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vitess

planetscale

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This version passed the hardening gate. Hardening updated the skill content and independently checked the resulting changes. Classified findings before hardening: 1. Classified findings closed: 1. Classified findings remaining: 0. Unclassified scanner findings remaining: 0. Review findings closed: 4. Review findings remaining: 5.

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Expand	File	Group	Subtype	Severity	Status
	SKILL.md	Prompt Injection	Third-party content as instructions	Low	Closed

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SKILL.md

Vitess

Vitess is a MySQL-compatible, cloud-native database system originally built at YouTube to scale MySQL. PlanetScale runs Vitess as a managed service. Core capabilities:

Horizontal sharding: Built-in sharding transparent to the application — no sharding logic in app code.
Connection pooling: VTTablet multiplexes client connections to MySQL, scaling concurrent connections far beyond native MySQL limits.
High availability: Automatic primary failure detection and repair. Resharding and data migrations with near-zero downtime.
Query rewriting and caching: VTGate rewrites and optimizes queries before routing to shards.
Schema management: Apply schema changes across all shards consistently, in the background, without disrupting workloads.
Materialized views and messaging: Cross-shard materialized views and publish/subscribe messaging via VStream.

Key concepts

Concept	What it is
Keyspace	Logical database mapping to one or more shards. Analogous to a MySQL schema.
Shard	A horizontal partition of a keyspace, each backed by a separate MySQL instance.
VSchema	Configuration defining how tables map to shards, vindex (sharding) keys, and routing rules.
Vindex	Sharding function mapping column values to shards (`hash`, `unicode_loose_xxhash`, `lookup`).
VTGate	Stateless proxy that plans and routes queries to the correct shard(s).
Online DDL	Non-blocking schema migrations. On PlanetScale, use deploy requests for production changes.

PlanetScale specifics

Branching: Git-like database branches for development; deploy requests for production schema changes.
Connections: MySQL protocol, port 3306 (direct) or 443 (serverless). SSL always required.

SQL compatibility

Vitess supports nearly all MySQL syntax — most applications work without query changes. Standard DML, DDL, joins, subqueries, CTEs and common built-in functions all work as expected.

Known limitations:

Stored procedures / triggers / events: Not supported through VTGate.
LOCK TABLES / GET_LOCK: Not supported through VTGate.
SELECT ... FOR UPDATE: Works within a single shard; cross-shard locking is not atomic.
Cross-shard joins: Supported but expensive (scatter-gather). Filter by vindex column for single-shard routing.
Correlated subqueries: May fail or perform poorly cross-shard. Rewrite as joins when possible.
IDs: Use Vitess Sequences (a global counter in an unsharded keyspace) or app-generated IDs (UUIDs, snowflake) to avoid collisions on sharded tables.
Aggregations on sharded tables: GROUP BY/ORDER BY/LIMIT merge in VTGate memory. Large result sets can be slow.
Foreign keys: Limited support. Prefer application-level referential integrity on sharded keyspaces.

References

Topic	Reference	Use for
VSchema		VSchema design, vindexes, sequences, sharding strategies
Schema Changes		Online DDL, managed migrations, ddl strategies, migration lifecycle
VReplication		MoveTables, Reshard, Materialize, VDiff, VStream
Architecture		VTGate, VTTablet, Topology Service, VTOrc, component interactions
Query Serving		Query routing, MySQL compatibility, cross-shard performance, EXPLAIN

Install

Install with chainctl


chainctl skill install public/planetscale/vitess:latest

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Provenance

Upstream sourcehttps://github.com/planetscale/database-skills

Upstream commit3fa574b476452c0075ea8a43f2002d53a9ccb31f

OCI reference

skills.cgr.dev/public/github.com/planetscale/skills/vitess:latest

License

MIT

Files

HARDENING.md

LICENSE

SKILL.md

references/architecture.md

references/query-serving.md

references/schema-changes.md

references/vreplication.md

references/vschema.md

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