A Data Lake is a (potentially huge) repository of data collected for future reuse. In classical data analytics, data was curated for storage in data warehouses, which support the core analysis tasks of an organization. Such architectures have been effective, but are expensive to develop and maintain. More agile uses of data, in which many data sets are combined in innovative ways are not really the focus of warehouses. In contrast, data lakes aim to bring together diverse data sets, which are combined as needed to produce new insights. This provides a schema-on-read approach, in which a schema is applied to the data when it is to be used, rather than when it is stored.
The schema-on-read model has the effect of deferring the pain of curating the data; finding, selecting, collating and cleaning the data from the data lake are still all likely to be necessary. However, there are also questions such as: What data that might be relevant to my problem is in the data lake? What are the quality problems that might be a barrier to using this data? How are the data sets in the data lake related to each other? How can I search the data lake without being overwhelmed with responses.
In our recent research, we have developed an approach to automating data preparation; given a description of what is required, a data preparation program can be generated that seeks to produce what is needed from the available data sets [1]. However, this assumes that the description of what is required (in the form of a table definition and some example data) is available. In a schema-on-read model, analyses are quite speculative, and may be adapted to what suitable data can be found. We have carried out some research on discovering data in data lakes [2], but this assumes that you know quite a lot about what you are looking for. The proposed research is to develop techniques for offering candidate data to users, along with information on the properties of the different possible data sets, that might then inform the creation of the most suitable data sets to use in practice.
This research might involve the following steps: (a) review existing work on discovering, grouping, annotating and linking data in data lakes; (b) experiment with existing techniques to understand their strengths and limitations; (c) propose new techniques that can be used to automatically index, homogenize, inter-relate or group data in the data lake; (d) evaluate (c) in practice on representative data lakes (for example involving open government data) and iterate.
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