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Tentative implementation of

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WL#4165 Prepared statements: validation 
WL#4166 Prepared statements: automatic re-prepare
Fixes
Bug#27430 Crash in subquery code when in PS and table DDL changed after PREPARE
Bug#27690 Re-execution of prepared statement after table was replaced with a view crashes
Bug#27420 A combination of PS and view operations cause error + assertion on shutdown

The basic idea of the patch is to keep track of table metadata between
prepared statement prepare and execute. If some table used in the statement
has changed, the prepared statement is re-prepared before execution.

See WL#4165 and WL#4166 contents and comments in the code for details
of the implementation.
This commit is contained in:
kostja@dipika.(none) 2008-04-08 20:01:20 +04:00
parent a9fff11f49
commit d1f9376229
21 changed files with 1028 additions and 118 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
include/my_global.h
View File

@ -568,7 +568,7 @@ typedef unsigned short ushort;
#define CMP_NUM(a,b) (((a) < (b)) ? -1 : ((a) == (b)) ? 0 : 1)
#define sgn(a) (((a) < 0) ? -1 : ((a) > 0) ? 1 : 0)
#define swap_variables(t, a, b) { register t dummy; dummy= a; a= b; b= dummy; }
#define swap_variables(t, a, b) { t dummy; dummy= a; a= b; b= dummy; }
#define test(a) ((a) ? 1 : 0)
#define set_if_bigger(a,b) do { if ((a) < (b)) (a)=(b); } while(0)
#define set_if_smaller(a,b) do { if ((a) > (b)) (a)=(b); } while(0)

19
mysql-test/r/ps_1general.result
View File

@ -143,32 +143,32 @@ b char(30)
);
insert into t5( a, b, c) values( 9, 'recreated table', 9);
execute stmt2 ;
a b c
9 recreated table 9
a c b
9 9 recreated table
drop table t5 ;
create table t5
(
a int primary key,
b char(30),
c int,
d timestamp default current_timestamp
d timestamp default '2008-02-23 09:23:45'
);
insert into t5( a, b, c) values( 9, 'recreated table', 9);
execute stmt2 ;
a b c
9 recreated table 9
a b c d
9 recreated table 9 2008-02-23 09:23:45
drop table t5 ;
create table t5
(
a int primary key,
d timestamp default current_timestamp,
d timestamp default '2008-02-23 09:23:45',
b char(30),
c int
);
insert into t5( a, b, c) values( 9, 'recreated table', 9);
execute stmt2 ;
a b c
9 recreated table 9
a d b c
9 2008-02-23 09:23:45 recreated table 9
drop table t5 ;
create table t5
(
@ -189,7 +189,8 @@ f3 int
);
insert into t5( f1, f2, f3) values( 9, 'recreated table', 9);
execute stmt2 ;
ERROR 42S22: Unknown column 'test.t5.a' in 'field list'
f1 f2 f3
9 recreated table 9
drop table t5 ;
prepare stmt1 from ' select * from t1 where a <= 2 ' ;
execute stmt1 ;

1
mysql-test/r/query_cache_merge.result
View File

@ -18,3 +18,4 @@ Variable_name Value
Qcache_queries_in_cache 0
drop table t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16,t17,t18,t19,t20,t21,t22,t23,t24,t25,t26,t27,t28,t29,t30,t31,t32,t33,t34,t35,t36,t37,t38,t39,t40,t41,t42,t43,t44,t45,t46,t47,t48,t49,t50,t51,t52,t53,t54,t55,t56,t57,t58,t59,t60,t61,t62,t63,t64,t65,t66,t67,t68,t69,t70,t71,t72,t73,t74,t75,t76,t77,t78,t79,t80,t81,t82,t83,t84,t85,t86,t87,t88,t89,t90,t91,t92,t93,t94,t95,t96,t97,t98,t99,t100,t101,t102,t103,t104,t105,t106,t107,t108,t109,t110,t111,t112,t113,t114,t115,t116,t117,t118,t119,t120,t121,t122,t123,t124,t125,t126,t127,t128,t129,t130,t131,t132,t133,t134,t135,t136,t137,t138,t139,t140,t141,t142,t143,t144,t145,t146,t147,t148,t149,t150,t151,t152,t153,t154,t155,t156,t157,t158,t159,t160,t161,t162,t163,t164,t165,t166,t167,t168,t169,t170,t171,t172,t173,t174,t175,t176,t177,t178,t179,t180,t181,t182,t183,t184,t185,t186,t187,t188,t189,t190,t191,t192,t193,t194,t195,t196,t197,t198,t199,t200,t201,t202,t203,t204,t205,t206,t207,t208,t209,t210,t211,t212,t213,t214,t215,t216,t217,t218,t219,t220,t221,t222,t223,t224,t225,t226,t227,t228,t229,t230,t231,t232,t233,t234,t235,t236,t237,t238,t239,t240,t241,t242,t243,t244,t245,t246,t247,t248,t249,t250,t251,t252,t253,t254,t255,t256,t257,t00;
SET @@global.query_cache_size=0;
set @@global.table_definition_cache=@save_table_definition_cache;

