Elasticsearch：使用 ILM 示例运行降采样 (downsampling)

如果你对降采样还不是很熟的话，请阅读之前的文章 “Elasticsearch：对时间序列数据流进行降采样（downsampling)”。这是一个简化的示例，可让你快速了解降采样如何作为 ILM 策略的一部分来减少一组采样指标的存储大小。该示例使用典型的 Kubernetes 集群监控数据。要使用 ILM 测试降采样，请执行以下步骤：

检查先决条件。
创建索引生命周期策略。
创建索引模板。
摄取时间序列数据。
查看结果。

以下展示是使用最新的 Elastic Stack 8.11 来进行的。

先决条件

请参阅时间序列数据流先决条件。
- 集群权限：manage_ilm 和 manage_index_templates。
- 索引权限：你创建或转换的任何 TSDS 的 create_doc 和 create_index。要滚动 TSDS，你必须具有 manage 权限。
在运行此示例之前，你可能需要尝试手动运行降采样示例。

创建索引生命周期策略

为你的时间序列数据创建 ILM 策略。虽然不是必需的，但建议使用 ILM 策略来自动管理时间序列数据流索引。

要启用降采样，请添加 Downsample 操作并将 fixed_interval 设置为要聚合原始时间序列数据的降采样间隔。

本例中为热阶段配置了 ILM 策略。降采样发生在索引滚动并且索引时间序列结束时间（index.time_series.end_time）已过之后，因为在此之前源索引仍有望接收主要写入。在索引结束时间过去之前，索引生命周期管理不会继续执行任何期望索引不再接收写入的操作。在继续等待结束时间之前的索引生命周期管理操作包括： - 删除 (Delete) - 降采样 (Downsample) - 强制合并 (Force merge) - 只读 (Read only) - 可搜索快照 (Searchable snapshot) - 收缩 (Shrink)

PUT _ilm/policy/datastream_policy
{"policy": {"phases": {"hot": {"actions": {"rollover" : {"max_age": "5m"},"downsample": {"fixed_interval": "1h"}}}}}
}

创建索引模板

这将为基本数据流创建索引模板。设置时间序列数据流中详细描述了索引模板的可用参数。

为了简单起见，在时间序列映射中，所有 time_series_metric 参数都设置为 gauge 类型，但也可以使 counter 指标类型。 time_series_metric 值确定降采样期间使用的统计表示的类型。

索引模板包含一组静态时间序列维度：主机 (host)、命名空间 (namespace)、节点 (node) 和 Pod。时间序列维度不会因降采样过程而改变。

PUT _index_template/datastream_template
{"index_patterns": ["datastream*"],"data_stream": {},"template": {"settings": {"index": {"mode": "time_series","number_of_replicas": 0,"number_of_shards": 2},"index.lifecycle.name": "datastream_policy"},"mappings": {"properties": {"@timestamp": {"type": "date"},"kubernetes": {"properties": {"container": {"properties": {"cpu": {"properties": {"usage": {"properties": {"core": {"properties": {"ns": {"type": "long"}}},"limit": {"properties": {"pct": {"type": "float"}}},"nanocores": {"type": "long","time_series_metric": "gauge"},"node": {"properties": {"pct": {"type": "float"}}}}}}},"memory": {"properties": {"available": {"properties": {"bytes": {"type": "long","time_series_metric": "gauge"}}},"majorpagefaults": {"type": "long"},"pagefaults": {"type": "long","time_series_metric": "gauge"},"rss": {"properties": {"bytes": {"type": "long","time_series_metric": "gauge"}}},"usage": {"properties": {"bytes": {"type": "long","time_series_metric": "gauge"},"limit": {"properties": {"pct": {"type": "float"}}},"node": {"properties": {"pct": {"type": "float"}}}}},"workingset": {"properties": {"bytes": {"type": "long","time_series_metric": "gauge"}}}}},"name": {"type": "keyword"},"start_time": {"type": "date"}}},"host": {"type": "keyword","time_series_dimension": true},"namespace": {"type": "keyword","time_series_dimension": true},"node": {"type": "keyword","time_series_dimension": true},"pod": {"type": "keyword","time_series_dimension": true}}}}}}
}

