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ha_myisammrg.cc
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ha_myisammrg.cc
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/* Copyright (c) 2000, 2016, 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 02110-1301 USA */
/*
MyISAM MERGE tables
A MyISAM MERGE table is kind of a union of zero or more MyISAM tables.
Besides the normal form file (.frm) a MERGE table has a meta file
(.MRG) with a list of tables. These are paths to the MyISAM table
files. The last two components of the path contain the database name
and the table name respectively.
When a MERGE table is open, there exists an TABLE object for the MERGE
table itself and a TABLE object for each of the MyISAM tables. For
abbreviated writing, I call the MERGE table object "parent" and the
MyISAM table objects "children".
A MERGE table is almost always opened through open_and_lock_tables()
and hence through open_tables(). When the parent appears in the list
of tables to open, the initial open of the handler does nothing but
read the meta file and collect a list of TABLE_LIST objects for the
children. This list is attached to the handler object as
ha_myisammrg::children_l. The end of the children list is saved in
ha_myisammrg::children_last_l.
Back in open_tables(), handler::extra(HA_EXTRA_ADD_CHILDREN_LIST) is
called. It updates each list member with the lock type and a back
pointer to the parent TABLE_LIST object TABLE_LIST::parent_l. The list
is then inserted in the list of tables to open, right behind the
parent. Consequently, open_tables() opens the children, one after the
other. The TABLE references of the TABLE_LIST objects are implicitly
set to the open tables by open_table(). The children are opened as
independent MyISAM tables, right as if they are used by the SQL
statement.
When all tables from the statement query list are open,
handler::extra(HA_EXTRA_ATTACH_CHILDREN) is called. It "attaches" the
children to the parent. All required references between parent and
children are set up.
The MERGE storage engine sets up an array with references to the
low-level MyISAM table objects (MI_INFO). It remembers the state of
the table in MYRG_INFO::children_attached.
If necessary, the compatibility of parent and children is checked.
This check is necessary when any of the objects are reopend. This is
detected by comparing the current table def version against the
remembered child def version. On parent open, the list members are
initialized to an "impossible"/"undefined" version value. So the check
is always executed on the first attach.
The version check is done in myisammrg_attach_children_callback(),
which is called for every child. ha_myisammrg::attach_children()
initializes 'need_compat_check' to FALSE and
myisammrg_attach_children_callback() sets it ot TRUE if a table
def version mismatches the remembered child def version.
The children chain remains in the statement query list until the table
is closed or the children are detached. This is done so that the
children are locked by lock_tables().
At statement end the children are detached. At the next statement
begin the open-add-attach sequence repeats. There is no exception for
LOCK TABLES. The fresh establishment of the parent-child relationship
before every statement catches numerous cases of ALTER/FLUSH/DROP/etc
of parent or children during LOCK TABLES.
---
On parent open the storage engine structures are allocated and initialized.
They stay with the open table until its final close.
*/
#define MYSQL_SERVER 1
#include "sql_priv.h"
#include "unireg.h"
#include "sql_cache.h" // query_cache_*
#include "sql_show.h" // append_identifier
#include "sql_table.h" // build_table_filename
#include "probes_mysql.h"
#include <mysql/plugin.h>
#include <m_ctype.h>
#include "../myisam/ha_myisam.h"
#include "ha_myisammrg.h"
#include "myrg_def.h"
#include "thr_malloc.h" // int_sql_alloc
#include "sql_class.h" // THD
#include "debug_sync.h"
#include <algorithm>
using std::min;
using std::max;
static handler *myisammrg_create_handler(handlerton *hton,
TABLE_SHARE *table,
MEM_ROOT *mem_root)
{
return new (mem_root) ha_myisammrg(hton, table);
}
/**
@brief Constructor
*/
ha_myisammrg::ha_myisammrg(handlerton *hton, TABLE_SHARE *table_arg)
:handler(hton, table_arg), file(0), is_cloned(0)
{
init_sql_alloc(&children_mem_root,
FN_REFLEN + ALLOC_ROOT_MIN_BLOCK_SIZE, 0);
}
/**
@brief Destructor
*/
ha_myisammrg::~ha_myisammrg(void)
{
free_root(&children_mem_root, MYF(0));
}
static const char *ha_myisammrg_exts[] = {
".MRG",
NullS
};
extern int table2myisam(TABLE *table_arg, MI_KEYDEF **keydef_out,
MI_COLUMNDEF **recinfo_out, uint *records_out);
extern int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
uint t1_keys, uint t1_recs,
MI_KEYDEF *t2_keyinfo, MI_COLUMNDEF *t2_recinfo,
uint t2_keys, uint t2_recs, bool strict,
TABLE *table_arg);
static void split_file_name(const char *file_name,
LEX_STRING *db, LEX_STRING *name);
extern "C" void myrg_print_wrong_table(const char *table_name)
{
LEX_STRING db= {NULL, 0}, name;
char buf[FN_REFLEN];
split_file_name(table_name, &db, &name);
memcpy(buf, db.str, db.length);
buf[db.length]= '.';
memcpy(buf + db.length + 1, name.str, name.length);
buf[db.length + name.length + 1]= 0;
/*
Push an error to be reported as part of CHECK/REPAIR result-set.
