[FLINK-41422][table] Remove built-in DEDUPLICATE_KEEP_FIRST process table function

AGENTS.md

@@ -212,7 +212,7 @@ A built-in function touches six modules. Each step names an example of that step
 2. **Define it** in `BuiltInFunctionDefinitions` in `flink-table-common`: name, kind, input and output type strategies, and how it runs, see step 3.
    - Write the name in upper case with underscores, such as `URL_DECODE`, so that SQL and the Table API use the same name.
    - Reuse a strategy from `InputTypeStrategies`, `TypeStrategies`, `SpecificInputTypeStrategies` or `SpecificTypeStrategies` before writing a new one.
-   - When a new strategy would repeat code that other strategies share, extract a shared abstraction instead of copying it. `ValidationOnlyInputTypeStrategy` is one: for a function that declares its arguments with `staticArguments(...)`, it fixes the argument count and signature, so a subclass only implements `inferInputTypes` to validate. The strategies of `FROM_CHANGELOG`, `TO_CHANGELOG` and `DEDUPLICATE_KEEP_FIRST` use it.
+   - When a new strategy would repeat code that other strategies share, extract a shared abstraction instead of copying it. `ValidationOnlyInputTypeStrategy` is one: for a function that declares its arguments with `staticArguments(...)`, it fixes the argument count and signature, so a subclass only implements `inferInputTypes` to validate. The strategies of `FROM_CHANGELOG` and `TO_CHANGELOG` use it.
    - Validate literal arguments in the input strategy, so that a malformed literal fails at planning time instead of on the first record.
    - Register the function only here. Don't also add a field for it to `FlinkSqlOperatorTable`: that class registers every field by reflection, and a second operator with the same name makes compiled plans that call the function fail to restore.
    - Every public class in `flink-table-common` and `flink-table-api-java`, nested classes included, needs a visibility annotation such as `@Internal`. ArchUnit checks this in `TableApiRules`.

docs/content.zh/docs/sql/built-in-functions/process-table-functions.md

@@ -32,7 +32,6 @@ The built-in process table functions (PTFs) take a table as input and return a t
 | `FROM_CHANGELOG(input => TABLE t [, ...])`              | Converts an append-only table with an explicit operation column into a dynamic table. See Changelog Conversion for the full list of arguments, semantics, and usage.                                                                                                                                           |
 | `TO_CHANGELOG(input => TABLE t [, ...])`                | Converts a dynamic table into an append-only table with an explicit operation column. See Changelog Conversion for the full list of arguments, semantics, and usage.                                                                                                                                           |
 | `SNAPSHOT(input => TABLE t [, ...])`                    | Returns the current state of a dynamic table `t`. `SNAPSHOT` can only be used in a `LATERAL` context and not as a stand-alone table function. See [LATERAL SNAPSHOT join]({{< ref "docs/sql/reference/queries/joins" >}}#lateral-snapshot-join) for the full list of arguments, the join semantics, and usage. |
-| `DEDUPLICATE_KEEP_FIRST(input => TABLE t [, ...])`      | Keeps the first record per key as an append-only table (first arrival, or earliest event time with `on_time`). See [Deduplicate Keep First]({{< ref "docs/sql/reference/queries/deduplicate-keep-first" >}}#deduplicate_keep_first) for the full list of arguments, semantics, and usage.                      |
 | `ML_PREDICT(TABLE t, MODEL m, DESCRIPTOR(...) [, ...])` | Applies the model `m` to the columns of table `t` that the `DESCRIPTOR` names, and returns the columns of `t` plus the prediction columns of the model. See [Model Inference]({{< ref "docs/sql/reference/queries/model-inference" >}}#ml_predict-函数) for the full list of arguments, semantics, and usage.  |
 
 Window table functions such as `TUMBLE` are listed under [Window]({{< ref "docs/sql/built-in-functions/window" >}}#window-table-functions). To implement your own PTF, see [Process Table Functions]({{< ref "docs/dev/table/functions/ptfs" >}}).

docs/content/docs/sql/built-in-functions/process-table-functions.md

@@ -32,7 +32,6 @@ The built-in process table functions (PTFs) take a table as input and return a t
 | `FROM_CHANGELOG(input => TABLE t [, ...])`              | Converts an append-only table with an explicit operation column into a dynamic table. See [Changelog Conversion]({{< ref "docs/sql/reference/queries/changelog" >}}#from_changelog) for the full list of arguments, semantics, and usage.                                                                         |
 | `TO_CHANGELOG(input => TABLE t [, ...])`                | Converts a dynamic table into an append-only table with an explicit operation column. See [Changelog Conversion]({{< ref "docs/sql/reference/queries/changelog" >}}#to_changelog) for the full list of arguments, semantics, and usage.                                                                           |
 | `SNAPSHOT(input => TABLE t [, ...])`                    | Returns the current state of a dynamic table `t`. `SNAPSHOT` can only be used in a `LATERAL` context and not as a stand-alone table function. See [LATERAL SNAPSHOT join]({{< ref "docs/sql/reference/queries/joins" >}}#lateral-snapshot-join) for the full list of arguments, the join semantics, and usage.    |
-| `DEDUPLICATE_KEEP_FIRST(input => TABLE t [, ...])`      | Keeps the first record per key as an append-only table (first arrival, or earliest event time with `on_time`). See [Deduplicate Keep First]({{< ref "docs/sql/reference/queries/deduplicate-keep-first" >}}#deduplicate_keep_first) for the full list of arguments, semantics, and usage.                         |
 | `ML_PREDICT(TABLE t, MODEL m, DESCRIPTOR(...) [, ...])` | Applies the model `m` to the columns of table `t` that the `DESCRIPTOR` names, and returns the columns of `t` plus the prediction columns of the model. See [Model Inference]({{< ref "docs/sql/reference/queries/model-inference" >}}#ml_predict-function) for the full list of arguments, semantics, and usage. |
 
 Window table functions such as `TUMBLE` are listed under [Window]({{< ref "docs/sql/built-in-functions/window" >}}#window-table-functions). To implement your own PTF, see [Process Table Functions]({{< ref "docs/dev/table/functions/ptfs" >}}).