show_refs
List branches and tags for Iceberg tables to track versions, manage snapshots, and maintain data lineage in Trino.
Instructions
Show Iceberg table references (branches and tags)
Input Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| catalog | Yes | catalog name | |
| schema_name | Yes | schema name | |
| table | Yes | The name of the table |
Output Schema
TableJSON Schema
| Name | Required | Description | Default |
|---|---|---|---|
| result | Yes |
Implementation Reference
- src/server.py:468-492 (handler)MCP tool handler for 'show_refs'. Decorated with @mcp.tool(), this function receives the tool call, validates inputs using Pydantic Fields, and delegates to the Trino client. Returns JSON-formatted table references.
@mcp.tool(description="Show Iceberg table references (branches and tags)") def show_refs( catalog: str = Field(description="catalog name "), schema_name: str = Field(description="schema name "), table: str = Field(description="The name of the table"), ) -> str: """Show Iceberg table references (branches and tags). The refs table contains: - name: Name of the reference - type: Type of reference (BRANCH or TAG) - snapshot_id: ID of referenced snapshot - max_reference_age_in_ms: Max age before reference expiry - min_snapshots_to_keep: Min snapshots to keep (branches only) - max_snapshot_age_in_ms: Max snapshot age in branch Args: catalog: catalog name schema_name: schema name table: The name of the table Returns: str: JSON-formatted table references """ return client.show_refs(catalog, schema_name, table) - src/trino_client.py:571-596 (helper)Core implementation of show_refs in the TrinoClient class. Constructs and executes a SQL query against Trino's Iceberg $refs metadata table. Handles default catalog/schema resolution and returns JSON-formatted results.
def show_refs(self, table: str, catalog: str, schema: str) -> str: """Show Iceberg table references (branches and tags). The refs table contains: - name: VARCHAR - Name of the reference - type: VARCHAR - Type of reference (BRANCH or TAG) - snapshot_id: BIGINT - ID of referenced snapshot - max_reference_age_in_ms: BIGINT - Max age before reference expiry - min_snapshots_to_keep: INTEGER - Min snapshots to keep (branches only) - max_snapshot_age_in_ms: BIGINT - Max snapshot age in branch Args: table: The name of the table catalog: Optional catalog name (defaults to configured catalog) schema: Optional schema name (defaults to configured schema) Returns: str: JSON-formatted string containing table references """ catalog = catalog or self.config.catalog schema = schema or self.config.schema if not catalog or not schema: raise CatalogSchemaError table_identifier = f"{catalog}.{schema}.{table}$refs" query = 'SELECT * FROM "{}"' return self.execute_query(query.format(table_identifier)) - src/server.py:468-473 (schema)Input schema definition for show_refs tool using Pydantic Field. Defines three string parameters: catalog, schema_name, and table with descriptive metadata for MCP tool discovery.
@mcp.tool(description="Show Iceberg table references (branches and tags)") def show_refs( catalog: str = Field(description="catalog name "), schema_name: str = Field(description="schema name "), table: str = Field(description="The name of the table"), ) -> str: - src/server.py:468-468 (registration)MCP tool registration point. The @mcp.tool() decorator registers show_refs with the FastMCP server, making it discoverable and callable via the Model Context Protocol.
@mcp.tool(description="Show Iceberg table references (branches and tags)")