<s>
Data	B-Operating_System
lineage	I-Operating_System
includes	O
the	O
data	O
origin	O
,	O
what	O
happens	O
to	O
it	O
,	O
and	O
where	O
it	O
moves	O
over	O
time	O
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
gives	O
visibility	O
while	O
greatly	O
simplifying	O
the	O
ability	O
to	O
trace	O
errors	O
back	O
to	O
the	O
root	O
cause	O
in	O
a	O
data	B-General_Concept
analytics	I-General_Concept
process	O
.	O
</s>
<s>
It	O
also	O
enables	O
replaying	O
specific	O
portions	O
or	O
inputs	O
of	O
the	O
data	B-Application
flow	I-Application
for	O
step-wise	O
debugging	O
or	O
regenerating	O
lost	O
output	O
.	O
</s>
<s>
Database	B-Application
systems	I-Application
use	O
such	O
information	O
,	O
called	O
data	O
provenance	O
,	O
to	O
address	O
similar	O
validation	O
and	O
debugging	O
challenges	O
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
can	O
be	O
represented	B-Application
visually	I-Application
to	O
discover	O
the	O
data	O
flow/movement	O
from	O
its	O
source	O
to	O
destination	O
via	O
various	O
changes	O
and	O
hops	O
on	O
its	O
way	O
in	O
the	O
enterprise	O
environment	O
,	O
how	O
the	O
data	O
gets	O
transformed	O
along	O
the	O
way	O
,	O
how	O
the	O
representation	O
and	O
parameters	O
change	O
,	O
and	O
how	O
the	O
data	O
splits	O
or	O
converges	O
after	O
each	O
hop	O
.	O
</s>
<s>
A	O
simple	O
representation	O
of	O
the	O
Data	B-Operating_System
Lineage	I-Operating_System
can	O
be	O
shown	O
with	O
dots	O
and	O
lines	O
,	O
where	O
dot	O
represents	O
a	O
data	O
container	O
for	O
data	O
points	O
and	O
lines	O
connecting	O
them	O
represents	O
the	O
transformations	O
the	O
data	O
point	O
undergoes	O
,	O
between	O
the	O
data	O
containers	O
.	O
</s>
<s>
Representation	O
broadly	O
depends	O
on	O
the	O
scope	O
of	O
the	O
metadata	B-General_Concept
management	I-General_Concept
and	O
reference	O
point	O
of	O
interest	O
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
provides	O
sources	O
of	O
the	O
data	O
and	O
intermediate	O
data	B-Application
flow	I-Application
hops	O
from	O
the	O
reference	O
point	O
with	O
backward	O
data	B-Operating_System
lineage	I-Operating_System
,	O
leading	O
to	O
the	O
final	O
destination	O
's	O
data	O
points	O
and	O
its	O
intermediate	O
data	B-Application
flows	I-Application
with	O
forward	O
data	B-Operating_System
lineage	I-Operating_System
.	O
</s>
<s>
Thus	O
,	O
the	O
best	O
feature	O
of	O
the	O
data	B-Operating_System
lineage	I-Operating_System
view	O
would	O
be	O
to	O
be	O
able	O
to	O
simplify	O
the	O
view	O
by	O
temporarily	O
masking	O
unwanted	O
peripheral	O
data	O
points	O
.	O
</s>
<s>
Tools	O
that	O
have	O
the	O
masking	O
feature	O
enable	O
scalability	B-Architecture
of	O
the	O
view	O
and	O
enhance	O
analysis	O
with	O
the	O
best	O
user	O
experience	O
for	O
both	O
technical	O
and	O
business	O
users	O
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
also	O
enables	O
companies	O
to	O
trace	O
sources	O
of	O
specific	O
business	O
data	O
for	O
the	O
purposes	O
of	O
tracking	O
errors	O
,	O
implementing	O
changes	O
in	O
processes	O
,	O
and	O
implementing	O
system	B-General_Concept
migrations	I-General_Concept
to	O
save	O
significant	O
amounts	O
of	O
time	O
and	O
resources	O
,	O
