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mariadb/sql/ha_federated.cc
unknown b3b5f8fb65 Fix confusing comments. 
sql/examples/ha_example.cc:
  fix comments, referring to renamed function
sql/ha_federated.cc:
  fix comments, referring to renamed function
2005-02-20 22:52:28 +03:00

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/* Copyright (C) 2004 MySQL AB
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; either version 2 of the License, or
(at your option) any later version.
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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
/*
MySQL Federated Storage Engine
ha_federated.cc - MySQL Federated Storage Engine
Patrick Galbraith and Brian Aker, 2004
This is a handler which uses a remote database as the data file, as
opposed to a handler like MyISAM, which uses .MYD files locally.
How this handler works
----------------------------------
Normal database files are local and as such: You create a table called
'users', a file such as 'users.MYD' is created. A handler reads, inserts,
deletes, updates data in this file. The data is stored in particular format,
so to read, that data has to be parsed into fields, to write, fields have to
be stored in this format to write to this data file.
With MySQL Federated storage engine, there will be no local files for each
table's data (such as .MYD). A remote database will store the data that would
normally be in this file. This will necessitate the use of MySQL client API
to read, delete, update, insert this data. The data will have to be retrieve
via an SQL call "SELECT * FROM users". Then, to read this data, it will have
to be retrieved via mysql_fetch_row one row at a time, then converted from
the column in this select into the format that the handler expects.
The create table will simply create the .frm file, and within the
"CREATE TABLE" SQL, there SHALL be any of the following :
comment=scheme://username:password@hostname:port/database/tablename
comment=scheme://username@hostname/database/tablename
comment=scheme://username:password@hostname/database/tablename
comment=scheme://username:password@hostname/database/tablename
An example would be:
comment=mysql://username:password@hostname:port/database/tablename
***IMPORTANT***
Only 'mysql://' is supported at this release.
This comment connection string is necessary for the handler to be
able to connect to the remote server.
The basic flow is this:
SQL calls issues locally ->
mysql handler API (data in handler format) ->
mysql client API (data converted to SQL calls) ->
remote database -> mysql client API ->
convert result sets (if any) to handler format ->
handler API -> results or rows affected to local
What this handler does and doesn't support
------------------------------------------
* Tables MUST be created on the remote server prior to any action on those
tables via the handler, first version. IMPORTANT: IF you MUST use the
federated storage engine type on the REMOTE end, MAKE SURE [ :) ] That
the table you connect to IS NOT a table pointing BACK to your ORIGNAL
table! You know and have heard the screaching of audio feedback? You
know putting two mirror in front of each other how the reflection
continues for eternity? Well, need I say more?!
* There will not be support for transactions.
* There is no way for the handler to know if the database on the remote end
has changed. The reason for this is that this database has to work like a
data file that would never be written to by anything other than the
database. The integrity of the data in the local table could be breached
if there was any change to the remote database.
* Support for SELECT, INSERT, UPDATE , DELETE, indexes.
* No ALTER TABLE, DROP TABLE or any other Data Definition Language calls.
* Prepared statements will not be used in the first implementation, it
remains to to be seen whether the limited subset of the client API for the
server supports this.
* This uses SELECT, INSERT, UPDATE, DELETE and not HANDLER for its
implementation.
* This will not work with the query cache.
Method calls
A two column table, with one record:
(SELECT)
"SELECT * FROM foo"
ha_federated::info
ha_federated::scan_time:
ha_federated::rnd_init: share->select_query SELECT * FROM foo
ha_federated::extra
<for every row of data retrieved>
ha_federated::rnd_next
ha_federated::convert_row_to_internal_format
ha_federated::rnd_next
</for every row of data retrieved>
ha_federated::rnd_end
ha_federated::extra
ha_federated::reset
(INSERT)
"INSERT INTO foo (id, ts) VALUES (2, now());"
ha_federated::write_row
<for every field/column>
Field::quote_data
Field::quote_data
</for every field/column>
ha_federated::reset
(UPDATE)
"UPDATE foo SET ts = now() WHERE id = 1;"
ha_federated::index_init
ha_federated::index_read
ha_federated::index_read_idx
Field::quote_data
ha_federated::rnd_next
ha_federated::convert_row_to_internal_format
ha_federated::update_row
<quote 3 cols, new and old data>
Field::quote_data
Field::quote_data
Field::quote_data
Field::quote_data
Field::quote_data
Field::quote_data
</quote 3 cols, new and old data>
ha_federated::extra
ha_federated::extra
ha_federated::extra
ha_federated::external_lock
ha_federated::reset
How do I use this handler?
--------------------------
First of all, you need to build this storage engine:
./configure --with-federated-storage-engine
make
Next, to use this handler, it's very simple. You must
have two databases running, either both on the same host, or
on different hosts.
One the server that will be connecting to the remote
host (client), you create your table as such:
CREATE TABLE test_table (
id int(20) NOT NULL auto_increment,
name varchar(32) NOT NULL default '',
other int(20) NOT NULL default '0',
PRIMARY KEY (id),
KEY name (name),
KEY other_key (other))
ENGINE="FEDERATED"
DEFAULT CHARSET=latin1
COMMENT='root@127.0.0.1:9306/federated/test_federated';
Notice the "COMMENT" and "ENGINE" field? This is where you
respectively set the engine type, "FEDERATED" and remote
host information, this being the database your 'client' database
will connect to and use as the "data file". Obviously, the remote
database is running on port 9306, so you want to start up your other
database so that it is indeed on port 9306, and your federated
database on a port other than that. In my setup, I use port 5554
for federated, and port 5555 for the remote.
Then, on the remote database:
CREATE TABLE test_table (
id int(20) NOT NULL auto_increment,
name varchar(32) NOT NULL default '',
other int(20) NOT NULL default '0',
PRIMARY KEY (id),
KEY name (name),
KEY other_key (other))
ENGINE="<NAME>" <-- whatever you want, or not specify
DEFAULT CHARSET=latin1 ;
This table is exactly the same (and must be exactly the same),
except that it is not using the federated handler and does
not need the URL.
How to see the handler in action
--------------------------------
When developing this handler, I compiled the federated database with
debugging:
./configure --with-federated-storage-engine
--prefix=/home/mysql/mysql-build/federated/ --with-debug
Once compiled, I did a 'make install' (not for the purpose of installing
the binary, but to install all the files the binary expects to see in the
diretory I specified in the build with --prefix,
"/home/mysql/mysql-build/federated".
