<s>
Lightning	B-Language
Memory-Mapped	I-Language
Database	I-Language
(	O
LMDB	B-Language
)	O
is	O
a	O
software	B-Library
library	I-Library
that	O
provides	O
an	O
embedded	O
transactional	O
database	O
in	O
the	O
form	O
of	O
a	O
key-value	B-Data_Structure
store	I-Data_Structure
.	O
</s>
<s>
LMDB	B-Language
is	O
written	O
in	O
C	B-Language
with	O
API	B-Application
bindings	O
for	O
several	O
programming	O
languages	O
.	O
</s>
<s>
LMDB	B-Language
stores	O
arbitrary	O
key/data	O
pairs	O
as	O
byte	O
arrays	O
,	O
has	O
a	O
range-based	O
search	O
capability	O
,	O
supports	O
multiple	O
data	O
items	O
for	O
a	O
single	O
key	O
and	O
has	O
a	O
special	O
mode	O
for	O
appending	O
records	O
(	O
MDB_APPEND	O
)	O
without	O
checking	O
for	O
consistency	O
.	O
</s>
<s>
LMDB	B-Language
is	O
not	O
a	O
relational	B-Application
database	I-Application
,	O
it	O
is	O
strictly	O
a	O
key-value	B-Data_Structure
store	I-Data_Structure
like	O
Berkeley	B-Language
DB	I-Language
and	O
dbm	B-General_Concept
.	O
</s>
<s>
LMDB	B-Language
may	O
also	O
be	O
used	O
concurrently	O
in	O
a	O
multi-threaded	O
or	O
multi-processing	O
environment	O
,	O
with	O
read	O
performance	O
scaling	O
linearly	O
by	O
design	O
.	O
</s>
<s>
LMDB	B-Language
databases	O
may	O
have	O
only	O
one	O
writer	O
at	O
a	O
time	O
,	O
however	O
unlike	O
many	O
similar	O
key-value	B-Data_Structure
databases	I-Data_Structure
,	O
write	O
transactions	O
do	O
not	O
block	O
readers	O
,	O
nor	O
do	O
readers	O
block	O
writers	O
.	O
</s>
<s>
LMDB	B-Language
is	O
also	O
unusual	O
in	O
that	O
multiple	O
applications	O
on	O
the	O
same	O
system	O
may	O
simultaneously	O
open	O
and	O
use	O
the	O
same	O
LMDB	B-Language
store	O
,	O
as	O
a	O
means	O
to	O
scale	O
up	O
performance	O
.	O
</s>
<s>
Also	O
,	O
LMDB	B-Language
does	O
not	O
require	O
a	O
transaction	O
log	O
(	O
thereby	O
increasing	O
write	O
performance	O
by	O
not	O
needing	O
to	O
write	O
data	O
twice	O
)	O
because	O
it	O
maintains	O
data	O
integrity	O
inherently	O
by	O
design	O
.	O
</s>
<s>
LMDB	B-Language
's	O
design	O
was	O
first	O
discussed	O
in	O
a	O
2009	O
post	O
to	O
the	O
OpenLDAP	B-Language
developer	O
mailing	O
list	O
,	O
in	O
the	O
context	O
of	O
exploring	O
solutions	O
to	O
the	O
cache	O
management	O
difficulty	O
caused	O
by	O
the	O
project	O
's	O
dependence	O
on	O
Berkeley	B-Language
DB	I-Language
.	O
</s>
<s>
A	O
specific	O
goal	O
was	O
to	O
replace	O
the	O
multiple	O
layers	O
of	O
configuration	O
and	O
caching	O
inherent	O
to	O
Berkeley	B-Language
DB	I-Language
's	O
design	O
with	O
a	O
single	O
,	O
automatically	O
managed	O
cache	O
under	O
the	O
control	O
of	O
the	O
host	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
Development	O
subsequently	O
began	O
,	O
initially	O
as	O
a	O
fork	B-Application
of	O
a	O
similar	O
implementation	O
from	O
the	O
OpenBSD	O
ldapd	O
project	O
.	O
</s>
<s>
The	O
first	O
publicly	O
available	O
version	O
appeared	O
in	O
the	O
OpenLDAP	B-Language
source	O