thereby	O
tremendously	O
improving	O
BI	B-General_Concept
efficiency	O
.	O
</s>
<s>
The	O
scope	O
of	O
the	O
data	B-Operating_System
lineage	I-Operating_System
determines	O
the	O
volume	O
of	O
metadata	O
required	O
to	O
represent	O
its	O
data	B-Operating_System
lineage	I-Operating_System
.	O
</s>
<s>
Usually	O
,	O
data	B-General_Concept
governance	I-General_Concept
,	O
and	O
data	B-General_Concept
management	I-General_Concept
determines	O
the	O
scope	O
of	O
the	O
data	B-Operating_System
lineage	I-Operating_System
based	O
on	O
their	O
regulations	O
,	O
enterprise	O
data	B-General_Concept
management	I-General_Concept
strategy	O
,	O
data	O
impact	O
,	O
reporting	O
attributes	O
,	O
and	O
critical	O
data	O
elements	O
of	O
the	O
organization	O
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
provides	O
the	O
audit	O
trail	O
of	O
the	O
data	O
points	O
at	O
the	O
highest	O
granular	O
level	O
,	O
but	O
presentation	O
of	O
the	O
lineage	O
may	O
be	O
done	O
at	O
various	O
zoom	O
levels	O
to	O
simplify	O
the	O
vast	O
information	O
,	O
similar	O
to	O
analytic	O
web	O
maps	O
.	O
</s>
<s>
Data	B-Operating_System
Lineage	I-Operating_System
can	O
be	O
visualized	O
at	O
various	O
levels	O
based	O
on	O
the	O
granularity	O
of	O
the	O
view	O
.	O
</s>
<s>
At	O
a	O
very	O
high	O
level	O
data	B-Operating_System
lineage	I-Operating_System
provides	O
what	O
systems	O
the	O
data	O
interacts	O
before	O
it	O
reaches	O
destination	O
.	O
</s>
<s>
As	O
the	O
granularity	O
increases	O
it	O
goes	O
up	O
to	O
the	O
data	O
point	O
level	O
where	O
it	O
can	O
provide	O
the	O
details	O
of	O
the	O
data	O
point	O
and	O
its	O
historical	O
behavior	O
,	O
attribute	O
properties	O
,	O
and	O
trends	O
and	O
data	O
quality	O
of	O
the	O
data	O
passed	O
through	O
that	O
specific	O
data	O
point	O
in	O
the	O
data	B-Operating_System
lineage	I-Operating_System
.	O
</s>
<s>
Data	B-General_Concept
governance	I-General_Concept
plays	O
a	O
key	O
role	O
in	O
metadata	B-General_Concept
management	I-General_Concept
for	O
guidelines	O
,	O
strategies	O
,	O
policies	O
,	O
implementation	O
.	O
</s>
<s>
Data	O
quality	O
,	O
and	O
master	B-General_Concept
data	I-General_Concept
management	I-General_Concept
helps	O
in	O
enriching	O
the	O
data	B-Operating_System
lineage	I-Operating_System
with	O
more	O
business	O
value	O
.	O
</s>
<s>
Even	O
though	O
the	O
final	O
representation	O
of	O
data	B-Operating_System
lineage	I-Operating_System
is	O
provided	O
in	O
one	O
interface	O
but	O
the	O
way	O
the	O
metadata	O
is	O
harvested	O
and	O
exposed	O
to	O
the	O
data	B-Operating_System
lineage	I-Operating_System
graphical	B-Application
user	I-Application
interface	I-Application
could	O
be	O
entirely	O
different	O
.	O
</s>
<s>
Thus	O
,	O
data	B-Operating_System
lineage	I-Operating_System
can	O
be	O
broadly	O
divided	O
into	O
three	O
categories	O
based	O
on	O
the	O
way	O
metadata	O
is	O
harvested	O
:	O
data	B-Operating_System
lineage	I-Operating_System
involving	O
software	O
packages	O
for	O
structured	B-Application
data	I-Application
,	O
programming	O
languages	O
,	O
and	O
big	B-Application
data	I-Application
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
information	O
includes	O