1
mysql-test/r/trigger.result
View File

@ -820,7 +820,6 @@ call p1();
drop trigger t1_bi;
create trigger t1_bi after insert on t1 for each row insert into t3 values (new.id);
execute stmt1;
ERROR 42S02: Table 'test.t3' doesn't exist
call p1();
ERROR 42S02: Table 'test.t3' doesn't exist
deallocate prepare stmt1;

1
mysql-test/t/disabled.def
View File

@ -18,6 +18,5 @@ federated_transactions : Bug#29523 Transactions do not work
lowercase_table3 : Bug#32667 lowercase_table3.test reports to error log
ctype_create : Bug#32965 main.ctype_create fails
status : Bug#32966 main.status fails
ps_ddl : Bug#12093 2007-12-14 pending WL#4165 / WL#4166
csv_alter_table : Bug#33696 2008-01-21 pcrews no .result file - bug allows NULL columns in CSV tables
cast : Bug#35594 2008-03-27 main.cast fails on Windows2003-64

5
mysql-test/t/ps_1general.test
View File

@ -181,7 +181,7 @@ create table t5
a int primary key,
b char(30),
c int,
d timestamp default current_timestamp
d timestamp default '2008-02-23 09:23:45'
);
insert into t5( a, b, c) values( 9, 'recreated table', 9);
execute stmt2 ;
@ -191,7 +191,7 @@ drop table t5 ;
create table t5
(
a int primary key,
d timestamp default current_timestamp,
d timestamp default '2008-02-23 09:23:45',
b char(30),
c int
);
@ -218,7 +218,6 @@ create table t5
f3 int
);
insert into t5( f1, f2, f3) values( 9, 'recreated table', 9);
--error 1054
execute stmt2 ;
drop table t5 ;

10
mysql-test/t/query_cache_merge.test
View File

@ -25,6 +25,15 @@ while ($1)
}
--enable_warnings
#
# In order for the test to pass in --ps-protocol, we must
# set table_definition_cache size to at least 258 elements.
# Otherwise table versions are bound to change between
# prepare and execute, and we will get a constant validation
# error. See WL#4165 for details.
#
set @save_table_definition_cache= @@global.table_definition_cache;
set @@global.table_definition_cache=512;
create table t00 (a int) engine=MERGE UNION=(t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16,t17,t18,t19,t20,t21,t22,t23,t24,t25,t26,t27,t28,t29,t30,t31,t32,t33,t34,t35,t36,t37,t38,t39,t40,t41,t42,t43,t44,t45,t46,t47,t48,t49,t50,t51,t52,t53,t54,t55,t56,t57,t58,t59,t60,t61,t62,t63,t64,t65,t66,t67,t68,t69,t70,t71,t72,t73,t74,t75,t76,t77,t78,t79,t80,t81,t82,t83,t84,t85,t86,t87,t88,t89,t90,t91,t92,t93,t94,t95,t96,t97,t98,t99,t100,t101,t102,t103,t104,t105,t106,t107,t108,t109,t110,t111,t112,t113,t114,t115,t116,t117,t118,t119,t120,t121,t122,t123,t124,t125,t126,t127,t128,t129,t130,t131,t132,t133,t134,t135,t136,t137,t138,t139,t140,t141,t142,t143,t144,t145,t146,t147,t148,t149,t150,t151,t152,t153,t154,t155,t156,t157,t158,t159,t160,t161,t162,t163,t164,t165,t166,t167,t168,t169,t170,t171,t172,t173,t174,t175,t176,t177,t178,t179,t180,t181,t182,t183,t184,t185,t186,t187,t188,t189,t190,t191,t192,t193,t194,t195,t196,t197,t198,t199,t200,t201,t202,t203,t204,t205,t206,t207,t208,t209,t210,t211,t212,t213,t214,t215,t216,t217,t218,t219,t220,t221,t222,t223,t224,t225,t226,t227,t228,t229,t230,t231,t232,t233,t234,t235,t236,t237,t238,t239,t240,t241,t242,t243,t244,t245,t246,t247,t248,t249,t250,t251,t252,t253,t254,t255,t256,t257) INSERT_METHOD=FIRST;
enable_query_log;
select count(*) from t00;
@ -36,5 +45,6 @@ show status like "Qcache_queries_in_cache";
drop table t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12,t13,t14,t15,t16,t17,t18,t19,t20,t21,t22,t23,t24,t25,t26,t27,t28,t29,t30,t31,t32,t33,t34,t35,t36,t37,t38,t39,t40,t41,t42,t43,t44,t45,t46,t47,t48,t49,t50,t51,t52,t53,t54,t55,t56,t57,t58,t59,t60,t61,t62,t63,t64,t65,t66,t67,t68,t69,t70,t71,t72,t73,t74,t75,t76,t77,t78,t79,t80,t81,t82,t83,t84,t85,t86,t87,t88,t89,t90,t91,t92,t93,t94,t95,t96,t97,t98,t99,t100,t101,t102,t103,t104,t105,t106,t107,t108,t109,t110,t111,t112,t113,t114,t115,t116,t117,t118,t119,t120,t121,t122,t123,t124,t125,t126,t127,t128,t129,t130,t131,t132,t133,t134,t135,t136,t137,t138,t139,t140,t141,t142,t143,t144,t145,t146,t147,t148,t149,t150,t151,t152,t153,t154,t155,t156,t157,t158,t159,t160,t161,t162,t163,t164,t165,t166,t167,t168,t169,t170,t171,t172,t173,t174,t175,t176,t177,t178,t179,t180,t181,t182,t183,t184,t185,t186,t187,t188,t189,t190,t191,t192,t193,t194,t195,t196,t197,t198,t199,t200,t201,t202,t203,t204,t205,t206,t207,t208,t209,t210,t211,t212,t213,t214,t215,t216,t217,t218,t219,t220,t221,t222,t223,t224,t225,t226,t227,t228,t229,t230,t231,t232,t233,t234,t235,t236,t237,t238,t239,t240,t241,t242,t243,t244,t245,t246,t247,t248,t249,t250,t251,t252,t253,t254,t255,t256,t257,t00;
SET @@global.query_cache_size=0;
set @@global.table_definition_cache=@save_table_definition_cache;
# End of 4.1 tests

