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1. Top results related to when to use wikidata's elasticsearch index?

   • when to use multilevel index

     Top Answer

     Answered May 07, 2013 · 1 votes

     First a slight terminological clarification...

     Primary index is simply an index under a primary key. Secondary index is any other index. So this is orthogonal to "simple" vs. "composite" (aka. "compound" or what you call "multilevel") index: primary index may or may not be composite and secondary index may or may not be composite.

     To answer your question...

     Depends on the database structure (PKs, FKs and clustering) and queries you intend to run.

     For example, the database structure might imply:

     • There will likely be a composite index on Course_module {course_code, module_code}, to support its PK.
     • There will likely be an index on Course_module {module_code} to support the FK.
     • If you wish to cluster (aka. "index-organize") the courses based on course_leader, there will be a clustering index on {course_leader}1.
     • Etc, etc...

     The querying needs might imply:

     • If you wish to find a course with given course_name, only and index on {course_name} is needed (for good performance).
     • If you wish to find a course with given course_name and course_leader a composite index on {course_name, course_leader} is needed.
     • If you wish to get courses that belong to the given course_leader you'll need an index on {course_leader}, but if your SELECT list contains only course_name, you might consider covering the query with the composite index {course_leader, course_name}.
     • Etc, etc...

     Each additional index lowers the performance of INSERT/UPDATE/DELETE so the index design is a balancing act between read and write performance.

     All this stems from the structure of B-Trees and how they are used to satisfy various database operations. The complete treatment of this subject is really beyond the scope of any single StackOverflow answer, but if you are interested, i warmly recommend reading from start to finish: Use The Index, Luke!

     1 Some DBMSes don't support clustering at all, and most of those that do require the clustering key to equal the PK. MS SQL Server is a notable exception - you can cluster the data on a key different from PK.

     Check all answers on Stack Overflow

     1/5

   • Elasticsearch does not work when try to use with python

     Top Answer

     Answered Nov 03, 2022 · 1 votes

     take a look at the docs, basically you need to use the below if you want to connect to Elasticsearch locally;

     client = Elasticsearch("http://localhost:9200")indexName = "art"client.indices.create(index=indexName)-

     • client tells where this instance needs to connect to to talk to Elasticsearch
     • indexName is the name of the index you want to use
     • the last line is the action, what you want to do, ie create the index you defined

     Check all answers on Stack Overflow

     2/5

   • when to use index.php instead of index.html

     Top Answer

     Answered Jan 08, 2013 · 58 votes

     You will have to choose the PHP extension (.php) when you want php code to be executed in the file. PHP code is code between the opening <?php or <? and the closing ?> tags.

     When no PHP code should be executed you can use the .html extension.

     Usually when using the .php extension you are telling the web server, that it should use a php interpreter to process the file before it will be delivered to the browser. The php interpreter will then replace all content between the <?php and ?> by the output of the PHP code. Just as if you wrote it manually. The processed file will then be delivered to the browser.

     However, using the .php extension to tell the web server to process php code is configurable. If you want you can use other file extensions too.

     There is another thing that should be pointed out. When you only type the url path (without a filename) like :

     http://www.myserver.com/-

     there is an order of extensions (filenames) which the webserver (apache) searches for an index document. For example an apache config may contain a section like:

     <IfModule mod_dir.c> DirectoryIndex index.html index.cgi index.pl index.php index.xhtml index.htm</IfModule>

     Meaning that the index document is searched in the order above. This means if you place an index.html and a index.php in the same folder - and having the configuration above - always the index.html would be delivered by the server.

     Other Answers

     Answered Nov 17, 2015 · 9 votes

     It will not hurt a website if you serve every page as .php. Apache is very fast to serve any php, let alone one which contains only static html.

     As a beginner you may find php will benefit you, by allowing you to creating simple templates. Site header and footer includes for instance could be written in one file, then included in all the other pages.

     Other Answers

     Answered Jan 08, 2013 · 8 votes

     Its not a big deal whether you use index.php or index.html. You ca use anyone of either. Only thing is you need PHP(or any other server side scripting language) to make your site dynamic.

     Like you have a login page,you can surely make it as inde.html but your logics would either have to be in a different file or embedded in HTMl.

     Check all answers on Stack Overflow

     3/5

   • When to use composite index and covering index in SQL Server?

     Top Answer

     Answered Dec 15, 2014 · 6 votes

     • The composite index (where all of the columns are “key” columns) will carry the data in all levels of the index; the INCLUDE index will only carry the “non key” columns in the leaf node. Take away: The INCLUDE index will be smaller than the equivalent composite index.
     • The INCLUDE columns(non-key) will not count towards the max index size (900 bytes).
     • Updates to non-key columns in INCLUDE indexes will not contribute to index fragmentation; updates to unused “key” columns in the composite index will result in fragmentation… IMO, this is a biggie.
     • Assuming low index fragmentation, both composite and INCLUDE indexes will perform comparably. All columns in the composite index need not be in the query predicate.