Then, I started the remote server:
/usr/local/mysql/bin/mysqld_safe
--user=mysql --log=/tmp/mysqld.5555.log -P 5555
Then, I went back to the directory containing the newly compiled mysqld,
<builddir>/sql/, started up gdb:
gdb ./mysqld
Then, withn the (gdb) prompt:
(gdb) run --gdb --port=5554 --socket=/tmp/mysqld.5554 --skip-innodb --debug
Next, I open several windows for each:
1. Tail the debug trace: tail -f /tmp/mysqld.trace|grep ha_fed
2. Tail the SQL calls to the remote database: tail -f /tmp/mysqld.5555.log
3. A window with a client open to the federated server on port 5554
4. A window with a client open to the federated server on port 5555
I would create a table on the client to the remote server on port
5555, and then to the federated server on port 5554. At this point,
I would run whatever queries I wanted to on the federated server,
just always remembering that whatever changes I wanted to make on
the table, or if I created new tables, that I would have to do that
on the remote server.
Another thing to look for is 'show variables' to show you that you have
support for federated handler support:
show variables like '%federat%'
and:
show storage engines;
Both should display the federated storage handler.
Testing
-------
There is a test for MySQL Federated Storage Handler in ./mysql-test/t,
federatedd.test It starts both a slave and master database using
the same setup that the replication tests use, with the exception that
it turns off replication, and sets replication to ignore the test tables.
After ensuring that you actually do have support for the federated storage
handler, numerous queries/inserts/updates/deletes are run, many derived
from the MyISAM tests, plus som other tests which were meant to reveal
any issues that would be most likely to affect this handler. All tests
should work! ;)
To run these tests, go into ./mysql-test (based in the directory you
built the server in)
./mysql-test-run federatedd
To run the test, or if you want to run the test and have debug info:
./mysql-test-run --debug federated
This will run the test in debug mode, and you can view the trace and
log files in the ./mysql-test/var/log directory
ls -l mysql-test/var/log/
-rw-r--r-- 1 patg patg 17 4 Dec 12:27 current_test
-rw-r--r-- 1 patg patg 692 4 Dec 12:52 manager.log
-rw-rw---- 1 patg patg 21246 4 Dec 12:51 master-bin.000001
-rw-rw---- 1 patg patg 68 4 Dec 12:28 master-bin.index
-rw-r--r-- 1 patg patg 1620 4 Dec 12:51 master.err
-rw-rw---- 1 patg patg 23179 4 Dec 12:51 master.log
-rw-rw---- 1 patg patg 16696550 4 Dec 12:51 master.trace
-rw-r--r-- 1 patg patg 0 4 Dec 12:28 mysqltest-time
-rw-r--r-- 1 patg patg 2024051 4 Dec 12:51 mysqltest.trace
-rw-rw---- 1 patg patg 94992 4 Dec 12:51 slave-bin.000001
-rw-rw---- 1 patg patg 67 4 Dec 12:28 slave-bin.index
-rw-rw---- 1 patg patg 249 4 Dec 12:52 slave-relay-bin.000003
-rw-rw---- 1 patg patg 73 4 Dec 12:28 slave-relay-bin.index
-rw-r--r-- 1 patg patg 1349 4 Dec 12:51 slave.err
-rw-rw---- 1 patg patg 96206 4 Dec 12:52 slave.log
-rw-rw---- 1 patg patg 15706355 4 Dec 12:51 slave.trace
-rw-r--r-- 1 patg patg 0 4 Dec 12:51 warnings
Of course, again, you can tail the trace log:
tail -f mysql-test/var/log/master.trace |grep ha_fed
As well as the slave query log:
tail -f mysql-test/var/log/slave.log
Files that comprise the test suit
---------------------------------
mysql-test/t/federated.test
mysql-test/r/federated.result
mysql-test/r/have_federated_db.require
mysql-test/include/have_federated_db.inc
Other tidbits
-------------
These were the files that were modified or created for this
Federated handler to work:
./configure.in
./sql/Makefile.am
./config/ac_macros/ha_federated.m4
./sql/handler.cc
./sql/mysqld.cc
./sql/set_var.cc
./sql/field.h
./sql/sql_string.h
./mysql-test/mysql-test-run(.sh)
./mysql-test/t/federated.test
./mysql-test/r/federated.result
./mysql-test/r/have_federated_db.require
./mysql-test/include/have_federated_db.inc
./sql/ha_federated.cc
./sql/ha_federated.h
*/
#ifdef __GNUC__
#pragma implementation // gcc: Class implementation
#endif
#include <mysql_priv.h>
#ifdef HAVE_FEDERATED_DB
#include "ha_federated.h"
#define MAX_REMOTE_SIZE IO_SIZE
/* Variables for federated share methods */
static HASH federated_open_tables; // Hash used to track open tables
pthread_mutex_t federated_mutex; // This is the mutex we use to init the hash
static int federated_init= 0; // Variable for checking the init state of hash
/*
Function we use in the creation of our hash to get key.
*/
static byte* federated_get_key(FEDERATED_SHARE *share,uint *length,
my_bool not_used __attribute__((unused)))
{
*length= share->table_name_length;
return (byte*) share->table_name;
}
/*
Parse connection info from table->s->comment
SYNOPSIS
parse_url()
share pointer to FEDERATED share
table pointer to current TABLE class
DESCRIPTION
populates the share with information about the connection
to the remote database that will serve as the data source.
This string must be specified (currently) in the "comment" field,
listed in the CREATE TABLE statement.
This string MUST be in the format of any of these:
scheme://username:password@hostname:port/database/table
scheme://username@hostname/database/table
scheme://username@hostname:port/database/table
scheme://username:password@hostname/database/table
An Example:
mysql://joe:joespass@192.168.1.111:9308/federated/testtable
***IMPORTANT***
Currently, only "mysql://" is supported.
'password' and 'port' are both optional.
