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2013-02-15-Data-Warehouse.html
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2013-02-15-Data-Warehouse.html
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<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en">
<head>
<title>2013-02-15-Data-Warehouse</title>
<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/>
<meta name="title" content="2013-02-15-Data-Warehouse"/>
<meta name="generator" content="Org-mode"/>
<meta name="generated" content="2013-02-15 07:59:48 PST"/>
<meta name="author" content="Jim Blomo"/>
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</head>
<body>
<div id="preamble">
</div>
<div id="content">
<h1 class="title">2013-02-15-Data-Warehouse</h1>
<div id="table-of-contents">
<h2>Table of Contents</h2>
<div id="text-table-of-contents">
<ul>
<li><a href="#sec-1">1 Data Warehouse</a></li>
<li><a href="#sec-2">2 Database Types</a>
<ul>
<li><a href="#sec-2-1">2.1 Data Mining</a></li>
</ul>
</li>
<li><a href="#sec-3">3 Properties</a>
<ul>
<li><a href="#sec-3-1">3.1 Examples</a></li>
</ul>
</li>
<li><a href="#sec-4">4 OLAP or OLTP?</a></li>
<li><a href="#sec-5">5 Overview</a>
<ul>
<li><a href="#sec-5-1">5.1 From the front</a></li>
</ul>
</li>
<li><a href="#sec-6">6 Types of Data Warehouses</a>
<ul>
<li><a href="#sec-6-1">6.1 Vendors</a></li>
</ul>
</li>
<li><a href="#sec-7">7 Metadata</a>
<ul>
<li><a href="#sec-7-1">7.1 Considerations</a></li>
</ul>
</li>
<li><a href="#sec-8">8 Overview</a>
<ul>
<li><a href="#sec-8-1">8.1 Data Cubes</a></li>
</ul>
</li>
<li><a href="#sec-9">9 Datacube</a></li>
<li><a href="#sec-10">10 Dimensions</a>
<ul>
<li><a href="#sec-10-1">10.1 Data… Square</a></li>
<li><a href="#sec-10-2">10.2 Cube: 3rd Dimension</a>
<ul>
<li><a href="#sec-10-2-1">10.2.1 More</a></li>
</ul>
</li>
<li><a href="#sec-10-3">10.3 Multi-Cube</a>
<ul>
<li><a href="#sec-10-3-1">10.3.1 More</a></li>
</ul>
</li>
<li><a href="#sec-10-4">10.4 Lattice</a>
<ul>
<li><a href="#sec-10-4-1">10.4.1 Moving</a></li>
</ul></li>
</ul>
</li>
<li><a href="#sec-11">11 Schemas</a>
<ul>
<li><a href="#sec-11-1">11.1 Fact table</a></li>
<li><a href="#sec-11-2">11.2 Dimension table</a></li>
<li><a href="#sec-11-3">11.3 Dimension tables</a></li>
<li><a href="#sec-11-4">11.4 Dimension tables</a></li>
<li><a href="#sec-11-5">11.5 Dimension tables</a></li>
<li><a href="#sec-11-6">11.6 Star Schema</a></li>
<li><a href="#sec-11-7">11.7 Dimensions of Dimensions</a></li>
<li><a href="#sec-11-8">11.8 Dimensions of Dimensions</a></li>
<li><a href="#sec-11-9">11.9 Dimensions of Dimensions</a></li>
<li><a href="#sec-11-10">11.10 Dimensions of Dimensions</a>
<ul>
<li><a href="#sec-11-10-1">11.10.1 Schema Name?</a></li>
</ul>
</li>
<li><a href="#sec-11-11">11.11 Snowflake Schema</a></li>
<li><a href="#sec-11-12">11.12 Constellation Schema</a></li>
</ul>
</li>
<li><a href="#sec-12">12 Data Warehouse Operations</a>
<ul>
<li><a href="#sec-12-1">12.1 Examples</a></li>
</ul>
</li>
<li><a href="#sec-13">13 Materialized Views</a>
<ul>
<li><a href="#sec-13-1">13.1 Usefulness</a></li>
</ul>
</li>
<li><a href="#sec-14">14 Architecture</a>
<ul>
<li><a href="#sec-14-1">14.1 Details</a></li>
</ul>
</li>
<li><a href="#sec-15">15 <b>Break</b></a></li>
</ul>
</div>
</div>
<div id="outline-container-1" class="outline-2">
<h2 id="sec-1"><span class="section-number-2">1</span> Data Warehouse <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-1">
</div>
</div>
<div id="outline-container-2" class="outline-2">
<h2 id="sec-2"><span class="section-number-2">2</span> Database Types <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-2">
<dl>
<dt>Data Warehouse</dt><dd>Database designed for using data to make decisions
</dd>
<dt>OLAP</dt><dd>OnLine Analytical Processing
</dd>
<dt>OLTP</dt><dd>OnLine Transactional Processing
</dd>
</dl>
</div>
<div id="outline-container-2-1" class="outline-3">
<h3 id="sec-2-1"><span class="section-number-3">2.1</span> Data Mining <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-2-1">
<ul>
<li>These databases are often the starting point for data mining in companies
</li>
<li>Most of the data sets from companies typical come from exporting some
portion of their data warehouse
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-3" class="outline-2">
<h2 id="sec-3"><span class="section-number-2">3</span> Properties <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-3">
<dl>
<dt>Subject Oriented</dt><dd>Focus on core business objects
</dd>
<dt>Integrated</dt><dd>Access to as much data as possible
</dd>
<dt>Time Variant</dt><dd>Contains historical data with time parameter