     Check all answers on Stack Overflow

     4/5

   • When to use a negative index for substring

     Top Answer

     Answered Aug 15, 2016 · 2 votes

     From Substring Documentation:

     Syntax for substring:

     SUBSTRING ( expression ,start , length ) -

     start

     Is an integer or bigint expression that specifies where the returned characters start. If start is less than 1, the returned expression will begin at the first character that is specified in expression. In this case, the number of characters that are returned is the largest value of either the sum of start + length- 1 or 0. If start is greater than the number of characters in the value expression, a zero-length expression is returned.

     length

     Is a positive integer or bigint expression that specifies how many characters of the expression will be returned. If length is negative, an error is generated and the statement is terminated. If the sum of start and length is greater than the number of characters in expression, the whole value expression beginning at start is returned

     Now coming to your question..

     SELECT SUBSTRING('ab,', 0, LEN('ab,')) -- why?---start at zero and get values till whatever count of `LEN('ab,')` this returnsSELECT SUBSTRING('ab,', -1, LEN('ab,') + 1) -- why?--We know if start is negative,substring starts at 0 from above documentationSELECT SUBSTRING('ab,', -2, LEN('ab,') + 2) -- why?--We know if start is negative,substring starts at 0 from above documentation

     when to use Negative Substring: As you can see ,it doesn't matter when you use negative start or zero,SQL will always start from 0 in both of the cases..

     There are no use cases,i can thinkoff, when the behaviour of specfying negative length is helpfull..

     this mighttt be added to documentation,since some times,when we want to add length of start dynamically and specify some thing like below..

     CHARINDEX('somesearchitem', 'Expression, 5)-10

     The above expression will some times lead to negative values,in this case SQL will start from starting of expression unlike throwing an error like in the case of length

     Check all answers on Stack Overflow

     5/5

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2. www.geeksforgeeks.org › using-the-elasticsearchUsing the Elasticsearch Bulk API for High-Performance Indexing

   www.geeksforgeeks.org › using-the-elasticsearch

   • Cached

   11 hours ago · The Elasticsearch Bulk API is a powerful tool for high-performance indexing, enabling you to efficiently ingest large volumes of data. By combining multiple operations into a single request, you can significantly improve indexing performance and throughput. This article has provided a comprehensive guide to using the Bulk API, including ...

3. convesio.com › knowledgebase › articleWhat Is Elasticsearch: A Comprehensive Guide - Convesio ...

   convesio.com › knowledgebase › article

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   1 day ago · Elasticsearch is an open-source, distributed search and analytics engine built on top of the Apache Lucene library. It is designed to be highly scalable and can handle large amounts of data seamlessly. Elasticsearch provides a real-time, full-text search capability, making it ideal for applications and use cases that require fast and accurate ...

4. www.geeksforgeeks.org › handling-document-updatesHandling Document Updates, Deletes, and Upserts in Elasticsearch

   www.geeksforgeeks.org › handling-document-updates

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   11 hours ago · Updating a document in Elasticsearch can be done using the _update API. This allows you to modify the fields of an existing document without reindexing the entire document. Example: Updating a Document. Assume we have an index called myindex with a document representing a user. Step 1: Indexing a Document.

5. www.softwaretestinghelp.com › elasticsearch-tutorialWhat is Elasticsearch: The Ultimate Tutorial for Beginners

   www.softwaretestinghelp.com › elasticsearch-tutorial

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   5 days ago · Elasticsearch is a search platform with fast search capabilities. It is a Lucene-based search engine that was developed in Java but supports clients in different languages like PHP, Python, C#, and Ruby. It is most useful for full-text search and analysis. So, what does it do?

6. professional.wiki › en › articlesSemantic Wikibase: Using Wikidata in Your Wiki

   professional.wiki › en › articles

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   3 days ago · Enriching local data sets with data from Wikidata. Visualizing data from Wikidata with all SMW visualization formats. Using existing SMW tooling to analyze and work with Wikidata data. Creating (simplified) projections of Wikidata data. Comparing local values with those in Wikidata.

7. trycatchdebug.net › news › 1267634Prefix Query Issue with Elasticsearch and Asset Numbers

   trycatchdebug.net › news › 1267634

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   4 days ago · In this article, we will discuss a common issue faced when retrieving documents using the prefix query in Elasticsearch, specifically when dealing with an index field named asset_number. Understanding the Prefix Query. The prefix query in Elasticsearch is a type of query that matches documents based on a specified prefix.

8. www.alibabacloud.com › help › enElasticsearch:Use ILM to separate hot data and cold data

   www.alibabacloud.com › help › en

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   4 days ago · This topic describes how to use the index lifecycle management (ILM) feature to separate hot data and cold data in an Alibaba Cloud Elasticsearch cluster. The separation enables the hot-warm architecture.