RETURN VALUE
0 success
-1 failure, wrong string format
*/
static int parse_url(FEDERATED_SHARE *share, TABLE *table, uint table_create_flag)
{
DBUG_ENTER("ha_federated::parse_url");
// This either get set or will remain the same.
share->port= 0;
uint error_num= table_create_flag ? ER_CANT_CREATE_TABLE : ER_CONNECT_TO_MASTER ;
share->scheme= my_strdup(table->s->comment, MYF(0));
if ((share->username= strstr(share->scheme, "://")))
{
share->scheme[share->username - share->scheme] = '\0';
if (strcmp(share->scheme, "mysql") != 0)
{
DBUG_PRINT("ha_federated::parse_url",
("The federated handler currently only supports connecting\
to a MySQL database!!!\n"));
my_error(error_num, MYF(0),
"ERROR: federated handler only supports remote 'mysql://' database");
DBUG_RETURN(-1);
}
share->username+= 3;
if ((share->hostname= strchr(share->username, '@')))
{
share->username[share->hostname - share->username]= '\0';
share->hostname++;
if ((share->password= strchr(share->username, ':')))
{
share->username[share->password - share->username]= '\0';
share->password++;
share->username= share->username;
// make sure there isn't an extra / or @
if ((strchr(share->password, '/') || strchr(share->hostname, '@')))
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
/*
Found that if the string is:
user:@hostname:port/database/table
Then password is a null string, so set to NULL
*/
if ((share->password[0] == '\0'))
share->password= NULL;
}
else
share->username= share->username;
// make sure there isn't an extra / or @
if ((strchr(share->username, '/')) || (strchr(share->hostname, '@')))
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
if ((share->database= strchr(share->hostname, '/')))
{
share->hostname[share->database - share->hostname]= '\0';
share->database++;
if ((share->sport= strchr(share->hostname, ':')))
{
share->hostname[share->sport - share->hostname]= '\0';
share->sport++;
if (share->sport[0] == '\0')
share->sport= NULL;
else
share->port= atoi(share->sport);
}
if ((share->table_base_name= strchr(share->database, '/')))
{
share->database[share->table_base_name - share->database]= '\0';
share->table_base_name++;
}
else
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
}
else
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
// make sure there's not an extra /
if ((strchr(share->table_base_name, '/')))
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
if (share->hostname[0] == '\0')
share->hostname= NULL;
DBUG_PRINT("ha_federated::parse_url",
("scheme %s username %s password %s \
hostname %s port %d database %s tablename %s\n",
share->scheme, share->username, share->password, share->hostname,
share->port, share->database, share->table_base_name));
}
else
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
}
else
{
DBUG_PRINT("ha_federated::parse_url",
("this connection string is not in the correct format!!!\n"));
my_error(error_num, MYF(0),
"this connection string is not in the correct format!!!\n");
DBUG_RETURN(-1);
}
DBUG_RETURN(0);
}
/*
Convert MySQL result set row to handler internal format
SYNOPSIS
convert_row_to_internal_format()
record Byte pointer to record
row MySQL result set row from fetchrow()
DESCRIPTION
This method simply iterates through a row returned via fetchrow with
values from a successful SELECT , and then stores each column's value
in the field object via the field object pointer (pointing to the table's
array of field object pointers). This is how the handler needs the data
to be stored to then return results back to the user
RETURN VALUE
0 After fields have had field values stored from record
*/
uint ha_federated::convert_row_to_internal_format(byte *record, MYSQL_ROW row)
{
unsigned long len;
int x= 0;
DBUG_ENTER("ha_federated::convert_row_to_internal_format");
// Question this
memset(record, 0, table->s->null_bytes);
for (Field **field=table->field; *field ; field++, x++)
{
if (!row[x])
(*field)->set_null();
else
/*
changed system_charset_info to default_charset_info because
testing revealed that german text was not being retrieved properly
*/
(*field)->store(row[x], strlen(row[x]), &my_charset_bin);
}
DBUG_RETURN(0);
}
bool ha_federated::create_where_from_key(String *to, KEY *key_info,
const byte *key, uint key_length)
{
uint second_loop= 0;
KEY_PART_INFO *key_part;
bool needs_quotes;
String tmp;
DBUG_ENTER("ha_federated::create_where_from_key");
for (key_part= key_info->key_part ; (int) key_length > 0 ; key_part++)
{
Field *field= key_part->field;
needs_quotes= field->needs_quotes();
//bool needs_quotes= type_quote(field->type());
DBUG_PRINT("ha_federated::create_where_from_key", ("key name %s type %d", field->field_name, field->type()));
uint length= key_part->length;
if (second_loop++ && to->append(" AND ",5))
DBUG_RETURN(1);
if (to->append('`') || to->append(field->field_name) ||
to->append("` ",2))
DBUG_RETURN(1); // Out of memory
if (key_part->null_bit)
{
if (*key++)
{
if (to->append("IS NULL",7))
DBUG_PRINT("ha_federated::create_where_from_key", ("NULL type %s", to->c_ptr_quick()));
DBUG_RETURN(1);
key_length-= key_part->store_length;
key+= key_part->store_length-1;
continue;
}
key_length--;
}
if (to->append("= "))
DBUG_RETURN(1);
if (needs_quotes && to->append("'"))
DBUG_RETURN(1);
if (key_part->type == HA_KEYTYPE_BIT)
{
/* This is can be threated as a hex string */
Field_bit *field= (Field_bit *) (key_part->field);
char buff[64+2], *ptr;
byte *end= (byte *)(key) + length;
buff[0]='0';
buff[1]='x';
for (ptr= buff+2 ; key < end ; key++)
{
uint tmp= (uint) (uchar) *key;
*ptr++=_dig_vec_upper[tmp >> 4];
*ptr++=_dig_vec_upper[tmp & 15];
}
if (to->append(buff, (uint) (ptr-buff)))
DBUG_RETURN(1);
DBUG_PRINT("ha_federated::create_where_from_key", ("bit type %s", to->c_ptr_quick()));
key_length-= length;
continue;
}
if (key_part->key_part_flag & HA_BLOB_PART)
{
uint blob_length= uint2korr(key);
key+= HA_KEY_BLOB_LENGTH;
key_length-= HA_KEY_BLOB_LENGTH;
tmp.set_quick((char*) key, blob_length, &my_charset_bin);
if (append_escaped(to, &tmp))
DBUG_RETURN(1);
DBUG_PRINT("ha_federated::create_where_from_key", ("blob type %s", to->c_ptr_quick()));
length= key_part->length;
}
else if (key_part->key_part_flag & HA_VAR_LENGTH_PART)
{
length= uint2korr(key);
key+= HA_KEY_BLOB_LENGTH;
tmp.set_quick((char*) key, length, &my_charset_bin);
if (append_escaped(to, &tmp))
DBUG_RETURN(1);
DBUG_PRINT("ha_federated::create_where_from_key", ("varchar type %s", to->c_ptr_quick()));
}
else
{
DBUG_PRINT("ha_federated::create_where_from_key", ("else block, unknown type so far"));
char buff[MAX_FIELD_WIDTH];
String str(buff, sizeof(buff), field->charset()), *res;
res= field->val_str(&str, (char *)(key));
if (field->result_type() == STRING_RESULT)
{
if (append_escaped(to, res))
DBUG_RETURN(1);
res= field->val_str(&str, (char *)(key));
DBUG_PRINT("ha_federated::create_where_from_key", ("else block, string type", to->c_ptr_quick()));
}
else if (to->append(res->ptr(), res->length()))
DBUG_RETURN(1);
}
if (needs_quotes && to->append("'"))
DBUG_RETURN(1);
DBUG_PRINT("ha_federated::create_where_from_key", ("final value for 'to' %s", to->c_ptr_quick()));
key+= length;
key_length-= length;
DBUG_RETURN(0);
}
DBUG_RETURN(1);
}
int load_conn_info(FEDERATED_SHARE *share, TABLE *table)
{
DBUG_ENTER("ha_federated::load_conn_info");
int retcode;
retcode= parse_url(share, table, 0);
if (retcode < 0)
{
DBUG_PRINT("ha_federated::load_conn_info",
("retcode %d, setting defaults", retcode));
/* sanity checks to make sure all needed pieces are present */
if (!share->port)
{
if (strcmp(share->hostname, "localhost") == 0)
share->socket= my_strdup("/tmp/mysql.sock",MYF(0));
else
share->port= 3306;
}
}
DBUG_PRINT("ha_federated::load_conn_info",
("returned from retcode %d", retcode));
DBUG_RETURN(retcode);
}
/*
Example of simple lock controls. The "share" it creates is structure we will
pass to each federated handler. Do you have to have one of these? Well, you
have pieces that are used for locking, and they are needed to function.