7
mysql-test/t/trigger.test
View File

@ -997,11 +997,10 @@ call p1();
# Altering trigger forcing it use different set of tables
drop trigger t1_bi;
create trigger t1_bi after insert on t1 for each row insert into t3 values (new.id);
# Until we implement proper mechanism for invalidation of PS/SP when table
# or SP's are changed these two statements will fail with 'Table ... was
# not locked' error (this mechanism should be based on the new TDC).
--error ER_NO_SUCH_TABLE
execute stmt1;
# Until we implement proper mechanism for invalidation of SP statements
# invoked whenever a table used in SP changes, this statement will fail with
# 'Table ... does not exist' error.
--error ER_NO_SUCH_TABLE
call p1();
deallocate prepare stmt1;

39
sql/item.cc
View File

@ -3161,6 +3161,45 @@ void Item_param::print(String *str, enum_query_type query_type)
}
/**
Preserve the original parameter types and values
when re-preparing a prepared statement.
Copy parameter type information and conversion function
pointers from a parameter of the old statement to the
corresponding parameter of the new one.
Move parameter values from the old parameters to the new
one. We simply "exchange" the values, which allows
to save on allocation and character set conversion in
case a parameter is a string or a blob/clob.
@param[in] src parameter item of the original
prepared statement
*/
void
Item_param::set_param_type_and_swap_value(Item_param *src)
{
unsigned_flag= src->unsigned_flag;
param_type= src->param_type;
set_param_func= src->set_param_func;
item_type= src->item_type;
item_result_type= src->item_result_type;
collation.set(src->collation.collation);
maybe_null= src->maybe_null;
null_value= src->null_value;
max_length= src->max_length;
decimals= src->decimals;
state= src->state;
value= src->value;
decimal_value.swap(src->decimal_value);
str_value.swap(src->str_value);
str_value_ptr.swap(src->str_value_ptr);
}
/****************************************************************************
Item_copy_string
****************************************************************************/

1
sql/item.h
View File

@ -1684,6 +1684,7 @@ public:
bool eq(const Item *item, bool binary_cmp) const;
/** Item is a argument to a limit clause. */
bool limit_clause_param;
void set_param_type_and_swap_value(Item_param *from);
};

8
sql/my_decimal.h
View File

@ -114,6 +114,14 @@ public:
bool sign() const { return decimal_t::sign; }
void sign(bool s) { decimal_t::sign= s; }
uint precision() const { return intg + frac; }
/** Swap two my_decimal values */
void swap(my_decimal &rhs)
{
swap_variables(my_decimal, *this, rhs);
/* Swap the buffer pointers back */
swap_variables(decimal_digit_t *, buf, rhs.buf);
}
};

40
sql/mysql_priv.h
View File

@ -259,6 +259,21 @@ protected:
#define USER_VARS_HASH_SIZE 16
#define TABLE_OPEN_CACHE_MIN 64
#define TABLE_OPEN_CACHE_DEFAULT 64
#define TABLE_DEF_CACHE_DEFAULT 256
/**
We must have room for at least 256 table definitions in the table
cache, since otherwise there is no chance prepared
statements that use these many tables can work.
Prepared statements use table definition cache ids (table_map_id)
as table version identifiers. If the table definition
cache size is less than the number of tables used in a statement,
the contents of the table definition cache is guaranteed to rotate
between a prepare and execute. This leads to stable validation
errors. In future we shall use more stable version identifiers,
for now the only solution is to ensure that the table definition
cache can contain at least all tables of a given statement.
*/
#define TABLE_DEF_CACHE_MIN 256
/*
Value of 9236 discovered through binary search 2006-09-26 on Ubuntu Dapper
@ -670,6 +685,31 @@ const char *set_thd_proc_info(THD *thd, const char *info,
const char *calling_file,
const unsigned int calling_line);
/**
Enumerate possible types of a table from re-execution
standpoint.
TABLE_LIST class has a member of this type.
At prepared statement prepare, this member is assigned a value
as of the current state of the database. Before (re-)execution
of a prepared statement, we check that the value recorded at
prepare matches the type of the object we obtained from the
table definition cache.
@sa check_and_update_metadata_version()
@sa Execute_observer
@sa Prepared_statement::reprepare()
*/
enum enum_metadata_type
{
/** Initial value set by the parser */
METADATA_NULL= 0,
METADATA_VIEW,
METADATA_BASE_TABLE,
METADATA_I_S_TABLE,
METADATA_TMP_TABLE
};
/*
External variables
*/

