feat: add smart auto aggregate selector

lib/timeseries/hoarder/sql/aggregate_selectors.sql

@@ -0,0 +1,127 @@
+CREATE OR REPLACE FUNCTION get_hypertable_caggs(target_table_name TEXT, target_table_schema TEXT DEFAULT 'public')
+RETURNS TABLE (table_name TEXT, table_schema TEXT)
+LANGUAGE SQL
+STABLE
+AS $BODY$
+WITH RECURSIVE cagg_tables as (
+    select vcu1.view_schema, vcu1.view_name
+    from information_schema.view_column_usage vcu1
+    where vcu1.table_schema = target_table_schema
+      and vcu1.table_name = target_table_name
+	
+    union all
+    
+	select vcu2.view_schema, vcu2.view_name
+    from information_schema.view_column_usage vcu2, cagg_tables t
+    where t.view_schema = vcu2.table_schema
+      and t.view_name = vcu2.table_name
+)
+SELECT DISTINCT view_name AS table_name,
+	view_schema AS table_schema	
+	FROM cagg_tables
+	WHERE view_schema != '_timescaledb_internal'
+$BODY$;
+
+CREATE OR REPLACE FUNCTION get_cagg_interval(table_name TEXT, table_schema TEXT DEFAULT 'public')
+RETURNS INTERVAL
+LANGUAGE SQL
+STABLE
+AS $BODY$
+SELECT bucket_width * INTERVAL '1us'
+FROM _timescaledb_catalog.continuous_agg 
+WHERE table_schema = user_view_schema AND table_name = user_view_name
+LIMIT 1
+$BODY$;
+
+CREATE OR REPLACE FUNCTION get_jsonb_table_columns(in_table_name TEXT, in_table_schema TEXT DEFAULT 'public')
+RETURNS JSONB
+LANGUAGE SQL
+STABLE
+AS $BODY$
+SELECT jsonb_agg(column_name)
+FROM information_schema.columns
+WHERE table_name = in_table_name AND table_schema = in_table_schema
+$BODY$;
+
+CREATE OR REPLACE FUNCTION aggregate_choice(hypertable TEXT, selection_interval INTERVAL, aggregate_types JSONB, hypertable_schema TEXT DEFAULT 'public')
+RETURNS JSONB
+LANGUAGE SQL
+STABLE
+AS $BODY$
+WITH available_tables AS (
+	SELECT table_name, table_schema, get_cagg_interval(table_name, table_schema) AS table_interval, get_jsonb_table_columns(table_name, table_schema) AS table_columns
+	FROM get_hypertable_caggs(hypertable, hypertable_schema)
+	
+	UNION ALL
+	
+	SELECT hypertable AS table_name, hypertable_schema AS table_schema, INTERVAL '0s' AS table_interval, get_jsonb_table_columns(hypertable, hypertable_schema) AS table_columns
+), available_aggregates AS (
+	SELECT *
+	FROM jsonb_array_elements(aggregate_types) AS j (aggregate_option)
+)
+SELECT jsonb_build_object('table_name', table_name, 
+'table_schema', table_schema,
+'table_interval', table_interval,
+'interval_matched', table_interval = selection_interval) || aggregate_option
+FROM available_tables, available_aggregates, (VALUES(1),(-1)) AS swp(interval_swap)
+WHERE table_columns@>(aggregate_option->'with_columns') AND (table_interval*interval_swap) <= selection_interval
+ORDER BY (table_interval*interval_swap) DESC
+LIMIT 1
+$BODY$;
+
+CREATE OR REPLACE FUNCTION ts_autoagg(hypertable TEXT, data_interval INTERVAL,
+	aggregate_choices JSONB, 
+	groupby_clause TEXT, filter_query TEXT,
+	hypertable_schema TEXT DEFAULT 'public',
+	time_column TEXT DEFAULT 'time')
+RETURNS SETOF RECORD
+LANGUAGE plpgsql
+STABLE
+AS $BODY$
+DECLARE
+	selected_parameters jsonb;
+
+	aggregator_column TEXT;
+BEGIN
+	SELECT aggregate_choice(hypertable, data_interval, aggregate_choices, hypertable_schema) INTO selected_parameters;
+
+	IF NOT FOUND THEN
+		RAISE EXCEPTION 'No fitting hypertable or aggregate found for given columns and table %!', hypertable;
+		RETURN;
+	END IF;
+
+	RAISE NOTICE 'Using parameter set %', selected_parameters;
+
+	aggregator_column := selected_parameters->>'aggregate';
+
+	IF aggregator_column IS NULL THEN
+		RAISE EXCEPTION 'No aggregator given!' USING HINT = 'Supply a "aggregate" field in the JSON aggregate object'
+		RETURN;
+	END IF;
+
+	RETURN QUERY EXECUTE format($qry$
+		SELECT time_bucket($1, %I) AS time, %s, %s
+		FROM %I.%I
+		%s
+		GROUP BY 1, %s
+		ORDER BY 1
+	$qry$, time_column, groupby_clause, aggregator_column,
+		selected_parameters->>'table_schema', selected_parameters->>'table_name',
+		filter_query,
+		groupby_clause) USING data_interval;
+END;
+$BODY$;
+
+
+SELECT *
+FROM ts_autoagg('cpu', INTERVAL '9m', $aggs$
+	[
+		{"with_columns":["values"], "aggregate":"avg(value) AS value"},
+		{"with_columns":["value_avg"], "aggregate":"avg(value_avg) AS value"}
+	]
+$aggs$,
+'tags',
+$$
+	WHERE time BETWEEN NOW()-INTERVAL'30d' AND NOW()-INTERVAL'10d'
+	AND tags@>'{"metric":"usage_idle","cpu":"cpu-total"}'
+$$) AS (time TIMESTAMP, tags JSONB, value DOUBLE PRECISION);