[Doc](point query) Modify the document to add constraints and limitations for optimizing high-concurrency point queries. (#19852)

docs/en/docs/query-acceleration/hight-concurrent-point-query.md

@@ -73,6 +73,8 @@ PROPERTIES (
 1. `enable_unique_key_merge_on_write` should be enabled, since we need primary key for quick point lookup in storage engine
 2. when condition only contains primary key like `select * from tbl_point_query where key = 123`, such query will go through the short fast path
 3. `light_schema_change` should also been enabled since we rely on `column unique id` of each column when doing a point query.
+4. It only supports equality queries on the key column of a single table and does not support joins or nested subqueries. The WHERE condition should consist of the key column alone and be an equality comparison. It can be considered as a type of key-value query.
+
 
 ## Using `PreparedStatement`
 

docs/zh-CN/docs/query-acceleration/hight-concurrent-point-query.md

@@ -70,6 +70,7 @@ PROPERTIES (
 1. `enable_unique_key_merge_on_write`应该被开启， 存储引擎需要根据主键来快速点查
 2. 当条件只包含主键时，如`select * from tbl_point_query where key = 123`，类似的查询会走短路径来优化查询
 3. `light_schema_change`应该被开启， 因为主键点查的优化依赖了轻量级 Schema Change 中的`column unique id`来定位列
+4. 只支持单表key列等值查询不支持join、嵌套子查询， **where条件里需要有且仅有key列的等值**， 可以认为是一种key value查询
 
 ## 使用 `PreparedStatement`