9
sql/mysqld.cc
View File

@ -3089,6 +3089,7 @@ SHOW_VAR com_status_vars[]= {
{"stmt_execute", (char*) offsetof(STATUS_VAR, com_stmt_execute), SHOW_LONG_STATUS},
{"stmt_fetch", (char*) offsetof(STATUS_VAR, com_stmt_fetch), SHOW_LONG_STATUS},
{"stmt_prepare", (char*) offsetof(STATUS_VAR, com_stmt_prepare), SHOW_LONG_STATUS},
{"stmt_reprepare", (char*) offsetof(STATUS_VAR, com_stmt_reprepare), SHOW_LONG_STATUS},
{"stmt_reset", (char*) offsetof(STATUS_VAR, com_stmt_reset), SHOW_LONG_STATUS},
{"stmt_send_long_data", (char*) offsetof(STATUS_VAR, com_stmt_send_long_data), SHOW_LONG_STATUS},
{"truncate", (char*) offsetof(STATUS_VAR, com_stat[(uint) SQLCOM_TRUNCATE]), SHOW_LONG_STATUS},
@ -3177,7 +3178,7 @@ static int init_common_variables(const char *conf_file_name, int argc,
We have few debug-only commands in com_status_vars, only visible in debug
builds. for simplicity we enable the assert only in debug builds
There are 7 Com_ variables which don't have corresponding SQLCOM_ values:
There are 8 Com_ variables which don't have corresponding SQLCOM_ values:
(TODO strictly speaking they shouldn't be here, should not have Com_ prefix
that is. Perhaps Stmt_ ? Comstmt_ ? Prepstmt_ ?)
@ -3186,6 +3187,7 @@ static int init_common_variables(const char *conf_file_name, int argc,
Com_stmt_execute => com_stmt_execute
Com_stmt_fetch => com_stmt_fetch
Com_stmt_prepare => com_stmt_prepare
Com_stmt_reprepare => com_stmt_reprepare
Com_stmt_reset => com_stmt_reset
Com_stmt_send_long_data => com_stmt_send_long_data
@ -3194,7 +3196,7 @@ static int init_common_variables(const char *conf_file_name, int argc,
of SQLCOM_ constants.
*/
compile_time_assert(sizeof(com_status_vars)/sizeof(com_status_vars[0]) - 1 ==
SQLCOM_END + 7);
SQLCOM_END + 8);
#endif
load_defaults(conf_file_name, groups, &argc, &argv);
@ -6757,7 +6759,8 @@ The minimum value for this variable is 4096.",
{"table_definition_cache", OPT_TABLE_DEF_CACHE,
"The number of cached table definitions.",
(uchar**) &table_def_size, (uchar**) &table_def_size,
0, GET_ULONG, REQUIRED_ARG, 128, 1, 512*1024L, 0, 1, 0},
0, GET_ULONG, REQUIRED_ARG, TABLE_DEF_CACHE_DEFAULT, TABLE_DEF_CACHE_MIN,
512*1024L, 0, 1, 0},
{"table_open_cache", OPT_TABLE_OPEN_CACHE,
"The number of cached open tables.",
(uchar**) &table_cache_size, (uchar**) &table_cache_size, 0, GET_ULONG,

6
sql/share/errmsg.txt
View File

@ -6120,3 +6120,9 @@ ER_NO_FORMAT_DESCRIPTION_EVENT_BEFORE_BINLOG_STATEMENT
eng "The BINLOG statement of type `%s` was not preceded by a format description BINLOG statement."
ER_SLAVE_CORRUPT_EVENT
eng "Corrupted replication event was detected"
ER_NEED_REPREPARE
eng "Prepared statement needs to be re-prepared"
ER_PS_REBIND
eng "Prepared statement result set has changed, a rebind needed"

