/
postgres.go
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/
postgres.go
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// Copyright 2019-present Facebook Inc. All rights reserved.
// This source code is licensed under the Apache 2.0 license found
// in the LICENSE file in the root directory of this source tree.
package schema
import (
"context"
"fmt"
"strings"
"github.com/facebook/ent/dialect"
"github.com/facebook/ent/dialect/sql"
"github.com/facebook/ent/schema/field"
)
// Postgres is a postgres migration driver.
type Postgres struct {
dialect.Driver
version string
}
// init loads the Postgres version from the database for later use in the migration process.
// It returns an error if the server version is lower than v10.
func (d *Postgres) init(ctx context.Context, tx dialect.Tx) error {
rows := &sql.Rows{}
if err := tx.Query(ctx, "SHOW server_version_num", []interface{}{}, rows); err != nil {
return fmt.Errorf("querying server version %v", err)
}
defer rows.Close()
if !rows.Next() {
if err := rows.Err(); err != nil {
return err
}
return fmt.Errorf("server_version_num variable was not found")
}
var version string
if err := rows.Scan(&version); err != nil {
return fmt.Errorf("scanning version: %v", err)
}
if len(version) < 6 {
return fmt.Errorf("malformed version: %s", version)
}
d.version = fmt.Sprintf("%s.%s.%s", version[:2], version[2:4], version[4:])
if compareVersions(d.version, "10.0.0") == -1 {
return fmt.Errorf("unsupported postgres version: %s", d.version)
}
return nil
}
// tableExist checks if a table exists in the database and current schema.
func (d *Postgres) tableExist(ctx context.Context, tx dialect.Tx, name string) (bool, error) {
query, args := sql.Dialect(dialect.Postgres).
Select(sql.Count("*")).From(sql.Table("INFORMATION_SCHEMA.TABLES").Unquote()).
Where(sql.And(
sql.EQ("table_schema", sql.Raw("CURRENT_SCHEMA()")),
sql.EQ("table_name", name),
)).Query()
return exist(ctx, tx, query, args...)
}
// tableExist checks if a foreign-key exists in the current schema.
func (d *Postgres) fkExist(ctx context.Context, tx dialect.Tx, name string) (bool, error) {
query, args := sql.Dialect(dialect.Postgres).
Select(sql.Count("*")).From(sql.Table("INFORMATION_SCHEMA.TABLE_CONSTRAINTS").Unquote()).
Where(sql.And(
sql.EQ("table_schema", sql.Raw("CURRENT_SCHEMA()")),
sql.EQ("constraint_type", "FOREIGN KEY"),
sql.EQ("constraint_name", name),
)).Query()
return exist(ctx, tx, query, args...)
}
// setRange sets restart the identity column to the given offset. Used by the universal-id option.
func (d *Postgres) setRange(ctx context.Context, tx dialect.Tx, t *Table, value int) error {
if value == 0 {
value = 1 // RESTART value cannot be < 1.
}
pk := "id"
if len(t.PrimaryKey) == 1 {
pk = t.PrimaryKey[0].Name
}
return tx.Exec(ctx, fmt.Sprintf("ALTER TABLE %s ALTER COLUMN %s RESTART WITH %d", t.Name, pk, value), []interface{}{}, nil)
}
// table loads the current table description from the database.
func (d *Postgres) table(ctx context.Context, tx dialect.Tx, name string) (*Table, error) {
rows := &sql.Rows{}
query, args := sql.Dialect(dialect.Postgres).
Select("column_name", "data_type", "is_nullable", "column_default").
From(sql.Table("INFORMATION_SCHEMA.COLUMNS").Unquote()).
