Metadata Arrays

Chroma now supports storing arrays of strings, numbers, and booleans in metadata fields, one of our most requested features. This means you can attach rich, multi-valued attributes like tags, categories, or scores directly to your documents without workarounds like comma-separated strings or serialization.

Querying arrays is just as natural. Use contains() and not_contains() operators (or $contains / $not_contains in dictionary syntax) to filter records based on whether an array includes a specific value. These work seamlessly with existing logical operators, so you can combine array filters with comparison and set operators in a single query.

All array elements must share the same type, and both K-expression and dictionary-style syntaxes are fully supported across Python, TypeScript, and Rust.

Multi-label tagging and categorization. Records can now hold references to multiple tags or categories:

collection.add(
    ids=["jpm_10k_2024", "gs_10k_2024"],
    documents=[
        "JPMorgan reported record net interest income amid higher rate environment...",
        "Goldman Sachs saw strong advisory revenue from M&A activity recovery...",
    ],
    metadatas=[
        {"topics": ["net-interest-income", "lending", "rates"], "filing_type": "10-K", "assets_b": 3900},
        {"topics": ["advisory", "m&a", "trading"], "filing_type": "10-K", "assets_b": 1600},
)

Multi-entity association. If you're indexing Slack messages or emails, you can track which users are mentioned in messages:

collection.add(
    ids=["1707321456.482901", "1707321499.003200"],
    documents=[
        "Hey @Kelly @Jason, I'll be 5 minutes late to standup",
        "@Jeff thank you!",
    ],
    metadatas=[
        {"mentions": ["kelly", "jason"], "channel": "engineering"},
        {"mentions": ["jeff"], "channel": "random"},
    ],
)

Access control. Store which roles or user groups can access records:

collection.add(
    ...,
    metadatas=[
        {"allowed": ["engineering", "execs"],
        {"allowed": ["execs"]},
    ],
)

Check out the documentation for full details and examples.