110
sql/sql_base.cc
View File

@ -3717,6 +3717,72 @@ void assign_new_table_id(TABLE_SHARE *share)
DBUG_VOID_RETURN;
}
/**
Compare metadata versions of an element obtained from the table
definition cache and its corresponding node in the parse tree.
If the new and the old values mismatch, invoke
Metadata_version_observer.
At prepared statement prepare, all TABLE_LIST version values are
NULL and we always have a mismatch. But there is no observer set
in THD, and therefore no error is reported. Instead, we update
the value in the parse tree, effectively recording the original
version.
At prepared statement execute, an observer may be installed. If
there is a version mismatch, we push an error and return TRUE.
For conventional execution (no prepared statements), the
observer is never installed.
@sa Execute_observer
@sa check_prepared_statement() to see cases when an observer is installed
@sa TABLE_LIST::is_metadata_version_equal()
@sa TABLE_SHARE::get_metadata_version()
@param[in] thd used to report errors
@param[in,out] tables TABLE_LIST instance created by the parser
Metadata version information in this object
is updated upon success.
@param[in] table_share an element from the table definition cache
@retval TRUE an error, which has been reported
@retval FALSE success, version in TABLE_LIST has been updated
*/
bool
check_and_update_table_version(THD *thd,
TABLE_LIST *tables, TABLE_SHARE *table_share)
{
if (! tables->is_metadata_version_equal(table_share))
{
if (thd->m_metadata_observer &&
thd->m_metadata_observer->check_metadata_change(thd))
{
/*
Version of the table share is different from the
previous execution of the prepared statement, and it is
unacceptable for this SQLCOM. Error has been reported.
*/
return TRUE;
}
/* Always maintain the latest version */
tables->set_metadata_version(table_share);
}
#if 0
#ifndef DBUG_OFF
/* Spuriously reprepare each statement. */
if (thd->m_metadata_observer && thd->stmt_arena->is_reprepared == FALSE)
{
thd->m_metadata_observer->check_metadata_change(thd);
return TRUE;
}
#endif
#endif
return FALSE;
}
/*
Load a table definition from file and open unireg table
@ -3762,6 +3828,8 @@ retry:
if (share->is_view)
{
if (check_and_update_table_version(thd, table_list, share))
goto err;
if (table_list->i_s_requested_object & OPEN_TABLE_ONLY)
goto err;
@ -3779,6 +3847,26 @@ retry:
release_table_share(share, RELEASE_NORMAL);
DBUG_RETURN((flags & OPEN_VIEW_NO_PARSE)? -1 : 0);
}
else if (table_list->view)
{
/*
We're trying to open a table for what was a view.
This can only happen during (re-)execution.
At prepared statement prepare the view has been opened and
merged into the statement parse tree. After that, someone
performed a DDL and replaced the view with a base table.
Don't try to open the table inside a prepared statement,
invalidate it instead.
Note, the assert below is known to fail inside stored
procedures (Bug#27011).
*/
DBUG_ASSERT(thd->m_metadata_observer);
check_and_update_table_version(thd, table_list, share);
/* Always an error. */
DBUG_ASSERT(thd->is_error());
goto err;
}
if (table_list->i_s_requested_object & OPEN_VIEW_ONLY)
goto err;
@ -4375,8 +4463,18 @@ int open_tables(THD *thd, TABLE_LIST **start, uint *counter, uint flags)
*/
if (tables->schema_table)
{
if (!mysql_schema_table(thd, thd->lex, tables))
/*
If this information_schema table is merged into a mergeable
view, ignore it for now -- it will be filled when its respective
TABLE_LIST is processed. This code works only during re-execution.
*/
if (tables->view)
goto process_view_routines;
if (!mysql_schema_table(thd, thd->lex, tables) &&
!check_and_update_table_version(thd, tables, tables->table->s))
{
continue;
}
DBUG_RETURN(-1);
}
(*counter)++;
@ -4524,6 +4622,12 @@ int open_tables(THD *thd, TABLE_LIST **start, uint *counter, uint flags)
}
tables->table->grant= tables->grant;
if (check_and_update_table_version(thd, tables, tables->table->s))
{
result= -1;
goto err;
}
/* Attach MERGE children if not locked already. */
DBUG_PRINT("tcache", ("is parent: %d is child: %d",
test(tables->table->child_l),
@ -4582,7 +4686,11 @@ process_view_routines:
error happens on a MERGE child, clear the parents TABLE reference.
*/
if (tables->parent_l)
{
if (tables->parent_l->next_global == tables->parent_l->table->child_l)
tables->parent_l->next_global= *tables->parent_l->table->child_last_l;
tables->parent_l->table= NULL;
}
tables->table= NULL;
}
DBUG_PRINT("tcache", ("returning: %d", result));

10
sql/sql_class.cc
View File

@ -359,6 +359,10 @@ char *thd_security_context(THD *thd, char *buffer, unsigned int length,
return thd->strmake(str.ptr(), str.length());
}
Metadata_version_observer::~Metadata_version_observer()
{
}
/**
Clear this diagnostics area.
@ -2767,7 +2771,8 @@ void THD::restore_backup_open_tables_state(Open_tables_state *backup)
DBUG_ASSERT(open_tables == 0 && temporary_tables == 0 &&
handler_tables == 0 && derived_tables == 0 &&
lock == 0 && locked_tables == 0 &&
prelocked_mode == NON_PRELOCKED);
prelocked_mode == NON_PRELOCKED &&
m_metadata_observer == NULL);
set_open_tables_state(backup);
DBUG_VOID_RETURN;
}
@ -2871,6 +2876,7 @@ void THD::reset_sub_statement_state(Sub_statement_state *backup,
first_successful_insert_id_in_prev_stmt;
backup->first_successful_insert_id_in_cur_stmt=
first_successful_insert_id_in_cur_stmt;
backup->m_metadata_observer= m_metadata_observer;
if ((!lex->requires_prelocking() || is_update_query(lex->sql_command)) &&
!current_stmt_binlog_row_based)
@ -2890,6 +2896,7 @@ void THD::reset_sub_statement_state(Sub_statement_state *backup,
cuted_fields= 0;
transaction.savepoints= 0;
first_successful_insert_id_in_cur_stmt= 0;
m_metadata_observer= 0;
}
@ -2938,6 +2945,7 @@ void THD::restore_sub_statement_state(Sub_statement_state *backup)
*/
examined_row_count+= backup->examined_row_count;
cuted_fields+= backup->cuted_fields;
m_metadata_observer= backup->m_metadata_observer;
}