Note that calling my_error() from handler is a hack which is kept
here to avoid refactoring. Normally engines should report errors
through return value which will be interpreted by caller using
handler::print_error() call.
*/
my_error(ER_ADMIN_WRONG_MRG_TABLE, MYF(0), buf);
}
const char **ha_myisammrg::bas_ext() const
{
return ha_myisammrg_exts;
}
const char *ha_myisammrg::index_type(uint key_number)
{
return ((table->key_info[key_number].flags & HA_FULLTEXT) ?
"FULLTEXT" :
(table->key_info[key_number].flags & HA_SPATIAL) ?
"SPATIAL" :
(table->key_info[key_number].algorithm == HA_KEY_ALG_RTREE) ?
"RTREE" :
"BTREE");
}
/**
Callback function for open of a MERGE parent table.
@param[in] callback_param data pointer as given to myrg_parent_open()
this is used to pass the handler handle
@param[in] filename file name of MyISAM table
without extension.
@return status
@retval 0 OK
@retval != 0 Error
@detail
This function adds a TABLE_LIST object for a MERGE child table to a
list of tables in the parent handler object. It is called for each
child table.
The list of child TABLE_LIST objects is kept in the handler object
of the parent for the whole life time of the MERGE table. It is
inserted in the statement query list behind the MERGE parent
TABLE_LIST object when the MERGE table is opened. It is removed from
the statement query list at end of statement or at children detach.
All memory used for the child TABLE_LIST objects and the strings
referred by it are taken from the parent
ha_myisammrg::children_mem_root. Thus they are all freed implicitly at
the final close of the table.
children_l -> TABLE_LIST::next_global -> TABLE_LIST::next_global
# # ^ # ^
# # | # |
# # +--------- TABLE_LIST::prev_global
# # |
# |<--- TABLE_LIST::prev_global |
# |
children_last_l -----------------------------------------+
*/
CPP_UNNAMED_NS_START
extern "C" int myisammrg_parent_open_callback(void *callback_param,
const char *filename)
{
ha_myisammrg *ha_myrg= (ha_myisammrg*) callback_param;
TABLE *parent= ha_myrg->table_ptr();
Mrg_child_def *mrg_child_def;
char *db;
char *table_name;
uint dirlen;
uint db_length;
uint table_name_length;
char dir_path[FN_REFLEN];
char name_buf[NAME_LEN];
DBUG_ENTER("myisammrg_parent_open_callback");
/*
Depending on MySQL version, filename may be encoded by table name to
file name encoding or not. Always encoded if parent table is created
by 5.1.46+. Encoded if parent is created by 5.1.6+ and child table is
in different database.
