Database Reference
In-Depth Information
70000
JDA_M
J
AQPOT
JDA_M
JAQPOT
160000
60000
140000
50000
120000
100000
40000
80000
30000
60000
20000
40000
10000
20000
0
0
0
2
4
6
8
10
0
2
4
6
8
10
Time (in Minutes)
Time (in Minutes)
(a) Linear Plan
(b) Bushy Plan
Fig. 12.
Impact of fluctuations in streams
1
1
JDA_M
JAQPOT
JDA_M
JAQPOT
0.8
0.8
0.6
0.6
0.4
0.4
0.2
0.2
0
0
0
20
40
60
80
100
0
20
40
60
80
100
Available Reso
u
rces as % of
Saturation Resources
Available Reso
u
rces as % of
Saturation Resources
(a) Linear Plan
(b) Bushy Plan
Fig. 13.
Impact of resource availability
measure throughput as
the cumulative join output tuples produced over time
.Weuse
an equi-join of 4 streams, namely, A, B, C and D with two different query shapes,
namely,
linear
(Fig. 9.b) and
bushy
(Fig. 9.c). While the join order of the
linear
plan
is (((A
D)). The data streams are
generated according to the
Poisson
distribution that models the arrival pattern of several
real-world stream applications. Overall, a variety of scenarios are evaluated by changing
the
B)
C)
D), that of the
bushy
plan is ((A
B)
(C
i
and S
I
parameters for each query shape (Fig. 11).
Impact of Fluctuating Stream Parameters.
The fluctuating input streams are simu-
lated by changing
operator selectivities
.The
window sizes
and
arrival rates
were ob-
served to have
similar
effects on the workload as that of the selectivities, thus we omit
them here. Query workloads can be adjusted by generating streams such that the join
selectivities become high (or low) as desired. Here, we fixed the
λ
i
,
σ
μ
to 30% of saturation
I
whereas
WINDOW predicates on each stream I.
In Fig. 12, we measure the cumulative throughput (y-axis) as time progresses (x-
axis) for a total of 10 mins of steady state query execution. In the
linear
plan (Fig.
12.a), the selectivities first change at
3mins.
from SEL1 (
F
is set to 1.5
×
1
=0.01
|
2
=0.01
|
3
= 0.05) to SEL2 (
1
=0.03
|
2
=0.03
|
3
= 0.05) and further
at 7 minutes
from
SEL2 to SEL3 (
1
=0.03
|
2
=0.03
|
3
= 0.1). From SEL1 to SEL2, the selectivities
of
1
and
2
triple
while keeping
3
constant. From SEL2 to SEL3, the selectivity
of the root
3
doubles
while the selectivities of
1
and
2
remain unchanged. This
change in the root operator
3
improves the throughput production by JAQPOT even
