Merge pull request #127 from vporoshok/master

Add support for multi-schema migrations in Postgres

Author: dhui

database/postgres/postgres.go

@@ -35,6 +35,7 @@ var (
 type Config struct {
 	MigrationsTable string
 	DatabaseName    string
+	SchemaName      string
 }
 
 type Postgres struct {
@@ -68,6 +69,18 @@ func WithInstance(instance *sql.DB, config *Config) (database.Driver, error) {
 
 	config.DatabaseName = databaseName
 
+	query = `SELECT CURRENT_SCHEMA()`
+	var schemaName string
+	if err := instance.QueryRow(query).Scan(&schemaName); err != nil {
+		return nil, &database.Error{OrigErr: err, Query: []byte(query)}
+	}
+
+	if len(schemaName) == 0 {
+		return nil, ErrNoSchema
+	}
+
+	config.SchemaName = schemaName
+
 	if len(config.MigrationsTable) == 0 {
 		config.MigrationsTable = DefaultMigrationsTable
 	}
@@ -133,7 +146,7 @@ func (p *Postgres) Lock() error {
 		return database.ErrLocked
 	}
 
-	aid, err := database.GenerateAdvisoryLockId(p.config.DatabaseName)
+	aid, err := database.GenerateAdvisoryLockId(p.config.DatabaseName, p.config.SchemaName)
 	if err != nil {
 		return err
 	}

database/postgres/postgres_test.go

@@ -178,6 +178,56 @@ func TestWithSchema(t *testing.T) {
 		})
 }
 
+func TestParallelSchema(t *testing.T) {
+	mt.ParallelTest(t, versions, isReady,
+		func(t *testing.T, i mt.Instance) {
+			p := &Postgres{}
+			addr := pgConnectionString(i.Host(), i.Port())
+			d, err := p.Open(addr)
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+			defer d.Close()
+
+			// create foo and bar schemas
+			if err := d.Run(bytes.NewReader([]byte("CREATE SCHEMA foo AUTHORIZATION postgres"))); err != nil {
+				t.Fatal(err)
+			}
+			if err := d.Run(bytes.NewReader([]byte("CREATE SCHEMA bar AUTHORIZATION postgres"))); err != nil {
+				t.Fatal(err)
+			}
+
+			// re-connect using that schemas
+			dfoo, err := p.Open(fmt.Sprintf("postgres://postgres@%v:%v/postgres?sslmode=disable&search_path=foo", i.Host(), i.Port()))
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+			defer dfoo.Close()
+
+			dbar, err := p.Open(fmt.Sprintf("postgres://postgres@%v:%v/postgres?sslmode=disable&search_path=bar", i.Host(), i.Port()))
+			if err != nil {
+				t.Fatalf("%v", err)
+			}
+			defer dbar.Close()
+
+			if err := dfoo.Lock(); err != nil {
+				t.Fatal(err)
+			}
+
+			if err := dbar.Lock(); err != nil {
+				t.Fatal(err)
+			}
+
+			if err := dbar.Unlock(); err != nil {
+				t.Fatal(err)
+			}
+
+			if err := dfoo.Unlock(); err != nil {
+				t.Fatal(err)
+			}
+		})
+}
+
 func TestWithInstance(t *testing.T) {
 
 }

database/util.go

@@ -3,12 +3,16 @@ package database
 import (
 	"fmt"
 	"hash/crc32"
+	"strings"
 )
 
 const advisoryLockIdSalt uint = 1486364155
 
 // GenerateAdvisoryLockId inspired by rails migrations, see https://goo.gl/8o9bCT
-func GenerateAdvisoryLockId(databaseName string) (string, error) {
+func GenerateAdvisoryLockId(databaseName string, additionalNames ...string) (string, error) {
+	if len(additionalNames) > 0 {
+		databaseName = strings.Join(append(additionalNames, databaseName), "\x00")
+	}
 	sum := crc32.ChecksumIEEE([]byte(databaseName))
 	sum = sum * uint32(advisoryLockIdSalt)
 	return fmt.Sprintf("%v", sum), nil

database/util_test.go

@@ -7,14 +7,33 @@ import (
 func TestGenerateAdvisoryLockId(t *testing.T) {
 	testcases := []struct {
 		dbname     string
+		additional []string
 		expectedID string // empty string signifies that an error is expected
 	}{
-		{dbname: "database_name", expectedID: "1764327054"},
+		{
+			dbname:     "database_name",
+			expectedID: "1764327054",
+		},
+		{
+			dbname:     "database_name",
+			additional: []string{"schema_name_1"},
+			expectedID: "2453313553",
+		},
+		{
+			dbname:     "database_name",
+			additional: []string{"schema_name_2"},
+			expectedID: "235207038",
+		},
+		{
+			dbname:     "database_name",
+			additional: []string{"schema_name_1", "schema_name_2"},
+			expectedID: "3743845847",
+		},
 	}
 
 	for _, tc := range testcases {
 		t.Run(tc.dbname, func(t *testing.T) {
-			if id, err := GenerateAdvisoryLockId("database_name"); err == nil {
+			if id, err := GenerateAdvisoryLockId(tc.dbname, tc.additional...); err == nil {
 				if id != tc.expectedID {
 					t.Error("Generated incorrect ID:", id, "!=", tc.expectedID)
 				}