How do you retrieve, update, and delete specific documents in ChromaDB?

Beyond querying by similarity, ChromaDB supports exact lookups by ID with get(), in-place updates with update() or upsert(), and deletion with delete().

import chromadb

client = chromadb.Client()
col = client.create_collection("items")
col.add(
    documents=["First document", "Second document", "Third document"],
    metadatas=[{"v": 1}, {"v": 2}, {"v": 3}],
    ids=["id1", "id2", "id3"],
)

# GET — fetch by specific IDs
result = col.get(ids=["id1", "id3"])
print(result["documents"])  # ["First document", "Third document"]

# GET all documents in the collection
all_docs = col.get()  # no ids= returns everything

# GET with include control
result = col.get(
    ids=["id1"],
    include=["documents", "metadatas", "embeddings"],
)

# UPDATE — must already exist, updates only specified fields
col.update(
    ids=["id1"],
    documents=["Updated first document"],
    metadatas=[{"v": 10, "updated": True}],
    # ChromaDB re-embeds the new document text automatically
)

# UPSERT — insert if not exists, update if exists (idempotent)
col.upsert(
    documents=["Brand new doc",        "Updated second doc"],
    metadatas=[{"v": 99},              {"v": 20}],
    ids=       ["id-new",              "id2"],
)
# id-new is inserted; id2 is updated

# DELETE by IDs
col.delete(ids=["id3"])
print(col.count())  # 3 (id1, id2, id-new remain)

# DELETE by metadata filter (where clause)
col.delete(where={"v": {"$gt": 15}})