86
sql/sql_class.h
View File

@ -23,6 +23,53 @@
#include "log.h"
#include "rpl_tblmap.h"
/**
An abstract interface that can be used to take an action when
the locking module notices that a table version has changed
since the last execution. "Table" here may refer to any kind of
table -- a base table, a temporary table, a view or an
information schema table.
When we open and lock tables for execution of a prepared
statement, we must verify that they did not change
since statement prepare. If some table did change, the statement
parse tree *may* be no longer valid, e.g. in case it contains
optimizations that depend on table metadata.
This class provides an abstract interface (a method) that is
invoked when such a situation takes place.
The implementation of the interface in most cases simply
reports an error, but the exact details depend on the nature of
the SQL statement.
At most 1 instance of this class is active at a time, in which
case THD::m_metadata_observer is not NULL.
@sa check_and_update_metadata_version() for details of the
version tracking algorithm
@sa Execute_observer for details of how we detect that
a metadata change is fatal and a re-prepare is necessary
@sa Open_tables_state::m_metadata_observer for the life cycle
of metadata observers.
*/
class Metadata_version_observer
{
protected:
virtual ~Metadata_version_observer();
public:
/**
Check if a change of metadata is OK. In future
the signature of this method may be extended to accept the old
and the new versions, but since currently the check is very
simple, we only need the THD to report an error.
*/
virtual bool check_metadata_change(THD *thd)= 0;
};
class Relay_log_info;
class Query_log_event;
@ -406,6 +453,7 @@ typedef struct system_status_var
ulong filesort_scan_count;
/* Prepared statements and binary protocol */
ulong com_stmt_prepare;
ulong com_stmt_reprepare;
ulong com_stmt_execute;
ulong com_stmt_send_long_data;
ulong com_stmt_fetch;
@ -436,7 +484,7 @@ void free_tmp_table(THD *thd, TABLE *entry);
/* The following macro is to make init of Query_arena simpler */
#ifndef DBUG_OFF
#define INIT_ARENA_DBUG_INFO is_backup_arena= 0
#define INIT_ARENA_DBUG_INFO is_backup_arena= 0; is_reprepared= FALSE;
#else
#define INIT_ARENA_DBUG_INFO
#endif
@ -452,6 +500,7 @@ public:
MEM_ROOT *mem_root; // Pointer to current memroot
#ifndef DBUG_OFF
bool is_backup_arena; /* True if this arena is used for backup. */
bool is_reprepared;
#endif
/*
The states relfects three diffrent life cycles for three
@ -788,6 +837,20 @@ enum prelocked_mode_type {NON_PRELOCKED= 0, PRELOCKED= 1,
class Open_tables_state
{
public:
/**
As part of class THD, this member is set during execution
of a prepared statement. When it is set, it is used
by the locking subsystem to report a change in table metadata.
When Open_tables_state part of THD is reset to open
a system or INFORMATION_SCHEMA table, the member is cleared
to avoid spurious ER_NEED_REPREPARE errors -- system and
INFORMATION_SCHEMA tables are not subject to metadata version
tracking.
@sa check_and_update_metadata_version()
*/
Metadata_version_observer *m_metadata_observer;
/**
List of regular tables in use by this thread. Contains temporary and
base tables that were opened with @see open_tables().
@ -891,6 +954,7 @@ public:
extra_lock= lock= locked_tables= 0;
prelocked_mode= NON_PRELOCKED;
state_flags= 0U;
m_metadata_observer= NULL;
}
};
@ -919,6 +983,25 @@ public:
bool enable_slow_log;
bool last_insert_id_used;
SAVEPOINT *savepoints;
/**
When inside a substatement (a stored function or trigger
statement), clear the metadata observer in THD, if any.
Remember the value of the observer here, to be able
to restore it when leaving the substatement.
We reset the observer to suppress errors when a substatement
uses temporary tables. If a temporary table does not exist
at start of the main statement, it's not prelocked
and thus is not validated with other prelocked tables.
Later on, when the temporary table is opened, metadata
versions mismatch, expectedly.
The proper solution for the problem is to re-validate tables
of substatements (Bug#12257, Bug#27011, Bug#32868, Bug#33000),
but it's not implemented yet.
*/
Metadata_version_observer *m_metadata_observer;
};
@ -2777,6 +2860,7 @@ public:
#define CF_STATUS_COMMAND 4
#define CF_SHOW_TABLE_COMMAND 8
#define CF_WRITE_LOGS_COMMAND 16
#define CF_REEXECUTION_FRAGILE 32
/* Functions in sql_class.cc */

25
sql/sql_parse.cc
View File

@ -218,14 +218,23 @@ void init_update_queries(void)
sql_command_flags[SQLCOM_ALTER_EVENT]= CF_CHANGES_DATA;
sql_command_flags[SQLCOM_DROP_EVENT]= CF_CHANGES_DATA;
sql_command_flags[SQLCOM_UPDATE]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_UPDATE_MULTI]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_INSERT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_INSERT_SELECT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_DELETE]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_DELETE_MULTI]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_REPLACE]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_REPLACE_SELECT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT;
sql_command_flags[SQLCOM_UPDATE]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_UPDATE_MULTI]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_INSERT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_INSERT_SELECT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_DELETE]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_DELETE_MULTI]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_REPLACE]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_REPLACE_SELECT]= CF_CHANGES_DATA | CF_HAS_ROW_COUNT |
CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_SELECT]= CF_REEXECUTION_FRAGILE;
sql_command_flags[SQLCOM_SHOW_STATUS_PROC]= CF_STATUS_COMMAND;
sql_command_flags[SQLCOM_SHOW_STATUS]= CF_STATUS_COMMAND;

