Relica

Relica is a lightweight, type-safe database query builder for Go with zero production dependencies.

✨ Features

• 🚀 Zero Production Dependencies - Uses only Go standard library
• ⚡ High Performance - LRU statement cache, batch operations (3.3x faster)
• 🎯 Type-Safe - Reflection-based struct scanning with compile-time checks
• 🔒 Transaction Support - Full ACID with all isolation levels
• 📦 Batch Operations - Efficient multi-row INSERT and UPDATE
• 🔗 JOIN Operations - INNER, LEFT, RIGHT, FULL, CROSS JOIN support (v0.2.0+)
• 📊 Sorting & Pagination - ORDER BY, LIMIT, OFFSET (v0.2.0+)
• 🔢 Aggregate Functions - COUNT, SUM, AVG, MIN, MAX, GROUP BY, HAVING (v0.2.0+)
• 🔍 Subqueries - IN, EXISTS, FROM subqueries, scalar subqueries (v0.3.0+)
• 🔀 Set Operations - UNION, UNION ALL, INTERSECT, EXCEPT (v0.3.0+)
• 🌳 Common Table Expressions - WITH clause, recursive CTEs (v0.3.0+)
• 🌐 Multi-Database - PostgreSQL, MySQL 8.0+, SQLite 3.25+ support
• 🧪 Well-Tested - 326+ tests, 93.3% coverage
• 📝 Clean API - Fluent builder pattern with context support

🎉 What's New in v0.4.1-beta

Convenience Methods - Shorter, more intuitive API for common operations:

// Before (v0.4.0):
db.Builder().Select("*").From("users").All(&users)

// After (v0.4.1):
db.Select("*").From("users").All(&users)  // 10 characters shorter!

• ✅ Shorter code - db.Select() vs db.Builder().Select()
• ✅ 100% backward compatible - Builder() continues working unchanged
• ✅ Zero performance overhead - Direct delegation to Builder()
• ✅ Same power - All query features still available (WHERE, JOIN, ORDER BY, etc.)
• 📝 When to use Builder() - For advanced features (CTEs, UNION, batch operations)

Previous: v0.4.0-beta - Better documentation & API stability:

• All methods visible on pkg.go.dev with complete documentation
• Wrapper types following industry best practices (sqlx, pgx, GORM patterns)
• Unwrap() methods for advanced use cases
• See docs/MIGRATION_GUIDE.md for v0.3.0 → v0.4.0 upgrade guide

🚀 Quick Start

Installation

go get github.com/coregx/relica

Note: Always import only the main relica package. Internal packages are protected and not part of the public API.

Basic Usage

package main

import (
    "context"
    "fmt"
    "log"

    "github.com/coregx/relica"
    _ "github.com/lib/pq" // PostgreSQL driver
)

type User struct {
    ID    int    `db:"id"`
    Name  string `db:"name"`
    Email string `db:"email"`
}

func main() {
    // Connect to database
    db, err := relica.Open("postgres", "postgres://user:pass@localhost/db")
    if err != nil {
        log.Fatal(err)
    }
    defer db.Close()

    ctx := context.Background()

    // SELECT - Query single row (v0.4.1+ convenience method)
    var user User
    err = db.Select("*").
        From("users").
        Where("id = ?", 1).
        WithContext(ctx).
        One(&user)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Printf("User: %+v\n", user)

    // SELECT - Query multiple rows (convenience method)
    var users []User
    err = db.Select("*").
        From("users").
        Where("age > ?", 18).
        All(&users)

    // INSERT (convenience method)
    result, err := db.Insert("users", map[string]interface{}{
        "name":  "Alice",
        "email": "alice@example.com",
    }).Execute()

    // UPDATE (convenience method)
    result, err = db.Update("users").
        Set(map[string]interface{}{
            "name": "Alice Updated",
        }).
        Where("id = ?", 1).
        Execute()

    // DELETE (convenience method)
    result, err = db.Delete("users").
        Where("id = ?", 1).
        Execute()

    // For advanced queries (CTEs, UNION, etc.), use Builder()
    err = db.Builder().
        With("stats", statsQuery).
        Select("*").
        From("stats").
        All(&results)
}

📚 Core Features

CRUD Operations

New in v0.4.1: Convenience methods for shorter, more intuitive code!

