Hi, Zardosht! On Jan 15, Zardosht Kasheff wrote: > Hello all, > > In MySQL/MariaDB 5.1, when a timestamp field was used as a key, we > used an integer compare to compare the fields. We assumed all integer > fields (including date, time, and timestamp) could use an integer > comparison to compare the fields, and that they were either 1, 2, 3, 4 > or 8 bytes long. > > We now see in MariaDB 5.3 and beyond that changes have been made to > the timestamp field, such that the length of the field may be > something other than 1, 2, 3, 4,or 8 bytes. > > Given a timestamp field of N bytes, how are we meant to compare them? > Are some meant to be integer comparisons? Are others supposed to be > memory comparisons?
It's stored as 4-byte bigendian number of the integer part of the timestamp, and then as 0- to 4-byte bigendian number for the fractional part. Because both parts are stored as bigendian numbers, I suppose, you can compare timestamps either as numbers or with memcmp. See Field_timestamp_hires::store_TIME(). But really the API-correct way is to use Field::key_type() method and compare the values using the specified method. It's more future-proof than to hard-code comparison method mapping based on the field types. Regards, Sergei _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
