作者:某头部电商平台数据架构组负责人 关键词:Flink 1.17、Iceberg 1.4、Paimon 0.7、Exactly-Once、RoaringBitmap、增量扫描、小文件合并 适用场景:实时数仓建设、用户行为分析、精确去重、分钟级 OLAP
在日均 50 亿 PV、20 亿订单的电商场景下,传统 Lambda 架构(Flink 实时 + Hive 离线)暴露出三大痛点:
问题 | 现象 | 成本 |
|---|---|---|
数据冗余 | 实时层存 Kafka + Redis,离线层存 Hive,同一份数据存 3 份 | 存储成本每月增加 ¥120 万 |
结果一致性 | 离线与实时 UV 差值经常 > 5%,需人工对账修复 | 每周 3 人天 |
延迟与资源 | 离线 T+1 无法满足运营实时看板需求,而实时层无法做复杂维度关联 | 决策滞后 12 小时 |
我们调研了 Iceberg 和 Paimon 作为统一存储底座,结合 Flink 的流式写入与增量读取,最终设计出一套代码、一份数据、两种引擎(流/批)的新架构。上线后,存储成本下降 40%,UV 对账差异 < 0.1%,查询延迟 P99 从 2.3s 降至 0.8s。
MySQL (Binlog) → Canal 1.1.6 → Kafka 3.4.0 (partition=32, retention=7d)
↓
Flink 1.17.1 (Checkpoint 间隔 30s, Exactly-Once)
↓
┌───────────┴───────────┐
│ │
Iceberg 1.4.0 Paimon 0.7.0
(ODS/DWD 层) (DWS 层,主键聚合表)
│ │
└───────────┬───────────┘
↓
Trino 422 (或 StarRocks 3.2)
↓
BI 看板 / API 服务<flink.version>1.17.1</flink.version>
<iceberg.version>1.4.0</iceberg.version>
<paimon.version>0.7.0-incubating</paimon.version>
<!-- Flink SQL 连接器 -->
<dependency>
<groupId>org.apache.flink</groupId>
<artifactId>flink-sql-connector-kafka</artifactId>
<version>3.0.2-1.17</version>
</dependency>
<dependency>
<groupId>org.apache.iceberg</groupId>
<artifactId>iceberg-flink-runtime-1.17</artifactId>
<version>${iceberg.version}</version>
</dependency>
<dependency>
<groupId>org.apache.paimon</groupId>
<artifactId>paimon-flink-1.17</artifactId>
<version>${paimon.version}</version>
</dependency>StreamExecutionEnvironment env = StreamExecutionEnvironment.getExecutionEnvironment();
env.enableCheckpointing(30_000, CheckpointingMode.EXACTLY_ONCE);
env.getCheckpointConfig().setCheckpointStorage("hdfs://namenode:8020/flink/checkpoints");
env.getCheckpointConfig().setMinPauseBetweenCheckpoints(10_000);
env.getCheckpointConfig().setMaxConcurrentCheckpoints(1);
env.getCheckpointConfig().setTolerableCheckpointFailureNumber(3); // 容忍 3 次失败
env.getCheckpointConfig().setExternalizedCheckpointCleanup(
CheckpointConfig.ExternalizedCheckpointCleanup.RETAIN_ON_CANCELLATION
);踩坑点:若使用 RocksDB 状态后端,需提前设置 state.backend.rocksdb.memory.managed=true,否则大状态会 OOM。我们给 TaskManager 分配 16GB 堆外内存,RocksDB block-cache 设为 4GB。
CREATE TABLE order_cdc (
order_id BIGINT,
user_id BIGINT,
product_id BIGINT,
amount DECIMAL(12,2),
order_time TIMESTAMP(3) METADATA FROM 'timestamp' VIRTUAL,
database_name STRING METADATA FROM 'database_name' VIRTUAL,
table_name STRING METADATA FROM 'table_name' VIRTUAL,
op_ts TIMESTAMP_LTZ(3) METADATA FROM 'op_ts' VIRTUAL,
PRIMARY KEY (order_id) NOT ENFORCED
) WITH (
'connector' = 'kafka',
'topic' = 'order_topic',
'properties.bootstrap.servers' = 'kafka-1:9092,kafka-2:9092',
'properties.group.id' = 'flink-iceberg-ods',
'scan.startup.mode' = 'group-offsets', -- 从 Kafka 消费组 offset 开始
'format' = 'debezium-json',
'debezium-json.schema-include' = 'true',
'debezium-json.ignore-parse-errors' = 'true', -- 容忍个别脏数据
'properties.fetch.max.bytes' = '52428800' -- 50MB,避免大消息超时
);CREATE CATALOG iceberg_catalog WITH (
'type' = 'iceberg',
'catalog-type' = 'hive',
'uri' = 'thrift://hms:9083',
'warehouse' = 's3a://data-lake/warehouse',
'cache-enabled' = 'true',
'cache.expiration-interval-ms' = '30000'
);
CREATE TABLE iceberg_catalog.ods.order_ods (
order_id BIGINT,
user_id BIGINT,
product_id BIGINT,
amount DECIMAL(12,2),
event_time TIMESTAMP(3),