technical	O
metadata	O
involving	O
data	O
transformations	O
.	O
</s>
<s>
Enriched	O
data	B-Operating_System
lineage	I-Operating_System
information	O
may	O
include	O
data	O
quality	O
test	O
results	O
,	O
reference	O
data	O
values	O
,	O
data	B-Application
models	I-Application
,	O
business	O
vocabulary	O
,	O
data	O
stewards	O
,	O
program	O
management	O
information	O
,	O
and	O
enterprise	B-Architecture
information	I-Architecture
systems	I-Architecture
linked	O
to	O
the	O
data	O
points	O
and	O
transformations	O
.	O
</s>
<s>
Masking	O
feature	O
in	O
the	O
data	B-Operating_System
lineage	I-Operating_System
visualization	O
allows	O
the	O
tools	O
to	O
incorporate	O
all	O
the	O
enrichments	O
that	O
matter	O
for	O
the	O
specific	O
use	O
case	O
.	O
</s>
<s>
Distributed	O
systems	O
like	O
Google	O
Map	B-Operating_System
Reduce	I-Operating_System
,	O
Microsoft	O
Dryad	O
,	O
Apache	O
Hadoop	O
(	O
an	O
open-source	O
project	O
)	O
and	O
Google	O
Pregel	O
provide	O
such	O
platforms	O
for	O
businesses	O
and	O
users	O
.	O
</s>
<s>
However	O
,	O
even	O
with	O
these	O
systems	O
,	O
big	B-Application
data	I-Application
analytics	I-Application
can	O
take	O
several	O
hours	O
,	O
days	O
or	O
weeks	O
to	O
run	O
,	O
simply	O
due	O
to	O
the	O
data	O
volumes	O
involved	O
.	O
</s>
<s>
Big	B-Application
data	I-Application
analytics	I-Application
is	O
the	O
process	O
of	O
examining	O
large	O
data	O
sets	O
to	O
uncover	O
hidden	O
patterns	O
,	O
unknown	O
correlations	O
,	O
market	O
trends	O
,	O
customer	O
preferences	O
and	O
other	O
useful	O
business	B-General_Concept
information	I-General_Concept
.	O
</s>
<s>
As	O
such	O
,	O
more	O
cost-efficient	O
ways	O
of	O
analyzing	O
data	B-Operating_System
intensive	I-Operating_System
scalable	I-Operating_System
computing	I-Operating_System
(	O
DISC	O
)	O
are	O
crucial	O
to	O
their	O
continued	O
effective	O
use	O
.	O
</s>
<s>
Unstructured	B-Application
data	I-Application
usually	O
refers	O
to	O
information	O
that	O
does	O
n't	O
reside	O
in	O
a	O
traditional	O
row-column	O
database	O
.	O
</s>
<s>
Unstructured	B-Application
data	I-Application
files	O
often	O
include	O
text	O
and	O
multimedia	O
content	O
.	O
</s>
<s>
And	O
the	O
amount	O
of	O
unstructured	B-Application
data	I-Application
in	O
enterprises	O
is	O
growing	O
significantly	O
often	O
many	O
times	O
faster	O
than	O
structured	O
databases	B-Application
are	O
growing	O
.	O
</s>
<s>
"	O
Big	B-Application
data	I-Application
can	O
include	O
both	O
structured	O
and	O
unstructured	B-Application
data	I-Application
,	O
but	O
IDC	O
estimates	O
that	O
90	O
percent	O
of	O
big	B-Application
data	I-Application
is	O
unstructured	O
data.	O
"	O
</s>
<s>
The	O
fundamental	O
challenge	O
of	O
unstructured	B-Application
data	I-Application
sources	O
is	O
that	O
they	O
are	O
difficult	O
for	O
non-technical	O
business	O
users	O
and	O
data	B-General_Concept
analysts	I-General_Concept
alike	O
to	O
unbox	O
,	O
understand	O
,	O
and	O
prepare	O
for	O
analytic	O
use	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
current	O
data	O
mining	O
techniques	O
often	O
leave	O
out	O
valuable	O
information	O
and	O
make	O
analyzing	O
unstructured	B-Application
data	I-Application