*/
if (!has_path(filename))
{
/* Child is in the same database as parent. */
db_length= parent->s->db.length;
db= strmake_root(&ha_myrg->children_mem_root, parent->s->db.str, db_length);
/* Child table name is encoded in parent dot-MRG starting with 5.1.46. */
if (parent->s->mysql_version >= 50146)
{
table_name_length= filename_to_tablename(filename, name_buf,
sizeof(name_buf));
table_name= strmake_root(&ha_myrg->children_mem_root, name_buf,
table_name_length);
}
else
{
table_name_length= strlen(filename);
table_name= strmake_root(&ha_myrg->children_mem_root, filename,
table_name_length);
}
}
else
{
DBUG_ASSERT(strlen(filename) < sizeof(dir_path));
fn_format(dir_path, filename, "", "", 0);
/* Extract child table name and database name from filename. */
dirlen= dirname_length(dir_path);
/* Child db/table name is encoded in parent dot-MRG starting with 5.1.6. */
if (parent->s->mysql_version >= 50106)
{
table_name_length= filename_to_tablename(dir_path + dirlen, name_buf,
sizeof(name_buf));
table_name= strmake_root(&ha_myrg->children_mem_root, name_buf,
table_name_length);
dir_path[dirlen - 1]= 0;
dirlen= dirname_length(dir_path);
db_length= filename_to_tablename(dir_path + dirlen, name_buf, sizeof(name_buf));
db= strmake_root(&ha_myrg->children_mem_root, name_buf, db_length);
}
else
{
table_name_length= strlen(dir_path + dirlen);
table_name= strmake_root(&ha_myrg->children_mem_root, dir_path + dirlen,
table_name_length);
dir_path[dirlen - 1]= 0;
dirlen= dirname_length(dir_path);
db_length= strlen(dir_path + dirlen);
db= strmake_root(&ha_myrg->children_mem_root, dir_path + dirlen,
db_length);
}
}
if (! db || ! table_name)
DBUG_RETURN(1);
DBUG_PRINT("myrg", ("open: '%.*s'.'%.*s'", (int) db_length, db,
(int) table_name_length, table_name));
/* Convert to lowercase if required. */
if (lower_case_table_names && table_name_length)
{
/* purecov: begin tested */
table_name_length= my_casedn_str(files_charset_info, table_name);
/* purecov: end */
}
mrg_child_def= new (&ha_myrg->children_mem_root)
Mrg_child_def(db, db_length, table_name, table_name_length);
if (! mrg_child_def ||
ha_myrg->child_def_list.push_back(mrg_child_def,
&ha_myrg->children_mem_root))
{
DBUG_RETURN(1);
}
DBUG_RETURN(0);
}
CPP_UNNAMED_NS_END
/**
Open a MERGE parent table, but not its children.
@param[in] name MERGE table path name
@param[in] mode read/write mode, unused
@param[in] test_if_locked_arg open flags
@return status
@retval 0 OK
@retval -1 Error, my_errno gives reason
@detail
This function initializes the MERGE storage engine structures
and adds a child list of TABLE_LIST to the parent handler.
*/
int ha_myisammrg::open(const char *name, int mode MY_ATTRIBUTE((unused)),
uint test_if_locked_arg)
{
DBUG_ENTER("ha_myisammrg::open");
DBUG_PRINT("myrg", ("name: '%s' table: 0x%lx", name, (long) table));
DBUG_PRINT("myrg", ("test_if_locked_arg: %u", test_if_locked_arg));
/* Must not be used when table is open. */
DBUG_ASSERT(!this->file);
/* Save for later use. */
test_if_locked= test_if_locked_arg;
/* In case this handler was open and closed before, free old data. */
free_root(&this->children_mem_root, MYF(MY_MARK_BLOCKS_FREE));
/*
Initialize variables that are used, modified, and/or set by
myisammrg_parent_open_callback().
'children_l' is the head of the children chain.
'children_last_l' points to the end of the children chain.
'my_errno' is set by myisammrg_parent_open_callback() in
case of an error.
*/
children_l= NULL;
children_last_l= NULL;
child_def_list.empty();
my_errno= 0;
/* retrieve children table list. */
if (is_cloned)
{
/*
Open and attaches the MyISAM tables,that are under the MERGE table
parent, on the MyISAM storage engine interface directly within the
MERGE engine. The new MyISAM table instances, as well as the MERGE
clone itself, are not visible in the table cache. This is not a
problem because all locking is handled by the original MERGE table
from which this is cloned of.
