Index: /trunk/cmd/soju/main.go
===================================================================
--- /trunk/cmd/soju/main.go	(revision 619)
+++ /trunk/cmd/soju/main.go	(revision 620)
@@ -62,5 +62,5 @@
 	}
 
-	db, err := soju.OpenSqliteDB(cfg.SQLDriver, cfg.SQLSource)
+	db, err := soju.OpenDB(cfg.SQLDriver, cfg.SQLSource)
 	if err != nil {
 		log.Fatalf("failed to open database: %v", err)
Index: /trunk/cmd/sojuctl/main.go
===================================================================
--- /trunk/cmd/sojuctl/main.go	(revision 619)
+++ /trunk/cmd/sojuctl/main.go	(revision 620)
@@ -44,5 +44,5 @@
 	}
 
-	db, err := soju.OpenSqliteDB(cfg.SQLDriver, cfg.SQLSource)
+	db, err := soju.OpenDB(cfg.SQLDriver, cfg.SQLSource)
 	if err != nil {
 		log.Fatalf("failed to open database: %v", err)
Index: /trunk/contrib/znc-import.go
===================================================================
--- /trunk/contrib/znc-import.go	(revision 619)
+++ /trunk/contrib/znc-import.go	(revision 620)
@@ -62,5 +62,5 @@
 	}
 
-	db, err := soju.OpenSqliteDB(cfg.SQLDriver, cfg.SQLSource)
+	db, err := soju.OpenDB(cfg.SQLDriver, cfg.SQLSource)
 	if err != nil {
 		log.Fatalf("failed to open database: %v", err)
Index: /trunk/db.go
===================================================================
--- /trunk/db.go	(revision 619)
+++ /trunk/db.go	(revision 620)
@@ -26,4 +26,15 @@
 	ListDeliveryReceipts(networkID int64) ([]DeliveryReceipt, error)
 	StoreClientDeliveryReceipts(networkID int64, client string, receipts []DeliveryReceipt) error
+}
+
+func OpenDB(driver, source string) (Database, error) {
+	switch driver {
+	case "sqlite3":
+		return OpenSqliteDB(source)
+	case "postgres":
+		return OpenPostgresDB(source)
+	default:
+		return nil, fmt.Errorf("unsupported database driver: %q", driver)
+	}
 }
 
Index: /trunk/db_postgres.go
===================================================================
--- /trunk/db_postgres.go	(revision 620)
+++ /trunk/db_postgres.go	(revision 620)
@@ -0,0 +1,402 @@
+package soju
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"math"
+	"strings"
+	"time"
+
+	_ "github.com/lib/pq"
+)
+
+const postgresConfigSchema = `
+CREATE TABLE IF NOT EXISTS "Config" (
+	id SMALLINT PRIMARY KEY,
+	version INTEGER NOT NULL,
+	CHECK(id = 1)
+);
+`
+
+const postgresSchema = `
+CREATE TABLE "User" (
+	id SERIAL PRIMARY KEY,
+	username VARCHAR(255) NOT NULL UNIQUE,
+	password VARCHAR(255),
+	admin BOOLEAN NOT NULL DEFAULT FALSE,
+	realname VARCHAR(255)
+);
+
+CREATE TABLE "Network" (
+	id SERIAL PRIMARY KEY,
+	name VARCHAR(255),
+	"user" INTEGER NOT NULL REFERENCES "User"(id) ON DELETE CASCADE,
+	addr VARCHAR(255) NOT NULL,
+	nick VARCHAR(255) NOT NULL,
+	username VARCHAR(255),
+	realname VARCHAR(255),
+	pass VARCHAR(255),
+	connect_commands VARCHAR(1023),
+	sasl_mechanism VARCHAR(255),
+	sasl_plain_username VARCHAR(255),
+	sasl_plain_password VARCHAR(255),
+	sasl_external_cert BYTEA DEFAULT NULL,
+	sasl_external_key BYTEA DEFAULT NULL,
+	enabled BOOLEAN NOT NULL DEFAULT TRUE,
+	UNIQUE("user", addr, nick),
+	UNIQUE("user", name)
+);
+
+CREATE TABLE "Channel" (
+	id SERIAL PRIMARY KEY,
+	network INTEGER NOT NULL REFERENCES "Network"(id) ON DELETE CASCADE,
+	name VARCHAR(255) NOT NULL,
+	key VARCHAR(255),
+	detached BOOLEAN NOT NULL DEFAULT FALSE,
+	detached_internal_msgid VARCHAR(255),
+	relay_detached INTEGER NOT NULL DEFAULT 0,
+	reattach_on INTEGER NOT NULL DEFAULT 0,
+	detach_after INTEGER NOT NULL DEFAULT 0,
