The convener had to rely on their own calculations to work out what local time in “Your Country” a local time in “My Country” corresponded to. Why are moments so hard to deal with?Įven as recently as just a couple of decades ago, it was rare to hold conference calls between widely geographically dispersed participants. But it turns out that the rules here are complex and confusing. This sounds as if it couldn’t be simpler. And when you add (or subtract) an interval value to (or from) a timestamp value, you get a timestamp value. When you subtract one timestamp value from another, you get an interval value. The second part deals with durations (how long things last). I’ll use, hereinafter, the short spellings (plain) timestamp and timestamptz, respectively, for these-and timestamp to denote either one of these. The relevant data types here are time, date, and timestamp-where the latter has a without time zone and a with time zone variant. It deals with the basic business of representing moments (when things happen) against the background that, for example, different participants in a live international conference call see that their clocks read different times when the call starts and ends from what other participants see. This is the first of a two part blog post series. I hope that my write-up will complement the PostgreSQL documentation and help you with your task. This subsection gives you the links to the accounts of that minimal subset of functionality.īut if you have to maintain an extant application whose developers are long gone, and that has little or no developer-oriented documentation, then you will have to study the whole topic. If your aim is to write a brand new database application, then you need to understand only what is sufficient for this-and it’s a remarkably small fraction of everything that there is to know in this space. They also provide far more functionality than a correct implementation will need-which surplus serves only to give you enough rope to hang yourself.PostgreSQL, and therefore YugabyteDB, give you sufficient functionality to let you straightforwardly and correctly meet any requirement that might be set in the date-time space.The exercise left me with these two high-level conclusions: I had no choice but to aim for total understanding-complete in breadth and depth. I recently completed a careful and exhaustive study of the topic so that I could write it all up in YugabyteDB’s YSQL documentation. So some YSQL users will find the topic challenging, too. YugabyteDB’s YSQL subsystem gives the application developer the same experience as PostgreSQL. Even experienced developers struggle when they first embark on a critical project that relies on this functionality. Anecdotal reports indicate that some PostgreSQL programmers are daunted by the date and time data types, and by how operations that use values of these data types might be affected by the session’s timezone setting.
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