// SELECT (v0.4.1+ convenience method)
var user User
db.Select("*").From("users").Where("id = ?", 1).One(&user)

// SELECT with multiple conditions
var users []User
db.Select("id", "name", "email").
    From("users").
    Where("age > ?", 18).
    Where("status = ?", "active").
    All(&users)

// INSERT (convenience method)
db.Insert("users", map[string]interface{}{
    "name": "Bob",
    "email": "bob@example.com",
}).Execute()

// UPDATE (convenience method)
db.Update("users").
    Set(map[string]interface{}{"status": "inactive"}).
    Where("last_login < ?", time.Now().AddDate(0, -6, 0)).
    Execute()

// DELETE (convenience method)
db.Delete("users").Where("id = ?", 123).Execute()

// For advanced operations, use Builder()
db.Builder().
    Upsert("users", map[string]interface{}{
        "id":    1,
        "name":  "Alice",
        "email": "alice@example.com",
    }).
    OnConflict("id").
    DoUpdate("name", "email").
    Execute()

// Builder() is still fully supported for all operations
db.Builder().Select("*").From("users").All(&users)

Expression API (v0.1.2+)

Relica supports fluent expression builders for type-safe, complex WHERE clauses:

HashExp - Simple Conditions

// Simple equality
db.Builder().Select().From("users").
    Where(relica.HashExp{"status": 1}).
    All(&users)

// Multiple conditions (AND)
db.Builder().Select().From("users").
    Where(relica.HashExp{
        "status": 1,
        "age":    30,
    }).
    All(&users)

// IN clause (slice values)
db.Builder().Select().From("users").
    Where(relica.HashExp{
        "status": []interface{}{1, 2, 3},
    }).
    All(&users)

// NULL handling
db.Builder().Select().From("users").
    Where(relica.HashExp{
        "deleted_at": nil,  // IS NULL
    }).
    All(&users)

// Combined: IN + NULL + equality
db.Builder().Select().From("users").
    Where(relica.HashExp{
        "status":     []interface{}{1, 2},
        "deleted_at": nil,
        "role":       "admin",
    }).
    All(&users)

Comparison Operators

// Greater than
db.Builder().Select().From("users").
    Where(relica.GreaterThan("age", 18)).
    All(&users)

// Less than or equal
db.Builder().Select().From("users").
    Where(relica.LessOrEqual("price", 100.0)).
    All(&products)

// Available: Eq, NotEq, GreaterThan, LessThan, GreaterOrEqual, LessOrEqual

IN and BETWEEN

// IN
db.Builder().Select().From("users").
    Where(relica.In("role", "admin", "moderator")).
    All(&users)

// NOT IN
db.Builder().Select().From("users").
    Where(relica.NotIn("status", 0, 99)).
    All(&users)

// BETWEEN
db.Builder().Select().From("orders").
    Where(relica.Between("created_at", startDate, endDate)).
    All(&orders)

LIKE with Automatic Escaping

// Default: %value% (partial match)
db.Builder().Select().From("users").
    Where(relica.Like("name", "john")).  // name LIKE '%john%'
    All(&users)

// Multiple values (AND)
db.Builder().Select().From("articles").
    Where(relica.Like("title", "go", "database")).  // title LIKE '%go%' AND title LIKE '%database%'
    All(&articles)

// Custom matching (prefix/suffix)
db.Builder().Select().From("files").
    Where(relica.Like("filename", ".txt").Match(false, true)).  // filename LIKE '%.txt'
    All(&files)

// OR logic
db.Builder().Select().From("users").
    Where(relica.OrLike("email", "gmail", "yahoo")).  // email LIKE '%gmail%' OR email LIKE '%yahoo%'
    All(&users)

