How to restore database in Golang?

There are multiple ways to restore a database in Go: dump and restore using the db dump and db load command line tools. Use the pgx library to perform more convenient database operations involving data import using CREATE TEMP TABLE temporary tables.

Database Restore in Go

Restore is a crucial step as it allows you to recover data from the previous version of the database. There are several ways to achieve this in Go.

Using db dump and db load

Command line method

You can use the following commands Dump data from database:

pg_dump -U username -h hostname -d database_name > dump.sql

To restore data from dump, run the following command:

psql -U username -h hostname database_name < dump.sql

Code implementation

In Go, You can execute these commands using the exec.Command() function:

import (
    "log"
    "os/exec"
)

func DumpDatabase(user, host, db string) {
    cmd := exec.Command("pg_dump", "-U", user, "-h", host, "-d", db)
    outfile, err := os.Create("dump.sql")
    if err != nil {
        log.Fatal(err)
    }
    defer outfile.Close()

    cmd.Stdout = outfile

    if err := cmd.Run(); err != nil {
        log.Fatal(err)
    }
}

func LoadDatabase(user, host, db, dumpfile string) {
    cmd := exec.Command("psql", "-U", user, "-h", host, db)
    infile, err := os.Open(dumpfile)
    if err != nil {
        log.Fatal(err)
    }
    defer infile.Close()

    cmd.Stdin = infile

    if err := cmd.Run(); err != nil {
        log.Fatal(err)
    }
}

func main() {
    DumpDatabase("dbuser", "localhost", "mydb")
    LoadDatabase("dbuser", "localhost", "mydb", "dump.sql")
}

Using the pgx library

Code implementation

pgx The library provides a more convenient way to perform database operations.

import (
    "context"
    "log"

    "github.com/jackc/pgx/v4"
)

const restoreStatement = `
CREATE TEMP TABLE imported_data (
    id SERIAL PRIMARY KEY,
    name TEXT
) ON COMMIT PRESERVE ROWS;
COPY imported_data (name) FROM stdin;
INSERT INTO mytable (name) SELECT name FROM imported_data;
DROP TABLE imported_data;
`

func RestoreDatabase(conn *pgx.Conn, dumpfile string) error {
    file, err := os.Open(dumpfile)
    if err != nil {
        return err
    }
    defer file.Close()

    _, err = conn.Exec(context.Background(), restoreStatement, pgx.CopyTo(file, pgx.RowEncoder(func([]interface{}) error { return nil })))
    if err != nil {
        return err
    }

    return nil
}

func main() {
    conn, err := pgx.Connect(context.Background(), "postgres://user:password@hostname/dbname")
    if err != nil {
        log.Fatal(err)
    }
    defer conn.Close()

    RestoreDatabase(conn, "dump.sql")
}

Practical case

This is an example of restoring a mail database:

pg_dump -U postgres -h localhost -d mail_db > db_backup.sql

To restore the database, you only need to run the following command:

psql -U postgres -h localhost mail_db < db_backup.sql

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