SherbyNet - /page/wikibook/entry.mu

Micron Document

<!DOCTYPE html>

<title>Semi-structured data</title>

</head>

<span id="openzim-page-title" class="mw-page-title-main"><span class="mw-page-title-main">Semi-structured data</span></span>

</h1>

</header>

<p><b>Semi-structured data</b><sup id="cite_ref-1" class="reference"><a href="#cite_note-1"><span class="cite-bracket">[</span>1<span class="cite-bracket">]</span></a></sup> is a form of <a href="Structured_data" class="mw-redirect" title="Structured data">structured data</a> that does not obey the tabular structure of data models associated with <a href="Relational_database" title="Relational database">relational databases</a> or other forms of <a href="Table_(database)" title="Table (database)">data tables</a>, but nonetheless contains <a href="Tag_(metadata)" title="Tag (metadata)">tags</a> or other markers to separate semantic elements and enforce hierarchies of records and fields within the data. Therefore, it is also known as <a href="Self-describing" class="mw-redirect" title="Self-describing">self-describing</a> structure.

</p><p>In semi-structured data, the entities belonging to the same class may have different <a href="Attribute_(research)" class="mw-redirect" title="Attribute (research)">attributes</a> even though they are grouped together, and the attributes' order is not important.

</p><p>Semi-structured data are increasingly occurring since the advent of the <a href="Internet" title="Internet">Internet</a> where <a href="Full-text" class="mw-redirect" title="Full-text">full-text</a> <a href="Documents" class="mw-redirect" title="Documents">documents</a> and <a href="Databases" class="mw-redirect" title="Databases">databases</a> are not the only forms of data anymore, and different applications need a medium for <a href="Information_exchange" title="Information exchange">exchanging information</a>. In <a href="Object_database" title="Object database">object-oriented databases</a>, one often finds semi-structured data.

</p>

<div class="mw-heading mw-heading2"><h2 id="Types">Types</h2></div>

<p><a href="XML" title="XML">XML</a>,<sup id="cite_ref-2" class="reference"><a href="#cite_note-2"><span class="cite-bracket">[</span>2<span class="cite-bracket">]</span></a></sup> other markup languages, <a href="Email" title="Email">email</a>, and <a href="Electronic_Data_Interchange" class="mw-redirect" title="Electronic Data Interchange">EDI</a> are all forms of semi-structured data. <a href="Object_Exchange_Model" title="Object Exchange Model">OEM</a> (Object Exchange Model)<sup id="cite_ref-3" class="reference"><a href="#cite_note-3"><span class="cite-bracket">[</span>3<span class="cite-bracket">]</span></a></sup> was created prior to XML as a means of self-describing a data structure. XML has been popularized by web services that are developed utilizing <a href="SOAP" title="SOAP">SOAP</a> principles.

</p><p>Some types of data described here as "semi-structured", especially XML, suffer from the impression that they are incapable of structural rigor at the same functional level as <a href="Relational_database" title="Relational database">Relational Tables</a> and Rows. Indeed, the view of XML as inherently semi-structured (previously, it was referred to as "unstructured") has handicapped its use for a widening range of data-centric applications. Even documents, normally thought of as the epitome of semi-structure, can be designed with virtually the same rigor as <a href="Database_schema" title="Database schema">database schema</a>, enforced by the <a href="XML_schema" title="XML schema">XML schema</a> and processed by both commercial and custom software programs without reducing their usability by human readers.

</p><p>In view of this fact, XML might be referred to as having "flexible structure" capable of human-centric flow and hierarchy as well as highly rigorous element structure and data typing.

</p><p>The concept of XML as "<a href="Human-readable" class="mw-redirect" title="Human-readable">human-readable</a>", however, can only be taken so far. Some implementations/dialects of XML, such as the XML representation of the contents of a <a href="Microsoft_Word" title="Microsoft Word">Microsoft Word</a> document, as implemented in <a href="Microsoft_Office_2007" title="Microsoft Office 2007">Office 2007</a> and later versions, utilize dozens or even hundreds of different kinds of tags that reflect a particular problem domain - in Word's case, formatting at the character and paragraph and document level, definitions of styles, inclusion of citations, etc. - which are nested within each other in complex ways. Understanding even a portion of such an XML document by reading it, let alone catching errors in its structure, is impossible without a very deep prior understanding of the specific XML implementation, along with assistance by software that understands the XML schema that has been employed. Such text is not "human-understandable" any more than a book written in Swahili (which uses the Latin alphabet) would be to an American or Western European who does not know a word of that language: the tags are symbols that are meaningless to a person unfamiliar with the domain.

