Fixed #22514 -- Prevented indexes on virtual fields [postgres].

    def sql_indexes_for_field(self, model, f, style):

        output = []

        if f.db_index or f.unique:

        db_type = f.db_type(connection=self.connection)

        if db_type is not None and (f.db_index or f.unique):

            qn = self.connection.ops.quote_name

            db_table = model._meta.db_table

            tablespace = f.db_tablespace or model._meta.db_tablespace

            # a second index that specifies their operator class, which is

            # needed when performing correct LIKE queries outside the

            # C locale. See #12234.

            db_type = f.db_type(connection=self.connection)

            if db_type.startswith('varchar'):

                output.append(get_index_sql('%s_%s_like' % (db_table, f.column),

                                            ' varchar_pattern_ops'))

from django.db import models

class CurrentTranslation(models.ForeignObject):

    """

    Creates virtual relation to the translation with model cache enabled.

    """

    # Avoid validation

    requires_unique_target = False

    def __init__(self, to, from_fields, to_fields, **kwargs):

        # Disable reverse relation

        kwargs['related_name'] = '+'

        # Set unique to enable model cache.

        kwargs['unique'] = True

        super(CurrentTranslation, self).__init__(to, from_fields, to_fields, **kwargs)

class ArticleTranslation(models.Model):

    article = models.ForeignKey('indexes.Article')

    language = models.CharField(max_length=10, unique=True)

    content = models.TextField()

class Article(models.Model):

    headline = models.CharField(max_length=100)

    pub_date = models.DateTimeField()

    # Add virtual relation to the ArticleTranslation model.

    translation = CurrentTranslation(ArticleTranslation, ['id'], ['article'])

    class Meta:

        index_together = [

            ["headline", "pub_date"],

        # unique=True and db_index=True should only create the varchar-specific

        # index (#19441).

        self.assertIn('("slug" varchar_pattern_ops)', index_sql[4])

    @skipUnless(connection.vendor == 'postgresql',

        "This is a postgresql-specific issue")

    def test_postgresql_virtual_relation_indexes(self):

        """Test indexes are not created for related objects"""

        index_sql = connection.creation.sql_indexes_for_model(Article, no_style())

        self.assertEqual(len(index_sql), 1)