laborious	O
and	O
expensive	O
.	O
</s>
<s>
Some	O
vendors	O
are	O
using	O
increased	O
memory	O
and	O
parallel	B-Operating_System
processing	I-Operating_System
to	O
crunch	O
large	O
volumes	O
of	O
data	O
quickly	O
.	O
</s>
<s>
Another	O
method	O
is	O
putting	O
data	O
in-memory	B-General_Concept
but	O
using	O
a	O
grid	B-Architecture
computing	I-Architecture
approach	O
,	O
where	O
many	O
machines	O
are	O
used	O
to	O
solve	O
a	O
problem	O
.	O
</s>
<s>
A	O
third	O
approach	O
of	O
advanced	O
data	O
discovery	O
solutions	O
combines	O
self-service	B-General_Concept
data	I-General_Concept
prep	I-General_Concept
with	O
visual	O
data	O
discovery	O
,	O
enabling	O
analysts	O
to	O
simultaneously	O
prepare	O
and	O
visualize	O
data	O
side-by-side	O
in	O
an	O
interactive	O
analysis	O
environment	O
offered	O
by	O
newer	O
companies	O
Trifacta	O
,	O
Alteryx	O
and	O
others	O
.	O
</s>
<s>
Another	O
method	O
to	O
track	O
data	B-Operating_System
lineage	I-Operating_System
is	O
spreadsheet	O
programs	O
such	O
as	O
Excel	O
that	O
do	O
offer	O
users	O
cell-level	O
lineage	O
,	O
or	O
the	O
ability	O
to	O
see	O
what	O
cells	O
are	O
dependent	O
on	O
another	O
,	O
but	O
the	O
structure	O
of	O
the	O
transformation	O
is	O
lost	O
.	O
</s>
<s>
Big	B-Application
Data	I-Application
platforms	O
have	O
a	O
very	O
complicated	O
structure	O
.	O
</s>
<s>
Debugging	O
of	O
a	O
big	B-Application
data	I-Application
pipeline	O
becomes	O
very	O
challenging	O
because	O
of	O
the	O
very	O
nature	O
of	O
the	O
system	O
.	O
</s>
<s>
Data	O
provenance	O
or	O
data	B-Operating_System
lineage	I-Operating_System
can	O
be	O
used	O
to	O
make	O
the	O
debugging	O
of	O
big	B-Application
data	I-Application
pipeline	O
easier	O
.	O
</s>
<s>
The	O
use	O
of	O
data	O
provenance	O
is	O
proposed	O
in	O
distributed	O
systems	O
to	O
trace	O
records	O
through	O
a	O
dataflow	B-Application
,	O
replay	O
the	O
dataflow	B-Application
on	O
a	O
subset	O
of	O
its	O
original	O
inputs	O
and	O
debug	O
data	B-Application
flows	I-Application
.	O
</s>
<s>
Intuitively	O
,	O
for	O
an	O
operator	O
T	O
producing	O
output	O
o	O
,	O
lineage	O
consists	O
of	O
triplets	O
of	O
form	O
{	O
I	O
,	O
T	O
,	O
o}	O
,	O
where	O
I	O
is	O
the	O
set	O
of	O
inputs	O
to	O
T	O
used	O
to	O
derive	O
o	O
.	O
Capturing	O
lineage	O
for	O
each	O
operator	O
T	O
in	O
a	O
dataflow	B-Application
enables	O
users	O
to	O
ask	O
questions	O
such	O
as	O
“	O
Which	O
outputs	O
were	O
produced	O
by	O
an	O
input	O
i	O
on	O
operator	O
T	O
?	O
”	O
and	O
“	O
Which	O
inputs	O
produced	O
output	O
o	O
in	O
operator	O
T	O
?	O
”	O
A	O
query	O
that	O
finds	O
the	O
inputs	O
deriving	O
an	O
output	O
is	O
called	O
a	O
backward	O
tracing	O
query	O
,	O
while	O
one	O
that	O
finds	O
the	O
outputs	O
produced	O
by	O
an	O
input	O
is	O
called	O
a	O
forward	O
tracing	O
query	O
.	O
</s>
<s>
Tracing	O
queries	O
also	O
form	O
the	O
basis	O
for	O
replaying	O
an	O
original	O
dataflow	B-Application
.	O
</s>
<s>
However	O
,	O
to	O
efficiently	O
use	O
lineage	O
in	O
a	O
DISC	O
system	O
,	O
we	O
need	O
to	O
be	O
able	O
to	O
capture	O
lineage	O
at	O
multiple	O
levels	O
(	O
or	O
granularities	O
)	O
of	O
operators	O
and	O
data	O
,	O
capture	O
accurate	O
lineage	O
for	O
