The log-structured merge-tree (LSM-tree)
type: Item
instance of: scholarly article
title: The log-structured merge-tree (LSM-tree)
zbMATH Open document ID: 0849.68014
author: Patrick E. O'Neil
author: Dieter Gawlick
author: Elizabeth O'Neil
author: Edward Y. C. Cheng
published in: Acta Informatica
publication date: 1995-11-19T00:00:00Z
review text: High-performance transaction system applications typically insert rows in a History table to provide an activity trace; at the same time the transaction system generates log records for purposes of system recovery. Both types of generated information can benefit from efficient indexing. An example in a well-known setting is the TPC-A benchmark application, modified to support efficient queries on the history for account activity of specific accounts. This requires an index by account-id on the fast-growing history table. Unfortunately, standard disk-based index structures such as the \(B\)-tree will effectively double the I/O cost of the transaction to maintain an index such as this in real time, increasing the total system cost up to fifty percent. Clearly a method for maintaining a real-time index at low cost is desirable. The Log-Structured Merge-tree (LSM-tree) is a disk-based data structure designed to provide low-cost indexing for a file experiencing a high rate of record inserts (and deletes) over an extended period. The LSM-tree uses an algorithm that defers and batches index changes, cascading the changes from a memory based component through one or more disk components in an efficient manner reminiscent of merge sort. During this process all index values are continuously accessible to retrievals (aside from very short locking periods), either through the memory component or one of the disk components. The algorithm greatly reduces disk arm movements compared to a traditional access methods such as \(B\)-trees, and will improve cost-performance in domains where disk arm costs for inserts with traditional access method overwhelm storage media costs. The LSM-tree approach also generalizes to operations other than insert and delete. However, indexed finds requiring immediate response will lose I/O efficiency in some cases, so the LSM-tree is most useful in applications where index inserts are more common than finds that retrieve the entries. This seems to be a…
Mathematics Subject Classification ID: 68P05
Mathematics Subject Classification ID: 68P20
zbMATH DE Number: 814157
zbMATH Keywords: log-structured merge-tree
zbMATH Keywords: transaction system
zbMATH Keywords: real-time index
zbMATH Keywords: disk-based data structure
zbMATH Keywords: low-cost indexing
zbMATH Keywords: History tables
zbMATH Keywords: log files
MaRDI profile type: Publication
description: scientific article; zbMATH DE number 814157