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  <doc>
    <id>3731</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
    <thesisYearAccepted/>
    <language>eng</language>
    <pageFirst>1605</pageFirst>
    <pageLast>1608</pageLast>
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    <publisherName>IEEE</publisherName>
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    <title language="eng">Curating Variational Data in Application Development</title>
    <abstract language="eng">Building applications for processing data lakes is a software engineering challenge. We present Darwin, a middleware for applications that operate on variational data. This concerns data with heterogeneous structure, usually stored within a schema-flexible NoSQL database. Darwin assists application developers in essential data and schema curation tasks: Upon request, Darwin extracts a schema description, discovers the history of schema versions, and proposes mappings between these versions. Users of Darwin may interactively choose which mappings are most realistic. Darwin is further capable of rewriting queries at runtime, to ensure that queries also comply with legacy data. Alternatively, Darwin can migrate legacy data to reduce the structural heterogeneity. Using Darwin, developers may thus evolve their data in sync with their code. In our hands-on demo, we curate synthetic as well as real-life datasets.</abstract>
    <parentTitle language="eng">2018 IEEE 34th International Conference on Data Engineering, 16-19 April 2018, Paris, France</parentTitle>
    <identifier type="doi">10.1109/ICDE.2018.00187</identifier>
    <enrichment key="opus.import.date">2022-04-28T18:57:25+00:00</enrichment>
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    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Uta Störl</author>
    <author>Daniel Müller</author>
    <author>Alexander Tekleab</author>
    <author>Stephane Tolale</author>
    <author>Julian Stenzel</author>
    <author>Meike Klettke</author>
    <author>Stefanie Scherzinger</author>
    <author>Uta Storl</author>
    <author>Daniel Muller</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>data migration</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Data mining</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Evolution (biology)</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>history</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>NoSQL databases</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>query rewriting</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>schema evolution</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>schema management</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Software</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Task analysis</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>variational data</value>
    </subject>
    <collection role="institutes" number="FakIM">Fakultät Informatik und Mathematik</collection>
    <collection role="othforschungsschwerpunkt" number="16311">Digitalisierung</collection>
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  <doc>
    <id>3778</id>
    <completedYear/>
    <publishedYear>2018</publishedYear>
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    <language>eng</language>
    <pageFirst>1662</pageFirst>
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    <publisherName>IEEE</publisherName>
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    <title language="eng">In for a Surprise When Migrating NoSQL Data</title>
    <abstract language="eng">Schema-flexible NoSQL data stores lend themselves nicely for storing versioned data, a product of schema evolution. In this lightning talk, we apply pending schema changes to records that have been persisted several schema versions back. We present first experiments with MongoDB and Cassandra, where we explore the trade-off between applying chains of pending changes stepwise (one after the other), and as composite operations. Contrary to intuition, composite migration is not necessarily faster. The culprit is the computational overhead for deriving the compositions. However, caching composition formulae achieves a speed up: For Cassandra, we can cut the runtime by nearly 80%. Surprisingly, the relative speedup seems to be system-dependent. Our take away message is that in applying pending schema changes in NoSQL data stores, we need to base our design decisions on experimental evidence rather than on intuition alone.</abstract>
    <parentTitle language="eng">2018 IEEE 34th International Conference on Data Engineering (ICDE), 16-19 April 2018, Paris, France</parentTitle>
    <identifier type="doi">10.1109/ICDE.2018.00202</identifier>
    <enrichment key="opus.import.date">2022-04-28T19:28:04+00:00</enrichment>
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    <licence>Keine Lizenz - Es gilt das deutsche Urheberrecht: § 53 UrhG</licence>
    <author>Uta Störl</author>
    <author>Alexander Tekleab</author>
    <author>Meike Klettke</author>
    <author>Stefanie Scherzinger</author>
    <author>Uta Storl</author>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>composite migration</value>
    </subject>
    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Conferences</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Data engineering</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>data migration</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Indexes</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Lightning</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>NoSQL databases</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Runtime</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>schema evolution</value>
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    <subject>
      <language>eng</language>
      <type>uncontrolled</type>
      <value>Tools</value>
    </subject>
    <collection role="institutes" number="FakIM">Fakultät Informatik und Mathematik</collection>
    <collection role="othforschungsschwerpunkt" number="16311">Digitalisierung</collection>
  </doc>
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