Guarantees

For the complete documentation index optimized for AI agents, see llms.txt.

HelixDB executes each query request as one transaction over a committed snapshot.

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Atomicity

All mutations in one write batch commit together or roll back. A failed operation does not leave earlier mutations from the same request committed.

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Consistency

Constraints such as unique indexed values, property encodings, vector dimensions, and text index value requirements are checked before the relevant write or index generation becomes active.

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Isolation

Transactions use serializable snapshot isolation:

• A request reads graph and index state from one committed snapshot.
• A write request reads its own mutations before commit.
• Conflicting writes are detected at commit; the request fails instead of committing against stale transactional state.
• Secondary, vector, and text lookups participate in the same request transaction.

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Durability

Canonical data is persisted by the selected storage source. In Cloud, local memory and disk caches are performance layers; object storage is canonical. Server clients can explicitly set shouldAwaitDurability(true) / should_await_durability(true) when the acknowledgement must wait for the configured durability boundary, or false when the application accepts an earlier acknowledgement. Embedded mode rejects this server-only option.

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Index activation

Index creation and deletion use durable lifecycle operations:

• A build scans existing entities and catches up concurrent mutations.
• A constructing generation is hidden from queries.
• Validation completes before one atomic activation step.
• A blocked or aborted generation never becomes partially queryable.

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Readers and read-after-write

The writer can serve a newly committed state immediately. A reader observes it after refreshing to a snapshot that contains the commit, so a request routed to a reader may temporarily lag. Use a writer-only server request when a separate request requires read-after-write: Set writerOnly() / writer_only(true) / the equivalent Go request option before sending the read. Embedded writer handles execute against their local writer. Embedded reader handles are read-only and refresh according to the underlying reader lifecycle.

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Cloud availability

Cloud availability and recovery depend on the purchased deployment topology. Contact founders@helix-db.com for current redundancy and SLA terms instead of assuming a topology from the SDK contract.