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Fix for BUG#25843: changing default database between PREPARE and EXECUTE

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of statement breaks binlog.

There were two problems discovered by this bug:

  1. Default (current) database is not fixed at the creation time.
     That leads to wrong output of DATABASE() function.

  2. Database attributes (@@collation_database) are not fixed at
     the creation time. That leads to wrong resultset.

Binlog breakage and Query Cache wrong output happened because of
the first problem.

The fix is to remember the current database at the PREPARE-time and
set it each time at EXECUTE.
This commit is contained in:
anozdrin/alik@ibm.opbmk
2007-08-31 20:42:14 +04:00
parent f141ba5e26
commit d6f94b062c
13 changed files with 891 additions and 153 deletions
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98
sql/sql_db.cc
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@@ -1350,8 +1350,67 @@ static void mysql_change_db_impl(THD *thd,
}
/**
@brief Change the current database and its attributes.
Backup the current database name before switch.
@param[in] thd thread handle
@param[in, out] saved_db_name IN: "str" points to a buffer where to store
the old database name, "length" contains the
buffer size
OUT: if the current (default) database is
not NULL, its name is copied to the
buffer pointed at by "str"
and "length" is updated accordingly.
Otherwise "str" is set to NULL and
"length" is set to 0.
*/
static void backup_current_db_name(THD *thd,
LEX_STRING *saved_db_name)
{
if (!thd->db)
{
/* No current (default) database selected. */
saved_db_name->str= NULL;
saved_db_name->length= 0;
}
else
{
strmake(saved_db_name->str, thd->db, saved_db_name->length);
saved_db_name->length= thd->db_length;
}
}
/**
Return TRUE if db1_name is equal to db2_name, FALSE otherwise.
The function allows to compare database names according to the MySQL
rules. The database names db1 and db2 are equal if:
- db1 is NULL and db2 is NULL;
or
- db1 is not-NULL, db2 is not-NULL, db1 is equal (ignoring case) to
db2 in system character set (UTF8).
*/
static inline bool
cmp_db_names(const char *db1_name,
const char *db2_name)
{
return
/* db1 is NULL and db2 is NULL */
!db1_name && !db2_name ||
/* db1 is not-NULL, db2 is not-NULL, db1 == db2. */
db1_name && db2_name &&
my_strcasecmp(system_charset_info, db1_name, db2_name) == 0;
}
/**
@brief Change the current database and its attributes unconditionally.
@param thd thread handle
@param new_db_name database name
@@ -1568,6 +1627,43 @@ bool mysql_change_db(THD *thd, const LEX_STRING *new_db_name, bool force_switch)
}
/**
Change the current database and its attributes if needed.
@param thd thread handle
@param new_db_name database name
@param[in, out] saved_db_name IN: "str" points to a buffer where to store
the old database name, "length" contains the
buffer size
OUT: if the current (default) database is
not NULL, its name is copied to the
buffer pointed at by "str"
and "length" is updated accordingly.
Otherwise "str" is set to NULL and
"length" is set to 0.
@param force_switch @see mysql_change_db()
@param[out] cur_db_changed out-flag to indicate whether the current
database has been changed (valid only if
the function suceeded)
*/
bool mysql_opt_change_db(THD *thd,
const LEX_STRING *new_db_name,
LEX_STRING *saved_db_name,
bool force_switch,
bool *cur_db_changed)
{
*cur_db_changed= !cmp_db_names(thd->db, new_db_name->str);
if (!*cur_db_changed)
return FALSE;
backup_current_db_name(thd, saved_db_name);
return mysql_change_db(thd, new_db_name, force_switch);
}
static int
lock_databases(THD *thd, const char *db1, uint length1,
const char *db2, uint length2)