*/
static FEDERATED_SHARE *get_share(const char *table_name, TABLE *table)
{
FEDERATED_SHARE *share;
char query_buffer[IO_SIZE];
String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
query.length(0);
uint table_name_length, table_base_name_length;
char *tmp_table_name, *tmp_table_base_name, *table_base_name, *select_query;
// share->table_name has the file location - we want the actual table's
// name!
table_base_name= (char *)table->s->table_name;
DBUG_PRINT("ha_federated::get_share",("table_name %s", table_base_name));
/*
So why does this exist? There is no way currently to init a storage engine.
Innodb and BDB both have modifications to the server to allow them to
do this. Since you will not want to do this, this is probably the next
best method.
*/
if (!federated_init)
{
/* Hijack a mutex for init'ing the storage engine */
pthread_mutex_lock(&LOCK_mysql_create_db);
if (!federated_init)
{
federated_init++;
VOID(pthread_mutex_init(&federated_mutex,MY_MUTEX_INIT_FAST));
(void) hash_init(&federated_open_tables,system_charset_info,32,0,0,
(hash_get_key) federated_get_key,0,0);
}
pthread_mutex_unlock(&LOCK_mysql_create_db);
}
pthread_mutex_lock(&federated_mutex);
table_name_length= (uint) strlen(table_name);
table_base_name_length= (uint) strlen(table_base_name);
if (!(share= (FEDERATED_SHARE*) hash_search(&federated_open_tables,
(byte*) table_name,
table_name_length)))
{
query.set_charset(system_charset_info);
query.append("SELECT * FROM ");
query.append(table_base_name);
if (!(share= (FEDERATED_SHARE *)
my_multi_malloc(MYF(MY_WME | MY_ZEROFILL),
&share, sizeof(*share),
&tmp_table_name, table_name_length+1,
&tmp_table_base_name, table_base_name_length+1,
&select_query, query.length()+1,
NullS)))
{
pthread_mutex_unlock(&federated_mutex);
return NULL;
}
load_conn_info(share, table);
share->use_count= 0;
share->table_name_length= table_name_length;
share->table_name= tmp_table_name;
share->table_base_name_length= table_base_name_length;
share->table_base_name= tmp_table_base_name;
share->select_query= select_query;
strmov(share->table_name,table_name);
strmov(share->table_base_name,table_base_name);
strmov(share->select_query,query.c_ptr_quick());
DBUG_PRINT("ha_federated::get_share",("share->select_query %s", share->select_query));
if (my_hash_insert(&federated_open_tables, (byte*) share))
goto error;
thr_lock_init(&share->lock);
pthread_mutex_init(&share->mutex,MY_MUTEX_INIT_FAST);
}
share->use_count++;
pthread_mutex_unlock(&federated_mutex);
return share;
error2:
thr_lock_delete(&share->lock);
pthread_mutex_destroy(&share->mutex);
error:
pthread_mutex_unlock(&federated_mutex);
my_free((gptr) share, MYF(0));
return NULL;
}
/*
Free lock controls. We call this whenever we close a table.
If the table had the last reference to the share then we
free memory associated with it.
*/
static int free_share(FEDERATED_SHARE *share)
{
pthread_mutex_lock(&federated_mutex);
if (!--share->use_count)
{
hash_delete(&federated_open_tables, (byte*) share);
thr_lock_delete(&share->lock);
pthread_mutex_destroy(&share->mutex);
my_free((gptr) share, MYF(0));
}
pthread_mutex_unlock(&federated_mutex);
return 0;
}
/*
If frm_error() is called then we will use this to to find out
what file extentions exist for the storage engine. This is
also used by the default rename_table and delete_table method
in handler.cc.
*/
const char **ha_federated::bas_ext() const
{ static const char *ext[]= { NullS }; return ext; }
/*
Used for opening tables. The name will be the name of the file.
A table is opened when it needs to be opened. For instance
when a request comes in for a select on the table (tables are not
open and closed for each request, they are cached).
Called from handler.cc by handler::ha_open(). The server opens
all tables by calling ha_open() which then calls the handler
specific open().