*/
if (!(file= myrg_open(name, table->db_stat, HA_OPEN_IGNORE_IF_LOCKED)))
{
DBUG_PRINT("error", ("my_errno %d", my_errno));
DBUG_RETURN(my_errno ? my_errno : -1);
}
file->children_attached= TRUE;
info(HA_STATUS_NO_LOCK | HA_STATUS_VARIABLE | HA_STATUS_CONST);
}
else if (!(file= myrg_parent_open(name, myisammrg_parent_open_callback, this)))
{
/* purecov: begin inspected */
DBUG_PRINT("error", ("my_errno %d", my_errno));
DBUG_RETURN(my_errno ? my_errno : -1);
/* purecov: end */
}
DBUG_PRINT("myrg", ("MYRG_INFO: 0x%lx child tables: %u",
(long) file, file->tables));
DBUG_RETURN(0);
}
/**
Add list of MERGE children to a TABLE_LIST chain.
@return status
@retval 0 OK
@retval != 0 Error
@detail
When a MERGE parent table has just been opened, insert the
TABLE_LIST chain from the MERGE handler into the table list used for
opening tables for this statement. This lets the children be opened
too.
*/
int ha_myisammrg::add_children_list(void)
{
TABLE_LIST *parent_l= this->table->pos_in_table_list;
THD *thd= table->in_use;
List_iterator_fast<Mrg_child_def> it(child_def_list);
Mrg_child_def *mrg_child_def;
DBUG_ENTER("ha_myisammrg::add_children_list");
DBUG_PRINT("myrg", ("table: '%s'.'%s' 0x%lx", this->table->s->db.str,
this->table->s->table_name.str, (long) this->table));
/* Must call this with open table. */
DBUG_ASSERT(this->file);
/* Ignore this for empty MERGE tables (UNION=()). */
if (!this->file->tables)
{
DBUG_PRINT("myrg", ("empty merge table union"));
goto end;
}
/* Must not call this with attached children. */
DBUG_ASSERT(!this->file->children_attached);
/* Must not call this with children list in place. */
DBUG_ASSERT(this->children_l == NULL);
/*
Prevent inclusion of another MERGE table, which could make infinite
recursion.
*/
if (parent_l->parent_l)
{
my_error(ER_ADMIN_WRONG_MRG_TABLE, MYF(0), parent_l->alias);
DBUG_RETURN(1);
}
while ((mrg_child_def= it++))
{
TABLE_LIST *child_l;
char *db;
char *table_name;
child_l= (TABLE_LIST*) thd->alloc(sizeof(TABLE_LIST));
db= (char*) thd->memdup(mrg_child_def->db.str, mrg_child_def->db.length+1);
table_name= (char*) thd->memdup(mrg_child_def->name.str,
mrg_child_def->name.length+1);
if (child_l == NULL || db == NULL || table_name == NULL)
DBUG_RETURN(1);
child_l->init_one_table(db, mrg_child_def->db.length,
table_name, mrg_child_def->name.length,
table_name, parent_l->lock_type);
/* Set parent reference. Used to detect MERGE in children list. */
child_l->parent_l= parent_l;
/* Copy select_lex. Used in unique_table() at least. */
child_l->select_lex= parent_l->select_lex;
/* Set the expected table version, to not cause spurious re-prepare. */
child_l->set_table_ref_id(mrg_child_def->get_child_table_ref_type(),
mrg_child_def->get_child_def_version());
/*
Copy parent's prelocking attribute to allow opening of child
temporary residing in the prelocking list.
*/
child_l->prelocking_placeholder= parent_l->prelocking_placeholder;
/*
For statements which acquire a SNW metadata lock on a parent table and
then later try to upgrade it to an X lock (e.g. ALTER TABLE), SNW
locks should be also taken on the children tables.