</dd>
<dt>Non-volatile</dt><dd>Updated (relatively) infrequently, in bulk
</dd>
</dl>
</div>
<div id="outline-container-3-1" class="outline-3">
<h3 id="sec-3-1"><span class="section-number-3">3.1</span> Examples <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-3-1">
<ul>
<li>Yelp users can be directed to a datacenter depending on conditions. This
data probably doesn't need to be in the DW
</li>
<li>Yelp has severl databases: log summaries, user info, salesforce. Most
useful if they are all in the same place
</li>
<li>Operationally, when someone changes their address, we just overwrite it in
the OLTP DB. But DW potentially cares about the old value
</li>
<li>OLTP writes to rows every time someone updates profile, review, etc. Lots of
simultaneous updates. DW: typically once a day, in bulk
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-4" class="outline-2">
<h2 id="sec-4"><span class="section-number-2">4</span> OLAP or OLTP? <span class="tag"><span class="slide">slide</span> <span class="animate">animate</span></span></h2>
<div class="outline-text-2" id="text-4">
<ul>
<li>Transactional Focus vs. Analytic Focus
</li>
<li>Used by Managers, Executives vs. DBAs, programmers
</li>
<li>Contains current information vs. Historical
</li>
<li>Variety of differently summarized data vs normalized
</li>
<li>Short transactions vs. Long queries
</li>
<li>Full table scans vs. Indexes on for fast lookups
</li>
<li>Simultaneous queries: 100s-1000s vs 1-100
</li>
<li>Simple updates vs Complex queries
</li>
<li>Guarenteed high performance vs Flexibility & Customization
</li>
</ul>
</div>
</div>
<div id="outline-container-5" class="outline-2">
<h2 id="sec-5"><span class="section-number-2">5</span> Overview <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-5">
<p> <img src="img/olap-overview.png" alt="img/olap-overview.png" />
</p>
</div>
<div id="outline-container-5-1" class="outline-3">
<h3 id="sec-5-1"><span class="section-number-3">5.1</span> From the front <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-5-1">
<ul>
<li>Analytics team uses charts, reports, et
</li>
<li>Generated from an OLAP server
</li>
<li>Which uses data from a data warehouse (often DW and OLAP server are
integrated)
</li>
<li>Uses a process (ETL) to move the data from other source into DW
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-6" class="outline-2">
<h2 id="sec-6"><span class="section-number-2">6</span> Types of Data Warehouses <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-6">
<dl>
<dt>Enterprise</dt><dd>turnkey solution, often expensive, sophisticated but complex
ingestion, integration, security features
</dd>
<dt>Data Mart</dt><dd>Smaller, limited in scope. Designed for specific team or
department
</dd>
<dt>Virtual</dt><dd>OLAP built on top of an OLTP database
</dd>
<dt>Cloud</dt><dd>Google BigQuery, Amazon RedShift
</dd>
</dl>
</div>
<div id="outline-container-6-1" class="outline-3">
<h3 id="sec-6-1"><span class="section-number-3">6.1</span> Vendors <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-6-1">
<dl>
<dt>Enterprise</dt><dd>Oracle, Greenplum, AsterData
</dd>
<dt>Data Mart</dt><dd>MySQL, PostgreSQL
</dd>
<dt>Virtual</dt><dd>MySQL, PostgreSQL views or admin interface
</dd>
</dl>
</div>
</div>
</div>
<div id="outline-container-7" class="outline-2">
<h2 id="sec-7"><span class="section-number-2">7</span> Metadata <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-7">
<ul>
<li>Data about the data being stored
</li>
<li>Overview: schema, languages
</li>
<li>Operational: last update, query latency
</li>
<li>Algorithms: normalization, transformation
</li>
<li>Performance: job dependencies
</li>
<li>Business: ownership, permissions
</li>
</ul>
</div>
<div id="outline-container-7-1" class="outline-3">
<h3 id="sec-7-1"><span class="section-number-3">7.1</span> Considerations <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-7-1">
<ul>
<li>As soon as several people start using the DW, they'll need to know about
how it is put together
</li>
<li>Metadata often comes as an after thought but is an important part of
scaling
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-8" class="outline-2">
<h2 id="sec-8"><span class="section-number-2">8</span> Overview <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-8">
<p> <img src="img/olap-overview.png" alt="img/olap-overview.png" />
</p>
</div>
<div id="outline-container-8-1" class="outline-3">
<h3 id="sec-8-1"><span class="section-number-3">8.1</span> Data Cubes <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-8-1">
<ul>
<li>Why are there cubes in the OLAP area?