*/
int ha_federated::open(const char *name, int mode, uint test_if_locked)
{
DBUG_ENTER("ha_federated::open");
int rc;
if (!(share= get_share(name, table)))
DBUG_RETURN(1);
thr_lock_data_init(&share->lock,&lock,NULL);
/* Connect to remote database mysql_real_connect() */
mysql= mysql_init(0);
DBUG_PRINT("ha_federated::open",("hostname %s", share->hostname));
DBUG_PRINT("ha_federated::open",("username %s", share->username));
DBUG_PRINT("ha_federated::open",("password %s", share->password));
DBUG_PRINT("ha_federated::open",("database %s", share->database));
DBUG_PRINT("ha_federated::open",("port %d", share->port));
if (!mysql_real_connect(mysql,
share->hostname,
share->username,
share->password,
share->database,
share->port,
NULL,
0))
{
my_error(ER_CONNECT_TO_MASTER, MYF(0), mysql_error(mysql));
DBUG_RETURN(ER_CONNECT_TO_MASTER);
}
DBUG_RETURN(0);
}
/*
Closes a table. We call the free_share() function to free any resources
that we have allocated in the "shared" structure.
Called from sql_base.cc, sql_select.cc, and table.cc.
In sql_select.cc it is only used to close up temporary tables or during
the process where a temporary table is converted over to being a
myisam table.
For sql_base.cc look at close_data_tables().
*/
int ha_federated::close(void)
{
DBUG_ENTER("ha_federated::close");
/* Disconnect from mysql */
mysql_close(mysql);
DBUG_RETURN(free_share(share));
}
/*
Checks if a field in a record is SQL NULL.
SYNOPSIS
field_in_record_is_null()
table TABLE pointer, MySQL table object
field Field pointer, MySQL field object
record char pointer, contains record
DESCRIPTION
This method uses the record format information in table to track
the null bit in record.
RETURN VALUE
1 if NULL
0 otherwise
*/
inline uint field_in_record_is_null (
TABLE* table, /* in: MySQL table object */
Field* field, /* in: MySQL field object */
char* record) /* in: a row in MySQL format */
{
int null_offset;
DBUG_ENTER("ha_federated::field_in_record_is_null");
if (!field->null_ptr)
DBUG_RETURN(0);
null_offset= (uint) ((char*) field->null_ptr - (char*) table->record[0]);
if (record[null_offset] & field->null_bit)
DBUG_RETURN(1);
DBUG_RETURN(0);
}
/*
write_row() inserts a row. No extra() hint is given currently if a bulk load
is happeneding. buf() is a byte array of data. You can use the field
information to extract the data from the native byte array type.
Example of this would be:
for (Field **field=table->field ; *field ; field++)
{
...
}
Called from item_sum.cc, item_sum.cc, sql_acl.cc, sql_insert.cc,
sql_insert.cc, sql_select.cc, sql_table.cc, sql_udf.cc, and sql_update.cc.
*/
int ha_federated::write_row(byte * buf)
{
int x= 0, num_fields= 0;
Field **field;
ulong current_query_id= 1;
ulong tmp_query_id= 1;
int all_fields_have_same_query_id= 1;
char insert_buffer[IO_SIZE];
char values_buffer[IO_SIZE], insert_field_value_buffer[IO_SIZE];
// The main insert query string
String insert_string(insert_buffer, sizeof(insert_buffer), &my_charset_bin);
insert_string.length(0);
// The string containing the values to be added to the insert
String values_string(values_buffer, sizeof(values_buffer), &my_charset_bin);
values_string.length(0);
// The actual value of the field, to be added to the values_string
String insert_field_value_string(insert_field_value_buffer,
sizeof(insert_field_value_buffer), &my_charset_bin);
insert_field_value_string.length(0);
DBUG_ENTER("ha_federated::write_row");
/*
I want to use this and the next line, but the repository needs to be
updated to do so
*/
statistic_increment(table->in_use->status_var.ha_write_count,&LOCK_status);
if (table->timestamp_field_type & TIMESTAMP_AUTO_SET_ON_INSERT)
table->timestamp_field->set_time();
/*
get the current query id - the fields that we add to the insert
statement to send to the remote will not be appended unless they match
this query id
*/
current_query_id= table->in_use->query_id;
DBUG_PRINT("ha_federated::write_row", ("current query id %d",
current_query_id));
// start off our string
insert_string.append("INSERT INTO ");
insert_string.append(share->table_base_name);
// start both our field and field values strings
insert_string.append(" (");
values_string.append(" VALUES (");
/*
Even if one field is different, all_fields_same_query_id can't remain
0 if it remains 0, then that means no fields were specified in the query
such as in the case of INSERT INTO table VALUES (val1, val2, valN)
*/
for (field= table->field; *field ; field++, x++)
{
if (x > 0 && tmp_query_id != (*field)->query_id)
all_fields_have_same_query_id= 0;
tmp_query_id= (*field)->query_id;
}
/*
loop through the field pointer array, add any fields to both the values
list and the fields list that match the current query id
*/
for (field= table->field; *field ; field++, x++)
{
DBUG_PRINT("ha_federated::write_row", ("field type %d", (*field)->type()));
// if there is a query id and if it's equal to the current query id
if ( ((*field)->query_id && (*field)->query_id == current_query_id )
|| all_fields_have_same_query_id)
{
num_fields++;
if ((*field)->is_null())
{
DBUG_PRINT("ha_federated::write_row",
("current query id %d field is_null query id %d",
current_query_id, (*field)->query_id));
insert_field_value_string.append("NULL");
}
else
{
DBUG_PRINT("ha_federated::write_row",
("current query id %d field is not null query ID %d",
current_query_id, (*field)->query_id));
(*field)->val_str(&insert_field_value_string);
}
// append the field name
insert_string.append((*field)->field_name);
// quote these fields if they require it
(*field)->quote_data(&insert_field_value_string);
// append the value
values_string.append(insert_field_value_string);
insert_field_value_string.length(0);
// append commas between both fields and fieldnames
insert_string.append(',');
values_string.append(',');
DBUG_PRINT("ha_federated::write_row",
("insert_string %s values_string %s insert_field_value_string %s",
insert_string.c_ptr_quick(), values_string.c_ptr_quick(),
insert_field_value_string.c_ptr_quick()));
}
}
/*
chop of the trailing comma, or if there were no fields, a '('
So, "INSERT INTO foo (" becomes "INSERT INTO foo "
or, with fields, "INSERT INTO foo (field1, field2," becomes
"INSERT INTO foo (field1, field2"
*/
insert_string.chop();
/*
if there were no fields, we don't want to add a closing paren
AND, we don't want to chop off the last char '('
insert will be "INSERT INTO t1 VALUES ();"
*/
DBUG_PRINT("ha_federated::write_row",("x %d num fields %d",
x, num_fields));
if (num_fields > 0)
{
// chops off leading commas
values_string.chop();
insert_string.append(')');
}
// we always want to append this, even if there aren't any fields
values_string.append(')');
// add the values
insert_string.append(values_string);
DBUG_PRINT("ha_federated::write_row",("insert query %s",
insert_string.c_ptr_quick()));
if (mysql_real_query(mysql, insert_string.c_ptr_quick(),
insert_string.length()))
{
my_error(ER_QUERY_ON_MASTER,MYF(0),mysql_error(mysql));
DBUG_RETURN(ER_QUERY_ON_MASTER);
}
DBUG_RETURN(0);
}
/*
Yes, update_row() does what you expect, it updates a row. old_data will have
the previous row record in it, while new_data will have the newest data in
it.