+	detach_on INTEGER NOT NULL DEFAULT 0,
+	UNIQUE(network, name)
+);
+
+CREATE TABLE "DeliveryReceipt" (
+	id SERIAL PRIMARY KEY,
+	network INTEGER NOT NULL REFERENCES "Network"(id) ON DELETE CASCADE,
+	target VARCHAR(255) NOT NULL,
+	client VARCHAR(255) NOT NULL DEFAULT '',
+	internal_msgid VARCHAR(255) NOT NULL,
+	UNIQUE(network, target, client)
+);
+`
+
+var postgresMigrations = []string{
+	"", // migration #0 is reserved for schema initialization
+}
+
+type PostgresDB struct {
+	db *sql.DB
+}
+
+func OpenPostgresDB(source string) (Database, error) {
+	sqlPostgresDB, err := sql.Open("postgres", source)
+	if err != nil {
+		return nil, err
+	}
+
+	db := &PostgresDB{db: sqlPostgresDB}
+	if err := db.upgrade(); err != nil {
+		sqlPostgresDB.Close()
+		return nil, err
+	}
+
+	return db, nil
+}
+
+func (db *PostgresDB) upgrade() error {
+	tx, err := db.db.Begin()
+	if err != nil {
+		return err
+	}
+	defer tx.Rollback()
+
+	if _, err := tx.Exec(postgresConfigSchema); err != nil {
+		return fmt.Errorf("failed to create Config table: %s", err)
+	}
+
+	var version int
+	err = tx.QueryRow(`SELECT version FROM "Config"`).Scan(&version)
+	if err != nil && !errors.Is(err, sql.ErrNoRows) {
+		return fmt.Errorf("failed to query schema version: %s", err)
+	}
+
+	if version == len(postgresMigrations) {
+		return nil
+	}
+	if version > len(postgresMigrations) {
+		return fmt.Errorf("soju (version %d) older than schema (version %d)", len(postgresMigrations), version)
+	}
+
+	if version == 0 {
+		if _, err := tx.Exec(postgresSchema); err != nil {
+			return fmt.Errorf("failed to initialize schema: %s", err)
+		}
+	} else {
+		for i := version; i < len(postgresMigrations); i++ {
+			if _, err := tx.Exec(postgresMigrations[i]); err != nil {
+				return fmt.Errorf("failed to execute migration #%v: %v", i, err)
+			}
+		}
+	}
+
+	_, err = tx.Exec(`INSERT INTO "Config" (id, version) VALUES (1, $1)
+		ON CONFLICT (id) DO UPDATE SET version = $1`, len(postgresMigrations))
+	if err != nil {
+		return fmt.Errorf("failed to bump schema version: %v", err)
+	}
+
+	return tx.Commit()
+}
+
+func (db *PostgresDB) Close() error {
+	return db.db.Close()
+}
+
+func (db *PostgresDB) Stats() (*DatabaseStats, error) {
+	var stats DatabaseStats
+	row := db.db.QueryRow(`SELECT
+		(SELECT COUNT(*) FROM "User") AS users,
+		(SELECT COUNT(*) FROM "Network") AS networks,
+		(SELECT COUNT(*) FROM "Channel") AS channels`)
+	if err := row.Scan(&stats.Users, &stats.Networks, &stats.Channels); err != nil {
+		return nil, err
+	}
+
+	return &stats, nil
+}
+
+func (db *PostgresDB) ListUsers() ([]User, error) {
+	rows, err := db.db.Query(`SELECT id, username, password, admin, realname FROM "User"`)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var users []User
+	for rows.Next() {
+		var user User
+		var password, realname sql.NullString
+		if err := rows.Scan(&user.ID, &user.Username, &password, &user.Admin, &realname); err != nil {
+			return nil, err
+		}
+		user.Password = password.String
+		user.Realname = realname.String
+		users = append(users, user)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return users, nil
+}
+
+func (db *PostgresDB) GetUser(username string) (*User, error) {
+	user := &User{Username: username}
+
+	var password, realname sql.NullString
+	row := db.db.QueryRow(
+		`SELECT id, password, admin, realname FROM "User" WHERE username = $1`,
+		username)
+	if err := row.Scan(&user.ID, &password, &user.Admin, &realname); err != nil {
