Method _columns_query

lib/sqlalchemy/dialects/postgresql/base.py:4129–4292

(self, schema, has_filter_names, scope, kind)

    @lru_cache()
    def _columns_query(self, schema, has_filter_names, scope, kind):
        class="cm"># NOTE: the query with the default and identity options scalar
        class="cm"># subquery is faster than trying to use outer joins for them
        generated = (
            pg_catalog.pg_attribute.c.attgenerated.label(class="st">"generated")
            if self.server_version_info >= (12,)
            else sql.null().label(class="st">"generated")
        )
        if self.server_version_info >= (10,):
            class="cm"># join lateral performs worse (~2x slower) than a scalar_subquery
            class="cm"># also the subquery can be run only if the column is an identity
            identity = sql.case(
                (  class="cm"># attidentity != class="st">'' is required or it will reflect also
                    class="cm"># serial columns as identity.
                    pg_catalog.pg_attribute.c.attidentity != class="st">"",
                    select(
                        sql.func.json_build_object(
                            class="st">"always",
                            pg_catalog.pg_attribute.c.attidentity == class="st">"a",
                            class="st">"start",
                            pg_catalog.pg_sequence.c.seqstart,
                            class="st">"increment",
                            pg_catalog.pg_sequence.c.seqincrement,
                            class="st">"minvalue",
                            pg_catalog.pg_sequence.c.seqmin,
                            class="st">"maxvalue",
                            pg_catalog.pg_sequence.c.seqmax,
                            class="st">"cache",
                            pg_catalog.pg_sequence.c.seqcache,
                            class="st">"cycle",
                            pg_catalog.pg_sequence.c.seqcycle,
                            type_=sqltypes.JSON(),
                        )
                    )
                    .select_from(pg_catalog.pg_sequence)
                    .where(
                        class="cm"># not needed but pg seems to like it
                        pg_catalog.pg_attribute.c.attidentity != class="st">"",
                        pg_catalog.pg_sequence.c.seqrelid
                        == sql.cast(
                            sql.cast(
                                pg_catalog.pg_get_serial_sequence(
                                    sql.cast(
                                        sql.cast(
                                            pg_catalog.pg_attribute.c.attrelid,
                                            REGCLASS,
                                        ),
                                        TEXT,
                                    ),
                                    pg_catalog.pg_attribute.c.attname,
                                ),
                                REGCLASS,
                            ),
                            OID,
                        ),
                    )
                    .correlate(pg_catalog.pg_attribute)
                    .scalar_subquery(),