Otherwise we end up in a situation where the thread trying to upgrade SNW
to X lock on the parent also holds a SR metadata lock and a read
thr_lock.c lock on the child. As a result, another thread might be
blocked on the thr_lock.c lock for the child after successfully acquiring
a SR or SW metadata lock on it. If at the same time this second thread
has a shared metadata lock on the parent table or there is some other
thread which has a shared metadata lock on the parent and is waiting for
this second thread, we get a deadlock. This deadlock cannot be properly
detected by the MDL subsystem as part of the waiting happens within
thr_lock.c. By taking SNW locks on the child tables we ensure that any
thread which waits for a thread doing SNW -> X upgrade, does this within
the MDL subsystem and thus potential deadlocks are exposed to the deadlock
detector.
We don't do the same thing for SNRW locks as this would allow
DDL on implicitly locked underlying tables of a MERGE table.
*/
if (! thd->locked_tables_mode &&
parent_l->mdl_request.type == MDL_SHARED_UPGRADABLE)
child_l->mdl_request.set_type(MDL_SHARED_NO_WRITE);
/* Link TABLE_LIST object into the children list. */
if (this->children_last_l)
child_l->prev_global= this->children_last_l;
else
{
/* Initialize children_last_l when handling first child. */
this->children_last_l= &this->children_l;
}
*this->children_last_l= child_l;
this->children_last_l= &child_l->next_global;
}
/* Insert children into the table list. */
if (parent_l->next_global)
parent_l->next_global->prev_global= this->children_last_l;
*this->children_last_l= parent_l->next_global;
parent_l->next_global= this->children_l;
this->children_l->prev_global= &parent_l->next_global;
/*
We have to update LEX::query_tables_last if children are added to
the tail of the table list in order to be able correctly add more
elements to it (e.g. as part of prelocking process).
*/
if (thd->lex->query_tables_last == &parent_l->next_global)
thd->lex->query_tables_last= this->children_last_l;
/*
The branch below works only when re-executing a prepared
statement or a stored routine statement:
We've just modified query_tables_last. Keep it in sync with
query_tables_last_own, if it was set by the prelocking code.
This ensures that the check that prohibits double updates (*)
can correctly identify what tables belong to the main statement.
(*) A double update is, e.g. when a user issues UPDATE t1 and
t1 has an AFTER UPDATE trigger that also modifies t1.
*/
if (thd->lex->query_tables_own_last == &parent_l->next_global)
thd->lex->query_tables_own_last= this->children_last_l;
end:
DBUG_RETURN(0);
}
/**
A context of myrg_attach_children() callback.
*/
class Mrg_attach_children_callback_param
{
public:
/**
'need_compat_check' is set by myisammrg_attach_children_callback()
if a child fails the table def version check.
*/
bool need_compat_check;
/** TABLE_LIST identifying this merge parent. */
TABLE_LIST *parent_l;
/** Iterator position, the current child to attach. */
TABLE_LIST *next_child_attach;
List_iterator_fast<Mrg_child_def> def_it;
Mrg_child_def *mrg_child_def;
public:
Mrg_attach_children_callback_param(TABLE_LIST *parent_l_arg,
TABLE_LIST *first_child,
List<Mrg_child_def> &child_def_list)
:need_compat_check(FALSE),
parent_l(parent_l_arg),
next_child_attach(first_child),
def_it(child_def_list),
mrg_child_def(def_it++)
{}
void next()
{
next_child_attach= next_child_attach->next_global;
if (next_child_attach && next_child_attach->parent_l != parent_l)
next_child_attach= NULL;
if (mrg_child_def)
mrg_child_def= def_it++;
}
};
/**
Callback function for attaching a MERGE child table.
@param[in] callback_param data pointer as given to myrg_attach_children()
this is used to pass the handler handle
@return pointer to open MyISAM table structure
@retval !=NULL OK, returning pointer
@retval NULL, Error.
@detail
This function retrieves the MyISAM table handle from the
next child table. It is called for each child table.
*/
CPP_UNNAMED_NS_START
extern "C" MI_INFO *myisammrg_attach_children_callback(void *callback_param)
{
Mrg_attach_children_callback_param *param=
(Mrg_attach_children_callback_param*) callback_param;
TABLE *parent= param->parent_l->table;
TABLE *child;
TABLE_LIST *child_l= param->next_child_attach;
Mrg_child_def *mrg_child_def= param->mrg_child_def;
MI_INFO *myisam= NULL;
DBUG_ENTER("myisammrg_attach_children_callback");
/*
Number of children in the list and MYRG_INFO::tables_count,
which is used by caller of this function, should always match.
