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MDEV-9519: Data corruption will happen on the Galera cluster size change

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If we have a 2+ node cluster which is replicating from an async master
and the binlog_format is set to STATEMENT and multi-row inserts are executed
on a table with an auto_increment column such that values are automatically
generated by MySQL, then the server node generates wrong auto_increment
values, which are different from what was generated on the async master.

In the title of the MDEV-9519 it was proposed to ban start slave on a Galera
if master binlog_format = statement and wsrep_auto_increment_control = 1,
but the problem can be solved without such a restriction.

The causes and fixes:

1. We need to improve processing of changing the auto-increment values
after changing the cluster size.

2. If wsrep auto_increment_control switched on during operation of
the node, then we should immediately update the auto_increment_increment
and auto_increment_offset global variables, without waiting of the next
invocation of the wsrep_view_handler_cb() callback. In the current version
these variables retain its initial values if wsrep_auto_increment_control
is switched on during operation of the node, which leads to inconsistent
results on the different nodes in some scenarios.

3. If wsrep auto_increment_control switched off during operation of the node,
then we must return the original values of the auto_increment_increment and
auto_increment_offset global variables, as the user has set. To make this
possible, we need to add a "shadow copies" of these variables (which stores
the latest values set by the user).

https://jira.mariadb.org/browse/MDEV-9519
This commit is contained in:
Julius Goryavsky
2019-02-25 21:49:04 +01:00
committed by Jan Lindström
parent 09bd213852
commit 50b3632fa4
16 changed files with 356 additions and 68 deletions
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50
sql/handler.cc
View File

@@ -3096,11 +3096,17 @@ compute_next_insert_id(ulonglong nr,struct system_variables *variables)
nr= nr + 1; // optimization of the formula below
else
{
nr= (((nr+ variables->auto_increment_increment -
variables->auto_increment_offset)) /
(ulonglong) variables->auto_increment_increment);
nr= (nr* (ulonglong) variables->auto_increment_increment +
variables->auto_increment_offset);
/*
Calculating the number of complete auto_increment_increment extents:
*/
nr= (nr + variables->auto_increment_increment -
variables->auto_increment_offset) /
(ulonglong) variables->auto_increment_increment;
/*
Adding an offset to the auto_increment_increment extent boundary:
*/
nr= nr * (ulonglong) variables->auto_increment_increment +
variables->auto_increment_offset;
}
if (unlikely(nr <= save_nr))
@@ -3154,8 +3160,14 @@ prev_insert_id(ulonglong nr, struct system_variables *variables)
}
if (variables->auto_increment_increment == 1)
return nr; // optimization of the formula below
nr= (((nr - variables->auto_increment_offset)) /
(ulonglong) variables->auto_increment_increment);
/*
Calculating the number of complete auto_increment_increment extents:
*/
nr= (nr - variables->auto_increment_offset) /
(ulonglong) variables->auto_increment_increment;
/*
Adding an offset to the auto_increment_increment extent boundary:
*/
return (nr * (ulonglong) variables->auto_increment_increment +
variables->auto_increment_offset);
}
@@ -3246,7 +3258,7 @@ int handler::update_auto_increment()
bool append= FALSE;
THD *thd= table->in_use;
struct system_variables *variables= &thd->variables;
int result=0, tmp;
int tmp;
enum enum_check_fields save_count_cuted_fields;
DBUG_ENTER("handler::update_auto_increment");
@@ -3397,10 +3409,23 @@ int handler::update_auto_increment()
if (unlikely(tmp)) // Out of range value in store
{
/*
It's better to return an error here than getting a confusing
'duplicate key error' later.
First, test if the query was aborted due to strict mode constraints
or new field value greater than maximum integer value:
*/
result= HA_ERR_AUTOINC_ERANGE;
if (thd->killed == KILL_BAD_DATA ||
nr > table->next_number_field->get_max_int_value())
DBUG_RETURN(HA_ERR_AUTOINC_ERANGE);
/*
Field refused this value (overflow) and truncated it, use the result
of the truncation (which is going to be inserted); however we try to
decrease it to honour auto_increment_* variables.
That will shift the left bound of the reserved interval, we don't
bother shifting the right bound (anyway any other value from this
interval will cause a duplicate key).
*/
nr= prev_insert_id(table->next_number_field->val_int(), variables);
if (unlikely(table->next_number_field->store((longlong)nr, TRUE)))
nr= table->next_number_field->val_int();
}
if (append)
{
@@ -3425,9 +3450,6 @@ int handler::update_auto_increment()
*/
insert_id_for_cur_row= nr;
if (result) // overflow
DBUG_RETURN(result);
/*
Set next insert id to point to next auto-increment value to be able to
handle multi-row statements.