Hi, On 2018-05-25 09:26:47 +0300, Heikki Linnakangas wrote: > Cool stuff!
Thanks! > On 25/05/18 06:35, Andres Freund wrote: > > For example, this converts this converts TPCH's Q01: > > > > tpch_1[26142][1]=# SET client_min_messages ='log'; > > tpch_1[26142][1]=# SELECT > > l_returnflag, > > l_linestatus, > > sum(l_quantity) AS sum_qty, > > sum(l_extendedprice) AS sum_base_price, > > sum(l_extendedprice * (1 - l_discount)) AS sum_disc_price, > > sum(l_extendedprice * (1 - l_discount) * (1 + l_tax)) AS sum_charge, > > avg(l_quantity) AS avg_qty, > > avg(l_extendedprice) AS avg_price, > > avg(l_discount) AS avg_disc, > > count(*) AS count_order > > FROM > > lineitem > > WHERE > > l_shipdate <= date '1998-12-01' - interval '74 days' > > GROUP BY > > l_returnflag, > > l_linestatus > > ORDER BY > > l_returnflag, > > l_linestatus; > > LOG: 00000: pp: > > > > into: > > > > 0: init_sort > > 1: seqscan_first > > 2: seqscan [j empty 5] > s0 > > 3: qual [j fail 2] < scan s0 > > 4: hashagg_tuple [j 2] < s0 > > 5: drain_hashagg [j empty 7] > s1 > > 6: sort_tuple [j 5] < s1 > > 7: sort > > 8: drain_sort [j empty 10] > s2 > > 9: return < s2 [next 8] > > 10: done > > > > where s are numbered slots, j are, potentially conditional, jumps. This > > works for a number of plans, but there's several where we currently bail > > out. > > How is this going to look like in EXPLAIN, even without ANALYZE? Would it > still show a tree plan, or this linear program, or both? I think we're going to have to continue showing the tree plan. I think the linear version is far too hard to understand for anything nontrivial. I'd definitely continue to expect the Plan tree to be tree shaped, and I'm currently not forseeing to entirely get rid of PlanState trees (albeit with smaller nodes, and potentially with relative rather than absolute pointers to children). So I don't really forsee a huge problem continuing to display a tree shaped plan. I'd expect there'd be an EXPLAIN option to show the linear plan, but that that'd not be used frequently outside of development work. Greetings, Andres Freund
