Hi, Here is a question on how we should define the meaning of an UPSERT statement. UPSERT is not part of the ISO/ANSI SQL standard, so we have some leeway to define it.
My personal feeling is that UPSERT should either insert a brand-new row or it should completely replace an existing row, but it should never combine columns from a new and an existing row. If users want the latter then they should use the MERGE command. We should probably follow what other DBMSs do. I could not yet find a DBMS that had an UPSERT command, although there probably is one. - PostgreSQL: Has an insert with a conflict clause, similar to our MERGE: http://www.postgresql.org/docs/current/static/sql-insert.html - MySQL: Has an insert with ON DUPLICATE KEY clause, similar to our MERGE: http://dev.mysql.com/doc/refman/5.7/en/insert-on-duplicate.html - Teradata: Has an update ... else insert ... command, similar to MERGE: https://forums.teradata.com/forum/enterprise/problem-using-upsert - Oracle just seems to have the MERGE statement and various methods to do upsert in PL/SQL: http://stackoverflow.com/questions/237327/oracle-how-to-upsert-update-or-insert-into-a-table This seems to support indirectly what I'm proposing. If we want to merge old and new row then we should use syntax specifying how to merge, which is what the other DBMSs have done. See also the discussion in https://github.com/apache/incubator-trafodion/pull/380. I wanted to see whether the user group has any input on this. Thanks, Hans