</p>

<p><a href="JSON" title="JSON">JSON</a> or JavaScript Object Notation, is an open standard format that uses human-readable text to transmit data objects. JSON has been popularized by web services developed utilizing <a href="REST" title="REST">REST</a> principles.

</p><p>Databases such as <a href="MongoDB" title="MongoDB">MongoDB</a> and <a href="Couchbase" class="mw-redirect" title="Couchbase">Couchbase</a> store data natively in JSON format, leveraging the pros of semi-structured data architecture.

</p>

/* start https://en.wikipedia.org/ */

.mw-parser-output .ambox{border:1px solid #a2a9b1;border-left:10px solid #36c;background-color:#fbfbfb;box-sizing:border-box}.mw-parser-output .ambox+link+.ambox,.mw-parser-output .ambox+link+style+.ambox,.mw-parser-output .ambox+link+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+style+.ambox,.mw-parser-output .ambox+.mw-empty-elt+link+link+.ambox{margin-top:-1px}html body.mediawiki .mw-parser-output .ambox.mbox-small-left{margin:4px 1em 4px 0;overflow:hidden;width:238px;border-collapse:collapse;font-size:88%;line-height:1.25em}.mw-parser-output .ambox-speedy{border-left:10px solid #b32424;background-color:#fee7e6}.mw-parser-output .ambox-delete{border-left:10px solid #b32424}.mw-parser-output .ambox-content{border-left:10px solid #f28500}.mw-parser-output .ambox-style{border-left:10px solid #fc3}.mw-parser-output .ambox-move{border-left:10px solid #9932cc}.mw-parser-output .ambox-protection{border-left:10px solid #a2a9b1}.mw-parser-output .ambox .mbox-text{border:none;padding:0.25em 0.5em;width:100%}.mw-parser-output .ambox .mbox-image{border:none;padding:2px 0 2px 0.5em;text-align:center}.mw-parser-output .ambox .mbox-imageright{border:none;padding:2px 0.5em 2px 0;text-align:center}.mw-parser-output .ambox .mbox-empty-cell{border:none;padding:0;width:1px}.mw-parser-output .ambox .mbox-image-div{width:52px}@media(min-width:720px){.mw-parser-output .ambox{margin:0 10%}}@media print{body.ns-0 .mw-parser-output .ambox{display:none!important}}

/* end https://en.wikipedia.org/ */

</style>

<div class="mw-heading mw-heading3"><h3 id="Advantages">Advantages</h3></div>

<ul><li>Programmers persisting objects from their application to a database do not need to worry about <a href="Object-relational_impedance_mismatch" class="mw-redirect" title="Object-relational impedance mismatch">object-relational impedance mismatch</a>, but can often serialize objects via a light-weight library.</li>

<li>Support for nested or hierarchical data often simplifies data models representing complex relationships between entities.</li>

<li>Support for lists of objects simplifies data models by avoiding messy translations of lists into a relational data model.</li></ul>

<div class="mw-heading mw-heading3"><h3 id="Disadvantages">Disadvantages</h3></div>

<ul><li>The traditional relational data model has a popular and ready-made query language, <a href="SQL" title="SQL">SQL</a>.</li>

<li>Prone to "garbage in, garbage out"; by removing restraints from the data model, there is less forethought that is necessary to operate a data application.</li></ul>

<div class="mw-heading mw-heading2"><h2 id="Semi-structured_model">Semi-structured model</h2></div>

<p>The <b>semi-structured model</b> is a <a href="Database_model" title="Database model">database model</a> where there is no separation between the <a href="Data_(computing)" class="mw-redirect" title="Data (computing)">data</a> and the <a href="Database_schema" title="Database schema">schema</a>, and the amount of structure used depends on the purpose.

</p><p>The advantages of this model are the following:

</p>

<ul><li>It can represent the information of some data sources that cannot be constrained by schema.</li>

<li>It provides a flexible format for data exchange between different types of databases.</li>

<li>It can be helpful to view structured data as semi-structured (for browsing purposes).</li>

<li>The schema can easily be changed.</li>

<li>The data transfer format may be portable.</li></ul>

<p>The primary trade-off being made in using a semi-structured <a href="Database_model" title="Database model">database model</a> is that queries cannot be made as efficiently as in a more constrained structure, such as in the <a href="Relational_model" title="Relational model">relational model</a>. Typically the records in a semi-structured database are stored with unique IDs that are referenced with pointers to their location on disk. This makes navigational or path-based queries quite efficient, but for doing searches over many records (as is typical in <a href="SQL" title="SQL">SQL</a>), it is not as efficient because it has to seek around the disk following pointers.