repository	O
in	O
June	O
2011	O
.	O
</s>
<s>
Internally	O
LMDB	B-Language
uses	O
B+	O
tree	O
data	O
structures	O
.	O
</s>
<s>
LMDB	B-Language
has	O
an	O
API	B-Application
similar	O
to	O
Berkeley	B-Language
DB	I-Language
and	O
dbm	B-General_Concept
.	O
</s>
<s>
LMDB	B-Language
treats	O
the	O
computer	O
's	O
memory	O
as	O
a	O
single	O
address	O
space	O
,	O
shared	O
across	O
multiple	O
processes	O
or	O
threads	O
using	O
shared	B-Operating_System
memory	I-Operating_System
with	O
copy-on-write	B-Language
semantics	O
(	O
known	O
historically	O
as	O
a	O
single-level	B-Device
store	I-Device
)	O
.	O
</s>
<s>
Most	O
former	O
modern	O
computing	O
architectures	O
had	O
a	O
32-bit	O
memory	O
address	O
space	O
,	O
imposing	O
a	O
hard	O
limit	O
of	O
4	O
GB	O
on	O
the	O
size	O
of	O
any	O
database	O
that	O
directly	O
mapped	O
into	O
a	O
single-level	B-Device
store	I-Device
.	O
</s>
<s>
However	O
,	O
today	O
's	O
64-bit	O
processors	O
now	O
mostly	O
implement	O
48-bit	O
address	O
spaces	O
,	O
giving	O
access	O
to	O
47-bit	O
addresses	O
or	O
128TB	O
of	O
database	O
size	O
,	O
making	O
databases	O
using	O
shared	B-Operating_System
memory	I-Operating_System
useful	O
once	O
again	O
in	O
real-world	O
applications	O
.	O
</s>
<s>
Specific	O
noteworthy	O
technical	O
features	O
of	O
LMDB	B-Language
are	O
:	O
</s>
<s>
Copy-on-write	B-Language
semantics	O
help	O
ensure	O
data	O
integrity	O
as	O
well	O
as	O
providing	O
transactional	O
guarantees	O
and	O
simultaneous	O
access	O
by	O
readers	O
without	O
requiring	O
any	O
locking	B-Operating_System
,	O
even	O
by	O
the	O
current	O
writer	O
.	O
</s>
<s>
New	O
memory	O
pages	O
required	O
internally	O
during	O
data	O
modifications	O
are	O
allocated	O
through	O
copy-on-write	B-Language
semantics	O
by	O
the	O
underlying	O
OS	O
:	O
the	O
LMDB	B-Language
library	O
itself	O
never	O
actually	O
modifies	O
older	O
data	O
being	O
accessed	O
by	O
readers	O
because	O
it	O
simply	O
cannot	O
do	O
so	O
:	O
any	O
shared-memory	B-Operating_System
updates	O
automatically	O
create	O
a	O
completely	O
independent	O
copy	O
of	O
the	O
memory-page	O
being	O
written	O
to	O
.	O
</s>
<s>
As	O
LMDB	B-Language
is	O
memory-mapped	O
,	O
it	O
can	O
return	O
direct	O
pointers	O
to	O
memory	O
addresses	O
of	O
keys	O
and	O
values	O
through	O
its	O
API	B-Application
,	O
thereby	O
avoiding	O
unnecessary	O
and	O
expensive	O
copying	O
of	O
memory	O
.	O
</s>
<s>
This	O
results	O
in	O
greatly-increased	O
performance	O
(	O
especially	O
when	O
the	O
values	O
stored	O
are	O
extremely	O
large	O
)	O
,	O
and	O
expands	O
the	O
potential	O
use	O
cases	O
for	O
LMDB	B-Language
.	O
</s>
<s>
LMDB	B-Language
also	O
tracks	O
unused	O
memory	O
pages	O
,	O
using	O
a	O
B+	O
tree	O
to	O
keep	O
track	O
of	O
pages	O
freed	O
(	O
no	O
longer	O
needed	O
)	O
during	O
transactions	O
.	O
</s>
<s>
On	O
a	O
modern	O
filesystem	O
with	O
sparse	B-General_Concept
file	I-General_Concept
support	O
,	O
this	O
helps	O
minimise	O
