6.82. preparetableforcopy(integer)

Function Properties

Language: PLPGSQL

Return Type: integer

Delete all data and suppress index maintenance

declare
	p_tab_id		alias for $1;
	v_tab_oid		oid;
	v_tab_fqname	text;
begin
	-- ----
	-- Get the OID and fully qualified name for the table
	-- ---
	select	PGC.oid,
			slon_quote_brute(PGN.nspname) || '.' ||
			slon_quote_brute(PGC.relname) as tab_fqname
		into v_tab_oid, v_tab_fqname
			from sl_table T,   
				"pg_catalog".pg_class PGC, "pg_catalog".pg_namespace PGN
				where T.tab_id = p_tab_id
				and T.tab_reloid = PGC.oid
				and PGC.relnamespace = PGN.oid;
	if not found then
		raise exception 'Table with ID % not found in sl_table', p_tab_id;
	end if;

	-- ----
	-- Try using truncate to empty the table and fallback to
	-- delete on error.
	-- ----
	perform TruncateOnlyTable(v_tab_fqname);
	raise notice 'truncate of % succeeded', v_tab_fqname;
	-- ----
	-- Setting pg_class.relhasindex to false will cause copy not to
	-- maintain any indexes. At the end of the copy we will reenable
	-- them and reindex the table. This bulk creating of indexes is
	-- faster.
	-- ----
	update pg_class set relhasindex = 'f' where oid = v_tab_oid;

	return 1;
	exception when others then
		raise notice 'truncate of % failed - doing delete', v_tab_fqname;
		update pg_class set relhasindex = 'f' where oid = v_tab_oid;
		execute 'delete from only ' || slon_quote_input(v_tab_fqname);
		return 0;
end;