什么是duckdb
DuckDB是一个开源的嵌入式SQL数据库管理系统。与传统的SQL数据库不同,DuckDB不需要一个服务器进程,
也不需要在系统上安装数据库软件。它被设计为轻量级和高性能,可以轻松嵌入到应用程序中,提供完整的SQL数据库功能。
以下是DuckDB的一些关键特性:
1. **轻量级**:DuckDB的二进制文件非常小,通常只有几百KB,这使得它非常适合嵌入式使用。
2. **高性能**:DuckDB利用现代硬件优化查询性能,支持索引、物化视图、查询优化等特性。
3. **标准SQL支持**:DuckDB遵循SQL标准,支持大多数SQL数据类型、函数和操作。
4. **跨平台**:DuckDB可以在多种操作系统上运行,包括Windows、macOS、Linux等。
5. **多种数据源**:DuckDB支持从CSV、Parquet、SQLite等不同数据源导入数据。
6. **并发控制**:DuckDB支持多线程查询,可以在多核处理器上并行执行。
7. **事务支持**:DuckDB支持ACID事务,确保数据的一致性和完整性。
8. **API支持**:DuckDB提供了多种编程语言的API,包括C、Python、R等,方便集成。
9. **无服务器模式**:DuckDB可以在无服务器环境中运行,适合云原生和容器化应用。
10. **可扩展性**:DuckDB允许用户通过扩展添加新的功能,如自定义函数、聚合函数等。
DuckDB适用于需要轻量级数据库解决方案的场景,如数据分析、数据科学、机器学习、嵌入式系统、Web应用等。
由于其轻量级和高性能的特点,DuckDB也适合作为教学和学习SQL的工具。
go操作库地址为 https://github.com/marcboeker/go-duckdb
main.go
package main
import (
"context"
"database/sql"
"log"
"time"
_ "github.com/marcboeker/go-duckdb"
)
var db *sql.DB
type user struct {
name string
age int
height float32
awesome bool
bday time.Time
}
func main() {
var err error
db, err = sql.Open("duckdb", "?access_mode=READ_WRITE") //设置读写权限
if err != nil {
log.Fatal(err)
}
defer db.Close()
check(db.Ping())
setting := db.QueryRowContext(context.Background(), "SELECT current_setting('access_mode')")
var am string
check(setting.Scan(&am))
log.Printf("DB opened with access mode %s", am)
//普通操作,建表,插入数据
check(db.ExecContext(context.Background(), "CREATE TABLE users(name VARCHAR, age INTEGER, height FLOAT, awesome BOOLEAN, bday DATE)"))
check(db.ExecContext(context.Background(), "INSERT INTO users VALUES('marc', 99, 1.91, true, '1970-01-01')"))
check(db.ExecContext(context.Background(), "INSERT INTO users VALUES('macgyver', 70, 1.85, true, '1951-01-23')"))
//查询
rows, err := db.QueryContext(
context.Background(), `
SELECT name, age, height, awesome, bday
FROM users
WHERE (name = ? OR name = ?) AND age > ? AND awesome = ?`,
"macgyver", "marc", 30, true,
)
check(err)
defer rows.Close()
//遍历打印
for rows.Next() {
u := new(user)
err := rows.Scan(&u.name, &u.age, &u.height, &u.awesome, &u.bday)
if err != nil {
log.Fatal(err)
}
log.Printf(
"%s is %d years old, %.2f tall, bday on %s and has awesomeness: %t\n",
u.name, u.age, u.height, u.bday.Format(time.RFC3339), u.awesome,
)
}
check(rows.Err())
//删除
res, err := db.ExecContext(context.Background(), "DELETE FROM users")
check(err)
ra, _ := res.RowsAffected()
log.Printf("Deleted %d rows\n", ra)
//事务
runTransaction()
//预操作
testPreparedStmt()
}
func check(args ...interface{}) {
err := args[len(args)-1]
if err != nil {
panic(err)
}
}
func runTransaction() {
log.Println("Starting transaction...")
tx, err := db.Begin()
check(err)
check(
tx.ExecContext(
context.Background(),
"INSERT INTO users VALUES('gru', 25, 1.35, false, '1996-04-03')",
),
)
row := tx.QueryRowContext(context.Background(), "SELECT COUNT(*) FROM users WHERE name = ?", "gru")
var count int64
check(row.Scan(&count))
if count > 0 {
log.Println("User Gru was inserted")
}
log.Println("Rolling back transaction...")
check(tx.Rollback())
row = db.QueryRowContext(context.Background(), "SELECT COUNT(*) FROM users WHERE name = ?", "gru")
check(row.Scan(&count))
if count > 0 {
log.Println("Found user Gru")
} else {
log.Println("Couldn't find user Gru")
}
}
func testPreparedStmt() {
stmt, err := db.PrepareContext(context.Background(), "INSERT INTO users VALUES(?, ?, ?, ?, ?)")
check(err)
defer stmt.Close()
check(stmt.ExecContext(context.Background(), "Kevin", 11, 0.55, true, "2013-07-06"))
check(stmt.ExecContext(context.Background(), "Bob", 12, 0.73, true, "2012-11-04"))
check(stmt.ExecContext(context.Background(), "Stuart", 13, 0.66, true, "2014-02-12"))
stmt, err = db.PrepareContext(context.Background(), "SELECT * FROM users WHERE age > ?")
check(err)
rows, err := stmt.QueryContext(context.Background(), 1)
check(err)
defer rows.Close()
for rows.Next() {
u := new(user)
err := rows.Scan(&u.name, &u.age, &u.height, &u.awesome, &u.bday)
if err != nil {
log.Fatal(err)
}
log.Printf(
"%s is %d years old, %.2f tall, bday on %s and has awesomeness: %t\n",
u.name, u.age, u.height, u.bday.Format(time.RFC3339), u.awesome,
)
}
}
输出
2024/06/17 10:59:30 DB opened with access mode read_write
2024/06/17 10:59:30 marc is 99 years old, 1.91 tall, bday on 1970-01-01T00:00:00Z and has awesomeness: true
2024/06/17 10:59:30 macgyver is 70 years old, 1.85 tall, bday on 1951-01-23T00:00:00Z and has awesomeness: true
2024/06/17 10:59:30 Deleted 2 rows
2024/06/17 10:59:30 Starting transaction...
2024/06/17 10:59:30 User Gru was inserted
2024/06/17 10:59:30 Rolling back transaction...
2024/06/17 10:59:30 Couldn't find user Gru
2024/06/17 10:59:30 Kevin is 11 years old, 0.55 tall, bday on 2013-07-06T00:00:00Z and has awesomeness: true
2024/06/17 10:59:30 Bob is 12 years old, 0.73 tall, bday on 2012-11-04T00:00:00Z and has awesomeness: true
2024/06/17 10:59:30 Stuart is 13 years old, 0.66 tall, bday on 2014-02-12T00:00:00Z and has awesomeness: true
标签:Background,err,DuckDB,db,duckdb,context,go,操作,check
From: https://www.cnblogs.com/qcy-blog/p/18251995