--- title: Cypher versions description: "relate, the embedded Cypher graph database (relatedb.ai): The version prefixes for Cypher 25 and Cypher 5, the default language and what ALTER DATABASE changes, RELATE_PREVIEW opt-ins, and the TCK record." type: reference surfaces: - cypher - cli status: stable verified: 0.1.2 verified_by: - cypher - cli canonical_url: https://relatedb.ai/docs/reference/cypher/cypher-versions/ prerequisites: [] related: - concepts/cypher-dialect - reference/cypher/overview - reference/cypher/differences-from-neo4j - reference/cli/environment-variables last_updated: 2026-11-08 --- # Cypher versions The version prefixes for Cypher 25 and Cypher 5, the default language and what ALTER DATABASE changes, RELATE_PREVIEW opt-ins, and the TCK record. > Verified against relate 0.1.2. If your `relate --version` is newer, read https://relatedb.ai/docs/reference/changelog/#since-0.1.2 Every [Cypher](https://relatedb.ai/docs/reference/glossary/#cypher) statement runs as [Cypher 25](https://relatedb.ai/docs/reference/glossary/#cypher-25), the Neo4j Cypher version aligned with [GQL](https://relatedb.ai/docs/reference/glossary/#gql), the ISO graph query language. A `CYPHER 5` prefix runs one statement as Cypher 5. Syntax that is not settled yet ships as a [preview feature](https://relatedb.ai/docs/reference/glossary/#preview-feature) and stays off until `RELATE_PREVIEW` names it. No other version exists, and nothing else changes the version a statement runs as. ## Synopsis ```text [CYPHER 5 | CYPHER 25] [EXPLAIN | PROFILE] ALTER DATABASE SET DEFAULT LANGUAGE CYPHER 5 | CYPHER 25 RELATE_PREVIEW=[, …] ``` `EXPLAIN` or `PROFILE` may also come before the version prefix. ## Version prefix | Prefix | Statement runs as | Notes | | ---------------- | ----------------- | ------------------------------------------------------------------------------------------------------------------------ | | None | Cypher 25 | The default for every statement | | `CYPHER 25` | Cypher 25 | | | `CYPHER 5` | Cypher 5 | Some Cypher 25 forms fail, as the next table shows | | Any other number | — | `syntax error: parse error: SyntaxError: 22N10 invalid pre-parser option value: "" is not a valid cypher version` | | Two prefixes | — | `syntax error: parse error: SyntaxError: 22N09 conflicting pre-parser combination: multiple values for 'cypher version'` | Under `CYPHER 5`, these Cypher 25 forms fail: | Form | Message | | ---------------------------- | --------------------------------------------------------------------------------------------------------------------- | | String interpolation, `s'…'` | `syntax error: SyntaxError: UnsupportedLanguageFeature: string interpolation (s'...') is only available in Cypher 25` | | `vector(…)` | `syntax error: UnknownFunction: unknown function 'vector'` | Other Cypher 25 forms, such as `LET` and the `||` operator, run under both prefixes. ## Default language Each [namespace](https://relatedb.ai/docs/reference/glossary/#namespace) records a default language, which `SHOW DATABASES` reports in the `defaultLanguage` column. | Setting | Value | | ---------------------------------------------------------- | -------------------------------------------------------------------------------------------------------- | | Recorded default | `CYPHER 25` for `neo4j`, `system` and `system_ontologies` | | `ALTER DATABASE SET DEFAULT LANGUAGE CYPHER 5` | Stores `CYPHER 5` in the store; `SHOW DATABASES` reports it in this process, and after the store reopens | | Effect on statements | None: a statement without a prefix still runs as Cypher 25. Only the prefix selects Cypher 5 | ## Preview features `RELATE_PREVIEW` is an environment variable of the process that opens the store. The [Cypher overview](https://relatedb.ai/docs/reference/cypher/overview/#preview-features) lists each feature, what it enables and the error it gives while off. | Rule | Behavior | | ------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------- | | Default | No feature enabled | | When it is read | Once, when the store opens | | Several features | Comma-separated; spaces around a name are accepted | | Names | Lowercase, exactly as listed: `Chronological-Comparisons` is unknown | | An unknown name | The open fails with exit code 1 and lists the known names | | A feature used while off | Usually `semantic error: SemanticError: preview feature '' is not enabled: set RELATE_PREVIEW=`; the overview lists the exceptions | | The cells on this site | Run on the WebAssembly build with no preview feature enabled | ## Conformance The openCypher Technology Compatibility Kit (TCK) is the