+		return nil, err
+	}
+	user.Password = password.String
+	user.Realname = realname.String
+	return user, nil
+}
+
+func (db *PostgresDB) StoreUser(user *User) error {
+	password := toNullString(user.Password)
+	realname := toNullString(user.Realname)
+	err := db.db.QueryRow(`
+		INSERT INTO "User" (username, password, admin, realname)
+		VALUES ($1, $2, $3, $4)
+		ON CONFLICT (username)
+		DO UPDATE SET password = $2, admin = $3, realname = $4
+		RETURNING id`,
+		user.Username, password, user.Admin, realname).Scan(&user.ID)
+	return err
+}
+
+func (db *PostgresDB) DeleteUser(id int64) error {
+	_, err := db.db.Exec(`DELETE FROM "User" WHERE id = $1`, id)
+	return err
+}
+
+func (db *PostgresDB) ListNetworks(userID int64) ([]Network, error) {
+	rows, err := db.db.Query(`
+		SELECT id, name, addr, nick, username, realname, pass, connect_commands, sasl_mechanism,
+			sasl_plain_username, sasl_plain_password, sasl_external_cert, sasl_external_key, enabled
+		FROM "Network"
+		WHERE "user" = $1`, userID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var networks []Network
+	for rows.Next() {
+		var net Network
+		var name, username, realname, pass, connectCommands sql.NullString
+		var saslMechanism, saslPlainUsername, saslPlainPassword sql.NullString
+		err := rows.Scan(&net.ID, &name, &net.Addr, &net.Nick, &username, &realname,
+			&pass, &connectCommands, &saslMechanism, &saslPlainUsername, &saslPlainPassword,
+			&net.SASL.External.CertBlob, &net.SASL.External.PrivKeyBlob, &net.Enabled)
+		if err != nil {
+			return nil, err
+		}
+		net.Name = name.String
+		net.Username = username.String
+		net.Realname = realname.String
+		net.Pass = pass.String
+		if connectCommands.Valid {
+			net.ConnectCommands = strings.Split(connectCommands.String, "\r\n")
+		}
+		net.SASL.Mechanism = saslMechanism.String
+		net.SASL.Plain.Username = saslPlainUsername.String
+		net.SASL.Plain.Password = saslPlainPassword.String
+		networks = append(networks, net)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return networks, nil
+}
+
+func (db *PostgresDB) StoreNetwork(userID int64, network *Network) error {
+	netName := toNullString(network.Name)
+	netUsername := toNullString(network.Username)
+	realname := toNullString(network.Realname)
+	pass := toNullString(network.Pass)
+	connectCommands := toNullString(strings.Join(network.ConnectCommands, "\r\n"))
+
+	var saslMechanism, saslPlainUsername, saslPlainPassword sql.NullString
+	if network.SASL.Mechanism != "" {
+		saslMechanism = toNullString(network.SASL.Mechanism)
+		switch network.SASL.Mechanism {
+		case "PLAIN":
+			saslPlainUsername = toNullString(network.SASL.Plain.Username)
+			saslPlainPassword = toNullString(network.SASL.Plain.Password)
+			network.SASL.External.CertBlob = nil
+			network.SASL.External.PrivKeyBlob = nil
+		case "EXTERNAL":
+			// keep saslPlain* nil
+		default:
+			return fmt.Errorf("soju: cannot store network: unsupported SASL mechanism %q", network.SASL.Mechanism)
+		}
+	}
+
+	err := db.db.QueryRow(`
+		INSERT INTO "Network" ("user", name, addr, nick, username, realname, pass, connect_commands,
+			sasl_mechanism, sasl_plain_username, sasl_plain_password, sasl_external_cert,
+			sasl_external_key, enabled)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14)
+		ON CONFLICT ("user", name)
+		DO UPDATE SET name = $2, addr = $3, nick = $4, username = $5, realname = $6, pass = $7,
+			connect_commands = $8, sasl_mechanism = $9, sasl_plain_username = $10,