actual	O
disk	O
usage	O
.	O
</s>
<s>
The	O
file	O
format	O
of	O
LMDB	B-Language
is	O
,	O
unlike	O
that	O
of	O
Berkeley	B-Language
DB	I-Language
,	O
architecture-dependent	O
.	O
</s>
<s>
LMDB	B-Language
employs	O
multiversion	B-Operating_System
concurrency	I-Operating_System
control	I-Operating_System
(	O
MVCC	O
)	O
and	O
allows	O
multiple	O
threads	O
within	O
multiple	O
processes	O
to	O
coordinate	O
simultaneous	O
access	O
to	O
a	O
database	O
.	O
</s>
<s>
While	O
write	O
transactions	O
are	O
globally	O
serialized	O
via	O
a	O
mutex	B-Operating_System
,	O
read-only	O
transactions	O
operate	O
in	O
parallel	O
,	O
including	O
in	O
the	O
presence	O
of	O
a	O
write	O
transaction	O
.	O
</s>
<s>
They	O
are	O
entirely	O
wait	B-Operating_System
free	I-Operating_System
except	O
for	O
the	O
first	O
read-only	O
transaction	O
on	O
a	O
thread	O
.	O
</s>
<s>
Each	O
thread	O
reading	O
from	O
a	O
database	O
gains	O
ownership	O
of	O
an	O
element	O
in	O
a	O
shared	B-Operating_System
memory	I-Operating_System
array	O
,	O
which	O
it	O
may	O
update	O
to	O
indicate	O
when	O
it	O
is	O
within	O
a	O
transaction	O
.	O
</s>
<s>
In	O
2011	O
Google	O
published	O
software	O
that	O
allowed	O
users	O
to	O
generate	O
micro-benchmarks	O
comparing	O
LevelDB	B-Language
's	O
performance	O
to	O
SQLite	B-Language
and	O
Kyoto	B-Language
Cabinet	I-Language
in	O
different	O
scenarios	O
.	O
</s>
<s>
In	O
2012	O
Symas	O
added	O
support	O
for	O
LMDB	B-Language
and	O
Berkeley	B-Language
DB	I-Language
and	O
made	O
the	O
updated	O
benchmarking	O
software	O
publicly	O
available	O
.	O
</s>
<s>
The	O
resulting	O
benchmarks	O
showed	O
that	O
LMDB	B-Language
outperformed	O
all	O
other	O
databases	O
in	O
read	O
and	O
batch	O
write	O
operations	O
.	O
</s>
<s>
SQLite	B-Language
with	O
LMDB	B-Language
excelled	O
in	O
write	O
operations	O
,	O
and	O
particularly	O
so	O
on	O
synchronous/transactional	O
writes	O
.	O
</s>
<s>
JFS	B-Application
with	O
an	O
external	O
journal	O
performs	O
well	O
,	O
especially	O
compared	O
to	O
other	O
modern	O
systems	O
like	O
Btrfs	B-Operating_System
and	O
ZFS	B-Application
.	O
</s>
<s>
Zimbra	O
has	O
tested	O
back-mdb	O
vs	O
back-hdb	O
performance	O
in	O
OpenLDAP	B-Language
,	O
with	O
LMDB	B-Language
clearly	O
outperforming	O
the	O
BDB	O
based	O
back-hdb	O
.	O
</s>
<s>
Many	O
other	O
OpenLDAP	B-Language
users	O
have	O
observed	O
similar	O
benefits	O
.	O
</s>
<s>
These	O
tests	O
show	O
that	O
LMDB	B-Language
performance	O
is	O
unmatched	O
on	O
all	O
in-memory	O
workloads	O
and	O
excels	O
in	O
all	O
disk-bound	O
read	O
workloads	O
and	O
disk-bound	O
write	O
workloads	O
using	O
large	O
record	O
sizes	O
.	O
</s>
<s>
The	O
benchmark	O
driver	O
code	O
was	O
subsequently	O
published	O
on	O
GitHub	B-Application
and	O
further	O
expanded	O
in	O
database	O
coverage	O
.	O
</s>
<s>
LMDB	B-Language
was	O
designed	O
to	O
resist	O
data	O
loss	O
in	O
the	O
face	O
of	O
system	O
and	O
application	O
crashes	O
.	O