DISC	O
processing	O
constructs	O
and	O
be	O
able	O
to	O
trace	O
through	O
multiple	O
dataflow	B-Application
stages	O
efficiently	O
.	O
</s>
<s>
Integrating	O
lineage	O
across	O
different	O
granularities	O
enables	O
users	O
to	O
ask	O
questions	O
such	O
as	O
“	O
Which	O
file	O
read	O
by	O
a	O
MapReduce	B-Operating_System
job	O
produced	O
this	O
particular	O
output	O
record	O
?	O
”	O
and	O
can	O
be	O
useful	O
in	O
debugging	O
across	O
different	O
operator	O
and	O
data	O
granularities	O
within	O
a	O
dataflow	B-Application
.	O
</s>
<s>
For	O
example	O
,	O
a	O
MapReduce	B-Operating_System
task	O
is	O
contained	O
in	O
a	O
job	O
.	O
</s>
<s>
The	O
concept	O
of	O
prescriptive	O
data	B-Operating_System
lineage	I-Operating_System
combines	O
both	O
the	O
logical	O
model	O
(	O
entity	O
)	O
of	O
how	O
that	O
data	O
should	O
flow	O
with	O
the	O
actual	O
lineage	O
for	O
that	O
instance	O
.	O
</s>
<s>
Data	B-Operating_System
lineage	I-Operating_System
and	O
provenance	O
typically	O
refers	O
to	O
the	O
way	O
or	O
the	O
steps	O
a	O
dataset	O
took	O
to	O
reach	O
its	O
current	O
state	O
of	O
Data	B-Operating_System
lineage	I-Operating_System
,	O
as	O
well	O
as	O
all	O
copies	O
or	O
derivatives	O
.	O
</s>
<s>
However	O
,	O
simply	O
looking	O
back	O
at	O
the	O
audit	O
or	O
log	O
correlations	O
to	O
determine	O
the	O
lineage	O
from	O
a	O
forensic	O
point	O
of	O
view	O
fails	O
for	O
certain	O
data	B-General_Concept
management	I-General_Concept
cases	O
.	O
</s>
<s>
Many	O
certified	O
compliance	O
reports	O
require	O
provenance	O
of	O
data	B-Application
flow	I-Application
as	O
well	O
as	O
the	O
end	O
state	O
data	O
for	O
a	O
specific	O
instance	O
.	O
</s>
<s>
However	O
,	O
to	O
answer	O
fine-grain	O
tracing	O
queries	O
,	O
they	O
must	O
replay	O
the	O
data	B-Application
flow	I-Application
on	O
all	O
(	O
or	O
a	O
large	O
part	O
)	O
of	O
its	O
input	O
and	O
collect	O
fine-grain	O
lineage	O
during	O
the	O
replay	O
.	O
</s>
<s>
Active	O
collection	O
systems	O
capture	O
entire	O
lineage	O
of	O
the	O
data	B-Application
flow	I-Application
at	O
run	O
time	O
.	O
</s>
<s>
The	O
kind	O
of	O
lineage	O
they	O
capture	O
may	O
be	O
coarse-grain	O
or	O
fine-grain	O
,	O
but	O
they	O
do	O
not	O
require	O
any	O
further	O
computations	O
on	O
the	O
data	B-Application
flow	I-Application
after	O
its	O
execution	O
.	O
</s>
<s>
An	O
actor	O
is	O
an	O
entity	O
that	O
transforms	O
data	O
;	O
it	O
may	O
be	O
a	O
Dryad	O
vertex	O
,	O
individual	O
map	O
and	O
reduce	O
operators	O
,	O
a	O
MapReduce	B-Operating_System
job	O
,	O
or	O
an	O
entire	O
dataflow	B-Application
pipeline	O
.	O
</s>
<s>
The	O
instrumentation	O
thus	O
captures	O
lineage	O
in	O
a	O
dataflow	B-Application
one	O
actor	O
at	O
a	O
time	O
,	O
piecing	O
it	O
into	O
a	O
set	O
of	O
associations	O
for	O
each	O
actor	O
.	O
</s>
<s>
Associations	O
are	O
the	O
basic	O
units	O
of	O
Data	B-Operating_System
Lineage	I-Operating_System
.	O
</s>
<s>
Big	B-Application
data	I-Application
systems	O
scale	O
horizontally	O
i.e.	O
</s>
<s>
The	O
system	O
should	O
continue	O
to	O
maintain	O
this	O
property	O
after	O
horizontal	O
scaling	B-Architecture
.	O
</s>
<s>
An	O
important	O
advantage	O
of	O
horizontal	O