Where(sql.And(
sql.EQ("table_schema", sql.Raw("CURRENT_SCHEMA()")),
sql.EQ("table_name", name),
)).Query()
if err := tx.Query(ctx, query, args, rows); err != nil {
return nil, fmt.Errorf("postgres: reading table description %v", err)
}
// Call `Close` in cases of failures (`Close` is idempotent).
defer rows.Close()
t := NewTable(name)
for rows.Next() {
c := &Column{}
if err := d.scanColumn(c, rows); err != nil {
return nil, err
}
t.AddColumn(c)
}
if err := rows.Err(); err != nil {
return nil, err
}
if err := rows.Close(); err != nil {
return nil, fmt.Errorf("closing rows %v", err)
}
idxs, err := d.indexes(ctx, tx, name)
if err != nil {
return nil, err
}
// Populate the index information to the table and its columns.
// We do it manually, because PK and uniqueness information does
// not exist when querying the INFORMATION_SCHEMA.COLUMNS above.
for _, idx := range idxs {
switch {
case idx.primary:
for _, name := range idx.columns {
c, ok := t.column(name)
if !ok {
return nil, fmt.Errorf("index %q column %q was not found in table %q", idx.Name, name, t.Name)
}
c.Key = PrimaryKey
t.PrimaryKey = append(t.PrimaryKey, c)
}
case idx.Unique && len(idx.columns) == 1:
name := idx.columns[0]
c, ok := t.column(name)
if !ok {
return nil, fmt.Errorf("index %q column %q was not found in table %q", idx.Name, name, t.Name)
}
c.Key = UniqueKey
c.Unique = true
fallthrough
default:
t.addIndex(idx)
}
}
return t, nil
}
// indexesQuery holds a query format for retrieving
// table indexes of the current schema.
const indexesQuery = `
SELECT i.relname AS index_name,
a.attname AS column_name,
idx.indisprimary AS primary,
idx.indisunique AS unique,
array_position(idx.indkey, a.attnum) as seq_in_index
FROM pg_class t,
pg_class i,
pg_index idx,
pg_attribute a,
pg_namespace n
WHERE t.oid = idx.indrelid
AND i.oid = idx.indexrelid
AND n.oid = t.relnamespace
AND a.attrelid = t.oid
AND a.attnum = ANY(idx.indkey)
AND t.relkind = 'r'
AND n.nspname = CURRENT_SCHEMA()
AND t.relname = '%s'
ORDER BY index_name, seq_in_index;
`
func (d *Postgres) indexes(ctx context.Context, tx dialect.Tx, table string) (Indexes, error) {
rows := &sql.Rows{}
if err := tx.Query(ctx, fmt.Sprintf(indexesQuery, table), []interface{}{}, rows); err != nil {
return nil, fmt.Errorf("querying indexes for table %s: %v", table, err)
}
defer rows.Close()
var (
idxs Indexes
names = make(map[string]*Index)
)
for rows.Next() {
var (
seqindex int
name, column string
unique, primary bool
)
if err := rows.Scan(&name, &column, &primary, &unique, &seqindex); err != nil {
return nil, fmt.Errorf("scanning index description: %v", err)
}
// If the index is prefixed with the table, it may was added by
// `addIndex` and it should be trimmed. But, since entc prefixes
// all indexes with schema-type, for uncountable types (like, media
// or equipment) this isn't correct, and we fallback for the real-name.
short := strings.TrimPrefix(name, table+"_")
idx, ok := names[short]
if !ok {
idx = &Index{Name: short, Unique: unique, primary: primary, realname: name}
idxs = append(idxs, idx)
names[short] = idx
}
idx.columns = append(idx.columns, column)
}
if err := rows.Err(); err != nil {
return nil, err
}
return idxs, nil
}
// maxCharSize defines the maximum size of limited character types in Postgres (10 MB).
const maxCharSize = 10 << 20
// scanColumn scans the information a column from column description.
