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adapter-schema-repository-postgres visitors Architecture Notes

Responsibilities

• Translate domain fields/specs into Postgres DDL operations.
• Support table create (column list) and schema updates (add columns).
• Delegate to the rules system for actual DDL statement generation.

Design

The visitors in this folder are now thin wrappers around the rules system (../rules/).

• Create Visitor: Calls schemaRuleResolver.upAll(rules, ctx) to generate ADD statements
• Delete Visitor: Calls schemaRuleResolver.downAll(rules, ctx) to generate DROP statements

This eliminates code duplication between create/delete logic and centralizes schema rule definitions.

Files

• ARCHITECTURE.md - Role: folder architecture note; Purpose: describe DDL visitors.
• PostgresTableSchemaFieldColumn.ts - Role: helper; Purpose: resolve field column names + data types.
• PostgresTableSchemaFieldCreateVisitor.ts - Role: field visitor; Purpose: delegates to rules system to generate create statements.
• PostgresTableSchemaFieldDeleteVisitor.ts - Role: field visitor; Purpose: delegates to rules system to generate drop statements.
• TableSchemaUpdateVisitor.ts - Role: spec visitor; Purpose: delegate field DDL to create/delete visitors during schema updates.

Rules System

See ../rules/ARCHITECTURE.md for details on the schema rules system.

Each field type maps to a set of rules via FieldSchemaRulesFactory. Rules include:

• ColumnRule - Standard column creation
• GeneratedColumnRule - GENERATED ALWAYS AS columns
• IndexRule / UniqueIndexRule - Indexes
• ForeignKeyRule - FK constraints
• JunctionTableRule - Junction tables for ManyMany/OneWay links
• ReferenceRule - Reference table entries

The SchemaRuleResolver handles dependency ordering and batch execution.