scalability	B-Architecture
is	O
that	O
it	O
can	O
provide	O
the	O
ability	O
to	O
increase	O
capacity	O
on	O
the	O
fly	O
.	O
</s>
<s>
The	O
biggest	O
plus	O
point	O
is	O
that	O
horizontal	O
scaling	B-Architecture
can	O
be	O
done	O
using	O
commodity	O
hardware	O
.	O
</s>
<s>
The	O
horizontal	O
scaling	B-Architecture
feature	O
of	O
Big	B-Application
Data	I-Application
systems	O
should	O
be	O
taken	O
into	O
account	O
while	O
creating	O
the	O
architecture	O
of	O
lineage	O
store	O
.	O
</s>
<s>
This	O
is	O
essential	O
because	O
the	O
lineage	O
store	O
itself	O
should	O
also	O
be	O
able	O
to	O
scale	O
in	O
parallel	O
with	O
the	O
Big	B-Application
data	I-Application
system	O
.	O
</s>
<s>
The	O
architecture	O
of	O
Big	B-Application
data	I-Application
systems	O
makes	O
the	O
use	O
of	O
a	O
single	O
lineage	O
store	O
not	O
appropriate	O
and	O
impossible	O
to	O
scale	O
.	O
</s>
<s>
It	O
allows	O
horizontal	O
scaling	B-Architecture
of	O
the	O
lineage	O
store	O
.	O
</s>
<s>
The	O
information	O
stored	O
in	O
terms	O
of	O
associations	O
needs	O
to	O
be	O
combined	O
by	O
some	O
means	O
to	O
get	O
the	O
data	B-Application
flow	I-Application
of	O
a	O
particular	O
job	O
.	O
</s>
<s>
The	O
lineage	O
of	O
the	O
entire	O
job	O
should	O
help	O
the	O
data	O
scientist	O
understand	O
the	O
data	B-Application
flow	I-Application
of	O
the	O
job	O
and	O
he/she	O
can	O
use	O
the	O
data	B-Application
flow	I-Application
to	O
debug	O
the	O
big	B-Application
data	I-Application
pipeline	O
.	O
</s>
<s>
The	O
data	B-Application
flow	I-Application
is	O
reconstructed	O
in	O
3	O
stages	O
.	O
</s>
<s>
The	O
first	O
stage	O
of	O
the	O
data	B-Application
flow	I-Application
reconstruction	O
is	O
the	O
computation	O
of	O
the	O
association	O
tables	O
.	O
</s>
<s>
The	O
second	O
step	O
in	O
data	B-Application
flow	I-Application
reconstruction	O
is	O
computing	O
an	O
association	O
graph	O
from	O
the	O
lineage	O
information	O
.	O
</s>
<s>
The	O
graph	O
represents	O
the	O
steps	O
in	O
the	O
data	B-Application
flow	I-Application
.	O
</s>
<s>
Each	O
actor	O
T	O
is	O
linked	O
to	O
its	O
upstream	O
and	O
downstream	O
actors	O
in	O
the	O
data	B-Application
flow	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
MapReduce	B-Operating_System
architecture	O
,	O
each	O
map	O
instance	O
knows	O
the	O
exact	O
record	O
reader	O
instance	O
whose	O
output	O
it	O
consumes	O
.	O
</s>
<s>
Developers	O
can	O
attach	O
data	B-Application
flow	I-Application
archetypes	B-Language
to	O
each	O
logical	O
actor	O
.	O
</s>
<s>
A	O
data	B-Application
flow	I-Application
archetype	B-Language
explains	O
how	O
the	O
children	O
types	O
of	O
an	O
actor	O
type	O
arrange	O
themselves	O
in	O
a	O
data	B-Application
flow	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
in	O
the	O
MapReduce	B-Operating_System
architecture	O
,	O
the	O
map	O
actor	O
type	O
is	O
the	O
source	O
for	O
reduce	O
,	O
and	O
vice	O
versa	O
.	O
</s>
<s>
The	O
system	O
infers	O
this	O
from	O
the	O
data	B-Application
flow	I-Application
archetypes	B-Language
and	O
duly	O
links	O
map	O
instances	O
with	O
reduce	O
instances	O
.	O
</s>
<s>
However	O
,	O
there	O
may	O
be	O
several	O
MapReduce	B-Operating_System
jobs	O
in	O
the	O
