139 lines
3.2 KiB
Markdown
139 lines
3.2 KiB
Markdown
# PostgreSQL Reader
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Reads schema information directly from a live PostgreSQL database.
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## Overview
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The PostgreSQL Reader connects to a PostgreSQL database and introspects its schema, extracting complete information about tables, columns, constraints, indexes, views, and sequences.
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## Features
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- Direct database introspection
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- Extracts complete schema information including:
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- Tables and columns
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- Primary keys, foreign keys, unique constraints, check constraints
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- Indexes
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- Views
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- Sequences
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- Supports multiple schemas
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- Captures constraint actions (ON DELETE, ON UPDATE)
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- Derives relationships from foreign keys
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## Usage
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### Basic Example
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```go
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package main
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import (
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"fmt"
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"git.warky.dev/wdevs/relspecgo/pkg/readers"
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"git.warky.dev/wdevs/relspecgo/pkg/readers/pgsql"
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)
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func main() {
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options := &readers.ReaderOptions{
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ConnectionString: "postgres://user:password@localhost:5432/mydb?sslmode=disable",
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}
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reader := pgsql.NewReader(options)
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db, err := reader.ReadDatabase()
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if err != nil {
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panic(err)
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}
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fmt.Printf("Database: %s\n", db.Name)
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fmt.Printf("Schemas: %d\n", len(db.Schemas))
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for _, schema := range db.Schemas {
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fmt.Printf(" Schema: %s, Tables: %d\n", schema.Name, len(schema.Tables))
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}
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}
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```
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### CLI Example
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```bash
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# Inspect PostgreSQL database and export to JSON
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relspec --input pgsql \
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--conn "postgres://user:password@localhost:5432/mydb" \
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--output json \
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--out-file schema.json
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# Generate GORM models from PostgreSQL database
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relspec --input pgsql \
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--conn "postgres://user:password@localhost:5432/mydb" \
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--output gorm \
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--out-file models.go
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# Export database structure to YAML
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relspec --input pgsql \
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--conn "postgres://localhost/mydb?sslmode=disable" \
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--output yaml \
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--out-file schema.yaml
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```
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## Connection String Format
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The reader uses PostgreSQL connection strings in the format:
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```
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postgres://username:password@hostname:port/database?parameters
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```
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Examples:
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```
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postgres://localhost/mydb
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postgres://user:pass@localhost:5432/mydb
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postgres://user@localhost/mydb?sslmode=disable
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postgres://user:pass@db.example.com:5432/production?sslmode=require
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```
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## Extracted Information
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### Tables
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- Table name and schema
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- Comments/descriptions
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- All columns with data types, nullable, defaults
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- Sequences
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### Columns
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- Column name, data type, length/precision
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- NULL/NOT NULL constraints
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- Default values
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- Auto-increment information
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- Primary key designation
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### Constraints
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- Primary keys
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- Foreign keys (with ON DELETE/UPDATE actions)
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- Unique constraints
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- Check constraints
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### Indexes
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- Index name and type (btree, hash, gist, gin, etc.)
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- Columns in index
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- Unique/non-unique
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- Partial indexes
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### Views
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- View definitions
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- Column information
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### Sequences
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- Sequence properties
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- Associated tables
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## Notes
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- Requires PostgreSQL connection permissions
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- Reads all non-system schemas (excludes pg_catalog, information_schema, pg_toast)
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- Captures PostgreSQL-specific data types
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- Automatically maps PostgreSQL types to canonical types
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- Preserves relationship metadata for downstream conversion
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## Requirements
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- Go library: `github.com/jackc/pgx/v5`
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- Database user must have SELECT permissions on system catalogs
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