Keep in mind that the server can do updates based on ordering if an ORDER BY
clause was used. Consecutive ordering is not guarenteed.
Currently new_data will not have an updated auto_increament record, or
and updated timestamp field. You can do these for federated by doing these:
if (table->timestamp_on_update_now)
update_timestamp(new_row+table->timestamp_on_update_now-1);
if (table->next_number_field && record == table->record[0])
update_auto_increment();
Called from sql_select.cc, sql_acl.cc, sql_update.cc, and sql_insert.cc.
*/
int ha_federated::update_row(
const byte * old_data,
byte * new_data
)
{
int x= 0;
uint has_a_primary_key= 0;
int primary_key_field_num;
char old_field_value_buffer[IO_SIZE], new_field_value_buffer[IO_SIZE];
char update_buffer[IO_SIZE], where_buffer[IO_SIZE];
// stores the value to be replaced of the field were are updating
String old_field_value(old_field_value_buffer, sizeof(old_field_value_buffer), &my_charset_bin);
old_field_value.length(0);
// stores the new value of the field
String new_field_value(new_field_value_buffer, sizeof(new_field_value_buffer), &my_charset_bin);
new_field_value.length(0);
// stores the update query
String update_string(update_buffer, sizeof(update_buffer), &my_charset_bin);
update_string.length(0);
// stores the WHERE clause
String where_string(where_buffer, sizeof(where_buffer), &my_charset_bin);
where_string.length(0);
DBUG_ENTER("ha_federated::update_row");
has_a_primary_key= table->s->primary_key == 0 ? 1 : 0;
primary_key_field_num= has_a_primary_key ?
table->key_info[table->s->primary_key].key_part->fieldnr -1 : -1;
if (has_a_primary_key)
DBUG_PRINT("ha_federated::update_row", ("has a primary key"));
update_string.append("UPDATE ");
update_string.append(share->table_base_name);
update_string.append(" SET ");
/*
In this loop, we want to match column names to values being inserted
(while building INSERT statement).
Iterate through table->field (new data) and share->old_filed (old_data)
using the same index to created an SQL UPDATE statement, new data is
used to create SET field=value and old data is used to create WHERE
field=oldvalue
*/
for (Field **field= table->field ; *field ; field++, x++)
{
/*
In all of these tests for 'has_a_primary_key', what I'm trying to
accomplish is to only use the primary key in the WHERE clause if the
table has a primary key, as opposed to a table without a primary key
in which case we have to use all the fields to create a WHERE clause
using the old/current values, as well as adding a LIMIT statement
*/
if (has_a_primary_key)
{
if (x == primary_key_field_num)
where_string.append((*field)->field_name);
}
else
where_string.append((*field)->field_name);
update_string.append((*field)->field_name);
update_string.append('=');
if ((*field)->is_null())
new_field_value.append("NULL");
else
{
// otherwise =
(*field)->val_str(&new_field_value);
(*field)->quote_data(&new_field_value);
if ( has_a_primary_key )
{
if (x == primary_key_field_num)
where_string.append("=");
}
else
if (! field_in_record_is_null(table, *field, (char*) old_data))
where_string.append("=");
}
if ( has_a_primary_key)
{
if (x == primary_key_field_num)
{
(*field)->val_str(&old_field_value,
(char *)(old_data + (*field)->offset()));
(*field)->quote_data(&old_field_value);
where_string.append(old_field_value);
}
}
else
{
if (field_in_record_is_null(table, *field, (char*) old_data))
where_string.append(" IS NULL ");
else
{
(*field)->val_str(&old_field_value,
(char *)(old_data + (*field)->offset()));
(*field)->quote_data(&old_field_value);
where_string.append(old_field_value);
}
}
update_string.append(new_field_value);
new_field_value.length(0);
if ((uint) x+1 < table->s->fields)
{
update_string.append(", ");
if (! has_a_primary_key)
where_string.append(" AND ");
}
old_field_value.length(0);
}
update_string.append(" WHERE ");
update_string.append(where_string.c_ptr_quick());
if (! has_a_primary_key)
update_string.append(" LIMIT 1");
DBUG_PRINT("ha_federated::update_row", ("Final update query: %s",
update_string.c_ptr_quick()));
if (mysql_real_query(mysql, update_string.c_ptr_quick(),
update_string.length()))
{
my_error(ER_QUERY_ON_MASTER,MYF(0),mysql_error(mysql));
DBUG_RETURN(ER_QUERY_ON_MASTER);
}
DBUG_RETURN(0);
}
/*
This will delete a row. 'buf' will contain a copy of the row to be deleted.
The server will call this right after the current row has been called (from
either a previous rnd_nexT() or index call).
If you keep a pointer to the last row or can access a primary key it will
make doing the deletion quite a bit easier.
Keep in mind that the server does no guarentee consecutive deletions.
ORDER BY clauses can be used.
Called in sql_acl.cc and sql_udf.cc to manage internal table information.
Called in sql_delete.cc, sql_insert.cc, and sql_select.cc. In sql_select
it is used for removing duplicates while in insert it is used for REPLACE
calls.