data	B-Application
flow	I-Application
,	O
and	O
linking	O
all	O
map	O
instances	O
with	O
all	O
reduce	O
instances	O
can	O
create	O
false	O
links	O
.	O
</s>
<s>
The	O
final	O
step	O
in	O
the	O
data	B-Application
flow	I-Application
reconstruction	O
is	O
the	O
topological	B-Algorithm
sorting	I-Algorithm
of	O
the	O
association	O
graph	O
.	O
</s>
<s>
This	O
inherit	O
order	O
of	O
the	O
actors	O
defines	O
the	O
data	B-Application
flow	I-Application
of	O
the	O
big	B-Application
data	I-Application
pipeline	O
or	O
task	O
.	O
</s>
<s>
This	O
is	O
the	O
most	O
crucial	O
step	O
in	O
big	B-Application
data	I-Application
debugging	O
.	O
</s>
<s>
The	O
captured	O
lineage	O
is	O
combined	O
and	O
processed	O
to	O
obtain	O
the	O
data	B-Application
flow	I-Application
of	O
the	O
pipeline	O
.	O
</s>
<s>
The	O
data	B-Application
flow	I-Application
helps	O
the	O
data	O
scientist	O
or	O
a	O
developer	O
to	O
look	O
deeply	O
into	O
the	O
actors	O
and	O
their	O
transformations	O
.	O
</s>
<s>
A	O
big	B-Application
data	I-Application
pipeline	O
can	O
go	O
wrong	O
in	O
two	O
broad	O
ways	O
.	O
</s>
<s>
The	O
first	O
is	O
a	O
presence	O
of	O
a	O
suspicious	O
actor	O
in	O
the	O
data-flow	B-Application
.	O
</s>
<s>
The	O
first	O
case	O
can	O
be	O
debugged	O
by	O
tracing	O
the	O
data-flow	B-Application
.	O
</s>
<s>
By	O
using	O
lineage	O
and	O
data-flow	B-Application
information	O
together	O
a	O
data	O
scientist	O
can	O
figure	O
out	O
how	O
the	O
inputs	O
are	O
converted	O
into	O
outputs	O
.	O
</s>
<s>
Either	O
these	O
actors	O
can	O
be	O
removed	O
from	O
the	O
data	B-Application
flow	I-Application
or	O
they	O
can	O
be	O
augmented	O
by	O
new	O
actors	O
to	O
change	O
the	O
data-flow	B-Application
.	O
</s>
<s>
The	O
improved	O
data-flow	B-Application
can	O
be	O
replayed	O
to	O
test	O
the	O
validity	O
of	O
it	O
.	O
</s>
<s>
Debugging	O
faulty	O
actors	O
include	O
recursively	O
performing	O
coarse-grain	O
replay	O
on	O
actors	O
in	O
the	O
data-flow	B-Application
,	O
which	O
can	O
be	O
expensive	O
in	O
resources	O
for	O
long	O
dataflows	B-Application
.	O
</s>
<s>
Another	O
approach	O
is	O
to	O
manually	O
inspect	O
lineage	O
logs	O
to	O
find	O
anomalies	O
,	O
which	O
can	O
be	O
tedious	O
and	O
time-consuming	O
across	O
several	O
stages	O
of	O
a	O
data-flow	B-Application
.	O
</s>
<s>
To	O
debug	O
analytics	O
without	O
known	O
bad	O
outputs	O
,	O
the	O
data	O
scientist	O
need	O
to	O
analyze	O
the	O
data-flow	B-Application
for	O
suspicious	O
behavior	O
in	O
general	O
.	O
</s>
<s>
This	O
section	O
describes	O
a	O
debugging	O
methodology	O
for	O
retrospectively	O
analyzing	O
lineage	O
to	O
identify	O
faulty	O
actors	O
in	O
a	O
multi-stage	O
data-flow	B-Application
.	O
</s>
<s>
Thus	O
,	O
mining	O
lineage	O
to	O
identify	O
such	O
changes	O
can	O
be	O
useful	O
in	O
debugging	O
faulty	O
actors	O
in	O
a	O
data-flow	B-Application
.	O
</s>
<s>
the	O
existence	O
of	O
outliers	O
can	O
also	O
be	O
identified	O
by	O
running	O
the	O
data-flow	B-Application
step	O
wise	O
and	O
looking	O
at	O
the	O
transformed	O
outputs	O
.	O
</s>
<s>
This	O
problem	O
can	O
be	O
solved	O
by	O
removing	O
the	O
set	O
of	O
outliers	O
from	O
the	O
data	O
and	O
replaying	O
the	O
entire	O
