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In computer science, an inverted index (also referred to as a postings list, postings file, or inverted file) is a database index storing a mapping from content, such as words or numbers, to its locations in a table, or in a document or a set of documents (named in contrast to a forward index, which maps from documents to content). [1]
Python uses the following syntax to express list comprehensions over finite lists: S = [ 2 * x for x in range ( 100 ) if x ** 2 > 3 ] A generator expression may be used in Python versions >= 2.4 which gives lazy evaluation over its input, and can be used with generators to iterate over 'infinite' input such as the count generator function which ...
In database management systems, a reverse key index strategy reverses the key value before entering it in the index. [1] E.g., the value 24538 becomes 83542 in the index. Reversing the key value is particularly useful for indexing data such as sequence numbers , where each new key value is greater than the prior value, i.e., values ...
To reduce contention for index blocks the best strategy is to implement a reverse index. In most situations the goal is to spread queries over a greater number of blocks, to avoid concentrating on any single one.
Soundex is a phonetic algorithm for indexing names by sound, as pronounced in English. The goal is for homophones to be encoded to the same representation so that they can be matched despite minor differences in spelling. [1] The algorithm mainly encodes consonants; a vowel will not be encoded unless it is the first letter.
The forward index is sorted to transform it to an inverted index. The forward index is essentially a list of pairs consisting of a document and a word, collated by the document. Converting the forward index to an inverted index is only a matter of sorting the pairs by the words. In this regard, the inverted index is a word-sorted forward index.
List of applications and frameworks that use skip lists: Apache Portable Runtime implements skip lists. [9] MemSQL uses lock-free skip lists as its prime indexing structure for its database technology. MuQSS, for the Linux kernel, is a CPU scheduler built on skip lists. [10] [11] Cyrus IMAP server offers a "skiplist" backend DB implementation [12]
The non-clustered index tree contains the index keys in sorted order, with the leaf level of the index containing the pointer to the record (page and the row number in the data page in page-organized engines; row offset in file-organized engines). In a non-clustered index, The physical order of the rows is not the same as the index order.