Add optimizer rule to replace inlist with or chain for small list #799
Description
Is your feature request related to a problem or challenge? Please describe what you are trying to do.
For TCP-H query 12, according to the profier about 16% (including IO) of the time is spent in the code in InListExpr.
The full query is:
select
l_shipmode,
sum(case
when o_orderpriority = '1-URGENT'
or o_orderpriority = '2-HIGH'
then 1
else 0
end) as high_line_count,
sum(case
when o_orderpriority <> '1-URGENT'
and o_orderpriority <> '2-HIGH'
then 1
else 0
end) as low_line_count
from
lineitem
join
orders
on
l_orderkey = o_orderkey
where
l_shipmode in ('MAIL', 'SHIP')
and l_commitdate < l_receiptdate
and l_shipdate < l_commitdate
and l_receiptdate >= date '1994-01-01'
and l_receiptdate < date '1995-01-01'
group by
l_shipmode
order by
l_shipmode;
We can replace:
x in (a, b)
with the equivalent of
(x==a or x==b)
for "small enough" lists for some performance improvement.
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