data-flow	B-Application
.	O
</s>
<s>
It	O
can	O
also	O
be	O
solved	O
by	O
modifying	O
the	O
machine	O
learning	O
algorithm	O
by	O
adding	O
,	O
removing	O
or	O
moving	O
actors	O
in	O
the	O
data-flow	B-Application
.	O
</s>
<s>
The	O
changes	O
in	O
the	O
data-flow	B-Application
are	O
successful	O
if	O
the	O
replayed	O
data-flow	B-Application
does	O
not	O
produce	O
bad	O
outputs	O
.	O
</s>
<s>
Even	O
though	O
the	O
use	O
of	O
data	B-Operating_System
lineage	I-Operating_System
approaches	O
is	O
a	O
novel	O
way	O
of	O
debugging	O
of	O
big	B-Application
data	I-Application
pipelines	O
,	O
the	O
process	O
is	O
not	O
simple	O
.	O
</s>
<s>
The	O
challenges	O
include	O
scalability	B-Architecture
of	O
the	O
lineage	O
store	O
,	O
fault	O
tolerance	O
of	O
the	O
lineage	O
store	O
,	O
accurate	O
capture	O
of	O
lineage	O
for	O
black	O
box	O
operators	O
and	O
many	O
others	O
.	O
</s>
<s>
These	O
challenges	O
must	O
be	O
considered	O
carefully	O
and	O
trade	O
offs	O
between	O
them	O
need	O
to	O
be	O
evaluated	O
to	O
make	O
a	O
realistic	O
design	O
for	O
data	B-Operating_System
lineage	I-Operating_System
capture	O
.	O
</s>
<s>
Lineage	O
capture	O
systems	O
must	O
also	O
be	O
fault	O
tolerant	O
to	O
avoid	O
rerunning	O
data	B-Application
flows	I-Application
to	O
capture	O
lineage	O
.	O
</s>
<s>
Lineage	O
systems	O
for	O
DISC	O
dataflows	B-Application
must	O
be	O
able	O
to	O
capture	O
accurate	O
lineage	O
across	O
black-box	O
operators	O
to	O
enable	O
fine-grain	O
debugging	O
.	O
</s>
<s>
Current	O
approaches	O
to	O
this	O
include	O
Prober	O
,	O
which	O
seeks	O
to	O
find	O
the	O
minimal	O
set	O
of	O
inputs	O
that	O
can	O
produce	O
a	O
specified	O
output	O
for	O
a	O
black-box	O
operator	O
by	O
replaying	O
the	O
data-flow	B-Application
several	O
times	O
to	O
deduce	O
the	O
minimal	O
set	O
,	O
and	O
dynamic	O
slicing	O
,	O
as	O
used	O
by	O
Zhang	O
et	O
al	O
.	O
</s>
<s>
to	O
capture	O
lineage	O
for	O
NoSQL	B-General_Concept
operators	O
through	O
binary	O
rewriting	O
to	O
compute	O
dynamic	O
slices	O
.	O
</s>
<s>
Thus	O
,	O
there	O
is	O
a	O
need	O
for	O
a	O
lineage	O
collection	O
system	O
for	O
DISC	O
dataflows	B-Application
that	O
can	O
capture	O
lineage	O
from	O
arbitrary	O
operators	O
with	O
reasonable	O
accuracy	O
,	O
and	O
without	O
significant	O
overheads	O
in	O
capture	O
or	O
tracing	O
.	O
</s>
<s>
can	O
perform	O
efficient	O
backward	O
tracing	O
queries	O
for	O
MapReduce	B-Operating_System
dataflows	B-Application
,	O
but	O
are	O
not	O
generic	O
to	O
different	O
DISC	O
systems	O
and	O
do	O
not	O
perform	O
efficient	O
forward	O
queries	O
.	O
</s>
<s>
Thus	O
,	O
there	O
is	O
a	O
need	O
for	O
a	O
lineage	O
system	O
that	O
enables	O
efficient	O
forward	O
and	O
backward	O
tracing	O
for	O
generic	O
DISC	O
systems	O
and	O
dataflows	B-Application
with	O
black-box	O
operators	O
.	O
</s>
<s>
Replaying	O
only	O
specific	O
inputs	O
or	O
portions	O
of	O
a	O
data-flow	B-Application
is	O
crucial	O
for	O
efficient	O
debugging	O
and	O
simulating	O
what-if	O
scenarios	O
.	O
</s>
<s>
In	O
long	O
dataflows	B-Application
with	O
several	O
hundreds	O
of	O
operators	O
or	O
tasks	O
,	O
manual	O
inspection	O
can	O
be	O
tedious	O
and	O
prohibitive	O
.	O
</s>