Logical Combinators

// AND
db.Builder().Select().From("users").
    Where(relica.And(
        relica.Eq("status", 1),
        relica.GreaterThan("age", 18),
    )).
    All(&users)

// OR
db.Builder().Select().From("users").
    Where(relica.Or(
        relica.Eq("role", "admin"),
        relica.Eq("role", "moderator"),
    )).
    All(&users)

// NOT
db.Builder().Select().From("users").
    Where(relica.Not(
        relica.In("status", 0, 99),
    )).
    All(&users)

// Nested combinations
db.Builder().Select().From("users").
    Where(relica.And(
        relica.Eq("status", 1),
        relica.Or(
            relica.Eq("role", "admin"),
            relica.GreaterThan("age", 30),
        ),
    )).
    All(&users)

Backward Compatibility

String-based WHERE still works:

// Old style (still supported)
db.Builder().Select().From("users").
    Where("status = ? AND age > ?", 1, 18).
    All(&users)

// Can mix both styles
db.Builder().Select().From("users").
    Where("status = ?", 1).
    Where(relica.GreaterThan("age", 18)).
    All(&users)

JOIN Operations (v0.2.0+)

Solve N+1 query problems with JOIN support - reduces 101 queries to 1 query (100x improvement).

// Simple INNER JOIN
var results []struct {
    UserID   int    `db:"user_id"`
    UserName string `db:"user_name"`
    PostID   int    `db:"post_id"`
    Title    string `db:"title"`
}

db.Builder().
    Select("u.id as user_id", "u.name as user_name", "p.id as post_id", "p.title").
    From("users u").
    InnerJoin("posts p", "p.user_id = u.id").
    All(&results)

// Multiple JOINs with aggregates
db.Builder().
    Select("messages.*", "users.name", "COUNT(attachments.id) as attachment_count").
    From("messages m").
    InnerJoin("users u", "m.user_id = u.id").
    LeftJoin("attachments a", "m.id = a.message_id").
    Where("m.status = ?", 1).
    GroupBy("messages.id").
    All(&results)

// All JOIN types supported
db.Builder().InnerJoin(table, on)  // INNER JOIN
db.Builder().LeftJoin(table, on)   // LEFT OUTER JOIN
db.Builder().RightJoin(table, on)  // RIGHT OUTER JOIN
db.Builder().FullJoin(table, on)   // FULL OUTER JOIN (PostgreSQL, SQLite)
db.Builder().CrossJoin(table)      // CROSS JOIN (no ON condition)

// JOIN with Expression API
db.Builder().
    Select().
    From("messages m").
    InnerJoin("users u", relica.And(
        relica.Raw("m.user_id = u.id"),
        relica.GreaterThan("u.status", 0),
    )).
    All(&results)

Performance: 100x query reduction (N+1 problem solved), 6-25x faster depending on database.

See JOIN Guide for comprehensive examples and best practices.

Sorting and Pagination (v0.2.0+)

Database-side sorting and pagination for efficient data retrieval - 100x memory reduction.

// ORDER BY with multiple columns
db.Builder().
    Select().
    From("messages").
    OrderBy("created_at DESC", "id ASC").
    All(&messages)

// Pagination with LIMIT and OFFSET
const pageSize = 100
const pageNumber = 2 // Third page (0-indexed)

db.Builder().
    Select().
    From("users").
    OrderBy("age DESC").
    Limit(pageSize).
    Offset(pageNumber * pageSize).
    All(&users)

// Table column references
db.Builder().
    Select().
    From("messages m").
    InnerJoin("users u", "m.user_id = u.id").
    OrderBy("m.created_at DESC", "u.name ASC").
    Limit(50).
    All(&results)

Performance: 100x memory reduction (fetch only what you need vs all rows), 6x faster.

Aggregate Functions (v0.2.0+)

Database-side aggregations for COUNT, SUM, AVG, MIN, MAX - 2,500,000x memory reduction.

