-- Tags: no-parallel, no-fasttest insert into function file(data_02723.csv) select number from numbers(5) settings engine_file_truncate_on_insert=1; set max_threads=2; -- { echoOn } set parallelize_output_from_storages=1; select startsWith(trimLeft(explain),'Resize') as resize from (explain pipeline select * from file(data_02723.csv)) where resize; -- no Resize in pipeline set parallelize_output_from_storages=0; select startsWith(trimLeft(explain),'Resize') as resize from (explain pipeline select * from file(data_02723.csv)) where resize; -- Data from URL source is immediately resized to max_treads streams, before any ExpressionTransform. set parallelize_output_from_storages=1; select match(arrayStringConcat(groupArray(explain), ''), '.*Resize 1 → 2 *URL 0 → 1 *$') from (explain pipeline select x, count() from url('https://example.com', Parquet, 'x Int64') group by x order by count() limit 10);