hash table
LowFormal Technical
Definition
Meaning
A data structure that implements an associative array, mapping keys to values, using a hash function to compute an index into an array of buckets or slots.
A fundamental computer science data structure for efficient lookup, insertion, and deletion of key-value pairs, widely used in programming for tasks like caching, database indexing, and implementing sets.
Linguistics
Semantic Notes
This is a highly technical term from computer science. It is a compound noun, often spelled with a hyphen ('hash-table') in some style guides but increasingly seen as two words. The 'hash' refers to the hash function used to compute indices.
Dialectal Variation
British vs American Usage
Differences
No significant lexical differences. Both dialects use the same term.
Connotations
Identical technical connotations.
Frequency
Equally low-frequency and confined to technical contexts in both regions.
Vocabulary
Collocations
Grammar
Valency Patterns
The [NOUN] uses a hash table for [PURPOSE].We store the [DATA] in a hash table.The hash table's [PROPERTY] (e.g., load factor) is critical.Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Usage
Context Usage
Business
Rare, except in tech companies discussing system architecture or software performance.
Academic
Common in computer science textbooks, research papers, and lectures on data structures and algorithms.
Everyday
Virtually never used.
Technical
The primary context. Used daily by software engineers, developers, and computer scientists.
Examples
By Part of Speech
verb
British English
- The system will hash-table the user sessions for quicker retrieval.
- We need to hash-table these entries before processing.
American English
- The framework hashtables the configuration data automatically.
- We decided to hash-table the dataset to improve performance.
adjective
British English
- The hash-table lookup was incredibly fast.
- They proposed a hash-table-based solution.
American English
- We ran into a hash-table collision issue.
- The hash-table implementation is memory-efficient.
Examples
By CEFR Level
- A hash table helps computers find information very quickly.
- Many apps use a hash table to remember your login.
- To speed up the search, the developer implemented a basic hash table.
- If the hash table becomes too full, its performance can degrade.
- The algorithm's efficiency hinges on a well-tuned hash table with an effective collision resolution strategy.
- Distributed hash tables form the backbone of many peer-to-peer network architectures.
Learning
Memory Aids
Mnemonic
Think of a 'hash table' like a library's index cards (hashed by author/title) that tell you exactly which shelf (bucket) to find a book (value).
Conceptual Metaphor
A SMART POST OFFICE: Keys are addresses (hashed to a sorting bin), and values are parcels. The hash function is the postcode sorter that quickly directs each parcel to the correct local depot (bucket).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Avoid literal translation as 'таблица хеша'. The standard term is 'хеш-таблица' or 'хэш-таблица'.
- Do not confuse with a general 'table' of data ('таблица'); it is a specific, non-visual data structure.
Common Mistakes
- Using 'hashtable' as one word is common in code but often stylistically incorrect in formal prose.
- Confusing 'hash table' (the structure) with 'hash function' (the component that enables it).
- Incorrect pluralisation: 'hash tables' is correct, not 'hashes table'.
Practice
Quiz
What is the primary purpose of the hash function in a hash table?
FAQ
Frequently Asked Questions
In formal writing and most style guides, it is two words ('hash table'). However, in programming contexts and some APIs, it is often written as one word ('Hashtable' or 'hashtable').
A hash collision occurs when two different keys are hashed by the hash function to the same index in the table. Good hash table designs include strategies (like chaining or open addressing) to handle this.
Yes, the built-in Python 'dict' type is an implementation of a hash table, providing fast key-value lookups.
Hash tables are less ideal when you need to maintain a sorted order of keys, when memory overhead is a critical concern, or in real-time systems where worst-case lookup time must be guaranteed (due to potential collisions).