// Simple COUNT
var count struct{ Total int `db:"total"` }
db.Builder().
    Select("COUNT(*) as total").
    From("messages").
    One(&count)

// Multiple aggregates
type Stats struct {
    Count int     `db:"count"`
    Sum   int64   `db:"sum"`
    Avg   float64 `db:"avg"`
    Min   int     `db:"min"`
    Max   int     `db:"max"`
}

var stats Stats
db.Builder().
    Select("COUNT(*) as count", "SUM(size) as sum", "AVG(size) as avg", "MIN(size) as min", "MAX(size) as max").
    From("messages").
    One(&stats)

// GROUP BY with HAVING
type UserStats struct {
    UserID       int `db:"user_id"`
    MessageCount int `db:"message_count"`
}

var userStats []UserStats
db.Builder().
    Select("user_id", "COUNT(*) as message_count").
    From("messages").
    GroupBy("user_id").
    Having("COUNT(*) > ?", 100).
    OrderBy("message_count DESC").
    All(&userStats)

Performance: 2,500,000x memory reduction (database aggregation vs fetching all rows), 20x faster.

See Aggregates Guide for comprehensive examples and patterns.

Advanced SQL Features (v0.3.0+)

Relica v0.3.0 adds powerful SQL features for complex queries.

Subqueries

IN/EXISTS Subqueries:

// Find users who have placed orders
sub := db.Builder().Select("user_id").From("orders").Where("status = ?", "completed")
db.Builder().Select("*").From("users").Where(relica.In("id", sub)).All(&users)

// Find users with at least one order (EXISTS is often faster)
orderCheck := db.Builder().Select("1").From("orders").Where("orders.user_id = users.id")
db.Builder().Select("*").From("users").Where(relica.Exists(orderCheck)).All(&users)

FROM Subqueries:

// Calculate aggregates, then filter
stats := db.Builder().
    Select("user_id", "COUNT(*) as order_count", "SUM(total) as total_spent").
    From("orders").
    GroupBy("user_id")

db.Builder().
    FromSelect(stats, "order_stats").
    Select("user_id", "order_count", "total_spent").
    Where("order_count > ? AND total_spent > ?", 10, 5000).
    All(&topCustomers)

See Subquery Guide for complete examples and performance tips.

Set Operations

UNION/UNION ALL:

// Combine active and archived users (UNION removes duplicates)
active := db.Builder().Select("name").From("users").Where("status = ?", 1)
archived := db.Builder().Select("name").From("archived_users").Where("status = ?", 1)
active.Union(archived).All(&allNames)

// UNION ALL is 2-3x faster (keeps duplicates)
active.UnionAll(archived).All(&allNames)

INTERSECT/EXCEPT (PostgreSQL, MySQL 8.0.31+, SQLite):

// Find users who have placed orders (INTERSECT)
allUsers := db.Builder().Select("id").From("users")
orderUsers := db.Builder().Select("user_id").From("orders")
allUsers.Intersect(orderUsers).All(&activeUsers)

// Find users without orders (EXCEPT)
allUsers.Except(orderUsers).All(&inactiveUsers)

See Set Operations Guide for database compatibility and workarounds.

Common Table Expressions (CTEs)

Basic CTEs:

// Define reusable query
orderTotals := db.Builder().
    Select("user_id", "SUM(total) as total").
    From("orders").
    GroupBy("user_id")

// Use CTE in main query
db.Builder().
    With("order_totals", orderTotals).
    Select("*").
    From("order_totals").
    Where("total > ?", 1000).
    All(&premiumUsers)

Recursive CTEs (organizational hierarchies, trees):

// Anchor: top-level employees
anchor := db.Builder().
    Select("id", "name", "manager_id", "1 as level").
    From("employees").
    Where("manager_id IS NULL")

// Recursive: children
recursive := db.Builder().
    Select("e.id", "e.name", "e.manager_id", "h.level + 1").
    From("employees e").
    InnerJoin("hierarchy h", "e.manager_id = h.id")

// Build hierarchy
db.Builder().
    WithRecursive("hierarchy", anchor.UnionAll(recursive)).
    Select("*").
    From("hierarchy").
    OrderBy("level", "name").
    All(&orgChart)

See CTE Guide for hierarchical data examples (org charts, bill of materials, category trees).