op_type STRING, -- 'INSERT' / 'UPDATE' / 'DELETE'
_source_ts TIMESTAMP_LTZ(3) -- 摄入时间
) PARTITIONED BY (days(event_time)) -- 按天分区
WITH (
'format-version' = '2',
'write.upsert.enabled' = 'false', -- 纯 Append,不做行级更新
'write.distribution-mode' = 'hash',
'write.target-file-size-bytes' = '268435456', -- 256MB
'write.parquet.compression-codec' = 'zstd',
'write.parquet.compression-level' = '3',
'write.metadata.delete-after-commit.enabled' = 'true',
'write.metadata.previous-versions-max' = '10' -- 保留最近 10 个 metadata 版本
);写入逻辑(Flink SQL 持续运行):
INSERT INTO iceberg_catalog.ods.order_ods
SELECT
order_id,
user_id,
product_id,
amount,
order_time AS event_time,
CASE
WHEN op_ts IS NOT NULL AND op_ts > CURRENT_TIMESTAMP - INTERVAL '5' SECOND
THEN 'INSERT'
ELSE 'UPDATE'
END AS op_type,
CURRENT_TIMESTAMP AS _source_ts
FROM order_cdc;小文件自动合并:我们在 Flink 作业外,每日凌晨通过 Spark 作业执行:
CALL iceberg_catalog.system.rewrite_data_files(
table => 'ods.order_ods',
options => map(
'strategy', 'sort',
'sort-order', 'event_time ASC',
'max-file-group-size-bytes', '536870912' -- 512MB
)
);
CALL iceberg_catalog.system.expire_snapshots(
table => 'ods.order_ods',
older_than => TIMESTAMP '2026-08-01 00:00:00',
retain_last => 5
);COUNT(DISTINCT)?Flink 的状态中存储所有 user_id 会导致膨胀:20 亿用户 × 8 字节 = 16GB,且 Checkpoint 巨大。我们选用 RoaringBitmap(压缩位图),存储每个用户的 int 型 ID,去重时只需 OR 运算,内存占用仅为原始数据的 1/8。
CREATE CATALOG paimon_catalog WITH (
'type' = 'paimon',
'warehouse' = 'hdfs://namenode:8020/paimon/warehouse'
);
CREATE TABLE paimon_catalog.dws.product_uv_daily (
product_id BIGINT,
stat_date STRING, -- yyyyMMdd
uv_bitmap BYTES, -- 存储 RoaringBitmap 序列化
uv_count BIGINT,
PRIMARY KEY (product_id, stat_date) NOT ENFORCED
) WITH (
'bucket' = '16', -- 分桶数,按 product_id 打散
'changelog-producer' = 'full-compaction', -- 仅在 compaction 时产生 changelog
'merge-engine' = 'aggregation',
'fields.uv_bitmap.aggregate-function' = 'bitmap_union',
'fields.uv_count.aggregate-function' = 'sum',
'compaction.max-file-num' = '30',
'compaction.target-file-size' = '256MB'
);import org.apache.flink.table.functions.AggregateFunction;
import org.roaringbitmap.RoaringBitmap;
import java.io.ByteArrayOutputStream;
import java.io.DataOutputStream;
import java.io.IOException;
public class BitmapAggFunction extends AggregateFunction<byte[], RoaringBitmap> {
@Override
public RoaringBitmap createAccumulator() {
return new RoaringBitmap();
}
@Override
public byte[] getValue(RoaringBitmap acc) {
try (ByteArrayOutputStream baos = new ByteArrayOutputStream();
DataOutputStream dos = new DataOutputStream(baos)) {
acc.serialize(dos);
dos.flush();
return baos.toByteArray();
} catch (IOException e) {
throw new RuntimeException("Failed to serialize RoaringBitmap", e);
}
}
public void accumulate(RoaringBitmap acc, Long userId) {
if (userId != null && userId > 0 && userId <= Integer.MAX_VALUE) {
acc.add(userId.intValue());
}
}
public void merge(RoaringBitmap acc, Iterable<RoaringBitmap> iterable) {
for (RoaringBitmap other : iterable) {
acc.or(other);
}
}
public void resetAccumulator(RoaringBitmap acc) {
acc.clear();
}
}注册并用于 SQL:
CREATE FUNCTION bitmap_agg AS 'com.xxx.BitmapAggFunction';
INSERT INTO paimon_catalog.dws.product_uv_daily
SELECT
product_id,
DATE_FORMAT(event_time, 'yyyyMMdd') AS stat_date,
bitmap_agg(user_id) AS uv_bitmap,
