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Re: Multiple default values for timestamps


Hi, Dolf!

On Jan 08, Dolf Schimmel wrote:
> Hey folks,
> On IRC I read somewhere that multiple timestamps cant have multiple
> default values using NOW() (error ER_TOO_MUCH_AUTO_TIMESTAMP_COLS). I
> tried to find out why this limitation is in place, but was not able to
> do so. The only thing I (or rather someone in #mysql and #maria) was
> able to find was this, in sql/field.cc (line 4729):
> > Actually SQL-99 says that we should allow niladic functions (like NOW())
> > as defaults for any field. Current limitations (only NOW() and only
> > for one TIMESTAMP field) are because of restricted binary .frm format
> > and should go away in the future.
> I removed the check that spits out this error and updated the tests.
> Now I'll admit I'm not sure how to properly test this, but so far the
> entire testsuite passes. It may be that I'm missing any reasons for
> this limitation, or that tests may be missing/inaccurate. If you have
> any opinions on this, please let me know.
> You can find it in:
> lp:~freeaqingme/maria/improv-allowMultipleCurTimestampInDefaultOnTable

Here's how to test it: create a table with few TIMESTAMP fields, say,
four or five. Make some of them DEFAULT CURRENT_TIMESTAMP and others
not - randomly, say second and fourth having DEFAULT CURRENT_TIMESTAMP
and others not. Then insert few rows and see how it works.


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