*/
DBUG_ASSERT(child_l);
child= child_l->table;
/* Prepare for next child. */
param->next();
if (!child)
{
DBUG_PRINT("error", ("failed to open underlying table '%s'.'%s'",
child_l->db, child_l->table_name));
goto end;
}
/*
Do a quick compatibility check. The table def version is set when
the table share is created. The child def version is copied
from the table def version after a successful compatibility check.
We need to repeat the compatibility check only if a child is opened
from a different share than last time it was used with this MERGE
table.
*/
DBUG_PRINT("myrg", ("table_def_version last: %llu current: %llu",
mrg_child_def->get_child_def_version(),
child->s->get_table_def_version()));
if (mrg_child_def->get_child_def_version() != child->s->get_table_def_version())
param->need_compat_check= TRUE;
/*
If child is temporary, parent must be temporary as well. Other
parent/child combinations are allowed. This check must be done for
every child on every open because the table def version can overlap
between temporary and non-temporary tables. We need to detect the
case where a non-temporary table has been replaced with a temporary
table of the same version. Or vice versa. A very unlikely case, but
it could happen. (Note that the condition was different from
5.1.23/6.0.4(Bug#19627) to 5.5.6 (Bug#36171): child->s->tmp_table !=
parent->s->tmp_table. Tables were required to have the same status.)
*/
if (child->s->tmp_table && !parent->s->tmp_table)
{
DBUG_PRINT("error", ("temporary table mismatch parent: %d child: %d",
parent->s->tmp_table, child->s->tmp_table));
goto end;
}
/* Extract the MyISAM table structure pointer from the handler object. */
if ((child->file->ht->db_type != DB_TYPE_MYISAM) ||
!(myisam= ((ha_myisam*) child->file)->file_ptr()))
{
DBUG_PRINT("error", ("no MyISAM handle for child table: '%s'.'%s' 0x%lx",
child->s->db.str, child->s->table_name.str,
(long) child));
}
DBUG_PRINT("myrg", ("MyISAM handle: 0x%lx", (long) myisam));
end:
if (!myisam &&
(current_thd->open_options & HA_OPEN_FOR_REPAIR))
{
char buf[2*NAME_LEN + 1 + 1];
strxnmov(buf, sizeof(buf) - 1, child_l->db, ".", child_l->table_name, NULL);
/*
Push an error to be reported as part of CHECK/REPAIR result-set.
Note that calling my_error() from handler is a hack which is kept
here to avoid refactoring. Normally engines should report errors
through return value which will be interpreted by caller using
handler::print_error() call.
*/
my_error(ER_ADMIN_WRONG_MRG_TABLE, MYF(0), buf);
}
DBUG_RETURN(myisam);
}
CPP_UNNAMED_NS_END
/**
Returns a cloned instance of the current handler.
@return A cloned handler instance.
*/
handler *ha_myisammrg::clone(const char *name, MEM_ROOT *mem_root)
{
MYRG_TABLE *u_table,*newu_table;
ha_myisammrg *new_handler=
(ha_myisammrg*) get_new_handler(table->s, mem_root, table->s->db_type());
if (!new_handler)
return NULL;
/* Inform ha_myisammrg::open() that it is a cloned handler */
new_handler->is_cloned= TRUE;
/*
Allocate handler->ref here because otherwise ha_open will allocate it
on this->table->mem_root and we will not be able to reclaim that memory
when the clone handler object is destroyed.
*/
if (!(new_handler->ref= (uchar*) alloc_root(mem_root, ALIGN_SIZE(ref_length)*2)))
{
delete new_handler;
return NULL;
}
if (new_handler->ha_open(table, name, table->db_stat,
HA_OPEN_IGNORE_IF_LOCKED))
{
delete new_handler;
return NULL;
}
/*
Iterate through the original child tables and
copy the state into the cloned child tables.
We need to do this because all the child tables
can be involved in delete.
