[question] get_metrics获取执行plan的实现原理？

get_metrics获取执行plan的实现原理是怎样的？
目前是否是提前定义好metrics的PromQL / Elasticsearch DSL / SQL模板，然后再把实体过滤、字段映射代入？

后续可以定义好指标，无需配置模板，自动解析出plan吗？
因为过滤、分组、聚合、关联子表等情况感觉难以通过单一的模板定义

Start by locating the get_metrics entry point and tracing how execution plans are produced for PromQL, Elasticsearch DSL, and SQL. The issue asks whether templates are used and proposes automatic plan generation, but it defines no specific files, tests, or acceptance criteria for what done would look like.

Written by the indexing model from the issue text.