*/
int ha_federated::delete_row(const byte * buf)
{
int x= 0;
char delete_buffer[IO_SIZE];
char data_buffer[IO_SIZE];
String delete_string(delete_buffer, sizeof(delete_buffer), &my_charset_bin);
delete_string.length(0);
String data_string(data_buffer, sizeof(data_buffer), &my_charset_bin);
data_string.length(0);
DBUG_ENTER("ha_federated::delete_row");
delete_string.append("DELETE FROM ");
delete_string.append(share->table_base_name);
delete_string.append(" WHERE ");
for (Field **field= table->field; *field; field++, x++)
{
delete_string.append((*field)->field_name);
if ((*field)->is_null())
{
delete_string.append(" IS ");
data_string.append("NULL");
}
else
{
delete_string.append("=");
(*field)->val_str(&data_string);
(*field)->quote_data(&data_string);
}
delete_string.append(data_string);
data_string.length(0);
if ((uint) x+1 < table->s->fields)
delete_string.append(" AND ");
}
delete_string.append(" LIMIT 1");
DBUG_PRINT("ha_federated::delete_row",
("Delete sql: %s", delete_string.c_ptr_quick()));
if ( mysql_real_query(mysql, delete_string.c_ptr_quick(),
delete_string.length()))
{
my_error(ER_QUERY_ON_MASTER,MYF(0),mysql_error(mysql));
DBUG_RETURN(ER_QUERY_ON_MASTER);
}
DBUG_RETURN(0);
}
/*
Positions an index cursor to the index specified in the handle. Fetches the
row if available. If the key value is null, begin at the first key of the
index. This method, which is called in the case of an SQL statement having
a WHERE clause on a non-primary key index, simply calls index_read_idx.
*/
int ha_federated::index_read(byte * buf, const byte * key,
uint key_len __attribute__((unused)),
enum ha_rkey_function find_flag
__attribute__((unused)))
{
DBUG_ENTER("ha_federated::index_read");
DBUG_RETURN(index_read_idx(buf, active_index, key, key_len, find_flag));
}
/*
Positions an index cursor to the index specified in key. Fetches the
row if any. This is only used to read whole keys.
This method is called via index_read in the case of a WHERE clause using
a regular non-primary key index, OR is called DIRECTLY when the WHERE clause
uses a PRIMARY KEY index.
*/
int ha_federated::index_read_idx(byte * buf, uint index, const byte * key,
uint key_len __attribute__((unused)),
enum ha_rkey_function find_flag
__attribute__((unused)))
{
char index_value[IO_SIZE];
char key_value[IO_SIZE];
char test_value[IO_SIZE];
String index_string(index_value, sizeof(index_value), &my_charset_bin);
index_string.length(0);
uint keylen;
char sql_query_buffer[IO_SIZE];
String sql_query(sql_query_buffer, sizeof(sql_query_buffer), &my_charset_bin);
sql_query.length(0);
DBUG_ENTER("ha_federated::index_read_idx");
statistic_increment(table->in_use->status_var.ha_read_key_count,&LOCK_status);
sql_query.append(share->select_query);
sql_query.append(" WHERE ");
keylen= strlen((char *)(key));
create_where_from_key(&index_string, &table->key_info[index], key, keylen);
sql_query.append(index_string);
DBUG_PRINT("ha_federated::index_read_idx",
("current key %d key value %s index_string value %s length %d", index, (char *)(key),index_string.c_ptr_quick(),
index_string.length()));
DBUG_PRINT("ha_federated::index_read_idx",
("current position %d sql_query %s", current_position,
sql_query.c_ptr_quick()));
if (mysql_real_query(mysql, sql_query.c_ptr_quick(), sql_query.length()))
{
my_error(ER_QUERY_ON_MASTER,MYF(0),mysql_error(mysql));
DBUG_RETURN(ER_QUERY_ON_MASTER);
}
result= mysql_store_result(mysql);
if (!result)
{
table->status= STATUS_NOT_FOUND;
DBUG_RETURN(HA_ERR_END_OF_FILE);
}
if (mysql_errno(mysql))
{
table->status= STATUS_NOT_FOUND;
DBUG_RETURN(mysql_errno(mysql));
}
DBUG_RETURN(rnd_next(buf));
}
/*
Initialized at each key walk (called multiple times unlike ::rnd_init())
*/
int ha_federated::index_init(uint keynr)
{
int error;
DBUG_ENTER("ha_federated::index_init");
DBUG_PRINT("ha_federated::index_init",
("table: '%s' key: %d", table->s->table_name, keynr));
active_index= keynr;
DBUG_RETURN(0);
}
/*
Used to read forward through the index.
*/
int ha_federated::index_next(byte * buf)
{
DBUG_ENTER("ha_federated::index_next");
DBUG_RETURN(rnd_next(buf));
}
/*
rnd_init() is called when the system wants the storage engine to do a table
scan.
This is the method that gets data for the SELECT calls.
See the federated in the introduction at the top of this file to see when
rnd_init() is called.
Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
sql_table.cc, and sql_update.cc.
*/
int ha_federated::rnd_init(bool scan)
{
DBUG_ENTER("ha_federated::rnd_init");
int num_fields, rows;
DBUG_PRINT("ha_federated::rnd_init",
("share->select_query %s", share->select_query));
if (mysql_real_query(mysql, share->select_query, strlen(share->select_query)))
{
my_error(ER_QUERY_ON_MASTER,MYF(0),mysql_error(mysql));
DBUG_RETURN(ER_QUERY_ON_MASTER);
}
result= mysql_store_result(mysql);
if (mysql_errno(mysql))
DBUG_RETURN(mysql_errno(mysql));
DBUG_RETURN(0);
}
int ha_federated::rnd_end()
{
DBUG_ENTER("ha_federated::rnd_end");
mysql_free_result(result);
DBUG_RETURN(index_end());
}
int ha_federated::index_end(void)
{
DBUG_ENTER("ha_federated::index_end");
active_index= MAX_KEY;
DBUG_RETURN(0);
}
/*
This is called for each row of the table scan. When you run out of records
you should return HA_ERR_END_OF_FILE. Fill buff up with the row information.
The Field structure for the table is the key to getting data into buf
in a manner that will allow the server to understand it.
Called from filesort.cc, records.cc, sql_handler.cc, sql_select.cc,
sql_table.cc, and sql_update.cc.
*/
int ha_federated::rnd_next(byte *buf)
{
MYSQL_ROW row;
DBUG_ENTER("ha_federated::rnd_next");
// Fetch a row, insert it back in a row format.
current_position= result->data_cursor;
if (! (row= mysql_fetch_row(result)))
DBUG_RETURN(HA_ERR_END_OF_FILE);
DBUG_RETURN(convert_row_to_internal_format(buf,row));
}
/*
'position()' is called after each call to rnd_next() if the data needs to be
ordered. You can do something like the following to store the position:
my_store_ptr(ref, ref_length, current_position);
The server uses ref to store data. ref_length in the above case is the size
needed to store current_position. ref is just a byte array that the server
will maintain. If you are using offsets to mark rows, then current_position
should be the offset. If it is a primary key like in BDB, then it needs to
be a primary key.