func (d *Postgres) scanColumn(c *Column, rows *sql.Rows) error {
var (
nullable sql.NullString
defaults sql.NullString
)
if err := rows.Scan(&c.Name, &c.typ, &nullable, &defaults); err != nil {
return fmt.Errorf("scanning column description: %v", err)
}
if nullable.Valid {
c.Nullable = nullable.String == "YES"
}
switch c.typ {
case "boolean":
c.Type = field.TypeBool
case "smallint":
c.Type = field.TypeInt16
case "integer":
c.Type = field.TypeInt32
case "bigint":
c.Type = field.TypeInt64
case "real":
c.Type = field.TypeFloat32
case "numeric", "decimal", "double precision":
c.Type = field.TypeFloat64
case "text":
c.Type = field.TypeString
c.Size = maxCharSize + 1
case "character", "character varying":
c.Type = field.TypeString
case "date", "time", "timestamp", "timestamp with time zone":
c.Type = field.TypeTime
case "bytea":
c.Type = field.TypeBytes
case "jsonb":
c.Type = field.TypeJSON
case "uuid":
c.Type = field.TypeUUID
}
switch {
case !defaults.Valid || c.Type == field.TypeTime:
return nil
case strings.Contains(defaults.String, "::"):
parts := strings.Split(defaults.String, "::")
defaults.String = strings.Trim(parts[0], "'")
fallthrough
default:
return c.ScanDefault(defaults.String)
}
}
// tBuilder returns the TableBuilder for the given table.
func (d *Postgres) tBuilder(t *Table) *sql.TableBuilder {
b := sql.Dialect(dialect.Postgres).
CreateTable(t.Name).IfNotExists()
for _, c := range t.Columns {
b.Column(d.addColumn(c))
}
for _, pk := range t.PrimaryKey {
b.PrimaryKey(pk.Name)
}
return b
}
// cType returns the PostgreSQL string type for this column.
func (d *Postgres) cType(c *Column) (t string) {
if c.SchemaType != nil && c.SchemaType[dialect.Postgres] != "" {
return c.SchemaType[dialect.Postgres]
}
switch c.Type {
case field.TypeBool:
t = "boolean"
case field.TypeUint8, field.TypeInt8, field.TypeInt16, field.TypeUint16:
t = "smallint"
case field.TypeInt32, field.TypeUint32:
t = "int"
case field.TypeInt, field.TypeUint, field.TypeInt64, field.TypeUint64:
t = "bigint"
case field.TypeFloat32:
t = c.scanTypeOr("real")
case field.TypeFloat64:
t = c.scanTypeOr("double precision")
case field.TypeBytes:
t = "bytea"
case field.TypeJSON:
t = "jsonb"
case field.TypeUUID:
t = "uuid"
case field.TypeString:
t = "varchar"
if c.Size > maxCharSize {
t = "text"
}
case field.TypeTime:
t = c.scanTypeOr("timestamp with time zone")
case field.TypeEnum:
// Currently, the support for enums is weak (application level only.
// like SQLite). Dialect needs to create and maintain its enum type.
t = "varchar"
default:
panic(fmt.Sprintf("unsupported type %q for column %q", c.Type.String(), c.Name))
}
return t
}
// addColumn returns the ColumnBuilder for adding the given column to a table.
func (d *Postgres) addColumn(c *Column) *sql.ColumnBuilder {
b := sql.Dialect(dialect.Postgres).
Column(c.Name).Type(d.cType(c)).Attr(c.Attr)
c.unique(b)
if c.Increment {
b.Attr("GENERATED BY DEFAULT AS IDENTITY")
}
c.nullable(b)
c.defaultValue(b)
return b
}
// alterColumn returns list of ColumnBuilder for applying in order to alter a column.
func (d *Postgres) alterColumn(c *Column) (ops []*sql.ColumnBuilder) {
b := sql.Dialect(dialect.Postgres)
ops = append(ops, b.Column(c.Name).Type(d.cType(c)))
if c.Nullable {
ops = append(ops, b.Column(c.Name).Attr("DROP NOT NULL"))
} else {
ops = append(ops, b.Column(c.Name).Attr("SET NOT NULL"))
}
return ops
}
// hasUniqueName reports if the index has a unique name in the schema.
func hasUniqueName(i *Index) bool {
name := i.Name
// The "_key" suffix is added by Postgres for implicit indexes.
if strings.HasSuffix(name, "_key") {
name = strings.TrimSuffix(name, "_key")
}
suffix := strings.Join(i.columnNames(), "_")
if !strings.HasSuffix(name, suffix) {
return true // Assume it has a custom storage-key.
