Method _create_index_sql

django/db/backends/base/schema.py:1569–1621

Return the SQL statement to create the index for one or several fields or expressions. `sql` can be specified if the syntax differs from the standard (GIS indexes, ...).

(
        self,
        model,
        *,
        fields=None,
        name=None,
        suffix="",
        using="",
        db_tablespace=None,
        col_suffixes=(),
        sql=None,
        opclasses=(),
        condition=None,
        include=None,
        expressions=None,
    )

        )

    def _create_index_sql(
        self,
        model,
        *,
        fields=None,
        name=None,
        suffix="",
        using="",
        db_tablespace=None,
        col_suffixes=(),
        sql=None,
        opclasses=(),
        condition=None,
        include=None,
        expressions=None,
    ):
        """
        Return the SQL statement to create the index for one or several fields
        or expressions. `sql` can be specified if the syntax differs from the
        standard (GIS indexes, ...).
        """
        fields = fields or []
        expressions = expressions or []
        compiler = Query(model, alias_cols=False).get_compiler(
            connection=self.connection,
        )
        tablespace_sql = self._get_index_tablespace_sql(
            model, fields, db_tablespace=db_tablespace
        )
        columns = [field.column for field in fields]
        sql_create_index = sql or self.sql_create_index
        table = model._meta.db_table

        def create_index_name(*args, **kwargs):
            nonlocal name
            if name is None:
                name = self._create_index_name(*args, **kwargs)
            return self.quote_name(name)

        return Statement(
            sql_create_index,
            table=Table(table, self.quote_name),
            name=IndexName(table, columns, suffix, create_index_name),
            using=using,
            columns=(
                self._index_columns(table, columns, col_suffixes, opclasses)
                if columns
                else Expressions(table, expressions, compiler, self.quote_value)
            ),
            extra=tablespace_sql,
            condition=self._index_condition_sql(condition),
            include=self._index_include_sql(model, include),
        )

    def _delete_index_sql(self, model, name, sql=None):
        statement = Statement(