mariadb/mysys/mf_cache.c
Monty b9f5793176 MDEV-9101 Limit size of created disk temporary files and tables
Two new variables added:
- max_tmp_space_usage : Limits the the temporary space allowance per user
- max_total_tmp_space_usage: Limits the temporary space allowance for
  all users.

New status variables: tmp_space_used & max_tmp_space_used
New field in information_schema.process_list: TMP_SPACE_USED

The temporary space is counted for:
- All SQL level temporary files. This includes files for filesort,
  transaction temporary space, analyze, binlog_stmt_cache etc.
  It does not include engine internal temporary files used for repair,
  alter table, index pre sorting etc.
- All internal on disk temporary tables created as part of resolving a
  SELECT, multi-source update etc.

Special cases:
- When doing a commit, the last flush of the binlog_stmt_cache
  will not cause an error even if the temporary space limit is exceeded.
  This is to avoid giving errors on commit. This means that a user
  can temporary go over the limit with up to binlog_stmt_cache_size.

Noteworthy issue:
- One has to be careful when using small values for max_tmp_space_limit
  together with binary logging and with non transactional tables.
  If a the binary log entry for the query is bigger than
  binlog_stmt_cache_size and one hits the limit of max_tmp_space_limit
  when flushing the entry to disk, the query will abort and the
  binary log will not contain the last changes to the table.
  This will also stop the slave!
  This is also true for all Aria tables as Aria cannot do rollback
  (except in case of crashes)!
  One way to avoid it is to use @@binlog_format=statement for
  queries that updates a lot of rows.

Implementation:
- All writes to temporary files or internal temporary tables, that
  increases the file size, are routed through temp_file_size_cb_func()
  which updates and checks the temp space usage.
- Most of the temporary file monitoring is done inside IO_CACHE.
  Temporary file monitoring is done inside the Aria engine.
- MY_TRACK and MY_TRACK_WITH_LIMIT are new flags for ini_io_cache().
  MY_TRACK means that we track the file usage. TRACK_WITH_LIMIT means
  that we track the file usage and we give an error if the limit is
  breached. This is used to not give an error on commit when
  binlog_stmp_cache is flushed.
- global_tmp_space_used contains the total tmp space used so far.
  This is needed quickly check against max_total_tmp_space_usage.
- Temporary space errors are using EE_LOCAL_TMP_SPACE_FULL and
  handler errors are using HA_ERR_LOCAL_TMP_SPACE_FULL.
  This is needed until we move general errors to it's own error space
  so that they cannot conflict with system error numbers.
- Return value of my_chsize() and mysql_file_chsize() has changed
  so that -1 is returned in the case my_chsize() could not decrease
  the file size (very unlikely and will not happen on modern systems).
  All calls to _chsize() are updated to check for > 0 as the error
  condition.
- At the destruction of THD we check that THD::tmp_file_space == 0
- At server end we check that global_tmp_space_used == 0
- As a precaution against errors in the tmp_space_used code, one can set
  max_tmp_space_usage and max_total_tmp_space_usage to 0 to disable
  the tmp space quota errors.
- truncate_io_cache() function added.
- Aria tables using static or dynamic row length are registered in 8K
  increments to avoid some calls to update_tmp_file_size().

Other things:
- Ensure that all handler errors are registered.  Before, some engine
  errors could be printed as "Unknown error".
- Fixed bug in filesort() that causes a assert if there was an error
  when writing to the temporay file.
- Fixed that compute_window_func() now takes into account write errors.
- In case of parallel replication, rpl_group_info::cleanup_context()
  could call trans_rollback() with thd->error set, which would cause
  an assert. Fixed by resetting the error before calling trans_rollback().
- Fixed bug in subselect3.inc which caused following test to use
  heap tables with low value for max_heap_table_size
- Fixed bug in sql_expression_cache where it did not overflow
  heap table to Aria table.
- Added Max_tmp_disk_space_used to slow query log.
- Fixed some bugs in log_slow_innodb.test
2024-05-27 12:39:04 +02:00

92 lines
2.5 KiB
C

/* Copyright (c) 2000, 2010, Oracle and/or its affiliates. All rights reserved.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */
/* Open a temporary file and cache it with io_cache. Delete it on close */
#include "mysys_priv.h"
#include <m_string.h>
#include "my_static.h"
#include "mysys_err.h"
/**
Open tempfile cached by IO_CACHE
Should be used when no seeks are done (only reinit_io_buff)
Return 0 if cache is inited ok
The actual file is created when the IO_CACHE buffer gets filled
If dir is not given, use TMPDIR.
*/
my_bool open_cached_file(IO_CACHE *cache, const char* dir, const char *prefix,
size_t cache_size, myf cache_myflags)
{
DBUG_ENTER("open_cached_file");
cache->dir= dir;
if (prefix)
{
DBUG_ASSERT(strlen(prefix) == 2);
memcpy(cache->prefix, prefix, 3);
}
else
cache->prefix[0]= 0;
cache->file_name=0;
cache->buffer=0; /* Mark that not open */
if (!init_io_cache(cache, -1, cache_size, WRITE_CACHE, 0L, 0,
MYF(cache_myflags | MY_NABP | MY_TRACK)))
{
DBUG_RETURN(0);
}
DBUG_RETURN(1);
}
/**
Create the temporary file
*/
my_bool real_open_cached_file(IO_CACHE *cache)
{
char name_buff[FN_REFLEN];
int error=1;
DBUG_ENTER("real_open_cached_file");
if ((cache->file= create_temp_file(name_buff, cache->dir,
cache->prefix[0] ? cache->prefix : 0,
O_BINARY, MYF(MY_WME | MY_TEMPORARY))) >= 0)
{
error=0;
}
DBUG_RETURN(error);
}
void close_cached_file(IO_CACHE *cache)
{
DBUG_ENTER("close_cached_file");
if (my_b_inited(cache))
{
File file= cache->file;
if (file >= 0)
{
(void) my_close(file,MYF(0));
#ifdef CANT_DELETE_OPEN_FILES
if (cache->file_name)
{
(void) my_delete(cache->file_name, MYF(MY_WME));
my_free(cache->file_name);
}
#endif
}
cache->file= -1; /* Don't flush data */
(void) end_io_cache(cache);
}
DBUG_VOID_RETURN;
}