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상태프로그래밍 영속성 이벤트 스토어용으로 RDB는 R2DBC(Reactive Drive)를 통해 여전히 높은 동시성 처리 저장장치로 활용할수 있습니다.

샘플은 Akka Actor에 연결되는 영속장치의 공식 DDL문입니다. - akka 2.7 기준 호환됨을 확인

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CREATE TABLE IF NOT EXISTS event_journal(
                                            slice INT NOT NULL,
                                            entity_type VARCHAR(255) NOT NULL,
    persistence_id VARCHAR(255) NOT NULL,
    seq_nr BIGINT NOT NULL,
    db_timestamp timestamp with time zone NOT NULL,

                               event_ser_id INTEGER NOT NULL,
                               event_ser_manifest VARCHAR(255) NOT NULL,
    event_payload BYTEA NOT NULL,

    deleted BOOLEAN DEFAULT FALSE NOT NULL,
    writer VARCHAR(255) NOT NULL,
    adapter_manifest VARCHAR(255),
    tags TEXT ARRAY,

    meta_ser_id INTEGER,
    meta_ser_manifest VARCHAR(255),
    meta_payload BYTEA,

    PRIMARY KEY(persistence_id, seq_nr)
    );

-- `event_journal_slice_idx` is only needed if the slice based queries are used
CREATE INDEX IF NOT EXISTS event_journal_slice_idx ON event_journal(slice, entity_type, db_timestamp, seq_nr);

CREATE TABLE IF NOT EXISTS snapshot(
                                       slice INT NOT NULL,
                                       entity_type VARCHAR(255) NOT NULL,
    persistence_id VARCHAR(255) NOT NULL,
    seq_nr BIGINT NOT NULL,
    write_timestamp BIGINT NOT NULL,
    ser_id INTEGER NOT NULL,
    ser_manifest VARCHAR(255) NOT NULL,
    snapshot BYTEA NOT NULL,
    meta_ser_id INTEGER,
    meta_ser_manifest VARCHAR(255),
    meta_payload BYTEA,

    PRIMARY KEY(persistence_id)
    );

CREATE TABLE IF NOT EXISTS durable_state (
    slice INT NOT NULL,
    entity_type VARCHAR(255) NOT NULL,
    persistence_id VARCHAR(255) NOT NULL,
    revision BIGINT NOT NULL,
    db_timestamp timestamp with time zone NOT NULL,
    state_ser_id INTEGER NOT NULL,
    state_ser_manifest VARCHAR(255),
    state_payload BYTEA NOT NULL,
    tags TEXT ARRAY,

PRIMARY KEY(persistence_id, revision)
);

-- `durable_state_slice_idx` is only needed if the slice based queries are used
CREATE INDEX IF NOT EXISTS durable_state_slice_idx ON durable_state(slice, entity_type, db_timestamp, revision);

-- Primitive offset types are stored in this table.
-- If only timestamp based offsets are used this table is optional.
-- Configure pekko.projection.r2dbc.offset-store.offset-table="" if the table is not created.
CREATE TABLE IF NOT EXISTS projection_offset_store (
                                                       projection_name VARCHAR(255) NOT NULL,
    projection_key VARCHAR(255) NOT NULL,
    current_offset VARCHAR(255) NOT NULL,
    manifest VARCHAR(32) NOT NULL,
    mergeable BOOLEAN NOT NULL,
    last_updated BIGINT NOT NULL,
    PRIMARY KEY(projection_name, projection_key)
    );

-- Timestamp based offsets are stored in this table.
CREATE TABLE IF NOT EXISTS projection_timestamp_offset_store (
                                                                 projection_name VARCHAR(255) NOT NULL,
    projection_key VARCHAR(255) NOT NULL,
    slice INT NOT NULL,
    persistence_id VARCHAR(255) NOT NULL,
    seq_nr BIGINT NOT NULL,
    -- timestamp_offset is the db_timestamp of the original event
    timestamp_offset timestamp with time zone NOT NULL,
    -- timestamp_consumed is when the offset was stored
    -- the consumer lag is timestamp_consumed - timestamp_offset
    timestamp_consumed timestamp with time zone NOT NULL,
                                     PRIMARY KEY(slice, projection_name, timestamp_offset, persistence_id, seq_nr)
    );

CREATE TABLE IF NOT EXISTS projection_management (
                                                     projection_name VARCHAR(255) NOT NULL,
    projection_key VARCHAR(255) NOT NULL,
    paused BOOLEAN NOT NULL,
    last_updated BIGINT NOT NULL,
    PRIMARY KEY(projection_name, projection_key)
    );

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이와같이 구현된 컨셉을, 액터모델없이 Kafka제공 순수 스트림프로그래밍을 통해 유사하게 구현해보겠습니다.

액터모델의 경우 OOP베이스에 함수형이 필요하면 혼합할수 있는 하이브리드 방식이라고 하면 스트리밍 프로그래밍은 함수형을 주로이용합니다.