</s>
<s>
Its	O
copy-on-write	B-Language
approach	O
never	O
overwrites	O
currently-in-use	O
data	O
.	O
</s>
<s>
Two	O
academic	O
papers	O
from	O
the	O
USENIX	O
OSDI	O
Symposium	O
covered	O
failure	O
modes	O
of	O
DB	O
engines	O
(	O
including	O
LMDB	B-Language
)	O
under	O
a	O
sudden	O
power	O
loss	O
or	O
system	O
crash	O
.	O
</s>
<s>
The	O
paper	O
from	O
Pillai	O
et	O
al.	O
,	O
did	O
not	O
find	O
any	O
failure	O
in	O
LMDB	B-Language
that	O
would	O
occur	O
in	O
the	O
real-world	O
file	O
systems	O
considered	O
;	O
the	O
single	O
failure	O
identified	O
by	O
the	O
study	O
in	O
LMDB	B-Language
only	O
relates	O
to	O
hypothetical	O
file	O
systems	O
.	O
</s>
<s>
paper	O
claims	O
to	O
point	O
out	O
failures	O
in	O
LMDB	B-Language
,	O
but	O
the	O
conclusion	O
depends	O
on	O
whether	O
fsync	O
or	O
fdatasync	O
is	O
utilised	O
.	O
</s>
<s>
The	O
selection	O
of	O
fsync	O
or	O
fdatasync	O
is	O
a	O
compile-time	O
switch	O
that	O
is	O
not	O
the	O
default	O
behavior	O
in	O
current	O
Linux	B-Application
builds	O
of	O
LMDB	B-Language
but	O
is	O
the	O
default	O
on	O
macOS	B-Application
,	O
*	O
BSD	O
,	O
Android	O
,	O
and	O
Windows	B-Application
.	O
</s>
<s>
Default	O
Linux	B-Application
builds	O
of	O
LMDB	B-Language
are	O
,	O
therefore	O
,	O
the	O
only	O
ones	O
vulnerable	O
to	O
the	O
problem	O
discovered	O
by	O
the	O
zhengmai	O
researchers	O
however	O
,	O
LMDB	B-Language
may	O
simply	O
be	O
rebuilt	O
by	O
Linux	B-Application
users	O
to	O
utilise	O
fsync	O
instead	O
.	O
</s>
<s>
When	O
provided	O
with	O
a	O
corrupt	O
database	O
,	O
such	O
as	O
one	O
produced	O
by	O
fuzzing	O
,	O
LMDB	B-Language
may	O
crash	O
.	O
</s>
<s>
LMDB	B-Language
's	O
author	O
considers	O
the	O
case	O
unlikely	O
to	O
be	O
concerning	O
but	O
has	O
produced	O
a	O
partial	O
fix	O
in	O
a	O
separate	O
branch	O
.	O
</s>
<s>
In	O
June	O
2013	O
,	O
Oracle	B-Application
changed	O
the	O
license	O
of	O
Berkeley	B-Language
DB	I-Language
(	O
a	O
related	O
project	O
)	O
from	O
the	O
Sleepycat	B-License
license	I-License
to	O
the	O
Affero	O
General	O
Public	O
License	O
,	O
thus	O
restricting	O
its	O
use	O
in	O
a	O
wide	O
variety	O
of	O
applications	O
.	O
</s>
<s>
The	O
discussion	O
was	O
sparked	O
over	O
whether	O
the	O
same	O
licensing	O
change	O
could	O
happen	O
to	O
LMDB	B-Language
.	O
</s>
<s>
Author	O
Howard	O
Chu	O
clarified	O
that	O
LMDB	B-Language
is	O
part	O
of	O
the	O
OpenLDAP	B-Language
project	O
,	O
which	O
had	O
its	O
BSD-style	O
license	O
before	O
he	O
joined	O
,	O
and	O
it	O
will	O
stay	O
like	O
it	O
.	O
</s>
<s>
No	O
copyright	O
is	O
transferred	O
to	O
anybody	O
by	O
checking	O
in	O
,	O
which	O
would	O
make	O
a	O
similar	O
move	O
like	O
Oracle	B-Application
's	O
impossible	O
.	O
</s>
<s>
The	O
Berkeley	B-Language
DB	I-Language
license	O
issue	O
has	O
caused	O
major	O
Linux	B-Application
distributions	O
such	O
as	O
Debian	O
to	O
completely	O
phase	O
out	O
their	O
use	O
of	O
Berkeley	B-Language
DB	I-Language
,	O
with	O
