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MDEV-30413 : run sequence nextval got [Note] WSREP: MDL BF-BF conflic…
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…t and [ERROR] Aborting

Sequence objects are implemented using special tables.
These tables do not have primary key and only one row.
NEXTVAL is basically update from existing value to new
value. In Galera this could mean that two write-sets
from different nodes do not conflict and this could
lead situation where write-sets are executed
concurrently and possibly in wrong seqno order.

This is fixed by using table-level exclusive key for
SEQUENCE updates. Note that this naturally works
correctly only if InnoDB storage engine is used for
sequence.

This fix does not contain a test case because while
it is possible to syncronize appliers using dbug_sync
it was too hard to syncronize MDL-lock requests to
exact objects. Testing done for this fix is documented
on MDEV.

Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
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@janlindstrom @sysprg
janlindstrom authored and sysprg committed Mar 30, 2023
1 parent 0760ad3 commit 169def1
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Showing 3 changed files with 59 additions and 45 deletions.
46 changes: 41 additions & 5 deletions storage/innobase/handler/ha_innodb.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -8543,6 +8543,37 @@ wsrep_calc_row_hash(

return(0);
}

/** Append table-level exclusive key.
@param thd MySQL thread handle
@param table table
@retval false on success
@retval true on failure */
ATTRIBUTE_COLD bool wsrep_append_table_key(MYSQL_THD thd, const dict_table_t &table)
{
char db_buf[NAME_LEN + 1];
char tbl_buf[NAME_LEN + 1];
ulint db_buf_len, tbl_buf_len;

if (!table.parse_name(db_buf, tbl_buf, &db_buf_len, &tbl_buf_len))
{
WSREP_ERROR("Parse_name for table key append failed: %s",
wsrep_thd_query(thd));
return true;
}

/* Append table-level exclusive key */
const int rcode = wsrep_thd_append_table_key(thd, db_buf,
tbl_buf, WSREP_SERVICE_KEY_EXCLUSIVE);
if (rcode)
{
WSREP_ERROR("Appending table key failed: %s, %d",
wsrep_thd_query(thd), rcode);
return true;
}

return false;
}
#endif /* WITH_WSREP */

/**
Expand Down Expand Up @@ -8713,11 +8744,16 @@ ha_innobase::update_row(
&& !wsrep_thd_ignore_table(m_user_thd)) {
DBUG_PRINT("wsrep", ("update row key"));

if (wsrep_append_keys(m_user_thd,
wsrep_protocol_version >= 4
? WSREP_SERVICE_KEY_UPDATE
: WSREP_SERVICE_KEY_EXCLUSIVE,
old_row, new_row)){
/* We use table-level exclusive key for SEQUENCES
and normal key append for others. */
if (table->s->table_type == TABLE_TYPE_SEQUENCE) {
if (wsrep_append_table_key(m_user_thd, *m_prebuilt->table))
DBUG_RETURN(HA_ERR_INTERNAL_ERROR);
} else if (wsrep_append_keys(m_user_thd,
wsrep_protocol_version >= 4
? WSREP_SERVICE_KEY_UPDATE
: WSREP_SERVICE_KEY_EXCLUSIVE,
old_row, new_row)) {
WSREP_DEBUG("WSREP: UPDATE_ROW_KEY FAILED");
DBUG_PRINT("wsrep", ("row key failed"));
DBUG_RETURN(HA_ERR_INTERNAL_ERROR);
Expand Down
10 changes: 10 additions & 0 deletions storage/innobase/include/ha_prototypes.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -462,5 +462,15 @@ void destroy_background_thd(MYSQL_THD thd);
void
innobase_reset_background_thd(MYSQL_THD);

#ifdef WITH_WSREP
/** Append table-level exclusive key.
@param thd MySQL thread handle
@param table table
@retval false on success
@retval true on failure */
struct dict_table_t;
bool wsrep_append_table_key(MYSQL_THD thd, const dict_table_t &table);
#endif /* WITH_WSREP */

#endif /* !UNIV_INNOCHECKSUM */
#endif /* HA_INNODB_PROTOTYPES_H */
48 changes: 8 additions & 40 deletions storage/innobase/row/row0ins.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,7 @@ Created 4/20/1996 Heikki Tuuri
#ifdef WITH_WSREP
#include <wsrep.h>
#include <mysql/service_wsrep.h>
#include "ha_prototypes.h"
#endif /* WITH_WSREP */

/*************************************************************************
Expand Down Expand Up @@ -2574,42 +2575,6 @@ but GCC 4.8.5 does not support pop_options. */
# pragma GCC optimize ("O0")
#endif

#ifdef WITH_WSREP
/** Start bulk insert operation for Galera by appending
table-level exclusive key for bulk insert.
@param trx transaction
@param index index
@retval false on success
@retval true on failure */
ATTRIBUTE_COLD static bool row_ins_wsrep_start_bulk(trx_t *trx, const dict_index_t &index)
{
char db_buf[NAME_LEN + 1];
char tbl_buf[NAME_LEN + 1];
ulint db_buf_len, tbl_buf_len;

if (!index.table->parse_name(db_buf, tbl_buf, &db_buf_len, &tbl_buf_len))
{
WSREP_ERROR("Parse_name for bulk insert failed: %s",
wsrep_thd_query(trx->mysql_thd));
trx->error_state = DB_ROLLBACK;
return true;
}

/* Append table-level exclusive key for bulk insert. */
const int rcode = wsrep_thd_append_table_key(trx->mysql_thd, db_buf,
tbl_buf, WSREP_SERVICE_KEY_EXCLUSIVE);
if (rcode)
{
WSREP_ERROR("Appending table key for bulk insert failed: %s, %d",
wsrep_thd_query(trx->mysql_thd), rcode);
trx->error_state = DB_ROLLBACK;
return true;
}

return false;
}
#endif

/***************************************************************//**
Tries to insert an entry into a clustered index, ignoring foreign key
constraints. If a record with the same unique key is found, the other
Expand Down Expand Up @@ -2770,10 +2735,13 @@ row_ins_clust_index_entry_low(
#ifdef WITH_WSREP
if (trx->is_wsrep())
{
if (!wsrep_thd_is_local_transaction(trx->mysql_thd))
goto skip_bulk_insert;
if (row_ins_wsrep_start_bulk(trx, *index))
goto err_exit;
if (!wsrep_thd_is_local_transaction(trx->mysql_thd))
goto skip_bulk_insert;
if (wsrep_append_table_key(trx->mysql_thd, *index->table))
{
trx->error_state = DB_ROLLBACK;
goto err_exit;
}
}
#endif /* WITH_WSREP */

Expand Down

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