How Can PostgreSQL's `tsrange` Simplify and Optimize Hours of Operation Queries?

How to Perform Hours of Operation Queries in PostgreSQL

Original Query Complexity

The original query, intended to identify records that are "open" (within the specified hours of operations), was complex due to the need to handle various scenarios where hours of operation might wrap around the end of the week. To simplify this process, we will adopt a different approach using a data structure called tsrange.

Introducing tsrange

tsrange is a data type in PostgreSQL that represents a range of timestamps without time zone. It provides a convenient way to store and manipulate time intervals.

Re-designing the Table Structure

We will replace the existing columns (opens_on, closes_on, opens_at, closes_at) with a single column called hours of type tsrange. Hours of operation will be stored as a set of tsrange values.

Example

For example, the following tsrange value represents hours of operation from Wednesday, 6 PM to Thursday, 5 AM:

'[1996-01-03 18:30, 1996-01-04 05:00]'

Query using tsrange

With the updated table structure, the query becomes much simpler:

SELECT *
FROM hoo
WHERE hours @> f_hoo_time(now())

The function f_hoo_time() converts a timestamp with time zone to a timestamp, while the containment operator (@>) checks if the current time falls within the specified time range.

Index and Performance

To optimize queries using tsrange, we recommend creating an SP-GiST index on the hours column. This index allows for efficient lookup of time ranges, resulting in faster query performance.

Conclusion

By leveraging tsrange and an SP-GiST index, we can greatly simplify the hours of operation query and improve its performance. This approach is more efficient and robust than the original query.

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