*/
newu_table= new_handler->file->open_tables;
for (u_table= file->open_tables; u_table < file->end_table; u_table++)
{
newu_table->table->state= u_table->table->state;
newu_table++;
}
return new_handler;
}
/**
Attach children to a MERGE table.
@return status
@retval 0 OK
@retval != 0 Error, my_errno gives reason
@detail
Let the storage engine attach its children through a callback
function. Check table definitions for consistency.
@note
Special thd->open_options may be in effect. We can make use of
them in attach. I.e. we use HA_OPEN_FOR_REPAIR to report the names
of mismatching child tables. We cannot transport these options in
ha_myisammrg::test_if_locked because they may change after the
parent is opened. The parent is kept open in the table cache over
multiple statements and can be used by other threads. Open options
can change over time.
*/
int ha_myisammrg::attach_children(void)
{
MYRG_TABLE *u_table;
MI_COLUMNDEF *recinfo;
MI_KEYDEF *keyinfo;
uint recs;
uint keys= table->s->keys;
TABLE_LIST *parent_l= table->pos_in_table_list;
int error;
Mrg_attach_children_callback_param param(parent_l, this->children_l, child_def_list);
DBUG_ENTER("ha_myisammrg::attach_children");
DBUG_PRINT("myrg", ("table: '%s'.'%s' 0x%lx", table->s->db.str,
table->s->table_name.str, (long) table));
DBUG_PRINT("myrg", ("test_if_locked: %u", this->test_if_locked));
/* Must call this with open table. */
DBUG_ASSERT(this->file);
/*
A MERGE table with no children (empty union) is always seen as
attached internally.
*/
if (!this->file->tables)
{
DBUG_PRINT("myrg", ("empty merge table union"));
goto end;
}
DBUG_PRINT("myrg", ("child tables: %u", this->file->tables));
/* Must not call this with attached children. */
DBUG_ASSERT(!this->file->children_attached);
DEBUG_SYNC(current_thd, "before_myisammrg_attach");
/* Must call this with children list in place. */
DBUG_ASSERT(this->table->pos_in_table_list->next_global == this->children_l);
if (myrg_attach_children(this->file, this->test_if_locked |
current_thd->open_options,
myisammrg_attach_children_callback, ¶m,
(my_bool *) ¶m.need_compat_check))
{
error= my_errno;
goto err;
}
DBUG_PRINT("myrg", ("calling myrg_extrafunc"));
myrg_extrafunc(file, query_cache_invalidate_by_MyISAM_filename_ref);
if (!(test_if_locked == HA_OPEN_WAIT_IF_LOCKED ||
test_if_locked == HA_OPEN_ABORT_IF_LOCKED))
myrg_extra(file,HA_EXTRA_NO_WAIT_LOCK,0);
info(HA_STATUS_NO_LOCK | HA_STATUS_VARIABLE | HA_STATUS_CONST);
if (!(test_if_locked & HA_OPEN_WAIT_IF_LOCKED))
myrg_extra(file,HA_EXTRA_WAIT_LOCK,0);
/*
The compatibility check is required only if one or more children do
not match their table def version from the last check. This will
always happen at the first attach because the reference child def
version is initialized to 'undefined' at open.
*/
DBUG_PRINT("myrg", ("need_compat_check: %d", param.need_compat_check));
if (param.need_compat_check)
{
TABLE_LIST *child_l;
if (table->s->reclength != stats.mean_rec_length && stats.mean_rec_length)
{
DBUG_PRINT("error",("reclength: %lu mean_rec_length: %lu",
table->s->reclength, stats.mean_rec_length));
if (test_if_locked & HA_OPEN_FOR_REPAIR)
{
/* purecov: begin inspected */
myrg_print_wrong_table(file->open_tables->table->filename);
/* purecov: end */
}
error= HA_ERR_WRONG_MRG_TABLE_DEF;
goto err;
}
/*
Both recinfo and keyinfo are allocated by my_multi_malloc(), thus
only recinfo must be freed.
