Prometheus
GreptimeDB 可以作为 Prometheus 的长期存储。使用 GreptimeDB 作为 Prometheus 的后端存储可以获得无缝体验。由于 Prometheus 支持在配置远程写和读的过程中设置基本的认证信息，用户只需要把配置的用户名和密码添加到配置 YAML 文件中，就可以了。
首先要为存储 Prometheus 的数据创建一个单独的数据库:
sql
CREATE DATABASE prometheus;CREATE DATABASE prometheus;请按照 Prometheus configuration (prometheus.yml) 中的设置进行配置：
yaml
remote_write:
- url: http://localhost:4000/v1/prometheus/write?db=prometheus
# basic_auth:
# username: greptime_user
# password: greptime_pwd
remote_read:
- url: http://localhost:4000/v1/prometheus/read?db=prometheus
# basic_auth:
# username: greptime_user
# password: greptime_pwdremote_write:
- url: http://localhost:4000/v1/prometheus/write?db=prometheus
# basic_auth:
# username: greptime_user
# password: greptime_pwd
remote_read:
- url: http://localhost:4000/v1/prometheus/read?db=prometheus
# basic_auth:
# username: greptime_user
# password: greptime_pwd注意：请将 greptime_user(username), greptime_pwd(password) 替换为用户自己的用户名和密码，详情请参考客户端鉴权认证。
url 中的 db 参数表示我们要写入的数据库，如果没有指定，则默认为 public。
写入数据成功后，使用下面的命令展示 Prometheus 数据库中的表：
sql
use prometheus;
show tables;use prometheus;
show tables;sql
+---------------------------------------------------------------+
| Tables |
+---------------------------------------------------------------+
| go_memstats_heap_inuse_bytes |
| go_memstats_last_gc_time_seconds |
| net_conntrack_listener_conn_closed_total |
| prometheus_remote_storage_enqueue_retries_total |
| prometheus_remote_storage_exemplars_pending |
| prometheus_remote_storage_read_request_duration_seconds_count |
| prometheus_rule_group_duration_seconds |
| prometheus_rule_group_duration_seconds_count |
| ...... |
+---------------------------------------------------------------++---------------------------------------------------------------+
| Tables |
+---------------------------------------------------------------+
| go_memstats_heap_inuse_bytes |
| go_memstats_last_gc_time_seconds |
| net_conntrack_listener_conn_closed_total |
| prometheus_remote_storage_enqueue_retries_total |
| prometheus_remote_storage_exemplars_pending |
| prometheus_remote_storage_read_request_duration_seconds_count |
| prometheus_rule_group_duration_seconds |
| prometheus_rule_group_duration_seconds_count |
| ...... |
+---------------------------------------------------------------+GreptimeDB 中的 Prometheus 指标
当指标被远程写入 GreptimeDB 时，它们将被转换为下面这样：
| Sample Metrics | In GreptimeDB | GreptimeDB Data Types |
|---|---|---|
| Name | Table (Auto-created) Name | String |
| Value | Column (greptime_value) | Double |
| Timestamp | Column (greptime_timestamp) | Timestamp |
| Label | Column | String |
所有标签列将会被自动创建为主键。当添加新的标签时，它也会自动添加到主键中。
举例: GreptimeDB 表中的 Prometheus 指标
txt
prometheus_remote_storage_samples_total{instance="localhost:9090", job="prometheus",
remote_name="648f0c", url="http://localhost:4000/v1/prometheus/write"} 500prometheus_remote_storage_samples_total{instance="localhost:9090", job="prometheus",
remote_name="648f0c", url="http://localhost:4000/v1/prometheus/write"} 500上面这个例子将被转化为表 prometheus_remote_storage_samples_total 中的一行：
| Column | Value | Column Data Type |
|---|---|---|
| instance | localhost:9090 | String |
| job | prometheus | String |
| remote_name | 648f0c | String |
| url | http://localhost:4000/v1/prometheus/write | String |
| greptime_value | 500 | Double |
| greptime_timestamp | The sample's unix timestamp | Timestamp |