<story><title>Parquet: An efficient, binary file format for table data</title><url>https://csvbase.com/blog/3</url></story><parent_chain><item><author>clord</author><text>“Parquet has both a date type and the datetime type (both sensibly recorded as integers in UTC).”&lt;p&gt;What does it mean for a date to be utc?  my date, but in the utc timezone? Usually when I write a date to a file, I want a naive date; since that’s the domain of the data. 2020-12-12 sales: $500. But splitting that by some other timezone seems to be introducing a mistake.&lt;p&gt;Often I want to think in local naive time too, especially for things like appointments that might change depending on dst or whatever. Converting to utc involves some scary things. Timestamps are also useful but I don’t want to transcode my data sometimes as the natural format is the most correct.</text></item></parent_chain><comment><author>spenczar5</author><text>Lot of confusion here. UTC is a time &lt;i&gt;standard,&lt;/i&gt; not a particular time zone. An instant written down in, say, the Pacific Standard Time Zone can be a UTC-scaled time.&lt;p&gt;An example of non-UTC time is TAI, which is International Atomic Time. The difference is that UTC has leap seconds to deal with changes in the rate of rotation of the earth, while TAI marches on without any discontinuities.&lt;p&gt;So for a date to be “in UTC” really just means it uses the leap seconds published by IERS. This article says “integers in UTC” which is a little ambiguous, but probably means “integer UTC seconds since the Unix Epoch.”</text></comment>
<story><title>Parquet: An efficient, binary file format for table data</title><url>https://csvbase.com/blog/3</url></story><parent_chain><item><author>clord</author><text>“Parquet has both a date type and the datetime type (both sensibly recorded as integers in UTC).”&lt;p&gt;What does it mean for a date to be utc?  my date, but in the utc timezone? Usually when I write a date to a file, I want a naive date; since that’s the domain of the data. 2020-12-12 sales: $500. But splitting that by some other timezone seems to be introducing a mistake.&lt;p&gt;Often I want to think in local naive time too, especially for things like appointments that might change depending on dst or whatever. Converting to utc involves some scary things. Timestamps are also useful but I don’t want to transcode my data sometimes as the natural format is the most correct.</text></item></parent_chain><comment><author>xahrepap</author><text>Agreed. I think this is where Java’s latest date&amp;#x2F;time libraries shine (heavily based on Joda time lib).&lt;p&gt;It makes a solid distinction between Dates, times, instants, and zone dates&amp;#x2F;times.&lt;p&gt;And Instant is a moment in time. Exposed as a UTC time stamp.&lt;p&gt;Birthdays etc are best expressed as LocalDates. There’s also LocalDateTime for zone-agnostic features.&lt;p&gt;If I were writing software like you describe I’d want an explicitly zone-agnostic date(time) to represent it.</text></comment>