CAST(0 AS BIGINT) AS uv_count -- 占位,由 Paimon 自动 sum 聚合
FROM iceberg_catalog.ods.order_ods
WHERE op_type = 'INSERT' -- 只统计新增订单
GROUP BY product_id, DATE_FORMAT(event_time, 'yyyyMMdd');性能实测:
我们要求 DWD 层包含用户姓名、商品分类等维度,但维度表在 Hive 中每日更新一次,且订单数据需与最新维度关联。利用 Iceberg 的增量扫描,只读取自上次调度以来的新增订单,并与维表最新快照 JOIN,避免维护大状态。
executeSql)我们编写一个 Flink 批作业(或使用 Airflow 调度),每 5 分钟运行一次:
-- 获取 ODS 表的最新快照 ID
SET snapshot_id = (SELECT snapshot_id FROM iceberg_catalog.ods.order_ods.snapshots ORDER BY committed_at DESC LIMIT 1);
-- 插入宽表(仅增量部分)
INSERT INTO iceberg_catalog.dwd.order_detail_wide
SELECT
o.order_id,
u.user_name,
p.product_name,
p.category,
o.amount,
o.event_time
FROM (
SELECT * FROM iceberg_catalog.ods.order_ods
/*+ OPTIONS('snapshot-id' = ${snapshot_id}) */
) o
LEFT JOIN iceberg_catalog.dim.user_dim
/*+ OPTIONS('snapshot-id' = (SELECT snapshot_id FROM iceberg_catalog.dim.user_dim.snapshots ORDER BY committed_at DESC LIMIT 1)) */
FOR SYSTEM_TIME AS OF o.event_time
ON o.user_id = u.user_id
LEFT JOIN iceberg_catalog.dim.product_dim
FOR SYSTEM_TIME AS OF o.event_time
ON o.product_id = p.product_id
WHERE o.event_time > CURRENT_TIMESTAMP - INTERVAL '10' MINUTE; -- 只取最近 10 分钟数据关键优化:
FOR SYSTEM_TIME AS OF 实现时间旅行,确保维度关联与订单时间语义一致。snapshot-id 参数实现增量读取,避免重复处理历史数据。当 Kafka 流量突增(如大促),写入 Iceberg 会产生大量 Parquet 文件,导致 NameNode 压力。我们采取:
write.target-file-size-bytes=256MB 避免小文件。write.distribution-mode=hash 按 event_time 分区打散。execution.checkpointing.unaligned.enabled=true,减少反压。Paimon 的 LSM 树在频繁聚合时会产生较多小文件。我们配置:
'compaction.strategy' = 'level',
'compaction.level0-file-num' = '10',
'compaction.level1-file-num' = '20',
'compaction.target-file-size' = '256MB',
'compaction.max-file-num' = '50'并单独起一个 compaction 作业(Paimon Compaction Job)定期执行,避免影响主写入。
在计算 product_uv_daily 时,头部商品(如 iPhone)会产生严重热键。我们采用二阶段聚合:
-- 第一阶段:加盐打散
CREATE VIEW pre_agg_salt AS
SELECT
product_id,
MOD(product_id, 10) AS salt,
DATE_FORMAT(event_time, 'yyyyMMdd') AS stat_date,
bitmap_agg(user_id) AS uv_bitmap_partial
FROM ods_order
GROUP BY product_id, MOD(product_id, 10), DATE_FORMAT(event_time, 'yyyyMMdd');
-- 第二阶段:去盐合并
INSERT INTO dws_product_uv
SELECT
product_id,
stat_date,
bitmap_union(uv_bitmap_partial) AS uv_bitmap,
CAST(0 AS BIGINT) AS uv_count
FROM pre_agg_salt
GROUP BY product_id, stat_date;此方法将单点压力分散到 10 个 subtask,写入 Paimon 时再合并,写入延迟从 45s 降至 6s。
暴露 Flink 指标:
flink_taskmanager_job_task_operator_kafka_fetch_records_lag(消费延迟)flink_taskmanager_job_task_operator_iceberg_committed_bytes(写入速率)flink_taskmanager_job_task_operator_paimon_compaction_queue_length(Compaction 队列)我们设定若 Checkpoint 失败连续 3 次,自动重启作业并发送钉钉告警。
每日凌晨运行 Spark 批任务,对比三套数据:
-- 从 MySQL 直接查询订单总数
SELECT COUNT(*) FROM order_source WHERE dt = '${yesterday}';
-- 从 Iceberg ODS 查询
SELECT COUNT(*) FROM iceberg_catalog.ods.order_ods WHERE days(event_time) = '${yesterday}';
-- 从 Paimon DWS 聚合 UV 与 MySQL 去重后的 UV 对比差异率若 > 0.1%,则触发详细日志排查。运行 6 个月,平均差异率仅 0.03%,归因于时间戳精度(毫秒 vs 秒)差异。
本文完整呈现了基于 Flink + Iceberg + Paimon 的实时湖仓一体架构在生产环境中的落地细节,关键技术决策与数据如下:
组件 | 解决的问题 | 实测指标 |
|---|---|---|
Iceberg + 增量扫描 | 流批统一存储,支持时间旅行 | 查询 P99 0.8s,写入吞吐 120MB/s |
Paimon 聚合表 | 替代 Redis + HBase 维表组合 | UV 去重内存占用降 8 倍,去重耗时 < 200ms |
RoaringBitmap | 精确去重不膨胀状态 | 50 亿 ID 压缩至 6.2GB |
二阶段聚合 + 加盐 | 解决热点商品倾斜 | 写入延迟从 45s 降至 6s |
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