How to Fix the 'pq: cannot drop the currently open database' Error in Postgres?

Troubleshooting Postgres Database Drop Error: "pq: cannot drop the currently open database"

In Postgres, you may encounter the error "pq: cannot drop the currently open database" when attempting to drop the database to which you're currently connected. This error arises because dropping a database requires disconnecting all open connections to it, which would disconnect your current connection and prevent you from executing the DROP DATABASE statement.

Solution:

As suggested in the Postgres documentation, you should connect to a different database and execute the DROP DATABASE command from there. This ensures that no active connections exist in the database you want to drop.

Example:

import (
    "database/sql"
    "fmt"
)

func main() {
    // Connect to a different database (e.g., "template1")
    conn, err := sql.Open("postgres", "host=localhost user=postgres dbname=template1")
    if err != nil {
        panic(err)
    }
    defer conn.Close()

    // Drop the original database from the new connection
    _, err = conn.Exec(fmt.Sprintf(`DROP DATABASE %s;`, "mydb"))
    if err != nil {
        panic(err)
    }

    fmt.Println("Database dropped successfully.")
}

Forcing Client Disconnection (Cautionary):

In scenarios where another client is connected to the database, you may consider forcibly disconnecting all clients to facilitate the database drop.

-- For PostgreSQL < 9.2
SELECT pg_terminate_backend(procpid) FROM pg_stat_activity WHERE datname = 'mydb';

-- For PostgreSQL >= 9.2
SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = 'mydb';

Note: This action requires superuser privileges and should be used with caution as it may interrupt active sessions.

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