a	O
preference	O
for	O
LMDB	B-Language
.	O
</s>
<s>
There	O
are	O
wrappers	O
for	O
several	O
programming	O
languages	O
,	O
such	O
as	O
C++	O
,	O
Java	O
,	O
Python	B-Language
,	O
Lua	O
,	O
Rust	O
,	O
Go	O
,	O
Ruby	O
,	O
Objective	O
C	B-Language
,	O
Javascript	O
,	O
C#	O
,	O
Perl	O
,	O
PHP	O
,	O
Tcl	O
and	O
Common	O
Lisp	O
.	O
</s>
<s>
Howard	O
Chu	O
ported	O
SQLite	B-Language
3.7.7.1	O
to	O
use	O
LMDB	B-Language
instead	O
of	O
its	O
original	O
B-tree	B-Architecture
code	O
,	O
calling	O
the	O
end	O
result	O
SQLightning	O
.	O
</s>
<s>
One	O
cited	O
insert	O
test	O
of	O
1000	O
records	O
was	O
20	O
times	O
faster	O
(	O
than	O
the	O
original	O
SQLite	B-Language
with	O
its	O
B-Tree	B-Architecture
implementation	O
)	O
.	O
</s>
<s>
LMDB	B-Language
is	O
available	O
as	O
a	O
backing	O
store	O
for	O
other	O
open	O
source	O
projects	O
including	O
Cyrus	O
SASL	O
,	O
Heimdal	O
Kerberos	O
,	O
and	O
OpenDKIM	O
.	O
</s>
<s>
LMDB	B-Language
was	O
used	O
to	O
make	O
the	O
in-memory	O
store	O
Redis	B-Operating_System
persist	O
data	O
on	O
disk	O
.	O
</s>
<s>
The	O
existing	O
back-end	O
in	O
Redis	B-Operating_System
showed	O
pathological	O
behaviour	O
in	O
rare	O
cases	O
,	O
and	O
a	O
replacement	O
was	O
sought	O
.	O
</s>
<s>
The	O
baroque	O
API	B-Application
of	O
LMDB	B-Language
was	O
criticized	O
though	O
,	O
forcing	O
a	O
lot	O
of	O
coding	O
to	O
get	O
simple	O
things	O
done	O
.	O
</s>
<s>
An	O
independent	O
third-party	O
software	O
developer	O
utilised	O
the	O
Python	B-Language
bindings	O
to	O
LMDB	B-Language
in	O
a	O
high-performance	O
environment	O
and	O
published	O
,	O
on	O
the	O
technology	O
news	O
site	O
Slashdot	O
,	O
how	O
the	O
system	O
managed	O
to	O
successfully	O
sustain	O
200,000	O
simultaneous	O
read	O
,	O
write	O
and	O
delete	O
operations	O
per	O
second	O
(	O
a	O
total	O
of	O
600,000	O
database	O
operations	O
per	O
second	O
)	O
.	O
</s>
<s>
An	O
up-to-date	O
list	O
of	O
applications	O
using	O
LMDB	B-Language
is	O
maintained	O
on	O
the	O
main	O
web	O
site	O
.	O
</s>
<s>
Many	O
popular	O
free	B-Application
software	I-Application
projects	O
distribute	O
or	O
include	O
support	O
for	O
LMDB	B-Language
,	O
often	O
as	O
the	O
primary	O
or	O
sole	O
storage	O
mechanism	O
.	O
</s>
<s>
The	O
Debian	O
,	O
Ubuntu	B-Operating_System
,	O
Fedora	O
,	O
and	O
OpenSuSE	B-Operating_System
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
OpenLDAP	B-Language
for	O
which	O
LMDB	B-Language
was	O
originally	O
developed	O
via	O
.	O
</s>
<s>
Postfix	B-Application
via	O
the	O
adapter	O
.	O
</s>
<s>
PowerDNS	B-Language
,	O
a	O
DNS	O
server	O
.	O
</s>
<s>
CFEngine	B-Protocol
uses	O
LMDB	B-Language
by	O
default	O
since	O
version	O
of	O
3.6.0	O
.	O
</s>
<s>
Shopify	O
use	O
LMDB	B-Language
in	O
their	O
SkyDB	O
system	O
.	O
</s>
<s>
Knot	B-Protocol
DNS	I-Protocol
a	O
high	O
performance	O
DNS	O
server	O
.	O
</s>
<s>
Monero	B-Protocol
an	O
open	O
source	O
cryptocurrency	O
created	O
in	O
April	O
2014	O
