TY - GEN

T1 - Implementing the Comparison-Based External Sort

AU - Polyntsov, Michael

AU - Grigorev, Valentin

AU - Smirnov, Kirill

AU - Chernishev, George

PY - 2022/8/29

Y1 - 2022/8/29

N2 - In the age of big data, sorting is an indispensable operation for DBMSes and similar systems. Having data sorted can help produce query plans with significantly lower run times. It also can provide other benefits like having non-blocking operators which will produce data steadily (without bursts), or operators with reduced memory footprint. Sorting may be required on any step of query processing, i.e., be it source data or intermediate results. At the same time, the data to be sorted may not fit into main memory. In this case, an external sort operator, which writes intermediate results to disk, should be used. In this paper we consider an external sort operator of the comparison-based sort type. We discuss its implementation and describe related design decisions. Our aim is to study the impact on performance of a data structure used on the merge step. For this, we have experimentally evaluated three data structures implemented inside a DBMS. Results have shown that it is worthwhile to make an effort to implement an efficient data structure for run merging, even on modern commodity computers which are usually disk-bound. Moreover, we demonstrated that using a loser tree is a more efficient approach than both the naive approach and the heap-based one.

AB - In the age of big data, sorting is an indispensable operation for DBMSes and similar systems. Having data sorted can help produce query plans with significantly lower run times. It also can provide other benefits like having non-blocking operators which will produce data steadily (without bursts), or operators with reduced memory footprint. Sorting may be required on any step of query processing, i.e., be it source data or intermediate results. At the same time, the data to be sorted may not fit into main memory. In this case, an external sort operator, which writes intermediate results to disk, should be used. In this paper we consider an external sort operator of the comparison-based sort type. We discuss its implementation and describe related design decisions. Our aim is to study the impact on performance of a data structure used on the merge step. For this, we have experimentally evaluated three data structures implemented inside a DBMS. Results have shown that it is worthwhile to make an effort to implement an efficient data structure for run merging, even on modern commodity computers which are usually disk-bound. Moreover, we demonstrated that using a loser tree is a more efficient approach than both the naive approach and the heap-based one.

KW - External sort

KW - Query engines

KW - Query processing

UR - https://www.mendeley.com/catalogue/b76006a7-3a35-3a77-8430-5d4a9bfbb419/

UR - http://www.scopus.com/inward/record.url?scp=85137992346&partnerID=8YFLogxK

U2 - 10.1007/978-3-031-15743-1_46

DO - 10.1007/978-3-031-15743-1_46

M3 - Conference contribution

SN - 978-3-031-15742-4

VL - 1652

T3 - Communications in Computer and Information Science

SP - 500

EP - 511

BT - New Trends in Database and Information Systems - ADBIS 2022 Short Papers, Doctoral Consortium and Workshops

A2 - Chiusano, Silvia

A2 - Cerquitelli, Tania

A2 - Wrembel, Robert

A2 - Nørvåg, Kjetil

A2 - Catania, Barbara

A2 - Vargas-Solar, Genoveva

A2 - Zumpano, Ester

PB - Springer Nature

CY - Cham

Y2 - 5 September 2022 through 8 September 2022

ER -