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Fix for BUG#20524 "auto_increment_* not observed when inserting

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a too large value": the bug was that if MySQL generated a value for an
auto_increment column, based on auto_increment_* variables, and this value
was bigger than the column's max possible value, then that max possible
value was inserted (after issuing a warning). But this didn't honour
auto_increment_* variables (and so could cause conflicts in a master-master
replication where one master is supposed to generated only even numbers,
and the other only odd numbers), so now we "round down" this max possible
value to honour auto_increment_* variables, before inserting it.
This commit is contained in:
guilhem@mysql.com
2006-07-06 14:37:09 +02:00
parent 337396d19a
commit 140b488c96
3 changed files with 134 additions and 3 deletions
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53
sql/handler.cc
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@@ -1471,6 +1471,46 @@ next_insert_id(ulonglong nr,struct system_variables *variables)
}
/*
Computes the largest number X:
- smaller than or equal to "nr"
- of the form: auto_increment_offset + N * auto_increment_increment
where N>=0.
SYNOPSIS
prev_insert_id
nr Number to "round down"
variables variables struct containing auto_increment_increment and
auto_increment_offset
RETURN
The number X if it exists, "nr" otherwise.
*/
inline ulonglong
prev_insert_id(ulonglong nr, struct system_variables *variables)
{
if (unlikely(nr < variables->auto_increment_offset))
{
/*
There's nothing good we can do here. That is a pathological case, where
the offset is larger than the column's max possible value, i.e. not even
the first sequence value may be inserted. User will receive warning.
*/
DBUG_PRINT("info",("auto_increment: nr: %lu cannot honour "
"auto_increment_offset: %lu",
nr, variables->auto_increment_offset));
return nr;
}
if (variables->auto_increment_increment == 1)
return nr; // optimization of the formula below
nr= (((nr - variables->auto_increment_offset)) /
(ulonglong) variables->auto_increment_increment);
return (nr * (ulonglong) variables->auto_increment_increment +
variables->auto_increment_offset);
}
/*
Update the auto_increment field if necessary
@@ -1580,10 +1620,19 @@ bool handler::update_auto_increment()
/* Mark that we should clear next_insert_id before next stmt */
thd->clear_next_insert_id= 1;
if (!table->next_number_field->store((longlong) nr, TRUE))
if (likely(!table->next_number_field->store((longlong) nr, TRUE)))
thd->insert_id((ulonglong) nr);
else
thd->insert_id(table->next_number_field->val_int());
{
/*
overflow of the field; we'll use the max value, however we try to
decrease it to honour auto_increment_* variables:
*/
nr= prev_insert_id(table->next_number_field->val_int(), variables);
thd->insert_id(nr);
if (unlikely(table->next_number_field->store((longlong) nr, TRUE)))
thd->insert_id(nr= table->next_number_field->val_int());
}
/*
We can't set next_insert_id if the auto-increment key is not the