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-9" class="outline-2">
<h2 id="sec-9"><span class="section-number-2">9</span> Datacube <span class="tag"><span class="slide">slide</span> <span class="two_col">two_col</span></span></h2>
<div class="outline-text-2" id="text-9">
<ul>
<li>Way of thinking about multi dimensional data
</li>
<li>Useful metaphor because one can reason about ways to satisfy a query
</li>
</ul>
<p> <img src="img/BorgFirstContact.jpg" alt="img/BorgFirstContact.jpg" />
</p>
</div>
</div>
<div id="outline-container-10" class="outline-2">
<h2 id="sec-10"><span class="section-number-2">10</span> Dimensions <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-10">
<table border="2" cellspacing="0" cellpadding="6" rules="groups" frame="hsides">
<caption></caption>
<colgroup><col class="left" /><col class="left" /><col class="left" /><col class="left" />
</colgroup>
<tbody>
<tr><td class="left"></td><td class="left">Day 1</td><td class="left">Day 2</td><td class="left">Day 3</td></tr>
<tr><td class="left">Region 1</td><td class="left">$200</td><td class="left">$80</td><td class="left">$600</td></tr>
<tr><td class="left">Region 2</td><td class="left">$300</td><td class="left">$90</td><td class="left">$650</td></tr>
<tr><td class="left">Region 2</td><td class="left">$400</td><td class="left">$100</td><td class="left">$700</td></tr>
</tbody>
</table>
</div>
<div id="outline-container-10-1" class="outline-3">
<h3 id="sec-10-1"><span class="section-number-3">10.1</span> Data… Square <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-10-1">
<ul>
<li>More of a data square: only 2 dimensions
</li>
<li>Advertising on Yelp
</li>
<li>Now we want to know Product TYpe of things sold (CPC, CPM, National)
</li>
</ul>
</div>
</div>
<div id="outline-container-10-2" class="outline-3">
<h3 id="sec-10-2"><span class="section-number-3">10.2</span> Cube: 3rd Dimension <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-10-2">
<p><img src="img/cube-3d.gif" alt="img/cube-3d.gif" />
</p>
</div>
<div id="outline-container-10-2-1" class="outline-4">
<h4 id="sec-10-2-1"><span class="section-number-4">10.2.1</span> More <span class="tag"><span class="notes">notes</span></span></h4>
<div class="outline-text-4" id="text-10-2-1">
<ul>
<li>Now we want to know Page Type (Business, Search, Home)
</li>
<li>Hard to draw 4 dimensions, so instead…
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-10-3" class="outline-3">
<h3 id="sec-10-3"><span class="section-number-3">10.3</span> Multi-Cube <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-10-3">
<p><img src="img/cube-4d.png" alt="img/cube-4d.png" />
</p>
</div>
<div id="outline-container-10-3-1" class="outline-4">
<h4 id="sec-10-3-1"><span class="section-number-4">10.3.1</span> More <span class="tag"><span class="notes">notes</span></span></h4>
<div class="outline-text-4" id="text-10-3-1">
<ul>
<li>Keep adding dimension as necessary
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-10-4" class="outline-3">
<h3 id="sec-10-4"><span class="section-number-3">10.4</span> Lattice <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-10-4">
<p> <img src="img/cube-lattice.jpg" alt="img/cube-lattice.jpg" />
</p>
</div>
<div id="outline-container-10-4-1" class="outline-4">
<h4 id="sec-10-4-1"><span class="section-number-4">10.4.1</span> Moving <span class="tag"><span class="notes">notes</span></span></h4>
<div class="outline-text-4" id="text-10-4-1">
<ul>
<li>Move back and forth from our 2d table
</li>
<li>To our 3d cube, to our 4d multi-cube