+			sasl_plain_password = $11, sasl_external_cert = $12, sasl_external_key = $13,
+			enabled = $14
+		RETURNING id`,
+		userID, netName, network.Addr, network.Nick, netUsername, realname, pass, connectCommands,
+		saslMechanism, saslPlainUsername, saslPlainPassword, network.SASL.External.CertBlob,
+		network.SASL.External.PrivKeyBlob, network.Enabled).Scan(&network.ID)
+	return err
+}
+
+func (db *PostgresDB) DeleteNetwork(id int64) error {
+	_, err := db.db.Exec(`DELETE FROM "Network" WHERE id = $1`, id)
+	return err
+}
+
+func (db *PostgresDB) ListChannels(networkID int64) ([]Channel, error) {
+	rows, err := db.db.Query(`
+		SELECT id, name, key, detached, detached_internal_msgid, relay_detached, reattach_on, detach_after,
+			detach_on
+		FROM "Channel"
+		WHERE network = $1`, networkID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var channels []Channel
+	for rows.Next() {
+		var ch Channel
+		var key, detachedInternalMsgID sql.NullString
+		var detachAfter int64
+		if err := rows.Scan(&ch.ID, &ch.Name, &key, &ch.Detached, &detachedInternalMsgID, &ch.RelayDetached, &ch.ReattachOn, &detachAfter, &ch.DetachOn); err != nil {
+			return nil, err
+		}
+		ch.Key = key.String
+		ch.DetachedInternalMsgID = detachedInternalMsgID.String
+		ch.DetachAfter = time.Duration(detachAfter) * time.Second
+		channels = append(channels, ch)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return channels, nil
+}
+
+func (db *PostgresDB) StoreChannel(networkID int64, ch *Channel) error {
+	key := toNullString(ch.Key)
+	detachAfter := int64(math.Ceil(ch.DetachAfter.Seconds()))
+	err := db.db.QueryRow(`
+		INSERT INTO "Channel" (network, name, key, detached, detached_internal_msgid, relay_detached, reattach_on,
+			detach_after, detach_on)
+		VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9)
+		ON CONFLICT (network, name)
+		DO UPDATE SET network = $1, name = $2, key = $3, detached = $4, detached_internal_msgid = $5,
+			relay_detached = $6, reattach_on = $7, detach_after = $8, detach_on = $9
+		RETURNING id`,
+		networkID, ch.Name, key, ch.Detached, toNullString(ch.DetachedInternalMsgID),
+		ch.RelayDetached, ch.ReattachOn, detachAfter, ch.DetachOn).Scan(&ch.ID)
+	return err
+}
+
+func (db *PostgresDB) DeleteChannel(id int64) error {
+	_, err := db.db.Exec(`DELETE FROM "Channel" WHERE id = $1`, id)
+	return err
+}
+
+func (db *PostgresDB) ListDeliveryReceipts(networkID int64) ([]DeliveryReceipt, error) {
+	rows, err := db.db.Query(`
+		SELECT id, target, client, internal_msgid
+		FROM "DeliveryReceipt"
+		WHERE network = $1`, networkID)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var receipts []DeliveryReceipt
+	for rows.Next() {
+		var rcpt DeliveryReceipt
+		if err := rows.Scan(&rcpt.ID, &rcpt.Target, &rcpt.Client, &rcpt.InternalMsgID); err != nil {
+			return nil, err
+		}
+		receipts = append(receipts, rcpt)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return receipts, nil
+}
+
+func (db *PostgresDB) StoreClientDeliveryReceipts(networkID int64, client string, receipts []DeliveryReceipt) error {
+	stmt, err := db.db.Prepare(`
+		INSERT INTO "DeliveryReceipt" (network, target, client, internal_msgid)
+		VALUES ($1, $2, $3, $4)
+		ON CONFLICT (network, target, client)
+		DO UPDATE SET internal_msgid = $4
+		RETURNING id`)
+	if err != nil {
+		return err
+	}
+	defer stmt.Close()
+
+	// No need for a transaction since all changes are atomic and don't break data coherence.