摄取时间序列数据

使用 bulk API 请求自动创建 TSDS 并为一组 10 个文档编制索引。

重要提示：在运行此批量请求之前，你需要将时间戳更新为当前时间后三到五个小时内。也就是说，搜索 2022-06-21T15 并替换为你当前的日期，并将小时调整为你当前的时间加三个小时。

PUT /datastream/_bulk?refresh
{"create": {}}
{"@timestamp":"2022-06-21T15:49:00Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":91153,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":463314616},"usage":{"bytes":307007078,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":585236},"rss":{"bytes":102728},"pagefaults":120901,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:45:50Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":124501,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":982546514},"usage":{"bytes":360035574,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1339884},"rss":{"bytes":381174},"pagefaults":178473,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:44:50Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":38907,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":862723768},"usage":{"bytes":379572388,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":431227},"rss":{"bytes":386580},"pagefaults":233166,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:44:40Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":86706,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":567160996},"usage":{"bytes":103266017,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1724908},"rss":{"bytes":105431},"pagefaults":233166,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:44:00Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":150069,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":639054643},"usage":{"bytes":265142477,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1786511},"rss":{"bytes":189235},"pagefaults":138172,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:42:40Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":82260,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":854735585},"usage":{"bytes":309798052,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":924058},"rss":{"bytes":110838},"pagefaults":259073,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:42:10Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":153404,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":279586406},"usage":{"bytes":214904955,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1047265},"rss":{"bytes":91914},"pagefaults":302252,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:40:20Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":125613,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":822782853},"usage":{"bytes":100475044,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":2109932},"rss":{"bytes":278446},"pagefaults":74843,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:40:10Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":100046,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":567160996},"usage":{"bytes":362826547,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1986724},"rss":{"bytes":402801},"pagefaults":296495,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2022-06-21T15:38:30Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":40018,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":1062428344},"usage":{"bytes":265142477,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":2294743},"rss":{"bytes":340623},"pagefaults":224530,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}

针对我的情况：

PUT /datastream/_bulk?refresh
{"create": {}}
{"@timestamp":"2023-11-30T06:49:00Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":91153,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":463314616},"usage":{"bytes":307007078,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":585236},"rss":{"bytes":102728},"pagefaults":120901,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:45:50Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":124501,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":982546514},"usage":{"bytes":360035574,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1339884},"rss":{"bytes":381174},"pagefaults":178473,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:44:50Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":38907,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":862723768},"usage":{"bytes":379572388,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":431227},"rss":{"bytes":386580},"pagefaults":233166,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:44:40Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":86706,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":567160996},"usage":{"bytes":103266017,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1724908},"rss":{"bytes":105431},"pagefaults":233166,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:44:00Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":150069,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":639054643},"usage":{"bytes":265142477,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1786511},"rss":{"bytes":189235},"pagefaults":138172,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:42:40Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":82260,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":854735585},"usage":{"bytes":309798052,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":924058},"rss":{"bytes":110838},"pagefaults":259073,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:42:10Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":153404,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":279586406},"usage":{"bytes":214904955,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1047265},"rss":{"bytes":91914},"pagefaults":302252,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:40:20Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":125613,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":822782853},"usage":{"bytes":100475044,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":2109932},"rss":{"bytes":278446},"pagefaults":74843,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:40:10Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":100046,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":567160996},"usage":{"bytes":362826547,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":1986724},"rss":{"bytes":402801},"pagefaults":296495,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}
{"create": {}}
{"@timestamp":"2023-11-30T06:38:30Z","kubernetes":{"host":"gke-apps-0","node":"gke-apps-0-0","pod":"gke-apps-0-0-0","container":{"cpu":{"usage":{"nanocores":40018,"core":{"ns":12828317850},"node":{"pct":2.77905e-05},"limit":{"pct":2.77905e-05}}},"memory":{"available":{"bytes":1062428344},"usage":{"bytes":265142477,"node":{"pct":0.01770037710617187},"limit":{"pct":9.923134671484496e-05}},"workingset":{"bytes":2294743},"rss":{"bytes":340623},"pagefaults":224530,"majorpagefaults":0},"start_time":"2021-03-30T07:59:06Z","name":"container-name-44"},"namespace":"namespace26"}}

