Taeyun Kim created PHOENIX-1997:
-----------------------------------
Summary: Join optimization: Apply one table's where condition to
the others
Key: PHOENIX-1997
URL: https://issues.apache.org/jira/browse/PHOENIX-1997
Project: Phoenix
Issue Type: Improvement
Reporter: Taeyun Kim
Priority: Minor
Joined tables are as follows:
create table table_a
(
time_id integer not null,
depth tinyint not null,
id0 integer not null,
id1 integer not null,
id2 integer not null,
id3 integer not null,
id integer not null,
record_type smallint not null,
c varbinary
constraint pk primary key(time_id, depth, id0, id1, id2, id3, id,
record_type)
)
salt_buckets=4,
compression='SNAPPY',
create table table_b
(
depth tinyint not null,
id0 integer not null,
id1 integer not null,
id integer not null,
c varbinary,
p varbinary
constraint pk primary key(depth, id0, id1, id)
)
salt_buckets=2,
compression='SNAPPY';
create index gas_m_cluster_index on gas_m_cluster (id, depth, id0, id1)
compression='SNAPPY';
The query is as follows:
select a.*, b.c
from table_a a inner join table_b b on (a.depth = b.depth and a.id0 = b.id0 and
a.id1 = b.id1 and a.id2 = b.id)
where a.time_id = 23796900 and a.depth = 1;
It is obvious that b.depth must also 1 since it's on the join condition. And
since the depth column is the first column of table_b, table_b should be range
scanned before join.
But the query explanation is as follows:
CLIENT PARALLEL 4-WAY RANGE SCAN OVER TABLE_A \[0,23796900,1]
CLIENT MERGE SORT
PARALLEL INNER-JOIN TABLE 0
CLIENT PARALLEL 2-WAY FULL SCAN OVER TABLE_B
CLIENT MERGE SORT
But when (b.depth = 1) condition is explicitly added to the query, the
explanation is changed as the expected one:
CLIENT PARALLEL 4-WAY RANGE SCAN OVER TABLE_A \[0,23796900,1]
CLIENT MERGE SORT
PARALLEL INNER-JOIN TABLE 0
CLIENT PARALLEL 2-WAY RANGE SCAN OVER TABLE_B [0,1]
CLIENT MERGE SORT
It would be nice if the optimizer could find this condition dependency and
apply it to the query plan.
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