Called from filesort.cc, sql_select.cc, sql_delete.cc and sql_update.cc.
*/
void ha_federated::position(const byte *record)
{
DBUG_ENTER("ha_federated::position");
//my_store_ptr Add seek storage
*(MYSQL_ROW_OFFSET *)ref=current_position; // ref is always aligned
DBUG_VOID_RETURN;
}
/*
This is like rnd_next, but you are given a position to use to determine the
row. The position will be of the type that you stored in ref. You can use
ha_get_ptr(pos,ref_length) to retrieve whatever key or position you saved
when position() was called.
This method is required for an ORDER BY.
Called from filesort.cc records.cc sql_insert.cc sql_select.cc sql_update.cc.
*/
int ha_federated::rnd_pos(byte * buf, byte *pos)
{
DBUG_ENTER("ha_federated::rnd_pos");
statistic_increment(table->in_use->status_var.ha_read_rnd_count,&LOCK_status);
memcpy_fixed(&current_position, pos, sizeof(MYSQL_ROW_OFFSET)); // pos is not aligned
result->current_row= 0;
result->data_cursor= current_position;
DBUG_RETURN(rnd_next(buf));
}
/*
::info() is used to return information to the optimizer.
Currently this table handler doesn't implement most of the fields
really needed. SHOW also makes use of this data
Another note, you will probably want to have the following in your
code:
if (records < 2)
records = 2;
The reason is that the server will optimize for cases of only a single
record. If in a table scan you don't know the number of records
it will probably be better to set records to two so you can return
as many records as you need.
Along with records a few more variables you may wish to set are:
records
deleted
data_file_length
index_file_length
delete_length
check_time
Take a look at the public variables in handler.h for more information.
Called in:
filesort.cc
ha_heap.cc
item_sum.cc
opt_sum.cc
sql_delete.cc
sql_delete.cc
sql_derived.cc
sql_select.cc
sql_select.cc
sql_select.cc
sql_select.cc
sql_select.cc
sql_show.cc
sql_show.cc
sql_show.cc
sql_show.cc
sql_table.cc
sql_union.cc
sql_update.cc
*/
// FIX: later version provide better information to the optimizer
void ha_federated::info(uint flag)
{
DBUG_ENTER("ha_federated::info");
records= 10000; // Fake!
DBUG_VOID_RETURN;
}
/*
Used to delete all rows in a table. Both for cases of truncate and
for cases where the optimizer realizes that all rows will be
removed as a result of a SQL statement.
Called from item_sum.cc by Item_func_group_concat::clear(),
Item_sum_count_distinct::clear(), and Item_func_group_concat::clear().
Called from sql_delete.cc by mysql_delete().
Called from sql_select.cc by JOIN::reinit().
Called from sql_union.cc by st_select_lex_unit::exec().
*/
int ha_federated::delete_all_rows()
{
DBUG_ENTER("ha_federated::delete_all_rows");
char query_buffer[IO_SIZE];
String query(query_buffer, sizeof(query_buffer), &my_charset_bin);
query.length(0);
query.set_charset(system_charset_info);
query.append("TRUNCATE ");
query.append(share->table_base_name);
if (mysql_real_query(mysql, query.c_ptr_quick(), query.length())) {
my_error(ER_QUERY_ON_MASTER,MYF(0),mysql_error(mysql));
DBUG_RETURN(ER_QUERY_ON_MASTER);
}
DBUG_RETURN(HA_ERR_WRONG_COMMAND);
}
/*
The idea with handler::store_lock() is the following:
The statement decided which locks we should need for the table
for updates/deletes/inserts we get WRITE locks, for SELECT... we get
read locks.
Before adding the lock into the table lock handler (see thr_lock.c)
mysqld calls store lock with the requested locks. Store lock can now
modify a write lock to a read lock (or some other lock), ignore the
lock (if we don't want to use MySQL table locks at all) or add locks
for many tables (like we do when we are using a MERGE handler).
Berkeley DB for federated changes all WRITE locks to TL_WRITE_ALLOW_WRITE
(which signals that we are doing WRITES, but we are still allowing other
reader's and writer's.
When releasing locks, store_lock() are also called. In this case one
usually doesn't have to do anything.
In some exceptional cases MySQL may send a request for a TL_IGNORE;
This means that we are requesting the same lock as last time and this
should also be ignored. (This may happen when someone does a flush
table when we have opened a part of the tables, in which case mysqld
closes and reopens the tables and tries to get the same locks at last
time). In the future we will probably try to remove this.
Called from lock.cc by get_lock_data().
*/
THR_LOCK_DATA **ha_federated::store_lock(THD *thd,
THR_LOCK_DATA **to,
enum thr_lock_type lock_type)
{
if (lock_type != TL_IGNORE && lock.type == TL_UNLOCK)
{
/*
Here is where we get into the guts of a row level lock.
If TL_UNLOCK is set
If we are not doing a LOCK TABLE or DISCARD/IMPORT
TABLESPACE, then allow multiple writers
*/
if ((lock_type >= TL_WRITE_CONCURRENT_INSERT &&
lock_type <= TL_WRITE) && !thd->in_lock_tables
&& !thd->tablespace_op)
lock_type= TL_WRITE_ALLOW_WRITE;
/*
In queries of type INSERT INTO t1 SELECT ... FROM t2 ...
MySQL would use the lock TL_READ_NO_INSERT on t2, and that
would conflict with TL_WRITE_ALLOW_WRITE, blocking all inserts
to t2. Convert the lock to a normal read lock to allow
concurrent inserts to t2.
*/
if (lock_type == TL_READ_NO_INSERT && !thd->in_lock_tables)
lock_type= TL_READ;
lock.type= lock_type;
}
*to++= &lock;
return to;
}
/*
create() does nothing, since we have no local setup of our own.
FUTURE: We should potentially connect to the remote database and
create tables if they do not exist.
*/
int ha_federated::create(const char *name, TABLE *table_arg,
HA_CREATE_INFO *create_info)
{
int retcode;
FEDERATED_SHARE tmp;
DBUG_ENTER("ha_federated::create");
retcode= parse_url(&tmp, table_arg, 1);
if (retcode < 0)
{
DBUG_PRINT("ha_federated::create",
("ERROR: on table creation for %s called parse_url, retcode %d",
create_info->data_file_name, retcode));
DBUG_RETURN(ER_CANT_CREATE_TABLE);
}
DBUG_RETURN(0);
}
#endif /* HAVE_FEDERATED_DB */
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