*/
if ((error= table2myisam(table, &keyinfo, &recinfo, &recs)))
{
/* purecov: begin inspected */
DBUG_PRINT("error", ("failed to convert TABLE object to MyISAM "
"key and column definition"));
goto err;
/* purecov: end */
}
for (u_table= file->open_tables; u_table < file->end_table; u_table++)
{
if (check_definition(keyinfo, recinfo, keys, recs,
u_table->table->s->keyinfo, u_table->table->s->rec,
u_table->table->s->base.keys,
u_table->table->s->base.fields, false, NULL))
{
DBUG_PRINT("error", ("table definition mismatch: '%s'",
u_table->table->filename));
error= HA_ERR_WRONG_MRG_TABLE_DEF;
if (!(this->test_if_locked & HA_OPEN_FOR_REPAIR))
{
my_free(recinfo);
goto err;
}
/* purecov: begin inspected */
myrg_print_wrong_table(u_table->table->filename);
/* purecov: end */
}
}
my_free(recinfo);
if (error == HA_ERR_WRONG_MRG_TABLE_DEF)
goto err; /* purecov: inspected */
List_iterator_fast<Mrg_child_def> def_it(child_def_list);
DBUG_ASSERT(this->children_l);
for (child_l= this->children_l; ; child_l= child_l->next_global)
{
Mrg_child_def *mrg_child_def= def_it++;
mrg_child_def->set_child_def_version(
child_l->table->s->get_table_ref_type(),
child_l->table->s->get_table_def_version());
if (&child_l->next_global == this->children_last_l)
break;
}
}
#if !defined(BIG_TABLES) || SIZEOF_OFF_T == 4
/* Merge table has more than 2G rows */
if (table->s->crashed)
{
DBUG_PRINT("error", ("MERGE table marked crashed"));
error= HA_ERR_WRONG_MRG_TABLE_DEF;
goto err;
}
#endif
end:
DBUG_RETURN(0);
err:
DBUG_PRINT("error", ("attaching MERGE children failed: %d", error));
print_error(error, MYF(0));
detach_children();
DBUG_RETURN(my_errno= error);
}
/**
Detach all children from a MERGE table and from the query list of tables.
@return status
@retval 0 OK
@retval != 0 Error, my_errno gives reason
@note
Detach must not touch the child TABLE objects in any way.
They may have been closed at ths point already.
All references to the children should be removed.
*/
int ha_myisammrg::detach_children(void)
{
TABLE_LIST *child_l;
DBUG_ENTER("ha_myisammrg::detach_children");
/* Must call this with open table. */
DBUG_ASSERT(this->file);
/* A MERGE table with no children (empty union) cannot be detached. */
if (!this->file->tables)
{
DBUG_PRINT("myrg", ("empty merge table union"));
goto end;
}
if (this->children_l)
{
THD *thd= table->in_use;
/* Clear TABLE references. */
for (child_l= this->children_l; ; child_l= child_l->next_global)
{
/*
Do not DBUG_ASSERT(child_l->table); open_tables might be
incomplete.
Clear the table reference.
*/
child_l->table= NULL;
/* Similarly, clear the ticket reference. */
child_l->mdl_request.ticket= NULL;
/* Break when this was the last child. */
if (&child_l->next_global == this->children_last_l)
break;
}
/*
Remove children from the table list. This won't fail if called
twice. The list is terminated after removal.
If the parent is LEX::query_tables_own_last and pre-locked tables
follow (tables used by stored functions or triggers), the children
are inserted behind the parent and before the pre-locked tables. But
we do not adjust LEX::query_tables_own_last. The pre-locked tables
could have chopped off the list by clearing
*LEX::query_tables_own_last. This did also chop off the children. If
we would copy the reference from *this->children_last_l in this
case, we would put the chopped off pre-locked tables back to the
list. So we refrain from copying it back, if the destination has
been set to NULL meanwhile.
*/
if (this->children_l->prev_global && *this->children_l->prev_global)
*this->children_l->prev_global= *this->children_last_l;
if (*this->children_last_l)
(*this->children_last_l)->prev_global= this->children_l->prev_global;
/*
If table elements being removed are at the end of table list we
need to adjust LEX::query_tables_last member to point to the