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I'm writing a very small REST API using Dart/Aqueduct hosted on Heroku utilizing PostgreSQL.

When communicating with this API, I need to fetch all data and store it in an application locally. The application will on reboot ask the API if any data has changed in any databases, which will only get modified through this API.

My question is: How do I check, whether data has been modified? Storing it in the Aqueduct channel is not viable, as Heroku will boot servers up as needed (and multiple at the same time) changing this modified date time each time.

PostgreSQL cannot supply this modified date time (https://dba.stackexchange.com/questions/58214/getting-last-modification-date-of-a-postgresql-database-table) - so what do I do? Is the only way to do this to have a seperate table storing this information? Can this be done more lightweight, so I wouldn't have to make a query to the databases when e.g. calling https://my-api.com/lastModified? Should I serve a static file, which should be written to on each data modification?

Maybe there exist a smart, lightweight solution! Cheers :)

zniwalla
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Yes, use a separate table to store the date - the ORM is already doing this to track migrations. I’m not sure what light weight means in this context, but you won’t run into any problems with this approach, whereas a file or in-memory storage won’t work at all.

Joe Conway
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  • Thanks for your reply, Joe! Just to clarify: You would update a table everytime someone issued PUT, UPDATE or DELETE on any of the endpoints? – zniwalla May 21 '19 at 15:25
  • It really depends on what you are doing - but I wouldn't worry about database query performance here and I would worry about transient runtimes and filesystems. You could also try your cloud provider's file storage (which likely has an HTTP interface). – Joe Conway May 22 '19 at 13:24