Hi! I expect form the FB engine to return the default value at INSERT/UPDATE TIME, not the current default value. So default values should be kept in the rdb$format table, because versioning is needed.
On 2017.03.24. 8:18, Dmitry Yemanov wrote: > 24.03.2017 09:33, Vlad Khorsun wrote: >>> Firebird is known to upgrade the record format while reading. "Upgrade" >>> here means using the latest (aka current) format. The current format is >>> the one that can be seen in RDB$RELATION_FIELDS. So one may expect that >>> the default value to be used is also the latest one, that's stored in >>> RDB$ tables. IIRC, this is how FB 2.5 works. >> Exactly. When i read the table and know that some field should have default >> value, i expect to see this value at system catalog. > It depends on the definition. In fact, adding a NOT NULL DEFAULT X > column means two things: (1) DEFAULT X will be used implicitly for > inserts or explicitly for the DEFAULT keyword and (2) X will be used to > replace the missing values. For (1), everything works as expected. For > (2), your expectation relies on the fact that X is substituted while > reading. But this is just an implementation detail. The contract is > "replacing missing values", whatever it could mean. Someone else does > not know such internals and expects this "replacement" happening by some > voodoo magic during ALTER ;-) > > Also, lets consider this: > > SQL> create table t (col1 int); > SQL> insert into t values (1); > SQL> commit; > SQL> alter table t add col2 int default 123 not null; > SQL> select * from t; > > COL1 COL2 > ============ ============ > 1 123 > > SQL> alter table t alter col2 drop default; > SQL> select * from t; > > COL1 COL2 > ============ ============ > 1 123 > > There's no default at the end, but COL2 is still returning 123. This > matches the "update" expectation, not the "convert missing to the > current default" one. > > Yesterday I considered this issue being a bug, but now I'm not that > sure. It may look obvious for some users but counter-intuitive for the > others. > > Anyone outside the development team cares to comment? :-) > > > Dmitry > > > ------------------------------------------------------------------------------ > Check out the vibrant tech community on one of the world's most > engaging tech sites, Slashdot.org! http://sdm.link/slashdot > Firebird-Devel mailing list, web interface at > https://lists.sourceforge.net/lists/listinfo/firebird-devel ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
