<s>
Sawzall	B-Application
is	O
a	O
procedural	O
domain-specific	B-Language
programming	I-Language
language	I-Language
,	O
used	O
by	O
Google	B-Application
to	O
process	O
large	O
numbers	O
of	O
individual	O
log	B-Application
records	O
.	O
</s>
<s>
Sawzall	B-Application
was	O
first	O
described	O
in	O
2003	O
,	O
and	O
the	O
szl	O
runtime	O
was	O
open-sourced	O
in	O
August	O
2010	O
.	O
</s>
<s>
However	O
,	O
since	O
the	O
MapReduce	B-Operating_System
table	O
aggregators	O
have	O
not	O
been	O
released	O
,	O
the	O
open-sourced	O
runtime	O
is	O
not	O
useful	O
for	O
large-scale	O
data	O
analysis	O
of	O
multiple	O
log	B-Application
files	I-Application
off	O
the	O
shelf	O
.	O
</s>
<s>
Sawzall	B-Application
has	O
been	O
replaced	O
by	O
Lingo	O
(	O
logs	O
in	O
Go	B-Application
)	O
for	O
most	O
purposes	O
within	O
Google	B-Application
.	I-Application
</s>
<s>
Google	B-Application
's	I-Application
server	O
logs	O
are	O
stored	O
as	O
large	O
collections	O
of	O
records	O
(	O
Protocol	B-Protocol
Buffers	I-Protocol
)	O
that	O
are	O
partitioned	O
over	O
many	O
disks	O
within	O
GFS	B-Application
.	O
</s>
<s>
In	O
order	O
to	O
perform	O
calculations	O
involving	O
the	O
logs	O
,	O
engineers	O
can	O
write	O
MapReduce	B-Operating_System
programs	O
in	O
C++	O
or	O
Java	O
.	O
</s>
<s>
MapReduce	B-Operating_System
programs	O
need	O
to	O
be	O
compiled	O
and	O
may	O
be	O
more	O
verbose	O
than	O
necessary	O
,	O
so	O
writing	O
a	O
program	O
to	O
analyze	O
the	O
logs	O
can	O
be	O
time-consuming	O
.	O
</s>
<s>
developed	O
the	O
Sawzall	B-Application
language	O
.	O
</s>
<s>
A	O
Sawzall	B-Application
script	O
runs	O
within	O
the	O
Map	O
phase	O
of	O
a	O
MapReduce	B-Operating_System
and	O
"	O
emits	O
"	O
values	O
to	O
tables	O
.	O
</s>
<s>
Currently	O
,	O
only	O
the	O
language	O
runtime	O
(	O
which	O
runs	O
a	O
Sawzall	B-Application
script	O
once	O
over	O
a	O
single	O
input	O
)	O
has	O
been	O
open-sourced	O
;	O
the	O
supporting	O
program	O
built	O
on	O
MapReduce	B-Operating_System
has	O
not	O
been	O
released	O
.	O
</s>
<s>
A	O
Sawzall	B-Application
script	O
has	O
a	O
single	O
input	O
(	O
a	O
log	B-Application
record	O
)	O
and	O
can	O
output	O
only	O
by	O
emitting	O
to	O
tables	O
.	O
</s>
<s>
Sawzall	B-Application
's	O
design	O
favors	O
efficiency	O
and	O
engine	O
simplicity	O
over	O
power	O
:	O
</s>
<s>
Sawzall	B-Application
is	O
statically	O
typed	O
,	O
and	O
the	O
engine	O
compiles	O
the	O
script	O
to	O
x86	B-Operating_System
before	O
running	O
it	O
.	O
</s>
<s>
Sawzall	B-Application
supports	O
the	O
compound	O
data	O
types	O
lists	O
,	O
maps	O
,	O
and	O
structs	O
.	O
</s>
<s>
This	O
complete	O
Sawzall	B-Application
program	O
will	O
read	O
the	O
input	O
and	O
produce	O
three	O
results	O
:	O
the	O
number	O
of	O
records	O
,	O
the	O
sum	O
of	O
the	O
values	O
,	O
</s>