查看结果

现在你已创建文档并将其添加到数据流中，请检查以确认新索引的当前状态。

GET _data_stream

如果尚未应用 ILM 策略，你的结果将如下所示。请注意原始索引名称：.ds-datastream-<timestamp>-000001。

{"data_streams": [{"name": "datastream","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": ".ds-datastream-2023.11.30-000001","index_uuid": "muM9y4_ORDK1wLY-t_UtnA","prefer_ilm": true,"ilm_policy": "datastream_policy","managed_by": "Index Lifecycle Management"}],"generation": 1,"status": "GREEN","template": "datastream_template","ilm_policy": "datastream_policy","next_generation_managed_by": "Index Lifecycle Management","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false,"time_series": {"temporal_ranges": [{"start": "2023-11-30T03:21:48.000Z","end": "2023-11-30T07:27:32.000Z"}]}},{"name": "kibana_sample_data_logs","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": ".ds-kibana_sample_data_logs-2023.11.21-000001","index_uuid": "JkbH5-8uTvyeZL6icuHN1A","prefer_ilm": true,"managed_by": "Unmanaged"}],"generation": 1,"status": "YELLOW","template": "kibana_sample_data_logs","next_generation_managed_by": "Unmanaged","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false},{"name": "my-data-stream","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": ".ds-my-data-stream-2023.11.30-000001-downsample","index_uuid": "KXtWAQCBRlW0sWYCVUu7Fw","prefer_ilm": true,"managed_by": "Unmanaged"},{"index_name": ".ds-my-data-stream-2023.11.30-000002","index_uuid": "yBDLixmpRDahmS4G5_uxQw","prefer_ilm": true,"managed_by": "Unmanaged"}],"generation": 4,"status": "GREEN","template": "my-data-stream-template","next_generation_managed_by": "Unmanaged","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false,"time_series": {"temporal_ranges": [{"start": "2023-11-30T02:24:20.000Z","end": "2023-11-30T08:32:32.000Z"}]}}]
}

接下来，运行搜索查询：

GET datastream/_search

经过一段时间后，它会变成如下的结果：

{"data_streams": [{"name": "datastream","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": "downsample-1h-.ds-datastream-2023.11.30-000001","index_uuid": "KQMxcaJATf24XAesWs6Xbw","prefer_ilm": true,"ilm_policy": "datastream_policy","managed_by": "Index Lifecycle Management"},{"index_name": ".ds-datastream-2023.11.30-000002","index_uuid": "yKLevDQkQuS-8yqJQb8gWw","prefer_ilm": true,"ilm_policy": "datastream_policy","managed_by": "Index Lifecycle Management"}],"generation": 3,"status": "GREEN","template": "datastream_template","ilm_policy": "datastream_policy","next_generation_managed_by": "Index Lifecycle Management","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false,"time_series": {"temporal_ranges": [{"start": "2023-11-30T03:21:48.000Z","end": "2023-11-30T10:45:44.000Z"}]}},{"name": "kibana_sample_data_logs","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": ".ds-kibana_sample_data_logs-2023.11.21-000001","index_uuid": "JkbH5-8uTvyeZL6icuHN1A","prefer_ilm": true,"managed_by": "Unmanaged"}],"generation": 1,"status": "YELLOW","template": "kibana_sample_data_logs","next_generation_managed_by": "Unmanaged","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false},{"name": "my-data-stream","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": ".ds-my-data-stream-2023.11.30-000001-downsample","index_uuid": "KXtWAQCBRlW0sWYCVUu7Fw","prefer_ilm": true,"managed_by": "Unmanaged"},{"index_name": ".ds-my-data-stream-2023.11.30-000002","index_uuid": "yBDLixmpRDahmS4G5_uxQw","prefer_ilm": true,"managed_by": "Unmanaged"}],"generation": 4,"status": "GREEN","template": "my-data-stream-template","next_generation_managed_by": "Unmanaged","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false,"time_series": {"temporal_ranges": [{"start": "2023-11-30T02:24:20.000Z","end": "2023-11-30T10:45:44.000Z"}]}}]
}

