diff --git a/docs/pages/concepts/database.md b/docs/pages/concepts/database.md
index be1c8235f..818947224 100644
--- a/docs/pages/concepts/database.md
+++ b/docs/pages/concepts/database.md
@@ -1,3 +1,10 @@
+## Basic Concepts of the Database
+
+We use the `JsonModel` class to define the structure of the database. This class is coming from [Redis-OM](https://github.com/redis/redis-om-node), which is a Redis Object Mapper for Node.js. You should learn a lot about how to use the database by reading their documentation.
+
+We do have more customized method `.all()` would return a list of all the corresponding objects in the database. Note that using `.all()` is going to block the database, so you should use it with caution.
+You might see codes using `all_pks()` which is a method from the `JsonModel` class. This method returns a list of all the primary keys of the corresponding objects in the database. This method is not blocking the database. However, it might not be as efficient as using `.all()`.
+
 ## Adding new characters and environments
 You can use the following function with the `**kwargs` being the properties of the `AgentProfile` class. This is the same for the scenarios/environments.
 ```python
@@ -98,10 +105,7 @@ It is very easy to serialize any database structures to JSON or CSV.
 ```python
 from sotopia.database import episodes_to_jsonl, EpisodeLog
 
-episodes: list[EpisodeLog] = [
-    EpisodeLog.get(pk=pk)
-    for pk in EpisodeLog.all_pks()
-]
+episodes: list[EpisodeLog] = EpisodeLog.all()
 
 episodes_to_jsonl(episodes, "episodes.jsonl")
 ```
@@ -111,15 +115,9 @@ episodes_to_jsonl(episodes, "episodes.jsonl")
 ```python
 from sotopia.database import environmentprofiles_to_jsonl, agentprofiles_to_jsonl
 
-agent_profiles: list[AgentProfile] = [
-    AgentProfile.get(pk=pk)
-    for pk in AgentProfile.all_pks()
-]
+agent_profiles: list[AgentProfile] = AgentProfile.all()
 
-environment_profiles: list[EnvironmentProfile] = [
-    EnvironmentProfile.get(pk=pk)
-    for pk in EnvironmentProfile.all_pks()
-]
+environment_profiles: list[EnvironmentProfile] = EnvironmentProfile.all()
 
 agentprofiles_to_jsonl(agent_profiles, "agent_profiles.jsonl")
 environmentprofiles_to_jsonl(environment_profiles, "environment_profiles.jsonl")
diff --git a/examples/benchmark_evaluator.py b/examples/benchmark_evaluator.py
index e07ce4efd..b35ce2247 100644
--- a/examples/benchmark_evaluator.py
+++ b/examples/benchmark_evaluator.py
@@ -25,8 +25,8 @@ def get_human_annotations(
     target_model_patterns: list[list[str]],
 ) -> list[AnnotationForEpisode]:
     episodes_with_human_annotation: list[AnnotationForEpisode] = []
-    for pk in AnnotationForEpisode.all_pks():
-        episode_human = AnnotationForEpisode.get(pk)
+    human_annotated_episodes = AnnotationForEpisode.all()
+    for episode_human in human_annotated_episodes:
         episode_model = EpisodeLog.get(episode_human.episode)
         if episode_model.models in target_model_patterns:
             episodes_with_human_annotation.append(episode_human)
diff --git a/examples/evaluate_existing_episode.py b/examples/evaluate_existing_episode.py
index 9a143bd99..8b80b4a43 100644
--- a/examples/evaluate_existing_episode.py
+++ b/examples/evaluate_existing_episode.py
@@ -98,10 +98,7 @@ def run_server(
     push_to_db: bool = True,
     verbose: bool = False,
 ) -> None:
-    annotated_episodes_pks = [
-        AnnotationForEpisode.get(anno).episode
-        for anno in AnnotationForEpisode.all_pks()
-    ]
+    annotated_episodes_pks = [anno.episode for anno in AnnotationForEpisode.all()]
     annotated_episodes_pks = list(set(annotated_episodes_pks))
     model = typing.cast(LLM_Name, model)
     # Call the function with the specified parameters
diff --git a/sotopia/database/__init__.py b/sotopia/database/__init__.py
index 34dd74de6..735d005ee 100644
--- a/sotopia/database/__init__.py
+++ b/sotopia/database/__init__.py
@@ -1,3 +1,5 @@
+from typing import TypeVar
+from redis_om import JsonModel
 from .annotators import Annotator
 from .env_agent_combo_storage import EnvAgentComboStorage
 from .logs import AnnotationForEpisode, EpisodeLog
@@ -60,3 +62,12 @@
     "jsonl_to_envagnetcombostorage",
     "get_rewards_from_episode",
 ]
+
+InheritedJsonModel = TypeVar("InheritedJsonModel", bound="JsonModel")
+
+
+def _json_model_all(cls: type[InheritedJsonModel]) -> list[InheritedJsonModel]:
+    return cls.find().all()  # type: ignore[return-value]
+
+
+JsonModel.all = classmethod(_json_model_all)  # type: ignore[assignment,method-assign]
diff --git a/sotopia/samplers/constraint_based_sampler.py b/sotopia/samplers/constraint_based_sampler.py
index 48eaea74d..624520dcd 100644
--- a/sotopia/samplers/constraint_based_sampler.py
+++ b/sotopia/samplers/constraint_based_sampler.py
@@ -86,6 +86,12 @@ def sample(
         env_profiles: list[EnvironmentProfile] = []
         agents_which_fit_scenario: list[list[str]] = []
 
