47 research outputs found
The End of Slow Networks: It's Time for a Redesign
Next generation high-performance RDMA-capable networks will require a
fundamental rethinking of the design and architecture of modern distributed
DBMSs. These systems are commonly designed and optimized under the assumption
that the network is the bottleneck: the network is slow and "thin", and thus
needs to be avoided as much as possible. Yet this assumption no longer holds
true. With InfiniBand FDR 4x, the bandwidth available to transfer data across
network is in the same ballpark as the bandwidth of one memory channel, and it
increases even further with the most recent EDR standard. Moreover, with the
increasing advances of RDMA, the latency improves similarly fast. In this
paper, we first argue that the "old" distributed database design is not capable
of taking full advantage of the network. Second, we propose architectural
redesigns for OLTP, OLAP and advanced analytical frameworks to take better
advantage of the improved bandwidth, latency and RDMA capabilities. Finally,
for each of the workload categories, we show that remarkable performance
improvements can be achieved
Tupleware: Redefining Modern Analytics
There is a fundamental discrepancy between the targeted and actual users of
current analytics frameworks. Most systems are designed for the data and
infrastructure of the Googles and Facebooks of the world---petabytes of data
distributed across large cloud deployments consisting of thousands of cheap
commodity machines. Yet, the vast majority of users operate clusters ranging
from a few to a few dozen nodes, analyze relatively small datasets of up to a
few terabytes, and perform primarily compute-intensive operations. Targeting
these users fundamentally changes the way we should build analytics systems.
This paper describes the design of Tupleware, a new system specifically aimed
at the challenges faced by the typical user. Tupleware's architecture brings
together ideas from the database, compiler, and programming languages
communities to create a powerful end-to-end solution for data analysis. We
propose novel techniques that consider the data, computations, and hardware
together to achieve maximum performance on a case-by-case basis. Our
experimental evaluation quantifies the impact of our novel techniques and shows
orders of magnitude performance improvement over alternative systems
FITing-Tree: A Data-aware Index Structure
Index structures are one of the most important tools that DBAs leverage to
improve the performance of analytics and transactional workloads. However,
building several indexes over large datasets can often become prohibitive and
consume valuable system resources. In fact, a recent study showed that indexes
created as part of the TPC-C benchmark can account for 55% of the total memory
available in a modern DBMS. This overhead consumes valuable and expensive main
memory, and limits the amount of space available to store new data or process
existing data.
In this paper, we present FITing-Tree, a novel form of a learned index which
uses piece-wise linear functions with a bounded error specified at construction
time. This error knob provides a tunable parameter that allows a DBA to FIT an
index to a dataset and workload by being able to balance lookup performance and
space consumption. To navigate this tradeoff, we provide a cost model that
helps determine an appropriate error parameter given either (1) a lookup
latency requirement (e.g., 500ns) or (2) a storage budget (e.g., 100MB). Using
a variety of real-world datasets, we show that our index is able to provide
performance that is comparable to full index structures while reducing the
storage footprint by orders of magnitude.Comment: 18 page
Structural features and kinetic characterization of alanine racemase from Staphylococcus aureus (Mu50)
The tertiary structure and kinetic properties of alanine racemase from Staphylococcus aureus are described and compared to other related alanine racemase structures
ChemInform Abstract: NEW S-PROTECTION FROM KNOWN N-PROTECTION: THIO ESTERS OF N-URETHANYL-N-METHYL-Γ-AMINOBUTYRIC ACID AS A CLASS OF PROTECTIVE GROUPS FOR THIOLS IN PEPTIDE SYNTHESIS
The prior thiol capture method for peptide synthesis
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 1984Includes bibliographical references.by Nicholas G. Galakatos.Ph. D.Ph.D. Massachusetts Institute of Technology, Department of Chemistr