默认情况下，索引生命周期管理每十分钟检查一次是否符合策略标准。等待大约十分钟（也许可以冲泡一杯咖啡或茶☕），然后重新运行 GET _data_stream 请求。

GET _data_stream

ILM 策略生效后，原始 .ds-datastream-2023.11.30-000001 索引将替换为新的降采样索引，在本例中为 downsample-1h-.ds-datastream-2023.11.30-000001。

{"data_streams": [{"name": "datastream","timestamp_field": {"name": "@timestamp"},"indices": [{"index_name": "downsample-1h-.ds-datastream-2023.11.30-000001","index_uuid": "KQMxcaJATf24XAesWs6Xbw","prefer_ilm": true,"ilm_policy": "datastream_policy","managed_by": "Index Lifecycle Management"},{"index_name": ".ds-datastream-2023.11.30-000002","index_uuid": "yKLevDQkQuS-8yqJQb8gWw","prefer_ilm": true,"ilm_policy": "datastream_policy","managed_by": "Index Lifecycle Management"}],"generation": 3,"status": "GREEN","template": "datastream_template","ilm_policy": "datastream_policy","next_generation_managed_by": "Index Lifecycle Management","prefer_ilm": true,"hidden": false,"system": false,"allow_custom_routing": false,"replicated": false,"time_series": {"temporal_ranges": [{"start": "2023-11-30T03:21:48.000Z","end": "2023-11-30T10:45:44.000Z"}]}},

在数据流上运行搜索查询（请注意，在查询降采样索引时，需要注意一些细微差别）。

GET datastream/_search

新的降采样索引仅包含一个文档，其中包括基于原始采样指标的 min、max、sum 和 value_count 统计信息。

{"took": 1,"timed_out": false,"_shards": {"total": 4,"successful": 4,"skipped": 0,"failed": 0},"hits": {"total": {"value": 1,"relation": "eq"},"max_score": 1,"hits": [{"_index": "downsample-1h-.ds-datastream-2023.11.30-000001","_id": "0eL0wC_4-45SnTNFAAABjB7QCwA","_score": 1,"_source": {"@timestamp": "2023-11-30T06:00:00.000Z","_doc_count": 10,"kubernetes": {"container": {"cpu": {"usage": {"core": {"ns": 12828317850},"limit": {"pct": 0.0000277905},"nanocores": {"min": 38907,"max": 153404,"sum": 992677,"value_count": 10},"node": {"pct": 0.0000277905}}},"memory": {"available": {"bytes": {"min": 279586406,"max": 1062428344,"sum": 7101494721,"value_count": 10}},"majorpagefaults": 0,"pagefaults": {"min": 74843,"max": 302252,"sum": 2061071,"value_count": 10},"rss": {"bytes": {"min": 91914,"max": 402801,"sum": 2389770,"value_count": 10}},"usage": {"bytes": {"min": 100475044,"max": 379572388,"sum": 2668170609,"value_count": 10},"limit": {"pct": 0.00009923134},"node": {"pct": 0.017700378}},"workingset": {"bytes": {"min": 431227,"max": 2294743,"sum": 14230488,"value_count": 10}}},"name": "container-name-44","start_time": "2021-03-30T07:59:06.000Z"},"host": "gke-apps-0","namespace": "namespace26","node": "gke-apps-0-0","pod": "gke-apps-0-0-0"}}}]}
}

使用数据流统计 API 获取数据流的统计信息，包括存储大小。

GET /_data_stream/datastream/_stats?human=true

此示例演示了降采样如何作为 ILM 策略的一部分来工作，以减少指标数据的存储大小，因为它变得不那么最新且查询频率较低。

你还可以尝试我们的手动运行降采样示例，了解降采样如何在 ILM 策略之外工作。