+        if self.env_candidates is None:
+            self.env_candidates = EnvironmentProfile.all()
+
+        if self.agent_candidates is None:
+            self.agent_candidates = AgentProfile.all()
+
         agent_candidate_ids: set[str] | None = None
         if self.agent_candidates:
             agent_candidate_ids = set(
@@ -120,13 +126,9 @@ def sample(
             )
         else:
             for _ in range(size):
-                if self.env_candidates:
-                    env_profile = random.choice(self.env_candidates)
-                    if isinstance(env_profile, str):
-                        env_profile = EnvironmentProfile.get(env_profile)
-                else:
-                    env_profile_id = random.choice(list(EnvironmentProfile.all_pks()))
-                    env_profile = EnvironmentProfile.get(env_profile_id)
+                env_profile = random.choice(self.env_candidates)
+                if isinstance(env_profile, str):
+                    env_profile = EnvironmentProfile.get(env_profile)
                 env_profiles.append(env_profile)
                 env_profile_id = env_profile.pk
                 assert env_profile_id, "Env candidate must have an id"
diff --git a/sotopia/samplers/uniform_sampler.py b/sotopia/samplers/uniform_sampler.py
index 9e4f36116..22c89f3c3 100644
--- a/sotopia/samplers/uniform_sampler.py
+++ b/sotopia/samplers/uniform_sampler.py
@@ -46,32 +46,19 @@ def sample(
 
         assert replacement, "Uniform sampling without replacement is not supported yet"
 
+        if self.env_candidates is None:
+            self.env_candidates = EnvironmentProfile.all()
+
+        if self.agent_candidates is None:
+            self.agent_candidates = AgentProfile.all()
+
         for _ in range(size):
-            if self.env_candidates:
-                env_profile = random.choice(self.env_candidates)
-                if isinstance(env_profile, str):
-                    env_profile = EnvironmentProfile.get(env_profile)
-            else:
-                env_profile_id = random.choice(list(EnvironmentProfile.all_pks()))
-                env_profile = EnvironmentProfile.get(env_profile_id)
+            env_profile = random.choice(self.env_candidates)
+            if isinstance(env_profile, str):
+                env_profile = EnvironmentProfile.get(env_profile)
             env = ParallelSotopiaEnv(env_profile=env_profile, **env_params)
 
-            if self.agent_candidates:
-                agent_profile_candidates = self.agent_candidates
-                if len(agent_profile_candidates) < n_agent:
-                    raise ValueError(
-                        f"Number of agent candidates ({len(agent_profile_candidates)}) is less than number of agents ({n_agent})"
-                    )
-            else:
-                agent_profile_candidates_keys = list(AgentProfile.all_pks())
-                if len(agent_profile_candidates_keys) < n_agent:
-                    raise ValueError(
-                        f"Number of agent profile candidates ({len(agent_profile_candidates_keys)}) in database is less than number of agents ({n_agent})"
-                    )
-                agent_profile_candidates = [
-                    AgentProfile.get(pk=pk) for pk in agent_profile_candidates_keys
-                ]
-
+            agent_profile_candidates = self.agent_candidates
             if len(agent_profile_candidates) == n_agent:
                 agent_profiles_maybe_id = agent_profile_candidates
             else:
diff --git a/stubs/redis_om/__init__.pyi b/stubs/redis_om/__init__.pyi
index 230b0e48c..038ca7ac4 100644
--- a/stubs/redis_om/__init__.pyi
+++ b/stubs/redis_om/__init__.pyi
@@ -27,6 +27,8 @@ class JsonModel(RedisModel, abc.ABC):
     @classmethod
     def all_pks(cls) -> Generator[str, None, None]: ...
     @classmethod
+    def all(cls: type[InheritedJsonModel]) -> list[InheritedJsonModel]: ...
+    @classmethod
     def find(cls, *args: Any, **kwargs: Any) -> FindQuery: ...
     def save(self) -> None: ...