[TAJO-2118] The join cost calculation before join order optimization should be same with that of after optimization

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Fix Version/s: 0.13.0
• Component/s: Planner/Optimizer
• Assignee: Unassigned
• Reporter: Jihoon Son
• Created: 15/Apr/16 01:46
• Updated: 02/Dec/17 17:33

Description

See the title.
When you run the below query,

// TPC-H Q10
default> select
    c_custkey,
    c_name,
    sum(l_extendedprice * (1 - l_discount)) as revenue,
    c_acctbal,
    n_name,
    c_address,
    c_phone,
    c_comment
from
    customer as c
    join nation as n
        on c.c_nationkey = n.n_nationkey
    join orders as o
        on c.c_custkey = o.o_custkey and o.o_orderdate >= '1993-10-01'::date and o.o_orderdate < '1994-01-01'::date
    join lineitem as l
        on l.l_orderkey = o.o_orderkey and l.l_returnflag = 'R'
group by
    c_custkey, c_name, c_acctbal, c_phone, n_name, c_address, c_comment
order by
    revenue desc

you can find the below log. The cost of before optimization is smaller than that after optimization. This is because the different cost calculation methods are used for each unoptimized and optimized plans.

...
Query Block Graph
-----------------------------
|-#ROOT
-----------------------------
Optimization Log:
[#ROOT]
        > Non-optimized join order: (((default.customer200 ⋈θ default.nation200) ⋈θ default.orders200) ⋈θ default.lineitem200) (cost: 3.19186301858328E32)
        > Optimized join order    : ((default.lineitem200 ⋈θ default.orders200) ⋈θ (default.customer200 ⋈θ default.nation200)) (cost: 1.0772537685263547E33)
-----------------------------
...