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Add DuckDB support with PostgreSQL parser reuse
This commit adds DuckDB as a supported database engine to sqlc by reusing the PostgreSQL parser and catalog while implementing a custom analyzer that connects to an in-memory DuckDB instance. Key changes: - Add EngineDuckDB constant to config (internal/config/config.go) - Implement DuckDB analyzer using go-duckdb driver (internal/engine/duckdb/analyzer/) - Register DuckDB engine in compiler with PostgreSQL parser/catalog (internal/compiler/engine.go) - Add DuckDB support to vet command (internal/cmd/vet.go) - Add go-duckdb v1.8.5 dependency (go.mod) - Create comprehensive example with schema, queries, and documentation (examples/duckdb/) The DuckDB implementation leverages PostgreSQL-compatible SQL syntax while providing accurate type inference through live database analysis. The analyzer uses an in-memory DuckDB instance to extract column and parameter types. Features: - PostgreSQL-compatible SQL parsing - In-memory database analysis - Schema migration support - Type-safe Go code generation - Thread-safe connection management 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude <noreply@anthropic.com>
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‎examples/duckdb/README.md‎

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# DuckDB Example
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This example demonstrates how to use sqlc with DuckDB.
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## Overview
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DuckDB is an in-process analytical database that supports PostgreSQL-compatible SQL syntax. This integration reuses sqlc's PostgreSQL parser and catalog while providing a DuckDB-specific analyzer that connects to an in-memory DuckDB instance.
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## Features
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- **PostgreSQL-compatible SQL**: DuckDB uses PostgreSQL-compatible syntax, so you can use familiar SQL constructs
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- **In-memory database**: Perfect for testing and development
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- **Type-safe Go code**: sqlc generates type-safe Go code from your SQL queries
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- **Live database analysis**: The analyzer connects to a DuckDB instance to extract accurate column types
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## Configuration
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The `sqlc.yaml` file configures sqlc to use the DuckDB engine:
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```yaml
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version: "2"
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sql:
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- name: "duckdb_example"
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engine: "duckdb" # Use DuckDB engine
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schema:
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- "schema.sql"
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queries:
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- "query.sql"
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database:
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managed: false
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uri: ":memory:" # Use in-memory database
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analyzer:
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database: true # Enable live database analysis
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gen:
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go:
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package: "db"
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out: "db"
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```
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## Database URI
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DuckDB supports several URI formats:
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- `:memory:` - In-memory database (default if not specified)
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- `file.db` - File-based database
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- `/path/to/file.db` - Absolute path to database file
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## Usage
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1. Generate Go code:
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```bash
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sqlc generate
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```
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2. Use the generated code in your application:
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```go
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package main
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import (
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"context"
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"database/sql"
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"log"
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_ "github.com/marcboeker/go-duckdb"
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"yourmodule/db"
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)
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func main() {
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// Open DuckDB connection
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conn, err := sql.Open("duckdb", ":memory:")
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if err != nil {
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log.Fatal(err)
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}
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defer conn.Close()
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// Create tables
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schema := `
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CREATE TABLE users (
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id INTEGER PRIMARY KEY,
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name VARCHAR NOT NULL,
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email VARCHAR UNIQUE NOT NULL,
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created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
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);
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`
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if _, err := conn.Exec(schema); err != nil {
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log.Fatal(err)
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}
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// Use generated queries
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queries := db.New(conn)
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ctx := context.Background()
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// Create a user
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user, err := queries.CreateUser(ctx, db.CreateUserParams{
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Name: "John Doe",
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Email: "john@example.com",
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})
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if err != nil {
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log.Fatal(err)
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}
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log.Printf("Created user: %+v\n", user)
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// Get the user
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fetchedUser, err := queries.GetUser(ctx, user.ID)
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if err != nil {
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log.Fatal(err)
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}
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log.Printf("Fetched user: %+v\n", fetchedUser)
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}
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```
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## Differences from PostgreSQL
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While DuckDB supports PostgreSQL-compatible SQL, there are some differences:
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1. **Data Types**: DuckDB has its own set of data types, though many are compatible with PostgreSQL
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2. **Functions**: Some PostgreSQL functions may not be available or may behave differently
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3. **Extensions**: DuckDB uses a different extension system than PostgreSQL
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## Benefits of DuckDB
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1. **Fast analytical queries**: Optimized for OLAP workloads
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2. **Embedded**: No separate server process needed
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3. **Portable**: Single file database
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4. **PostgreSQL-compatible**: Familiar SQL syntax
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## Requirements
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- Go 1.24.0 or later
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- `github.com/marcboeker/go-duckdb` driver
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## Notes
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- The DuckDB analyzer uses an in-memory instance to extract query metadata
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- Schema migrations are applied to the analyzer instance automatically
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- Type inference is done by preparing queries against the DuckDB instance