+	for i := range receipts {
+		rcpt := &receipts[i]
+		err := stmt.QueryRow(networkID, rcpt.Target, client, rcpt.InternalMsgID).Scan(&rcpt.ID)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
Index: /trunk/db_sqlite.go
===================================================================
--- /trunk/db_sqlite.go	(revision 619)
+++ /trunk/db_sqlite.go	(revision 620)
@@ -143,6 +143,6 @@
 }
 
-func OpenSqliteDB(driver, source string) (Database, error) {
-	sqlSqliteDB, err := sql.Open(driver, source)
+func OpenSqliteDB(source string) (Database, error) {
+	sqlSqliteDB, err := sql.Open("sqlite3", source)
 	if err != nil {
 		return nil, err
Index: /trunk/doc/soju.1.scd
===================================================================
--- /trunk/doc/soju.1.scd	(revision 619)
+++ /trunk/doc/soju.1.scd	(revision 620)
@@ -107,6 +107,16 @@
 	Enable TLS support. The certificate and the key files must be PEM-encoded.
 
-*db* sqlite3 <path>
-	Set the SQLite database path (default: "soju.db" in the current directory).
+*db* <driver> <source>
+	Set the database location for user, network and channel storage. By default,
+	a _sqlite3_ database is opened in "./soju.db".
+
+	Supported drivers:
+
+	- _sqlite3_ expects _source_ to be a path to the SQLite file
+	- _postgres_ expects _source_ to be a space-separated list of _key=value_
+	  parameters, e.g. _db postgres "host=/run/postgresql dbname=soju"_. Note
+	  that _sslmode_ defaults to _require_. For more information on connection
+	  strings, see:
+	  <https://pkg.go.dev/github.com/lib/pq#hdr-Connection_String_Parameters>.
 
 *log* fs <path>
Index: /trunk/go.mod
===================================================================
--- /trunk/go.mod	(revision 619)
+++ /trunk/go.mod	(revision 620)
@@ -8,4 +8,5 @@
 	github.com/emersion/go-sasl v0.0.0-20200509203442-7bfe0ed36a21
 	github.com/klauspost/compress v1.13.5 // indirect
+	github.com/lib/pq v1.10.3
 	github.com/mattn/go-sqlite3 v1.14.8
 	github.com/pires/go-proxyproto v0.6.1
Index: /trunk/go.sum
===================================================================
--- /trunk/go.sum	(revision 619)
+++ /trunk/go.sum	(revision 620)
@@ -44,4 +44,6 @@
 github.com/leodido/go-urn v1.2.0 h1:hpXL4XnriNwQ/ABnpepYM/1vCLWNDfUNts8dX3xTG6Y=
 github.com/leodido/go-urn v1.2.0/go.mod h1:+8+nEpDfqqsY+g338gtMEUOtuK+4dEMhiQEgxpxOKII=
+github.com/lib/pq v1.10.3 h1:v9QZf2Sn6AmjXtQeFpdoq/eaNtYP6IN+7lcrygsIAtg=
+github.com/lib/pq v1.10.3/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/mattn/go-isatty v0.0.12 h1:wuysRhFDzyxgEmMf5xjvJ2M9dZoWAXNNr5LSBS7uHXY=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
Index: /trunk/server_test.go
===================================================================
--- /trunk/server_test.go	(revision 619)
+++ /trunk/server_test.go	(revision 620)
@@ -17,5 +17,5 @@
 
 func createTempDB(t *testing.T) Database {
-	db, err := OpenSqliteDB("sqlite3", ":memory:")
+	db, err := OpenDB("sqlite3", ":memory:")
 	if err != nil {
 		t.Fatalf("failed to create temporary SQLite database: %v", err)
