Planner — TPC-H — TPCH-Q17

Engine Compare

Accuracy chart, rows processed ?
	Scan Scan	Seek Seek	Join Probe Join	Sort Sort	Hash Build Hash	Aggregate Agg	Distribute Dist
ClickHouse	Estimation Error Est Err Row Operations Ops 12,002,628 12M Rank		Estimation Error Est Err Row Operations Ops 206,029 206K Rank	Estimation Error Est Err Row Operations Ops 0 0 Rank	Estimation Error Est Err Row Operations Ops 6,001,413 6M Rank	Estimation Error Est Err Row Operations Ops 6,001,752 6M Rank	Estimation Error Est Err Row Operations Ops 0 Rank
Databricks	Estimation Error Est Err Row Operations Ops 12,002,826 12M Rank		Estimation Error Est Err Row Operations Ops 265,413 265K Rank	Estimation Error Est Err Row Operations Ops 0 0 Rank	Estimation Error Est Err Row Operations Ops 735 735 Rank	Estimation Error Est Err Row Operations Ops 6,401,948 6.4M Rank	Estimation Error Est Err Row Operations Ops 0 Rank
DuckDB	Estimation Error Est Err Row Operations Ops 11,995,356 12M Rank		Estimation Error Est Err Row Operations Ops 12,007,216 12M Rank	Estimation Error Est Err Row Operations Ops 0 0 Rank	Estimation Error Est Err Row Operations Ops 18,285 18K Rank	Estimation Error Est Err Row Operations Ops 6,566 6.6K Rank	Estimation Error Est Err Row Operations Ops 0 Rank
PostgreSQL	Estimation Error Est Err Row Operations Ops 6,191,386 6.2M Rank	Estimation Error Est Err Row Operations Ops 189,973 190K Rank	Estimation Error Est Err Row Operations Ops 6,001,215 6M Rank	Estimation Error Est Err Row Operations Ops 0 0 Rank	Estimation Error Est Err Row Operations Ops 537 537 Rank	Estimation Error Est Err Row Operations Ops 190,510 191K Rank	Estimation Error Est Err Row Operations Ops 0 Rank
SQL Server	Estimation Error Est Err Row Operations Ops 18,285 18K Rank		Estimation Error Est Err Row Operations Ops 6,566 6.6K Rank	Estimation Error Est Err Row Operations Ops 6,029 6K Rank	Estimation Error Est Err Row Operations Ops 12,058 12K Rank	Estimation Error Est Err Row Operations Ops 12,595 13K Rank	Estimation Error Est Err Row Operations Ops 0 Rank

