The failing reason was inconsistent truncation rules: the value of virtual
column could have been evaluated to '2000' sometimes instead of '0000' for
value 'a'.
The reason why `c YEAR AS ('aaaa')` was not evaluated same is that len=4 is
a special case insidew Field_year::store.
The correct fix is: always evaluate a bad value to 0000 instead 2000.
The truncated values should be evaluated as usual.
$support_virtual_index is finally changed to 1 in gcol.gcol_ins_upd_innodb,
which is also enough for testing.
The test from original bug report is also added.
The assertion is improved: storage engines like myisam always have to store
at least one field, so the assertion does not cover tables with no stored
columns.
Add a proper error handling of innobase_get_computed_value results in
row_upd_store_row/row_upd_store_v_row.
Also add an assertion in row_vers_build_clust_v_col to fail during row
purge.
Add one more assertion in row_sel_sec_rec_is_for_clust_rec for possible
future catches.
SQL Standard behavior for DROP COLUMN xxx RESTRICT:
* If a constraint (UNIQUE or CHECK) uses only the dropped column,
it's automatically dropped too. If it uses many columns - an error.
otherwise we'd need to store sql_mode *per vcol*
(consider CREATE INDEX...) and how SHOW CREATE TABLE would
support that?
Additionally, get rid of vcol::expr_str, just to make sure
the string is always generated and never leaked in the
original form.
* don't issue an error for ER_KEY_BASED_ON_GENERATED_VIRTUAL_COLUMN
* support keyread on vcols
* callback into the server to compute vcol values from mi_check/mi_repair
* DMLs just work. Automatically.
