Workshop on Database Aspects Explored by Wisconsin's New DB Researchers 


December 11, 2017 from 9:30AM-10:45AM, and

December 13, 2017 from 9:30AM-10:45AM

in 1257 CS
Madison, WI


icnic Point at dawn
Picnic Point at Dawn. Photo by: Jeff Miller, UW-Madison University Communications


Dec 11, 2017                9:30AM-10:45AM, 1257 CS

9:30-9:45 AM

Adding Global Indices in Quickstep

Lokananda Dhage Munisamappa and Om Jadhav

Quickstep is a new data processing platform being developed at the U. Wisconsin. It currently has a block-based storage that includes support for indices that are local to a block; i.e. there are not traditional global indices. In this talk we describe our design and implement of a global index in Quickstep.

9:45-10:00 AM

Building a Suffix Tree/Array index on string attributes in QuickStep
Sudarshan Avish Maru and Arpith Neelavara

The goal of this project is to study suffix trees and arrays, compare them with respect to time and space efficiency and build an index-based search for the string attributes in Quickstep. A suffix tree is a data structure which represents all the suffixes of a given string whereas a suffix array is an ordered array of suffixes of the text. As these are very powerful data structures, they have numerous applications. Some of these are string matching, finding longest common substring or subsequence between two strings etc. Our aim here is to study these for implementing an efficient search for string patterns in Quickstep, and in this talk we describe our initial approach.

10:00-10:15 AM

Decomposing the Monolithic Database

Dennis Zhou


Databases today adhere to a monolithic process model where all services are consolidated. While this makes sense for box product databases, this model is problematic at scale where cloud providers must keep these services online. Furthermore, when partnering with a cloud provider that also owns the software, there is the opportunity to roll out both bug fixes and performance improvements. In this talk, I will discuss decomposing the monolithic model and the benefits of such a model in the cloud.

10:15-10:30 AM

Revisiting query scheduling policies for Lambda Functions

Karan Bavishi

Lambda Functions have been gaining a lot of traction recently as a way of deploying applications. They promise reduced costs as the user is only charged for the actual execution time and not idle capacity. Lambdas also have a deadline associated with them equal to the configured timeout. Current query scheduling algorithms such as FIFO can result in higher costs, especially for short queries. We explore an alternative policy based on Earliest Deadline First, which tries to exploit buffer pool locality by comparing predicates. Results show that median job response time is improved by about 5.6X, but results in 2.7X worse times for the 99th %ile

10:30-10:45 AM

Efficient Storage and Retrieval of JSON objects in relational systems

Saranya Baskaran and Palaniappan Nagarajan

There has been an explosion of RESTful services, that uses JSON format for exchanging data, including using NOSQL storage for such data. Although these NoSQL storages have few significant advantages in storing semi structured data, they lack the advantages of traditional RDBMS. Our proposal is an efficient way to store and manipulate such semi structured/unstructured JSON data on top of a relational/SQL based system. We present our approach and point to our plans to conduct a detailed evaluation.


Dec 13, 2017                9:30AM-10:45AM, 1257 CS

9:30-9:45 AM

Adding Fine-grained Concurrency control in Quickstep
Aribhit Mishra and Akila Nagamani

Quickstep is a new data processing kernel that is being developed in the Computer Sciences Department at the University of Wisconsin. Currently, the system has a basic DB-level locking scheme, where the entire database gets locked for a transaction. This project aims to modify the Lock manager in Quickstep to use intentional locks at a lower granularity level; and potentially, extend it to perform lock escalation when necessary. In this talk, we will describe our work on implementing a Gray-style locking manager in Quickstep.

9:45-10:00 AM

Pre-Execution Concurrency Control Using Predicate Logic
Robert Claus and Yuanchen Li

To achieve fully serializability, we propose a mechanism that enforces a serialized transaction order prior to query execution. To do this we analyze the theoretical tuples (based on the SQL request) a query could possibly touch before beginning query execution. This allows the database system to admit only those queries that are known not to conflict with other active queries. Compared to other locking mechanisms, this approach reduces runtime system complexity since isolation is handled completely outside of query execution.

10:00-10:15 AM

Integration of Bitweaving and Quickstep
Song Zhao and Kan Wu

Modern servers have a large amount of compute power and optimizing single box performance is important. In this talk, we will introduce our work to integrate BitWeaving in the current open-source version of Quickstep, with the goal of exploiting the full potential of a single machine for scan. We present our implementation and selected benchmark results.

10:15-10:30 AM

Comparing Different Join Algorithms: Partitioning vs Non-partitioning

Philip Martinkus and Zubeyr Eryilmaz

We have compared several in-memory hash-based joining algorithms on a modern multicore system. We have focused on the best two algorithms: radix partitioning and no partitioning. Our results show that each algorithm has its own strengths and weaknesses. For uniform data the radix partitioning is faster and for skewed data no partitioning performs better.

10:30-10:45 AM

Fusing Multiple Hash Join Operators

Dylan Bacon and Aarati Kakaraparthy


We will discuss the inefficiencies faced by Quickstep with how it processes multiple equijoin hash joins in a row. Our solution, to attempt to fuse together multiple operators into single operators to save on the processing and data streaming between operators, will be presented, as well as challenges and results that we have seen along the way with this work. Future expansions of the new operators will also be discussed.


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