</p><p>The <a href="Object_Exchange_Model" title="Object Exchange Model">Object Exchange Model</a> (OEM) is one standard to express semi-structured data, another way is <a href="XML" title="XML">XML</a>.

</p>

<ul><li><a href="NoSQL" title="NoSQL">NoSQL</a></li>

<li><a href="Unstructured_data" title="Unstructured data">Unstructured data</a></li>

<li><a href="Structured_data" class="mw-redirect" title="Structured data">Structured data</a></li></ul>

<div class="mw-heading mw-heading2"><h2 id="References">References</h2></div>

/* start https://en.wikipedia.org/ */

.mw-parser-output cite.citation{font-style:inherit;word-wrap:break-word}.mw-parser-output .citation q{quotes:"\"""\"""'""'"}.mw-parser-output .citation:target{background-color:rgba(0,127,255,0.133)}.mw-parser-output .id-lock-free.id-lock-free a{background:url("./mw/Lock-green.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-limited.id-lock-limited a,.mw-parser-output .id-lock-registration.id-lock-registration a{background:url("./mw/Lock-gray-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .id-lock-subscription.id-lock-subscription a{background:url("./mw/Lock-red-alt-2.svg")right 0.1em center/9px no-repeat}.mw-parser-output .cs1-ws-icon a{background:url("./mw/Wikisource-logo.svg")right 0.1em center/12px no-repeat}body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-free a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-limited a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-registration a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .id-lock-subscription a,body:not(.skin-timeless):not(.skin-minerva) .mw-parser-output .cs1-ws-icon a{background-size:contain;padding:0 1em 0 0}.mw-parser-output .cs1-code{color:inherit;background:inherit;border:none;padding:inherit}.mw-parser-output .cs1-hidden-error{display:none;color:var(--color-error,#d33)}.mw-parser-output .cs1-visible-error{color:var(--color-error,#d33)}.mw-parser-output .cs1-maint{display:none;color:#085;margin-left:0.3em}.mw-parser-output .cs1-kern-left{padding-left:0.2em}.mw-parser-output .cs1-kern-right{padding-right:0.2em}.mw-parser-output .citation .mw-selflink{font-weight:inherit}@media screen{.mw-parser-output .cs1-format{font-size:95%}html.skin-theme-clientpref-night .mw-parser-output .cs1-maint{color:#18911f}}@media screen and (prefers-color-scheme:dark){html.skin-theme-clientpref-os .mw-parser-output .cs1-maint{color:#18911f}}

/* end https://en.wikipedia.org/ */

</style><cite id="CITEREFPeter_Buneman1997" class="citation web cs1">Peter Buneman (1997). <a rel="nofollow" class="external text" href="https://homepages.inf.ed.ac.uk/opb/papers/PODS1997a.pdf">"Semistructured data"</a> <span class="cs1-format">(PDF)</span>. <i>Symposium on Principles of Database Systems</i>.</cite></span>

</li>

<li id="cite_note-2"><span class="mw-cite-backlink"><b><a href="#cite_ref-2">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://db.cis.upenn.edu/research/SS_XML.html">The Penn database group has semi-structured and XML data project</a></span>

</li>

<li id="cite_note-3"><span class="mw-cite-backlink"><b><a href="#cite_ref-3">^</a></b></span> <span class="reference-text"><a rel="nofollow" class="external text" href="http://infolab.stanford.edu/lore/home/index.html">Stanford Universities Lore DBMS</a></span>

</li>

</ol></div>

<div class="mw-heading mw-heading2"><h2 id="External_links">External links</h2></div>

<ul><li><a rel="nofollow" class="external text" href="http://db.cis.upenn.edu/research/SS_XML.html">UPenn Database Group</a> – semi-structured data and XML</li>

<li><a rel="nofollow" class="external text" href="http://www.ibmbigdatahub.com/blog/semi-structured-data-analytics-relational-or-hadoop-platform-part-1">Semi-Structured data analytics: Relational or Hadoop platform?</a> by IBM</li>

<li><a rel="nofollow" class="external text" href="https://www.crowdstrike.com/en-us/cybersecurity-101/cloud-security/semi-structured-data/">Semi-Structured Data Explained</a> by CROWDSTRIKE</li></ul></div><div><div class="zim-footer">

This article is issued from <a class="external text" title="Last edited on 2025-08-03" href="https://en.wikipedia.org/wiki/?title=Semi-structured_data&oldid=1304016268">Wikipedia</a>. The text is available under <a class="external text" href="https://creativecommons.org/licenses/by-sa/4.0/deed.en">Creative Commons Attribution-Share Alike 4.0</a> unless otherwise noted. Additional terms may apply for the media files.

</div>

</div></div>

</div>

</main>

</div>

</body></html>