516
sql/sql_prepare.cc
View File

@ -116,6 +116,39 @@ public:
#endif
};
/**
If a metadata changed, report a respective error to trigger
re-prepare of a prepared statement.
*/
class Execute_observer: public Metadata_version_observer
{
public:
virtual bool check_metadata_change(THD *thd);
/** Set to TRUE if metadata of some used table has changed since prepare */
bool m_invalidated;
};
/**
Push an error to the error stack and return TRUE for now.
In future we must take special care of statements like CREATE
TABLE ... SELECT. Should we re-prepare such statements every
time?
*/
bool
Execute_observer::check_metadata_change(THD *thd)
{
bool save_thd_no_warnings_for_error= thd->no_warnings_for_error;
DBUG_ENTER("Execute_observer::notify_about_metadata_change");
thd->no_warnings_for_error= TRUE;
my_error(ER_NEED_REPREPARE, MYF(0));
thd->no_warnings_for_error= save_thd_no_warnings_for_error;
m_invalidated= TRUE;
DBUG_RETURN(TRUE);
}
/****************************************************************************/
/**
@ -156,20 +189,27 @@ public:
bool set_name(LEX_STRING *name);
inline void close_cursor() { delete cursor; cursor= 0; }
inline bool is_in_use() { return flags & (uint) IS_IN_USE; }
inline bool is_protocol_text() const { return protocol == &thd->protocol_text; }
bool prepare(const char *packet, uint packet_length);
bool execute(String *expanded_query, bool open_cursor);
bool execute_loop(String *expanded_query,
bool open_cursor,
uchar *packet_arg, uchar *packet_end_arg);
/* Destroy this statement */
void deallocate();
private:
/**
Store the parsed tree of a prepared statement here.
*/
LEX main_lex;
/**
The memory root to allocate parsed tree elements (instances of Item,
SELECT_LEX and other classes).
*/
MEM_ROOT main_mem_root;
private:
bool set_db(const char *db, uint db_length);
bool set_parameters(String *expanded_query,
uchar *packet, uchar *packet_end);
bool execute(String *expanded_query, bool open_cursor);
bool reprepare();
bool validate_metadata(Prepared_statement *copy);
void swap_prepared_statement(Prepared_statement *copy);
};
@ -941,6 +981,55 @@ static bool emb_insert_params_with_log(Prepared_statement *stmt,
#endif /*!EMBEDDED_LIBRARY*/
/**
Setup data conversion routines using an array of parameter
markers from the original prepared statement.
Move the parameter data of the original prepared
statement to the new one.
Used only when we re-prepare a prepared statement.
There are two reasons for this function to exist:
1) In the binary client/server protocol, parameter metadata
is sent only at first execute. Consequently, if we need to
reprepare a prepared statement at a subsequent execution,
we may not have metadata information in the packet.
In that case we use the parameter array of the original
prepared statement to setup parameter types of the new
prepared statement.
2) In the binary client/server protocol, we may supply
long data in pieces. When the last piece is supplied,
we assemble the pieces and convert them from client
character set to the connection character set. After
that the parameter value is only available inside
the parameter, the original pieces are lost, and thus
we can only assign the corresponding parameter of the
reprepared statement from the original value.
@param[out] param_array_dst parameter markers of the new statement
@param[in] param_array_src parameter markers of the original
statement
@param[in] param_count total number of parameters. Is the
same in src and dst arrays, since
the statement query is the same
@return this function never fails
*/
static void
swap_parameter_array(Item_param **param_array_dst,
Item_param **param_array_src,
uint param_count)
{
Item_param **dst= param_array_dst;
Item_param **src= param_array_src;
Item_param **end= param_array_dst + param_count;
for (; dst < end; ++src, ++dst)
(*dst)->set_param_type_and_swap_value(*src);
}
/**
Assign prepared statement parameters from user variables.
@ -1264,7 +1353,7 @@ error:
*/
static int mysql_test_select(Prepared_statement *stmt,
TABLE_LIST *tables, bool text_protocol)
TABLE_LIST *tables)
{
THD *thd= stmt->thd;
LEX *lex= stmt->lex;
@ -1300,7 +1389,7 @@ static int mysql_test_select(Prepared_statement *stmt,
*/
if (unit->prepare(thd, 0, 0))
goto error;
if (!lex->describe && !text_protocol)
if (!lex->describe && !stmt->is_protocol_text())
{
/* Make copy of item list, as change_columns may change it */
List<Item> fields(lex->select_lex.item_list);
@ -1708,8 +1797,7 @@ static bool mysql_test_insert_select(Prepared_statement *stmt,
TRUE error, error message is set in THD (but not sent)
*/
static bool check_prepared_statement(Prepared_statement *stmt,
