From: Andrei
When mysqldump run on mysql system database it generates inserts sql commands
into mysql.gtid_slave_pos. After running the backup script those
inserts did not produce an expected gtid state on slave.
In particular the maximum of mysql.gtid_slave_pos.sub_id did not make
into
rpl_global_gtid_slave_state.last_sub_id
a memory object that the table persists.
And that was regardless of whether --gtid option in or out.
Later when the backup recipient server starts as slave in *non-gtid*
mode this desychronization may lead to a duplicate key error.
This effect is corrected for --gtid mode mysqldump/mariadb-dump only
as the following.
The fixes ensure the insert block of the dump script is followed
with a "summing-up" SET @global.gtid_slave_pos assignment.
To address MDEV-34615 the assignment makes sure a possibly
pre-existing gtid state (e.g reflecting another domain) remains as a
sub-state upon the dump installation.
A new test provides a how-to-reproduce mode as well.
For the implemenation part, note a deferred print-out of SET-gtid_slave_pos
and associated comments is prefered over relocating of the entire blocks
if (opt_master,slave_data && do_show_master,slave_status) ...
because of compatiblity concern. Namely an error inside
do_show_*()
is handled in the new code the same way, as early, as before.
---
client/mysqldump.c | 53 +++++++++++++++++++++++++++++++++++-----------
1 file changed, 41 insertions(+), 12 deletions(-)
diff --git a/client/mysqldump.c b/client/mysqldump.c
index 1c9d92d6e09..0be890e2528 100644
--- a/client/mysqldump.c
+++ b/client/mysqldump.c
@@ -5985,8 +5985,13 @@ static int dump_selected_tables(char *db, char **table_names, int tables)
} /* dump_selected_tables */
+const char fmt_gtid_pos[] = "%sSET GLOBAL gtid_slave_pos=concat('%s', "
+ "if(length(@@global.gtid_slave_pos) = 0, '', ','), "
+ "@@global.gtid_slave_pos);\n";
+
static int do_show_master_status(MYSQL *mysql_con, int consistent_binlog_pos,
- int have_mariadb_gtid, int use_gtid)
+ int have_mariadb_gtid, int use_gtid,
+ char *set_gtid_pos)
{
MYSQL_ROW row;
MYSQL_RES *UNINIT_VAR(master);
@@ -6054,8 +6059,11 @@ static int do_show_master_status(MYSQL *mysql_con, int consistent_binlog_pos,
fprintf(md_result_file,
"%sCHANGE MASTER TO MASTER_USE_GTID=slave_pos;\n",
comment_prefix);
- fprintf(md_result_file,
- "%sSET GLOBAL gtid_slave_pos='%s';\n",
+ /*
+ Defer print of SET gtid_slave_pos until after its placeholder
+ table is guaranteed to have been dumped.
+ */
+ sprintf(set_gtid_pos, fmt_gtid_pos,
(!use_gtid ? "-- " : comment_prefix), gtid_pos);
}
@@ -6140,8 +6148,8 @@ static int add_slave_statements(void)
return(0);
}
-static int do_show_slave_status(MYSQL *mysql_con, int use_gtid,
- int have_mariadb_gtid)
+static int do_show_slave_status(MYSQL *mysql_con, int have_mariadb_gtid,
+ int use_gtid, char* set_gtid_pos)
{
MYSQL_RES *UNINIT_VAR(slave);
MYSQL_ROW row;
@@ -6181,10 +6189,8 @@ static int do_show_slave_status(MYSQL *mysql_con, int use_gtid,
mysql_free_result(slave);
return 1;
}
- print_comment(md_result_file, 0,
- "-- GTID position to start replication:\n");
- fprintf(md_result_file, "%sSET GLOBAL gtid_slave_pos='%s';\n",
- gtid_comment_prefix, gtid_pos);
+ /* similarly to do_show_master_status */
+ sprintf(set_gtid_pos, fmt_gtid_pos, gtid_comment_prefix, gtid_pos);
}
if (use_gtid)
print_comment(md_result_file, 0,
@@ -6905,6 +6911,19 @@ static void dynstr_realloc_checked(DYNAMIC_STRING *str, ulong additional_size)
die(EX_MYSQLERR, DYNAMIC_STR_ERROR_MSG);
}
+/**
+ Print earlier prepared SET to @@global.gtid_slave_pos.
+
+ @param set_gtid_pos[in] formatted sql set statement
+**/
+static void do_print_set_gtid_slave_pos(const char *set_gtid_pos)
+{
+ DBUG_ASSERT(opt_master_data || opt_slave_data);
+ if (opt_slave_data)
+ print_comment(md_result_file, 0,
+ "-- GTID position to start replication:\n");
+ fprintf(md_result_file, "%s", set_gtid_pos);
+}
int main(int argc, char **argv)
{
@@ -6913,6 +6932,11 @@ int main(int argc, char **argv)
int exit_code;
int consistent_binlog_pos= 0;
int have_mariadb_gtid= 0;
+ /*
+ to hold SET @@global.gtid_slave_pos which is deferred to print
+ until the function epilogue.
+ */
+ char set_gtid_pos[3 + sizeof(fmt_gtid_pos) + MAX_GTID_LENGTH]= {0};
MY_INIT(argv[0]);
sf_leaking_memory=1; /* don't report memory leaks on early exits */
@@ -7016,10 +7040,12 @@ int main(int argc, char **argv)
goto err;
if (opt_master_data && do_show_master_status(mysql, consistent_binlog_pos,
- have_mariadb_gtid, opt_use_gtid))
+ have_mariadb_gtid,
+ opt_use_gtid, set_gtid_pos))
goto err;
- if (opt_slave_data && do_show_slave_status(mysql, opt_use_gtid,
- have_mariadb_gtid))
+ if (opt_slave_data && do_show_slave_status(mysql,
+ have_mariadb_gtid,
+ opt_use_gtid, set_gtid_pos))
goto err;
if (opt_single_transaction && do_unlock_tables(mysql)) /* unlock but no commit! */
goto err;
@@ -7087,6 +7113,9 @@ int main(int argc, char **argv)
if (opt_system & OPT_SYSTEM_TIMEZONES)
dump_all_timezones();
+ if ((opt_master_data || opt_slave_data) && set_gtid_pos[0])
+ do_print_set_gtid_slave_pos(set_gtid_pos);
+
/* add 'START SLAVE' to end of dump */
if (opt_slave_apply && add_slave_statements())
goto err;
--
2.39.2