language contract. relate's published compliance record states that "no engine document publishes a current TCK pass count any more": coverage is measured by a spec harness that reports on each pull request ready for review and never blocks a merge. The retired in-repository figures are on the [Cypher overview](https://relatedb.ai/docs/reference/cypher/overview/#conformance), and [the Cypher dialect](https://relatedb.ai/docs/concepts/cypher-dialect/) explains why the pin carried deviations. ## Examples The cells run in page order on one in-memory store. The default language of each namespace: ```cypher run name=languages SHOW DATABASES YIELD name, defaultLanguage RETURN name, defaultLanguage ``` ```table | name | defaultLanguage | |---------------------|-----------------| | "neo4j" | "CYPHER 25" | | "system" | "CYPHER 25" | | "system_ontologies" | "CYPHER 25" | 3 rows ``` String interpolation is a Cypher 25 form: ```cypher run name=prefix-25 CYPHER 25 RETURN s'{1 + 1} hops' AS label ``` ```table | label | |----------| | "2 hops" | 1 row ``` ```cypher run name=prefix-5 expect=error CYPHER 5 RETURN s'{1 + 1} hops' AS label ``` ```table error: syntax error: SyntaxError: UnsupportedLanguageFeature: string interpolation (s'...') is only available in Cypher 25 ``` ```cypher run name=prefix-4 expect=error CYPHER 4 RETURN 1 AS one ``` ```table error: syntax error: parse error: SyntaxError: 22N10 invalid pre-parser option value: "4" is not a valid cypher version CYPHER 4 RETURN 1 AS one ^ ``` Setting the default language to Cypher 5 changes what `SHOW DATABASES` reports: ```cypher run name=set-default ALTER DATABASE neo4j SET DEFAULT LANGUAGE CYPHER 5; SHOW DATABASES YIELD name, defaultLanguage WHERE name = 'neo4j' RETURN name, defaultLanguage ``` ```table | name | defaultLanguage | |---------|-----------------| | "neo4j" | "CYPHER 5" | 1 row ``` A statement without a prefix still runs as Cypher 25: ```cypher run name=default-unchanged RETURN s'{1 + 1} hops' AS label ``` ```table | label | |----------| | "2 hops" | 1 row ``` A preview feature without its opt-in: ```cypher run name=preview-off expect=error RETURN datetime('2026-01-01T00:00Z') IS BEFORE datetime('2026-06-01T00:00Z') AS earlier ``` ```table error: semantic error: SemanticError: preview feature 'chronological-comparisons' is not enabled: set RELATE_PREVIEW=chronological-comparisons ``` The same statement on the CLI, with the opt-in in the command's environment: ```bash verify RELATE_PREVIEW=chronological-comparisons relate --mode table "RETURN datetime('2026-01-01T00:00Z') IS BEFORE datetime('2026-06-01T00:00Z') AS earlier" ``` ```text +---------+ | earlier | +---------+ | true | +---------+ ``` A name that is not a preview feature fails the open: ```bash verify RELATE_PREVIEW=chronological relate --mode table "RETURN 1 AS one" ``` ```text Failed to open Relate: semantic error: SemanticError: invalid RELATE_PREVIEW value: unknown preview feature 'chronological' (known features: hybrid-search, local-callables, graph-type-opt-props, graph-type-default-values, graph-type-implied-labels, ontology, obfuscated-literals, mixed-label-syntax, float16-coordinate-types, chronological-comparisons, complex-search-patterns, coll-zip, coll-has, gql-stddev-aliases) ``` ## See also - [The Cypher dialect](https://relatedb.ai/docs/concepts/cypher-dialect/): why relate targets Cypher 25 and how the layers fit. - [Cypher overview](https://relatedb.ai/docs/reference/cypher/overview/): the supported Cypher 25 features and every preview feature. - [Differences from Neo4j](https://relatedb.ai/docs/reference/cypher/differences-from-neo4j/): the Neo4j habits that fail in relate. - [Environment variables](https://relatedb.ai/docs/reference/cli/environment-variables/): `RELATE_PREVIEW` beside the other variables the CLI reads. ## Terms used on this page - **Cypher**: The declarative graph query language relate runs, written as ASCII-art patterns such as `(a)-[:KNOWS]->(b)`; relate follows Neo4j's Cypher 25 by default. - **Cypher 25**: The Neo4j Cypher version aligned with GQL; the default language of every relate namespace, with `CYPHER 5` as the per-statement alternative. - **GQL**: The ISO standard graph query language; Neo4j's Cypher 25 aligns Cypher with it, and relate follows that alignment. - **preview feature**: A Cypher feature from a not-yet-settled proposal that relate ships switched off; it runs only when `RELATE_PREVIEW` names it when the store opens. - **namespace**: One of the three fixed graphs in every store: `neo4j` for user data, `system` for administration, and `system_ontologies`, listed but not queryable.