← Back to team overview

maria-developers team mailing list archive

Re: Review: MDEV-29075 Changing explicit_defaults_for_timestamp within stored procedure works inconsistently


Hello Sergei,

On 7/30/22 14:34, Sergei Golubchik wrote:
Hi, Alexander,

On Jul 29, Alexander Barkov wrote:
    Hello Sergei,

I have a couple of suggestions:

commit 7b8304045272111a6f4d44196d6b37cbfef06f37
Author: Sergei Golubchik <serg@xxxxxxxxxxx>
Date:   Wed Jul 20 17:31:48 2022 +0200

     MDEV-29075 Changing explicit_defaults_for_timestamp within stored procedure works inconsistently
move the OPTION_EXPLICIT_DEF_TIMESTAMP check from the parsing step
     to the execution

diff --git a/sql/field.cc b/sql/field.cc
index 2e0c70d3d13..23ebb07b7f7 100644
--- a/sql/field.cc
+++ b/sql/field.cc
@@ -10824,6 +10824,7 @@ Column_definition::Column_definition(
    comment=    old_field->comment;
    vcol_info=  old_field->vcol_info;
    option_list= old_field->option_list;
+  explicitly_nullable= !(old_field->flags & NOT_NULL_FLAG);

This introduces asymmetry in how NULL and NOT NULL attributes are handled.

I suggest considering these ways:

1. Change "bool explicitly_nullable" to "bool explicit_nullability",
which will be:

- false if nothing was specified
- true if NULL or NOT NULL was specified.

I've done that, see commit 7120195ac1c,
but I don't like how it looks. When NOT_NULL_FLAG is set, the value is
redundant, it's not used anywhere and only adds few pointless
assignments to sql_yacc.yy.

We only need to know how to interpret the case when NOT_NULL_FLAG is not
set, that's what explicitly_nullable was doing.

I checked 7120195ac1c. Indeed the new version does not look better.
I won't insist.

2. Or don't store NOT_NULL_FLAG in Column_definition::flags at all.

Add a new Column_definition enum member with three values for:
- not specified
- explicit NULL
- explicit NOT NULL

As discussed on slack, the latter will need some changes.
But I think not that much, as only Column_definition needs changes,
while Field does not seem to need at this point.

I don't know how to do it in a robust way. Column_definition and Field
have both the same flags member, one typically just copies it back and
forth. Having just one bit out of Column_definition::flags is very
error-prone, I'd prefer all flags to be stored very differently in
Column_definition, so that one couldn't just copy them. But this
explicitly_nullable thing cannot justify such a big change.

I agreed.

I have no other suggestion. Thanks for your explanation.

VP of MariaDB Server Engineering
and security@xxxxxxxxxxx