}
// The codegen prefixes by default indexes with the type name.
// For example, an index "users"("name"), will named as "user_name".
return name != suffix
}
// addIndex returns the querying for adding an index to PostgreSQL.
func (d *Postgres) addIndex(i *Index, table string) *sql.IndexBuilder {
name := i.Name
if !hasUniqueName(i) {
// Since index name should be unique in pg_class for schema,
// we prefix it with the table name and remove on read.
name = fmt.Sprintf("%s_%s", table, i.Name)
}
idx := sql.Dialect(dialect.Postgres).
CreateIndex(name).Table(table)
if i.Unique {
idx.Unique()
}
for _, c := range i.Columns {
idx.Column(c.Name)
}
return idx
}
// dropIndex drops a Postgres index.
func (d *Postgres) dropIndex(ctx context.Context, tx dialect.Tx, idx *Index, table string) error {
name := idx.Name
build := sql.Dialect(dialect.Postgres)
if prefix := table + "_"; !strings.HasPrefix(name, prefix) && !hasUniqueName(idx) {
name = prefix + name
}
query, args := sql.Dialect(dialect.Postgres).
Select(sql.Count("*")).From(sql.Table("INFORMATION_SCHEMA.TABLE_CONSTRAINTS").Unquote()).
Where(sql.And(
sql.EQ("table_schema", sql.Raw("CURRENT_SCHEMA()")),
sql.EQ("constraint_type", "UNIQUE"),
sql.EQ("constraint_name", name),
)).
Query()
exists, err := exist(ctx, tx, query, args...)
if err != nil {
return err
}
query, args = build.DropIndex(name).Query()
if exists {
query, args = build.AlterTable(table).DropConstraint(name).Query()
}
return tx.Exec(ctx, query, args, nil)
}
// isImplicitIndex reports if the index was created implicitly for the unique column.
func (d *Postgres) isImplicitIndex(idx *Index, col *Column) bool {
return strings.TrimSuffix(idx.Name, "_key") == col.Name && col.Unique
}
// renameColumn returns the statement for renaming a column.
func (d *Postgres) renameColumn(t *Table, old, new *Column) sql.Querier {
return sql.Dialect(dialect.Postgres).
AlterTable(t.Name).
RenameColumn(old.Name, new.Name)
}
// renameIndex returns the statement for renaming an index.
func (d *Postgres) renameIndex(t *Table, old, new *Index) sql.Querier {
if sfx := "_key"; strings.HasSuffix(old.Name, sfx) && !strings.HasSuffix(new.Name, sfx) {
new.Name += sfx
}
if pfx := t.Name + "_"; strings.HasPrefix(old.realname, pfx) && !strings.HasPrefix(new.Name, pfx) {
new.Name = pfx + new.Name
}
return sql.Dialect(dialect.Postgres).AlterIndex(old.realname).Rename(new.Name)
}
// tableSchema returns the query for getting the table schema.
func (d *Postgres) tableSchema() sql.Querier {
return sql.Raw("(CURRENT_SCHEMA())")
}
// alterColumns returns the queries for applying the columns change-set.
func (d *Postgres) alterColumns(table string, add, modify, drop []*Column) sql.Queries {
b := sql.Dialect(dialect.Postgres).AlterTable(table)
for _, c := range add {
b.AddColumn(d.addColumn(c))
}
for _, c := range modify {
b.ModifyColumns(d.alterColumn(c)...)
}
for _, c := range drop {
b.DropColumn(sql.Dialect(dialect.Postgres).Column(c.Name))
}
if len(b.Queries) == 0 {
return nil
}
return sql.Queries{b}
}