util_internal_table_ddl.sql

-- This file and its contents are licensed under the Apache License 2.0.
-- Please see the included NOTICE for copyright information and
-- LICENSE-APACHE for a copy of the license.

-- This file contains functions associated with creating new
-- hypertables.

-- Outputs the create_hypertable command to recreate the given hypertable.
--
-- This is currently used internally for our single hypertable backup tool
-- so that it knows how to restore the hypertable without user intervention.
--
-- It only works for hypertables with up to 2 dimensions.
CREATE OR REPLACE FUNCTION _timescaledb_functions.get_create_command(
    table_name NAME
)
    RETURNS TEXT LANGUAGE PLPGSQL VOLATILE AS
$BODY$
DECLARE
    h_id             INTEGER;
    schema_name      NAME;
    time_column      NAME;
    time_interval    BIGINT;
    space_column     NAME;
    space_partitions INTEGER;
    dimension_cnt    INTEGER;
    dimension_row    record;
    ret              TEXT;
BEGIN
    SELECT h.id, h.schema_name
    FROM _timescaledb_catalog.hypertable AS h
    WHERE h.table_name = get_create_command.table_name
    INTO h_id, schema_name;

    IF h_id IS NULL THEN
        RAISE EXCEPTION 'hypertable "%" not found', table_name
        USING ERRCODE = 'TS101';
    END IF;

    SELECT COUNT(*)
    FROM _timescaledb_catalog.dimension d
    WHERE d.hypertable_id = h_id
    INTO STRICT dimension_cnt;

    IF dimension_cnt > 2 THEN
        RAISE EXCEPTION 'get_create_command only supports hypertables with up to 2 dimensions'
        USING ERRCODE = 'TS101';
    END IF;

    FOR dimension_row IN
        SELECT *
        FROM _timescaledb_catalog.dimension d
        WHERE d.hypertable_id = h_id
        LOOP
        IF dimension_row.interval_length IS NOT NULL THEN
            time_column := dimension_row.column_name;
            time_interval := dimension_row.interval_length;
        ELSIF dimension_row.num_slices IS NOT NULL THEN
            space_column := dimension_row.column_name;
            space_partitions := dimension_row.num_slices;
        END IF;
    END LOOP;

    ret := format($$SELECT create_hypertable('%I.%I', '%s'$$, schema_name, table_name, time_column);
    IF space_column IS NOT NULL THEN
        ret := ret || format($$, '%I', %s$$, space_column, space_partitions);
    END IF;
    ret := ret || format($$, chunk_time_interval => %s, create_default_indexes=>FALSE);$$, time_interval);

    RETURN ret;
END
$BODY$ SET search_path TO pg_catalog, pg_temp;

-- Raise an error if a logical replication slot still has pending changes
-- against the given relation. Intended to be called before recreating a
-- TimescaleDB user catalog table during an extension upgrade: once the old
-- relation is dropped, a slot that still needs to decode changes to it can no
-- longer be decoded ("could not find pg_class entry"), so the slot must be
-- advanced or dropped first.
CREATE OR REPLACE FUNCTION _timescaledb_functions.ensure_catalog_replication(
    rel REGCLASS
) RETURNS VOID AS '@MODULE_PATHNAME@', 'ts_ensure_catalog_replication' LANGUAGE C VOLATILE STRICT;