结合Posts集合结构的Firestore读取计数计算问题咨询

Posts ( collection )

⤷ Post_1 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_2 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_3 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_4 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_2 ) ( field )

⤷ Post_5 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_100 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_1000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_2 ) ( field )

⤷ Post_5000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_10000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_2 ) ( field )

⤷ Post_15000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_2 ) ( field )

⤷ Post_20000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_2 ) ( field )

⤷ Post_25000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_1 ) ( field )

⤷ Post_50000 ( document )
  ⤷ post_id ( field )
  ⤷ post_description ( field )
  ⤷ category ( value = category_2 ) ( field )

问题1 #

Firestore 仅对实际获取文档的操作计入读取次数，创建文档、更新文档都属于写入操作，不会触发读取计数。
该场景中只有1次新增帖子的写入操作，和1次更新字段的写入操作，没有任何读取文档的行为，总读取次数为0。

问题2 #

Firestore 查询的读取次数按照实际返回的文档数量计算，和查询范围、过滤条件无关，每返回1篇文档计1次读取。
post_20000 到 post_20100 区间共包含 101 篇文档（首尾都计入），总读取次数为101。

问题3 #

和区间查询的计费逻辑一致，按查询返回的符合条件的文档总数计数。
已知 category_1 分类下共有13833篇帖子，查询会返回全部符合条件的文档，总读取次数为13833。

内容的提问来源于stack exchange，提问作者Taha Sami