Update documentations for the evaluation and dump functionality

docs/docs/core/cli.mdx

@@ -65,6 +65,7 @@ The following subcommands are available:
 | `setup` | Check and apply setup changes for flows, including the internal and target storage (to export). |
 | `show` | Show the spec for a specific flow. |
 | `update` | Update the index defined by the flow. |
+| `evaluate` | Evaluate the flow and dump flow outputs to files.  Instead of updating the index, it dumps what should be indexed to files. Mainly used for evaluation purpose. |
 
 Use `--help` to see the full list of subcommands, and `subcommand --help` to see the usage of a specific one.
 

docs/docs/core/flow_methods.mdx

@@ -12,7 +12,7 @@ After a flow is defined as discussed in [Flow Definition](/docs/core/flow_def),
 
 ## update
 
-The `update()` method will update will update the index defined by the flow.
+The `update()` method will update the index defined by the flow.
 
 Once the function returns, the indice is fresh up to the moment when the function is called.
 
@@ -23,5 +23,25 @@ Once the function returns, the indice is fresh up to the moment when the functio
 flow.update()
 ```
 
+</TabItem>
+</Tabs>
+
+## evaluate_and_dump
+
+The `evaluate_and_dump()` method evaluates the flow and dump flow outputs to files.
+
+It takes a `EvaluateAndDumpOptions` dataclass as input to configure, with the following fields:
+
+*   `output_dir` (type: `str`, required): The directory to dump the result to.
+*   `use_cache` (type: `bool`, default: `True`): Use already-cached intermediate data if available.
+    Note that we only reuse existing cached data without updating the cache even if it's turned on.
+
+<Tabs>
+<TabItem value="python" label="Python" default>
+
+```python
+flow.evaluate_and_dump(EvaluateAndDumpOptions(output_dir="./eval_output"))
+```
+
 </TabItem>
 </Tabs>

python/cocoindex/__init__.py

@@ -2,7 +2,7 @@
 Cocoindex is a framework for building and running indexing pipelines.
 """
 from . import flow, functions, query, sources, storages, cli
-from .flow import FlowBuilder, DataScope, DataSlice, Flow, flow_def
+from .flow import FlowBuilder, DataScope, DataSlice, Flow, flow_def, EvaluateAndDumpOptions
 from .llm import LlmSpec, LlmApiType
 from .vector import VectorSimilarityMetric
 from .lib import *

python/cocoindex/cli.py

@@ -57,13 +57,18 @@ def update(flow_name: str | None):
 @click.argument("flow_name", type=str, required=False)
 @click.option(
     "-o", "--output-dir", type=str, required=False,
-    help="The directory to dump the evaluation output to.")
+    help="The directory to dump the output to.")
 @click.option(
     "-c", "--use-cache", is_flag=True, show_default=True, default=True,
-    help="Use cached evaluation results if available.")
+    help="Use already-cached intermediate data if available. "
+         "Note that we only reuse existing cached data without updating the cache "
+         "even if it's turned on.")
 def evaluate(flow_name: str | None, output_dir: str | None, use_cache: bool = True):
     """
-    Evaluate and dump the flow.
+    Evaluate the flow and dump flow outputs to files.
+
+    Instead of updating the index, it dumps what should be indexed to files.
+    Mainly used for evaluation purpose.
     """
     fl = _flow_by_name(flow_name)
     if output_dir is None:

python/cocoindex/flow.py

@@ -372,7 +372,7 @@ def update(self):
 
     def evaluate_and_dump(self, options: EvaluateAndDumpOptions):
         """
-        Evaluate and dump the flow.
+        Evaluate the flow and dump flow outputs to files.
         """
         return self._lazy_engine_flow().evaluate_and_dump(_dump_engine_object(options))