‎examples/duckdb/query.sql‎

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-- name: GetUser :one
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SELECT id, name, email, created_at
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FROM users
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WHERE id = $1;
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-- name: ListUsers :many
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SELECT id, name, email, created_at
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FROM users
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ORDER BY name;
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-- name: CreateUser :one
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INSERT INTO users (name, email)
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VALUES ($1, $2)
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RETURNING id, name, email, created_at;
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-- name: GetUserPosts :many
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SELECT p.id, p.title, p.content, p.published, p.created_at
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FROM posts p
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WHERE p.user_id = $1
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ORDER BY p.created_at DESC;
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-- name: CreatePost :one
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INSERT INTO posts (user_id, title, content, published)
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VALUES ($1, $2, $3, $4)
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RETURNING id, user_id, title, content, published, created_at;

‎examples/duckdb/schema.sql‎

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-- Example DuckDB schema
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CREATE TABLE users (
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id INTEGER PRIMARY KEY,
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name VARCHAR NOT NULL,
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email VARCHAR UNIQUE NOT NULL,
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created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
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);
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CREATE TABLE posts (
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id INTEGER PRIMARY KEY,
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user_id INTEGER NOT NULL,
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title VARCHAR NOT NULL,
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content TEXT,
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published BOOLEAN DEFAULT false,
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created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
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FOREIGN KEY (user_id) REFERENCES users(id)
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);

‎examples/duckdb/sqlc.yaml‎

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version: "2"
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sql:
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- name: "duckdb_example"
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engine: "duckdb"
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schema:
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- "schema.sql"
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queries:
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- "query.sql"
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database:
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managed: false
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uri: ":memory:"
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analyzer:
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database: true
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gen:
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go:
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package: "db"
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out: "db"
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sql_package: "database/sql"

‎go.mod‎

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github.com/fatih/structtag v1.2.0
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github.com/go-sql-driver/mysql v1.9.3
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github.com/google/cel-go v0.26.1
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github.com/marcboeker/go-duckdb v1.8.5
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github.com/google/go-cmp v0.7.0
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github.com/jackc/pgx/v4 v4.18.3
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github.com/jackc/pgx/v5 v5.7.6

‎internal/cmd/vet.go‎

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"github.com/google/cel-go/cel"
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"github.com/google/cel-go/ext"
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"github.com/jackc/pgx/v5"
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_ "github.com/marcboeker/go-duckdb"
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"github.com/spf13/cobra"
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"google.golang.org/protobuf/encoding/protojson"
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// SQLite really doesn't want us to depend on the output of EXPLAIN
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// QUERY PLAN: https://www.sqlite.org/eqp.html
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expl = nil
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case config.EngineDuckDB:
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db, err := sql.Open("duckdb", dburl)
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if err != nil {
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return fmt.Errorf("database: connection error: %s", err)
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}
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if err := db.PingContext(ctx); err != nil {
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return fmt.Errorf("database: connection error: %s", err)
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}
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defer db.Close()
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prep = &dbPreparer{db}
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// DuckDB supports EXPLAIN
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expl = nil
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default:
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return fmt.Errorf("unsupported database uri: %s", s.Engine)
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}

‎internal/compiler/engine.go‎

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"github.com/sqlc-dev/sqlc/internal/config"
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"github.com/sqlc-dev/sqlc/internal/dbmanager"
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"github.com/sqlc-dev/sqlc/internal/engine/dolphin"
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duckdbanalyze "github.com/sqlc-dev/sqlc/internal/engine/duckdb/analyzer"
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"github.com/sqlc-dev/sqlc/internal/engine/postgresql"
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pganalyze "github.com/sqlc-dev/sqlc/internal/engine/postgresql/analyzer"
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"github.com/sqlc-dev/sqlc/internal/engine/sqlite"
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)
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}
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}
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case config.EngineDuckDB:
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// DuckDB uses PostgreSQL-compatible SQL, so we reuse the PostgreSQL parser and catalog
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c.parser = postgresql.NewParser()
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c.catalog = postgresql.NewCatalog()
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c.selector = newDefaultSelector()
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if conf.Database != nil {
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if conf.Analyzer.Database == nil || *conf.Analyzer.Database {
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c.analyzer = analyzer.Cached(
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duckdbanalyze.New(c.client, *conf.Database),
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combo.Global,
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*conf.Database,
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)
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}
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}
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default:
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return nil, fmt.Errorf("unknown engine: %s", conf.Engine)
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}

‎internal/config/config.go‎

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EngineMySQL Engine = "mysql"
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EnginePostgreSQL Engine = "postgresql"
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EngineSQLite Engine = "sqlite"
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EngineDuckDB Engine = "duckdb"
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)
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type Config struct {

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