Window Functions

Relica supports window functions via SelectExpr() for advanced analytics:

// Rank users by order total within each country
db.Builder().
    SelectExpr("user_id", "country", "total",
        "RANK() OVER (PARTITION BY country ORDER BY total DESC) as rank").
    From("orders").
    All(&rankedOrders)

// Running totals with frame specification
db.Builder().
    SelectExpr("date", "amount",
        "SUM(amount) OVER (ORDER BY date ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) as running_total").
    From("transactions").
    OrderBy("date").
    All(&runningTotals)

See Window Functions Guide for complete reference with RANK(), ROW_NUMBER(), LAG(), LEAD(), and frame specifications.

Transactions

// Start transaction
tx, err := db.BeginTx(ctx, &relica.TxOptions{
    Isolation: sql.LevelSerializable,
})
if err != nil {
    return err
}
defer tx.Rollback() // Rollback if not committed

// Execute queries within transaction
_, err = tx.Builder().Insert("users", userData).Execute()
if err != nil {
    return err
}

_, err = tx.Builder().
    Update("accounts").
    Set(map[string]interface{}{"balance": newBalance}).
    Where("user_id = ?", userID).
    Execute()
if err != nil {
    return err
}

// Commit transaction
return tx.Commit()

Batch Operations

Batch INSERT (3.3x faster than individual inserts):

result, err := db.Builder().
    BatchInsert("users", []string{"name", "email"}).
    Values("Alice", "alice@example.com").
    Values("Bob", "bob@example.com").
    Values("Charlie", "charlie@example.com").
    Execute()

// Or from a slice
users := []User{
    {Name: "Alice", Email: "alice@example.com"},
    {Name: "Bob", Email: "bob@example.com"},
}

batch := db.Builder().BatchInsert("users", []string{"name", "email"})
for _, user := range users {
    batch.Values(user.Name, user.Email)
}
result, err := batch.Execute()

Batch UPDATE (updates multiple rows with different values):

result, err := db.Builder().
    BatchUpdate("users", "id").
    Set(1, map[string]interface{}{"name": "Alice Updated", "status": "active"}).
    Set(2, map[string]interface{}{"name": "Bob Updated", "status": "active"}).
    Set(3, map[string]interface{}{"age": 30}).
    Execute()

Context Support

// Query with timeout
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

var users []User
err := db.Builder().
    WithContext(ctx).
    Select().
    From("users").
    All(&users)

// Context on query level
err = db.Builder().
    Select().
    From("users").
    WithContext(ctx).
    One(&user)

// Transaction context auto-propagates
tx, _ := db.BeginTx(ctx, nil)
tx.Builder().Select().From("users").One(&user) // Uses ctx automatically

🏗️ Database Support

Database	Status	Placeholders	Identifiers	UPSERT
PostgreSQL	✅ Full	$1, $2, $3	"users"	ON CONFLICT
MySQL	✅ Full	?, ?, ?	`users`	ON DUPLICATE KEY
SQLite	✅ Full	?, ?, ?	"users"	ON CONFLICT

⚡ Performance

Statement Cache

• Default capacity: 1000 prepared statements
• Hit latency: <60ns
• Thread-safe: Concurrent access optimized
• Metrics: Hit rate, evictions, cache size

// Configure cache capacity
db, err := relica.Open("postgres", dsn,
    relica.WithStmtCacheCapacity(2000),
    relica.WithMaxOpenConns(25),
    relica.WithMaxIdleConns(5),
)

// Check cache statistics
stats := db.stmtCache.Stats()
fmt.Printf("Cache hit rate: %.2f%%\n", stats.HitRate*100)

Batch Operations Performance

Operation	Rows	Time	vs Single	Memory
Batch INSERT	100	327ms	3.3x faster	-15%
Single INSERT	100	1094ms	Baseline	Baseline
Batch UPDATE	100	1370ms	2.5x faster	-55% allocs