that	O
focuses	O
on	O
privacy	O
,	O
decentralisation	O
and	O
scalability	O
.	O
</s>
<s>
Enduro/X	B-Application
middleware	O
uses	O
LMDB	B-Language
for	O
optional	O
XATMI	O
Microservices	O
(	O
SOA	O
)	O
cache	O
.	O
</s>
<s>
So	O
that	O
for	O
first	O
request	O
the	O
actual	O
service	O
is	O
invoked	O
,	O
in	O
next	O
request	O
client	O
process	O
reads	O
saved	O
result	O
directly	O
from	O
LMDB	B-Language
.	O
</s>
<s>
Nano	B-Protocol
a	O
peer-to-peer	O
,	O
open	O
source	O
cryptocurrency	O
created	O
in	O
2015	O
that	O
prioritizes	O
fast	O
and	O
fee-less	O
transactions	O
.	O
</s>
<s>
LMDB-IndexedDB	O
is	O
a	O
JavaScript	O
wrapper	O
around	O
IndexedDB	O
to	O
provide	O
support	O
for	O
LMDB	B-Language
in	O
web	O
browsers	O
.	O
</s>
<s>
LMDB	B-Language
makes	O
novel	O
use	O
of	O
well-known	O
computer	O
science	O
techniques	O
such	O
as	O
copy-on-write	B-Language
semantics	O
and	O
B+	O
trees	O
to	O
provide	O
atomicity	O
and	O
reliability	O
guarantees	O
as	O
well	O
as	O
performance	O
that	O
can	O
be	O
hard	O
to	O
accept	O
,	O
given	O
the	O
library	O
's	O
relative	O
simplicity	O
and	O
that	O
no	O
other	O
similar	O
key-value	B-Data_Structure
store	I-Data_Structure
database	O
offers	O
the	O
same	O
guarantees	O
or	O
overall	O
performance	O
,	O
even	O
though	O
the	O
authors	O
explicitly	O
state	O
in	O
presentations	O
that	O
LMDB	B-Language
is	O
read-optimised	O
not	O
write-optimised	O
.	O
</s>
<s>
Additionally	O
,	O
as	O
LMDB	B-Language
was	O
primarily	O
developed	O
for	O
use	O
in	O
OpenLDAP	B-Language
,	O
its	O
developers	O
are	O
focused	O
mainly	O
on	O
the	O
development	O
and	O
maintenance	O
of	O
OpenLDAP	B-Language
,	O
not	O
on	O
LMDB	B-Language
per	O
se	O
.	O
</s>
<s>
The	O
developers	O
limited	O
time	O
spent	O
presenting	O
the	O
first	O
benchmark	O
results	O
was	O
therefore	O
criticized	O
as	O
not	O
stating	O
limitations	O
and	O
for	O
giving	O
a	O
"	O
silver	O
bullet	O
impression	O
"	O
not	O
adequate	O
to	O
address	O
an	O
engineers	O
attitude	O
(	O
it	O
has	O
to	O
be	O
pointed	O
out	O
that	O
the	O
concerns	O
raised	O
however	O
were	O
later	O
adequately	O
addressed	O
to	O
the	O
reviewer	O
's	O
satisfaction	O
by	O
the	O
key	O
developer	O
behind	O
LMDB	B-Language
.	O
)	O
</s>
<s>
Database	O
developer	O
Oren	O
Eini	O
wrote	O
a	O
12-part	O
series	O
of	O
articles	O
on	O
his	O
analysis	O
of	O
LMDB	B-Language
,	O
beginning	O
July	O
9	O
,	O
2013	O
.	O
</s>
<s>
This	O
review	O
,	O
conducted	O
by	O
a	O
.NET	O
developer	O
with	O
no	O
former	O
experience	O
of	O
C	B-Language
,	O
concluded	O
on	O
August	O
22	O
,	O
2013	O
with	O
"	O
beyond	O
my	O
issues	O
with	O
the	O
code	O
,	O
the	O
implementation	O
is	O
really	O
quite	O
brilliant	O
.	O
</s>
<s>
The	O
way	O
LMDB	B-Language
manages	O
to	O
pack	O
so	O
much	O
functionality	O
by	O
not	O
doing	O
things	O
is	O
quite	O
impressive	O
...	O
</s>
<s>
Multiple	O
other	O
reviews	O
cover	O
LMDB	B-Language
in	O
various	O
languages	O
including	O
Chinese	O
.	O
</s>