Actual Query Plans

Query Plan per Engine ?
	Query Plan
ClickHouse	Estimate Actual Operator - 1 PROJECT a2 / 7. AS avg_yearly - 1 AGGREGATE SUM(l_extendedprice) AS a2 - 537 PROJECT l_extendedprice - 537 FILTER l_quantity < a8 - 6029 PROJECT a8, l_extendedprice, l_quantity - 6029 INNER JOIN HASH ON PROJECTION_386.p_partkey = PROJECTION_383.l_partkey - 6001215 │└PROJECT l_partkey, l_extendedprice, l_quantity - 6001215 │ PROJECT l_extendedprice, l_partkey, l_quantity - 6001215 │ TABLE SCAN lineitem - 198 PROJECT p_partkey, a8 - 198 PROJECT p_partkey, a8 - 198 INNER JOIN HASH ON PROJECTION_392.l_partkey = PROJECTION_389.p_partkey - 198 │└PROJECT p_partkey AS p_partkey_right - 198 │ PROJECT p_partkey - 198 │ TABLE SCAN part WHERE (p_brand = 'Brand#13') AND (p_container = 'MED CAN') - 200000 PROJECT p_partkey, a8 - 200000 PROJECT 0.2 * a9 AS a8, l_partkey AS p_partkey - 200000 AGGREGATE AVG(l_quantity) AS a9 GROUP BY HASH l_partkey - 6001215 PROJECT l_quantity, l_partkey, l_partkey - 6001215 PROJECT l_quantity, l_partkey, l_partkey - 6001215 TABLE SCAN lineitem WHERE l_partkey = l_partkey
DuckDB	Estimate Actual Operator 1 1 PROJECT avg_yearly - 1 AGGREGATE SUM(#0) 170091 537 PROJECT l_extendedprice 170091 537 FILTER CAST(l_quantity AS DOUBLE) < SUBQUERY 0 0 RIGHT SEMI INNER JOIN HASH ON p_partkey IS NOT DISTINCT FROM p_partkey 112547 198 │└AGGREGATE GROUP BY HASH #3 0 6029 │ RIGHT OUTER JOIN HASH ON p_partkey IS NOT DISTINCT FROM p_partkey - 0 │ │└SCAN EMPTY 1770559 198 │ PROJECT l_avg, p_partkey 1770559 198 │ AGGREGATE AVG(#1) GROUP BY HASH #0 3541118 6029 │ PROJECT p_partkey, l_quantity 3541118 6029 │ INNER JOIN HASH ON l_partkey = p_partkey 112547 0 │ │└SCAN MATERIALISED 6001215 5997579 │ TABLE SCAN lineitem 170091 6029 INNER JOIN HASH ON l_partkey = p_partkey 5406 198 │└TABLE SCAN part WHERE p_brand = 'Brand#13' AND p_container = 'MED CAN' 6001215 5997579 TABLE SCAN lineitem
Databricks	Estimate Actual Operator 957 0 SEQUENCE 1 1 ├─AGGREGATE SUM(l_extendedprice) 1 4 │ DISTRIBUTE GATHER 1 4 │ AGGREGATE SUM(l_extendedprice) 29800 537 │ INNER JOIN HASH ON p_partkey = l_partkey 957 198 │ │└INNER JOIN HASH ON p_partkey = li.l_partkey 957 198 │ │ │└DISTRIBUTE GATHER 6000000 198 │ │ │ TABLE SCAN part WHERE (p_brand = 'Brand#13'collate UTF8_BINARY) AND (p_container = 'MED CAN'collate UTF8_BINARY) - 200000 │ │ FILTER l_avg IS NOT NULL - 200000 │ │ AGGREGATE AVG(li.l_quantity) GROUP BY HASH li.l_partkey - 399994 │ │ DISTRIBUTE HASH ON li.l_partkey - 399994 │ │ AGGREGATE AVG(li.l_quantity) GROUP BY HASH li.l_partkey - 6001215 │ │ TABLE SCAN lineitem 29800 65413 │ DISTRIBUTE HASH ON l_partkey 193000 65413 │ FILTER 6000000 6001215 │ TABLE SCAN lineitem 957 0 └─FILTER 200000 1 DISTRIBUTE GATHER 200000 1 AGGREGATE blockbloomfilteraggregate(bloomexpr(p_partkey,p_partkey),198L,2048L) 200000 198 TABLE SCAN part WHERE (p_brand = 'Brand#13'collate UTF8_BINARY) AND (p_container = 'MED CAN'collate UTF8_BINARY)
PostgreSQL	`Estimate Actual Operator 1 1 SEQUENCE 6029 6029 ├─AGGREGATE 0.2 * AVG(l_quantity) 186899 189973 │ TABLE SEEK lineitem AS li 1 1 └─AGGREGATE SUM(l_extendedprice) / 7.0 2000 537 INNER JOIN HASH ON l_partkey = p_partkey AND (l_quantity < (SubPlan 1)) 249 198 │└TABLE SCAN part AS part WHERE (p_brand = 'Brand#13') AND (p_container = 'MED CAN') 6001215 6001215 TABLE SCAN lineitem AS lineitem`
SQL Server	Estimate Actual Operator 1 1 SEQUENCE 30545 6029 ├─MATERIALISE AS m5 30545 6029 │ GROUP BY SORT l_partkey 30545 6029 │ SORT l_partkey 30545 6029 │ INNER JOIN HASH ON l_partkey = p_partkey 1017 198 │ │└TABLE SCAN part WHERE p_container = 'MED CAN' AND p_brand = 'Brand#13' 60012 6029 │ TABLE SCAN lineitem WHERE BLOOM(l_partkey) 1 1 └─PROJECT Expr1010 / 7.0 AS Expr1011 1 1 PROJECT CASE WHEN Expr1056 = 0 THEN NULL ELSE Expr1057 END AS Expr1010 1 1 AGGREGATE COUNT() AS Expr1056, SUM(l_extendedprice) AS Expr1057 30 537 INNER JOIN LOOP ON l_quantity < 0.2 Expr1008 30 6029 │└SCAN MATERIALISED m5 1 198 PROJECT CASE WHEN Expr1054 = 0 THEN NULL ELSE Expr1055 / CONVERT_IMPLICIT(decimal(19,0),Expr1054,0) END AS Expr1008 1 198 AGGREGATE COUNT(*) AS Expr1054, SUM(l_quantity) AS Expr1055 30 6029 SCAN MATERIALISED m5

Commentary

The Correlated Subquery

Consider this expression:

l_quantity < (SELECT 0.2 * AVG(l_quantity)
                    FROM tpch.lineitem
                    WHERE l_partkey = p_partkey);

The crucial optimisation is for the optimiser to rewrite inoto this:

SELECT SUM(l_extendedprice) / 7.0 AS avg_yearly
FROM tpch.lineitem
INNER JOIN tpch.part
    ON l_partkey = p_partkey
INNER JOIN (SELECT l_partkey
                 , 0.2 * AVG(l_quantity) AS avg_quantity
            FROM tpch.lineitem
            GROUP BY l_partkey) AS decorrelated
    ON decorrelated.l_partkey = p_partkey
WHERE p_brand = 'Brand#13'
  AND p_container = 'MED CAN'
  AND l_quantity < decorrelated.avg_quantityh;

That allows much higher speed hash joins.

Agggressive pushdown

It is possible to push down the highly selective filters on p_brand and p_container into the subquery, further reducing the amount of data processed.