</li>
<li>The lower dimensions summarize table
</li>
<li>At the extreme is just the total (ie all money made)
</li>
</ul>
</div>
</div>
</div>
</div>
<div id="outline-container-11" class="outline-2">
<h2 id="sec-11"><span class="section-number-2">11</span> Schemas <span class="tag"><span class="slide">slide</span> <span class="two_col">two_col</span></span></h2>
<div class="outline-text-2" id="text-11">
<ul>
<li>Data cube a way of visualizing multi dimensional data
</li>
<li>Star schema is a way store the data in a database
</li>
</ul>
<p> <img src="img/sun.jpg" alt="img/sun.jpg" />
</p>
</div>
<div id="outline-container-11-1" class="outline-3">
<h3 id="sec-11-1"><span class="section-number-3">11.1</span> Fact table <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-1">
<p> <img src="img/star-1.png" alt="img/star-1.png" />
</p>
</div>
</div>
<div id="outline-container-11-2" class="outline-3">
<h3 id="sec-11-2"><span class="section-number-3">11.2</span> Dimension table <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-2">
<p> <img src="img/star-2.png" alt="img/star-2.png" />
</p>
</div>
</div>
<div id="outline-container-11-3" class="outline-3">
<h3 id="sec-11-3"><span class="section-number-3">11.3</span> Dimension tables <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-3">
<p> <img src="img/star-3.png" alt="img/star-3.png" />
</p>
</div>
</div>
<div id="outline-container-11-4" class="outline-3">
<h3 id="sec-11-4"><span class="section-number-3">11.4</span> Dimension tables <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-4">
<p> <img src="img/star-4.png" alt="img/star-4.png" />
</p>
</div>
</div>
<div id="outline-container-11-5" class="outline-3">
<h3 id="sec-11-5"><span class="section-number-3">11.5</span> Dimension tables <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-5">
<p> <img src="img/star-5.png" alt="img/star-5.png" />
</p>
</div>
</div>
<div id="outline-container-11-6" class="outline-3">
<h3 id="sec-11-6"><span class="section-number-3">11.6</span> Star Schema <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-6">
<p> <img src="img/star-schema.jpg" alt="img/star-schema.jpg" />
</p>
</div>
</div>
<div id="outline-container-11-7" class="outline-3">
<h3 id="sec-11-7"><span class="section-number-3">11.7</span> Dimensions of Dimensions <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-7">
<p> <img src="img/star-6.png" alt="img/star-6.png" />
</p>
</div>
</div>
<div id="outline-container-11-8" class="outline-3">
<h3 id="sec-11-8"><span class="section-number-3">11.8</span> Dimensions of Dimensions <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-8">
<p> <img src="img/star-7.png" alt="img/star-7.png" />
</p>
</div>
</div>
<div id="outline-container-11-9" class="outline-3">
<h3 id="sec-11-9"><span class="section-number-3">11.9</span> Dimensions of Dimensions <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-9">
<p> <img src="img/star-8.png" alt="img/star-8.png" />
</p>
</div>
</div>
<div id="outline-container-11-10" class="outline-3">
<h3 id="sec-11-10"><span class="section-number-3">11.10</span> Dimensions of Dimensions <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-10">
<p> <img src="img/star-9.png" alt="img/star-9.png" />
</p>
</div>
<div id="outline-container-11-10-1" class="outline-4">
<h4 id="sec-11-10-1"><span class="section-number-4">11.10.1</span> Schema Name? <span class="tag"><span class="notes">notes</span></span></h4>
<div class="outline-text-4" id="text-11-10-1">
<ul>
<li>Any guesses what this fractal looking schema is called?