🔧 Configuration

db, err := relica.Open("postgres", dsn,
    // Connection pool
    relica.WithMaxOpenConns(25),
    relica.WithMaxIdleConns(5),

    // Statement cache
    relica.WithStmtCacheCapacity(1000),
)

Connection Management

Standard Connection

// Create new connection with Relica managing the pool
db, err := relica.Open("postgres", dsn)
defer db.Close()

Wrap Existing Connection (v0.3.0+)

Use WrapDB() when you need to integrate Relica with an existing *sql.DB connection:

import (
    "database/sql"
    "time"

    "github.com/coregx/relica"
    _ "github.com/lib/pq"
)

// Create and configure external connection pool
sqlDB, err := sql.Open("postgres", dsn)
if err != nil {
    log.Fatal(err)
}

// Apply custom pool settings
sqlDB.SetMaxOpenConns(100)
sqlDB.SetMaxIdleConns(50)
sqlDB.SetConnMaxLifetime(time.Hour)
sqlDB.SetConnMaxIdleTime(10 * time.Minute)

// Wrap with Relica query builder
db := relica.WrapDB(sqlDB, "postgres")

// Use Relica's fluent API
var users []User
err = db.Builder().
    Select().
    From("users").
    Where("status = ?", 1).
    All(&users)

// Caller is responsible for closing the connection
defer sqlDB.Close()  // NOT db.Close()

Use Cases for WrapDB:

• Existing Codebase Integration: Add Relica to projects with established *sql.DB connections
• Custom Pool Configuration: Apply advanced connection pool settings before wrapping
• Shared Connections: Multiple parts of your application can share the same pool
• Testing: Wrap test database connections without managing lifecycle

Important Notes:

• Each WrapDB() call creates a new Relica instance with its own statement cache
• The caller is responsible for closing the underlying *sql.DB connection
• Multiple wraps of the same connection are isolated (separate caches)

📖 Documentation

User Guides (v0.3.0+)

• Subquery Guide - IN, EXISTS, FROM, scalar subqueries with performance tips
• Set Operations Guide - UNION, INTERSECT, EXCEPT with database compatibility
• CTE Guide - WITH clauses, recursive CTEs for hierarchical data
• Window Functions Guide - Analytics with RANK(), ROW_NUMBER(), LAG(), LEAD()

Additional Resources

• Transaction Guide
• UPSERT Examples
• Batch Operations
• Zero Dependencies Achievement
• API Reference

🧪 Testing

# Run unit tests
go test ./...

# Run with coverage
go test -cover ./...

# Run integration tests (requires Docker)
go test -tags=integration ./test/...

# Run benchmarks
go test -bench=. -benchmem ./benchmark/...

🎯 Design Philosophy

1. Zero Dependencies - Production code uses only Go standard library
2. Type Safety - Compile-time checks, runtime safety
3. Performance - Statement caching, batch operations, zero allocations in hot paths
4. Simplicity - Clean API, easy to learn, hard to misuse
5. Correctness - ACID transactions, proper error handling
6. Observability - Built-in metrics, context support for tracing

📊 Project Status

• Version: v0.4.1-beta
• Go Version: 1.25+
• Production Ready: Yes (beta)
• Test Coverage: 93.3%
• Dependencies: 0 (production), 2 (tests only)
• API: Stable public API, internal packages protected

🤝 Contributing

Contributions are welcome! Please read our Contributing Guide first.

📝 License

Relica is released under the MIT License.

🙏 Acknowledgments

• Inspired by ozzo-dbx
• Built with Go 1.25+ features
• Zero-dependency philosophy inspired by Go standard library

📞 Support

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Email: support@coregx.dev

✨ Special Thanks

Professor Ancha Baranova - This project would not have been possible without her invaluable help and support. Her assistance was crucial in bringing Relica to life.

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Made with ❤️ by COREGX Team

Relica - Lightweight, Fast, Zero-Dependency Database Query Builder for Go