The select API is a powerful way for users to access the data offered to them through the Rich Data Services. The select API is based on a very familiar idea, users want to view their data in different ways. They may want to see all the data available or they may want to apply filters which allow them to see only specific records (rows) or variables (columns). While this functionality may seem similar to what a standard relational database can do, RDS takes it a step further by powering the selection capabilities with underlying metadata which allows for querying by Regular Expressions, and Keywords.
The select API will return to users the data that corresponds with their request. In addition to this each query returns a basic summary of the results, including the limits placed on the columns and rows, the offsets where the query started, and indicators as to whether there are more records/variables available.
Standard Select
The standard select query will show all variables and all records of a given data source to a point. The results will be limited by default to one hundred variables and one hundred records in order to preserve efficiency. The results can easily be paged using some convenience attributes.
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Catalog
Discover and navigate collections and data sources in RDS. The catalog provides information about the collections and data sources overall, and can aid in helping users locate data of interest.
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Data
Select and tabulate data in an efficient manner. Selecting data can be done with traditional parameters but also includes innovative features such as the ability to use regular expressions or keywords/concepts to select variables, the option of performing on the fly recodes or computing new values, and paging to control the data flow. Tabulation can be done through the use of specialized parameters to easily and rapidly produce aggregated data or tables.
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Metadata
Capture extensive knowledge around the data, such as provenance, extended column/variable information (e.g. plain labels, definitions, questions, concepts), classifications (code/value labels), and other custom properties. This metadata is an essential part to the application and improves the querying, formatting, and packaging services of RDS. The metadata can be injected and returned alongside the data in JSON, or directly queried using dedicated metadata services. This section will cover the ability to query the metadata by itself.
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