Encoding (memory)

About: Encoding (memory) is a research topic. Over the lifetime, 7547 publications have been published within this topic receiving 120214 citations. The topic is also known as: memory encoding & encoding of memories.

Adaptive String Dictionary Compression in In-Memory Column-Store Database Systems

Abstract: Domain encoding is a common technique to compress the columns of a column store and to accelerate many types of queries at the same time. It is based on the assumption that most columns contain a relatively small set of distinct values, in particular string columns. In this paper, we argue that domain encoding is not the end of the story. In real world systems, we observe that a substantial amount of the columns are of string types. Moreover, most of the memory space is consumed by only a small fraction of these columns. To address this issue, we make three main contributions: First we survey several approaches and variants for dictionary compression, i. e., data structures that store the dictionary of domain encoding in a compressed way. As expected, there is a trade-off between size of the data structure and its access performance. This observation can be used to compress rarely accessed data more than frequently accessed data. Furthermore the question which approach has the best compression ratio for a certain column heavily depends on specific characteristics of its content. Consequently, as a second contribution, we present non-trivial sampling schemes for all our dictionary formats, enabling us to estimate their size for a given column. This way it is possible to identify compression schemes specialized for the content of a specific column. Third, we draft how to fully automate the decision of the dictionary format. We sketch a compression manager that selects the most appropriate dictionary format based on column access and update patterns, characteristics of the underlying data, and costs for set-up and access of the different data structures. We evaluate an off-line prototype of a compression manager using a variation of the TPC-H benchmark [15]. The compression manager can configure the database system to be anywhere in a large range of the space / time trade-off with a fine granularity, providing significantly better trade-offs than any fixed dictionary format.

Why maps improve memory for text: The influence of structural information on working memory operations

Abstract: In order to test how associated verbal and spatial stimuli are processed in memory, undergraduates studied a reference map as either an intact unit or as a series of individual features, and read a text containing facts related to map features. In addition, the map was presented either before or after reading the text. Seeing the intact map prior to the text led to better recall of both map information and facts from the text. These results support a dual coding model, where stimuli such as maps possess a retrieval advantage because they allow simultaneous representation in working memory. This advantage occurs because information from the map can be used to cue retrieval of associated verbal facts, without exceeding the processing constraints of the memorial system.

Short-term memory factors in ground controller/pilot communication

Abstract: Communication between ground controllers and pilots was simulated in a short-term memory task in order to explore sources of memory errors in the air traffic control system. As expected from prior short-term memory research, two major determinants of error probability were (1) amount of information that the pilot has to process in a given time and (2) retention interval between the time information is transmitted from the controller and the time it is acted on (recalled) by the pilot. Additionally, the manner of encoding numerical information was varied. The results of this manipulation indicated that, as suggested by recent research in cognitive psychology, the current information-encoding scheme has substantial room for improvement in terms of minimizing memory failure.

Implementation of an Experimental Fault-Tolerant Memory System

Abstract: The experimental fault-tolerant memory system described in this paper has been designed to enable the modular addition of spares, to validate the theoretical fault-secure and self-testing properties of the translator/corrector, to provide a basis for experiments using the new testing and correction processes for recovery, and to determine the practicality of such systems. The hardware design and implementation are described, together with methods of fault insertion. The hardware/ software interface, including a restricted single error correction/double error detection (SEC/DED) code, is specified. Procedures are carefully described which, 1) test for specified physical faults, 2) ensure that single error corrections are not miscorrections due to triple faults, and 3) enable recovery from double errors.