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-11-11" class="outline-3">
<h3 id="sec-11-11"><span class="section-number-3">11.11</span> Snowflake Schema <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-11">
<ul>
<li>Schema with radiating dimension tables
</li>
</ul>
<p> <img src="img/star-snowflake.jpg" alt="img/star-snowflake.jpg" />
</p>
</div>
</div>
<div id="outline-container-11-12" class="outline-3">
<h3 id="sec-11-12"><span class="section-number-3">11.12</span> Constellation Schema <span class="tag"><span class="slide">slide</span></span></h3>
<div class="outline-text-3" id="text-11-12">
<ul>
<li>Schema with several fact tables and related dimensions
</li>
</ul>
<p> <img src="img/star-constilation.jpg" alt="img/star-constilation.jpg" />
</p>
</div>
</div>
</div>
<div id="outline-container-12" class="outline-2">
<h2 id="sec-12"><span class="section-number-2">12</span> Data Warehouse Operations <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-12">
<dl>
<dt>Rollup</dt><dd>Summarize data along fewer dimensions
</dd>
<dt>Drill-down</dt><dd>Get details within a particular dimension
</dd>
<dt>Slice</dt><dd>Select a particular value in a dimension
</dd>
<dt>Dice</dt><dd>Consider a subset of the values in a dimension
</dd>
<dt>Pivot</dt><dd>Swap, or rotate dimensions
</dd>
</dl>
</div>
<div id="outline-container-12-1" class="outline-3">
<h3 id="sec-12-1"><span class="section-number-3">12.1</span> Examples <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-12-1">
<dl>
<dt>Rollup</dt><dd>What countries are selling the most ads?
</dd>
<dt>Drill-down</dt><dd>Spike in Q1 ad views. Which month most responsible?
</dd>
<dt>Slice</dt><dd>Chart sales only for CPC
</dd>
<dt>Dice</dt><dd>Only look at sales in US, IT, DE
</dd>
<dt>Pivot</dt><dd>Swap axis on a chart
</dd>
</dl>
</div>
</div>
</div>
<div id="outline-container-13" class="outline-2">
<h2 id="sec-13"><span class="section-number-2">13</span> Materialized Views <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-13">
<dl>
<dt>View</dt><dd>virtual table defined by a query
</dd>
<dt>Full</dt><dd>Pre-compute and store
</dd>
<dt>None</dt><dd>Calculate summaries on the fly
</dd>
<dt>Partial</dt><dd>Variety of strategies: eg. cache results after calculating
</dd>
</dl>
</div>
<div id="outline-container-13-1" class="outline-3">
<h3 id="sec-13-1"><span class="section-number-3">13.1</span> Usefulness <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-13-1">
<ul>
<li>In DW, often storing different cubes in the lattice
</li>
<li>For the country sample, do we have those summaries stored in another DB
table? On disk? By month? Year?
</li>
<li>Storing all possible summarize expensive when loading data, and requires a
lot more storage
</li>
</ul>
</div>
</div>
</div>
<div id="outline-container-14" class="outline-2">
<h2 id="sec-14"><span class="section-number-2">14</span> Architecture <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-14">
<dl>
<dt>ROLAP</dt><dd>Relational. Implement OLAP on top of a relational database
</dd>
<dt>MOLAP</dt><dd>Multidimensional. Implements data cube as storage paradigm
</dd>
<dt>HOLAP</dt><dd>Hybrid. Data in ROLAP, rollups in MOLAP
</dd>
<dt>Specialized</dt><dd>Often distributed storage, parallel DB technology
</dd>
<dt>NoSQL</dt><dd>Store data as key-value pairs, optimized in different ways
</dd>
</dl>
</div>
<div id="outline-container-14-1" class="outline-3">
<h3 id="sec-14-1"><span class="section-number-3">14.1</span> Details <span class="tag"><span class="notes">notes</span></span></h3>
<div class="outline-text-3" id="text-14-1">
<dl>
<dt>ROLAP</dt><dd>MySQL, PostgreSQL
</dd>
<dt>MOLAP</dt><dd>Oracle, Palo
</dd>
<dt>HOLAP</dt><dd>MS SQL
</dd>
<dt>???</dt><dd>Specialized: AsterData, Greenplumb
</dd>
<dt>???</dt><dd>NoSQL: Hive, BigTable, Cassandra
</dd>
</dl>
</div>
</div>
</div>
<div id="outline-container-15" class="outline-2">
<h2 id="sec-15"><span class="section-number-2">15</span> <b>Break</b> <span class="tag"><span class="slide">slide</span></span></h2>
<div class="outline-text-2" id="text-15">
<script type="text/javascript" src="production/org-html-slideshow.js"></script>
</div>
</div>
</div>
<div id="postamble">
<p class="date">Date: 2013-02-15 07:59:48 PST</p>
<p class="author">Author: Jim Blomo</p>
<p class="creator">Org version 7.8.02 with Emacs version 23</p>
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