Hi Evgenij, Thanks for the explanation, very helpful!
Wondering if you could would know any additional details ... With respect to "Hibernate reads it back it gets a rounded value instead of expected original one" do you have any further details as to exactly HOW this fails if for example, the timestamps are indeed *different *or is this a problem only when the timestamp differences are microsecond or nanoseconds apart? Is there some kind of hashing and equals checks that fail somehow internally? In other words, initial insert using nanoseconds but rounded to microsecods is followed by an update some microseconds later ... wouldn't those two timestamps be different despite the rounding that occurred? On Thursday, January 5, 2023 at 7:00:39 AM UTC-6 Evgenij Ryazanov wrote: > Hello! > > Resolution of system timestamps in JVM depends on Java version and > operating system. Old versions of Java (Java 8 and older) provide only 3 > digits. Resolution was improved in Java 9, this version provides 7 digits > on Windows, but only 6 digits on Linux, because it uses an old system > function with this limitation. Java 15 and newer versions use a modern > function and provide 9 digits instead of 6 on Linux. > > There are two data types in the SQL Standard and H2 for datetime values > with both date and time parts: TIMESTAMP > <https://h2database.com/html/datatypes.html#timestamp_type> and TIMESTAMP > WITH TIME ZONE > <https://h2database.com/html/datatypes.html#timestamp_with_time_zone_type>. > Both data types have default fractional seconds precision of 6 as required > by the Standard and some database systems, including the H2, support larger > precision. > > (DATETIME is silently replaced with standard TIMESTAMP data type, actually > you normally should use TIMESTAMP(9) WITH TIME ZONE for Instant values in > H2 to avoid issues on DST or other time zone transitions.) > > Instant values in Java also support up to 9 fractional digits. When you > insert a value with non-zero nanoseconds into a column with lower > fractional seconds precision, this value is rounded to that precision by H2 > (the SQL Standard doesn't specify an exact behavior, it only requires an > implementation-defined rounding or truncation). When Hibernate reads it > back it gets a rounded value instead of expected original one. To avoid it, > you must define an explicit fractional seconds precision of 9 for this > column. > -- You received this message because you are subscribed to the Google Groups "H2 Database" group. To unsubscribe from this group and stop receiving emails from it, send an email to h2-database+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/h2-database/f4a6c51f-c76b-4f40-b456-1285b9ed0fc9n%40googlegroups.com.
