx_table_name_schema_name_deleted_select_order (table_name,schema_name,deleted,select_order) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `sequence` (`id`, `schema_name`, `table_name`, `begin_value`, `next_value`, `end_value`, `select_order`, `step`, `skip_n_steps`, `version`, `deleted`)
VALUES (1, 'logical_shema_name', 'logical_table_name', 0, 0, NULL, 0, NULL, NULL, 0, 0);

• config client

DataSource dataSource = ;// TODO: specify the dataSource which can access the sequence table
String schemaName = ;// TODO: specify the schema name which the sequence table belongs to.
IdRangeGetter idRangeGetter = new DatabaseIdRangeGetter(dataSource, schemaName);
// NOTICE: 'logical_shema_name' and 'logical_table_name' are just used as a query condition.
// It doesn't strictly bind with your business table name, but generally using business table name is a good recommendation.
// eg: imagine that you can a group of split user table:user_0,user_1,.... and these tables belong to base schema.
// in this case you should use 'base' and 'user' to replace 'logical_shema_name' and 'logical_table_name'
Sequence sequence = new SingleSequence("logical_shema_name", "logical_table_name", 100, 5, 200, idRangeGetter, 100);

Long id = sequence.nextValue();