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Save and clear run context before executing a stored function or trigger and restore it afterwards.

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This allows us to use statement replication with functions and triggers
The following things are fixed with this patch:
- NOW() and automatic timestamps takes the value from the main event for functions and triggers (which allows these to replicate with statement level logging)
- No side effects for triggers or functions with auto-increment values(), last_insert_id(), rand() or found_rows()
- Triggers can't return result sets

Fixes bugs:
#12480: NOW() is not constant in a trigger
#12481: Using NOW() in a stored function breaks statement based replication
#12482: Triggers has side effects with auto_increment values
#11587: trigger causes lost connection error
This commit is contained in:
monty@mysql.com
2005-08-15 18:15:12 +03:00
parent 4963388cc1
commit df32f7d621
15 changed files with 505 additions and 111 deletions
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84
sql/sql_class.cc
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@ -174,7 +174,7 @@ THD::THD()
:Statement(CONVENTIONAL_EXECUTION, 0, ALLOC_ROOT_MIN_BLOCK_SIZE, 0),
Open_tables_state(refresh_version),
lock_id(&main_lock_id),
user_time(0), in_sub_stmt(FALSE), global_read_lock(0), is_fatal_error(0),
user_time(0), in_sub_stmt(0), global_read_lock(0), is_fatal_error(0),
rand_used(0), time_zone_used(0),
last_insert_id_used(0), insert_id_used(0), clear_next_insert_id(0),
in_lock_tables(0), bootstrap(0), derived_tables_processing(FALSE),
@ -1836,3 +1836,85 @@ void THD::restore_backup_open_tables_state(Open_tables_state *backup)
set_open_tables_state(backup);
DBUG_VOID_RETURN;
}
/****************************************************************************
Handling of statement states in functions and triggers.
This is used to ensure that the function/trigger gets a clean state
to work with and does not cause any side effects of the calling statement.
It also allows most stored functions and triggers to replicate even
if they are used items that would normally be stored in the binary
replication (like last_insert_id() etc...)
The following things is done
- Disable binary logging for the duration of the statement
- Disable multi-result-sets for the duration of the statement
- Value of last_insert_id() is reset and restored
- Value set by 'SET INSERT_ID=#' is reset and restored
- Value for found_rows() is reset and restored
- examined_row_count is added to the total
- cuted_fields is added to the total
NOTES:
Seed for random() is saved for the first! usage of RAND()
We reset examined_row_count and cuted_fields and add these to the
result to ensure that if we have a bug that would reset these within
a function, we are not loosing any rows from the main statement.
****************************************************************************/
void THD::reset_sub_statement_state(Sub_statement_state *backup,
uint new_state)
{
backup->options= options;
backup->in_sub_stmt= in_sub_stmt;
backup->no_send_ok= net.no_send_ok;
backup->enable_slow_log= enable_slow_log;
backup->last_insert_id= last_insert_id;
backup->next_insert_id= next_insert_id;
backup->insert_id_used= insert_id_used;
backup->limit_found_rows= limit_found_rows;
backup->examined_row_count= examined_row_count;
backup->sent_row_count= sent_row_count;
backup->cuted_fields= cuted_fields;
backup->client_capabilities= client_capabilities;
options&= ~OPTION_BIN_LOG;
/* Disable result sets */
client_capabilities &= ~CLIENT_MULTI_RESULTS;
in_sub_stmt|= new_state;
last_insert_id= 0;
next_insert_id= 0;
insert_id_used= 0;
examined_row_count= 0;
sent_row_count= 0;
cuted_fields= 0;
#ifndef EMBEDDED_LIBRARY
/* Surpress OK packets in case if we will execute statements */
net.no_send_ok= TRUE;
#endif
}
void THD::restore_sub_statement_state(Sub_statement_state *backup)
{
options= backup->options;
in_sub_stmt= backup->in_sub_stmt;
net.no_send_ok= backup->no_send_ok;
enable_slow_log= backup->enable_slow_log;
last_insert_id= backup->last_insert_id;
next_insert_id= backup->next_insert_id;
insert_id_used= backup->insert_id_used;
limit_found_rows= backup->limit_found_rows;
sent_row_count= backup->sent_row_count;
client_capabilities= backup->client_capabilities;
/*
The following is added to the old values as we are interested in the
total complexity of the query
*/
examined_row_count+= backup->examined_row_count;
cuted_fields+= backup->cuted_fields;
}