How do you reset or clear a ChromaDB collection without deleting and recreating it?

ChromaDB does not have a direct clear() or truncate() method. The idiomatic way to reset a collection is to delete it and recreate it with the same parameters. For selective deletion, use delete() with ID lists or where filters.

import chromadb

client = chromadb.PersistentClient(path="./reset_demo")

# Setup
col = client.get_or_create_collection(
    "my_col",
    metadata={"hnsw:space": "cosine", "version": "1"},
)
col.add(
    documents=[f"Document {i}" for i in range(100)],
    ids=[str(i) for i in range(100)],
    metadatas=[{"batch": i // 10} for i in range(100)],
)
print(col.count())  # 100

# --- Option 1: Reset (delete all + recreate) ---
def reset_collection(client, name: str, metadata: dict = None):
    """Delete and recreate a collection, preserving its configuration."""
    saved_meta = {}
    try:
        saved_meta = client.get_collection(name).metadata or {}
    except Exception:
        pass
    client.delete_collection(name)
    return client.create_collection(
        name=name,
        metadata=metadata or saved_meta,
    )

col = reset_collection(client, "my_col")
print(col.count())  # 0

# Re-add fresh data after reset
col.add(documents=["Fresh start"], ids=["new-1"])

# --- Option 2: Selective delete by filter ---
col2 = client.get_or_create_collection("selective")
col2.add(
    documents=[f"Doc {i}" for i in range(20)],
    ids=[str(i) for i in range(20)],
    metadatas=[{"batch": i // 5} for i in range(20)],
)

# Delete only batch 0 (documents 0-4)
col2.delete(where={"batch": 0})
print(col2.count())  # 15 remaining

# Delete specific IDs
col2.delete(ids=["5","6","7"])
print(col2.count())  # 12 remaining

# Delete ALL via get + delete (when no useful metadata filter exists)
all_ids = col2.get(include=[])["ids"]  # get all IDs
if all_ids:
    col2.delete(ids=all_ids)
print(col2.count())  # 0