Hi, A bit of a late reply, but an example of using aliases to rename fields is already part of the tests: org.apache.avro.TestReadingWritingDataInEvolvedSchemas#aliasesInSchema <https://github.com/apache/avro/blob/master/lang/java/avro/src/test/java/org/apache/avro/TestReadingWritingDataInEvolvedSchemas.java#L404>
Kind regards, Oscar On Fri, 18 Aug 2023 at 13:18, Michael A. Smith <mich...@smith-li.com> wrote: > Thanks for the explanation, Oscar. Would you be willing to add some small > demo schema to your spec PR? It can serve as an example as well as a simple > interop test case. > > Thanks again, > Michael > > On Fri, Aug 18, 2023 at 03:17 Oscar Westra van Holthe - Kind < > os...@westravanholthe.nl> wrote: > > > On Fri, 18 Aug 2023 at 04:32, Michael A. Smith <mich...@smith-li.com> > > wrote: > > > > > I found I'm still a little confused at how using aliases to correct > > > invalid names should work. Maybe you can define an alias that is an > > > invalid name, but having done so, can you use it? I tried this schema > > > in both the Python and Java implementations. > > > > > > > Correcting names -- and other projections -- happen during schema > > resolution > > when reading Avro data. Such a process requires that the write schema is > > parsed > > without any validation. An exception when parsing the write schema means > > the > > data becomes unreadable. > > > > When reading the data, the read schema is first resolved against the > write > > schema. > > One of the things that happen during schema resolution is that the names > in > > the > > write schema are matched against the names and aliases in the read > schema. > > > > This means you won't be using the aliases directly. > > > > You can test this theory by encoding data as Avro bytes without any > header. > > You'll > > find you can decode the bytes using a different schema that is identical > > except for > > its names. This works, as these schemata yield the same sequence of > bytes. > > > > Names and aliases in the schemas allow enhancing process to do other nice > > things: > > - skip written fields that were removed from the read schema > > - fill in default values for new fields added to the read schema > > - match different type orders in unions > > - do some conversions, like reading an int as a long > > > > > > Kind regards, > > Oscar > > > > -- > > > > ✉️ Oscar Westra van Holthe - Kind <os...@westravanholthe.nl> > > > -- ✉️ Oscar Westra van Holthe - Kind <opw...@apache.org> 🌐 https://github.com/opwvhk/
