added 'iterator.grouping.size' option to documentation

Author: fe2s

doc/dataframe.md

@@ -332,16 +332,17 @@ root
 
 ## DataFrame options
 
-| Name                | Description                                                                               | Type                  | Default |
-| ------------------- | ------------------------------------------------------------------------------------------| --------------------- | ------- |
-| model               | defines Redis model used to persist DataFrame, see [Persistence model](#persistence-model)| `enum [binary, hash]` | `hash`  |
-| filter.keys.by.type | make sure the underlying data structures match persistence model                          | `Boolean`             | `false` |
-| partitions.number   | number of partitions (applies only when reading dataframe)                                | `Int`                 | `3`     |
-| key.column          | when writing - specifies unique column used as a Redis key, by default a key is auto-generated. <br/> When reading - specifies column name to store hash key | `String`              | -       |
-| ttl                 | data time to live in `seconds`. Data doesn't expire if `ttl` is less than `1`             | `Int`                 | `0`     |
-| infer.schema        | infer schema from random row, all columns will have `String` type                         | `Boolean`             | `false` |
-| max.pipeline.size   | maximum number of commands per pipeline (used to batch commands)                          | `Int`                 | 100     |
-| scan.count          | count option of SCAN command (used to iterate over keys)                                  | `Int`                 | 100     |
+| Name                   | Description                                                                               | Type                  | Default |
+| -----------------------| ------------------------------------------------------------------------------------------| --------------------- | ------- |
+| model                  | defines Redis model used to persist DataFrame, see [Persistence model](#persistence-model)| `enum [binary, hash]` | `hash`  |
+| filter.keys.by.type    | make sure the underlying data structures match persistence model                          | `Boolean`             | `false` |
+| partitions.number      | number of partitions (applies only when reading dataframe)                                | `Int`                 | `3`     |
+| key.column             | when writing - specifies unique column used as a Redis key, by default a key is auto-generated. <br/> When reading - specifies column name to store hash key | `String`              | -       |
+| ttl                    | data time to live in `seconds`. Data doesn't expire if `ttl` is less than `1`             | `Int`                 | `0`     |
+| infer.schema           | infer schema from random row, all columns will have `String` type                         | `Boolean`             | `false` |
+| max.pipeline.size      | maximum number of commands per pipeline (used to batch commands)                          | `Int`                 | 100     |
+| scan.count             | count option of SCAN command (used to iterate over keys)                                  | `Int`                 | 100     |
+| iterator.grouping.size | the number of items to be grouped when iterating over underlying RDD partition            | `Int`                 | 1000    |
 
 
 ## Known limitations