bool text_protocol)
static bool check_prepared_statement(Prepared_statement *stmt)
{
THD *thd= stmt->thd;
LEX *lex= stmt->lex;
@ -1752,7 +1840,7 @@ static bool check_prepared_statement(Prepared_statement *stmt,
break;
case SQLCOM_SELECT:
res= mysql_test_select(stmt, tables, text_protocol);
res= mysql_test_select(stmt, tables);
if (res == 2)
{
/* Statement and field info has already been sent */
@ -1867,8 +1955,8 @@ static bool check_prepared_statement(Prepared_statement *stmt,
break;
}
if (res == 0)
DBUG_RETURN(text_protocol? FALSE : (send_prep_stmt(stmt, 0) ||
thd->protocol->flush()));
DBUG_RETURN(stmt->is_protocol_text() ?
FALSE : (send_prep_stmt(stmt, 0) || thd->protocol->flush()));
error:
DBUG_RETURN(TRUE);
}
@ -2309,11 +2397,10 @@ void mysql_stmt_execute(THD *thd, char *packet_arg, uint packet_length)
ulong flags= (ulong) packet[4];
/* Query text for binary, general or slow log, if any of them is open */
String expanded_query;
#ifndef EMBEDDED_LIBRARY
uchar *packet_end= packet + packet_length;
#endif
Prepared_statement *stmt;
bool error;
bool open_cursor;
DBUG_ENTER("mysql_stmt_execute");
packet+= 9; /* stmt_id + 5 bytes of flags */
@ -2338,44 +2425,12 @@ void mysql_stmt_execute(THD *thd, char *packet_arg, uint packet_length)
sp_cache_flush_obsolete(&thd->sp_proc_cache);
sp_cache_flush_obsolete(&thd->sp_func_cache);
#ifndef EMBEDDED_LIBRARY
if (stmt->param_count)
{
uchar *null_array= packet;
if (setup_conversion_functions(stmt, &packet, packet_end) ||
stmt->set_params(stmt, null_array, packet, packet_end,
&expanded_query))
goto set_params_data_err;
}
#else
/*
In embedded library we re-install conversion routines each time
we set params, and also we don't need to parse packet.
So we do it in one function.
*/
if (stmt->param_count && stmt->set_params_data(stmt, &expanded_query))
goto set_params_data_err;
#endif
if (!(specialflag & SPECIAL_NO_PRIOR))
my_pthread_setprio(pthread_self(),QUERY_PRIOR);
open_cursor= test(flags & (ulong) CURSOR_TYPE_READ_ONLY);
/*
If the free_list is not empty, we'll wrongly free some externally
allocated items when cleaning up after validation of the prepared
statement.
*/
DBUG_ASSERT(thd->free_list == NULL);
stmt->execute_loop(&expanded_query, open_cursor, packet, packet_end);
error= stmt->execute(&expanded_query,
test(flags & (ulong) CURSOR_TYPE_READ_ONLY));
if (!(specialflag & SPECIAL_NO_PRIOR))
my_pthread_setprio(pthread_self(), WAIT_PRIOR);
DBUG_VOID_RETURN;
set_params_data_err:
my_error(ER_WRONG_ARGUMENTS, MYF(0), "mysql_stmt_execute");
reset_stmt_params(stmt);
DBUG_VOID_RETURN;
}
@ -2421,24 +2476,8 @@ void mysql_sql_stmt_execute(THD *thd)
DBUG_PRINT("info",("stmt: 0x%lx", (long) stmt));
/*
If the free_list is not empty, we'll wrongly free some externally
allocated items when cleaning up after validation of the prepared
statement.
*/
DBUG_ASSERT(thd->free_list == NULL);
(void) stmt->execute_loop(&expanded_query, FALSE, NULL, NULL);
if (stmt->set_params_from_vars(stmt, lex->prepared_stmt_params,
&expanded_query))
goto set_params_data_err;
(void) stmt->execute(&expanded_query, FALSE);
DBUG_VOID_RETURN;
set_params_data_err:
my_error(ER_WRONG_ARGUMENTS, MYF(0), "EXECUTE");
reset_stmt_params(stmt);
DBUG_VOID_RETURN;
}
@ -2742,7 +2781,7 @@ Select_fetch_protocol_binary::send_data(List<Item> &fields)
****************************************************************************/
Prepared_statement::Prepared_statement(THD *thd_arg, Protocol *protocol_arg)
:Statement(&main_lex, &main_mem_root,
:Statement(0, &main_mem_root,
INITIALIZED, ++thd_arg->statement_id_counter),
thd(thd_arg),
result(thd_arg),
@ -2813,7 +2852,11 @@ Prepared_statement::~Prepared_statement()
like Item_param, don't free everything until free_items()
*/
free_items();
delete lex->result;
if (lex)
{
delete lex->result;
delete (st_lex_local *) lex;
}
free_root(&main_mem_root, MYF(0));
DBUG_VOID_RETURN;
}
@ -2849,6 +2892,34 @@ bool Prepared_statement::set_name(LEX_STRING *name_arg)
return name.str == 0;
}
/**
Remember the current database.
We must reset/restore the current database during execution of
a prepared statement since it affects execution environment:
privileges, @@character_set_database, and other.
@return Returns an error if out of memory.
*/
bool
Prepared_statement::set_db(const char *db_arg, uint db_length_arg)
{
/* Remember the current database. */
if (db_arg && db_length_arg)
{
db= this->strmake(db_arg, db_length_arg);
db_length= db_length_arg;
}
else
{
db= NULL;
db_length= 0;
}
return db_arg != NULL && db == NULL;
}
/**************************************************************************
Common parts of mysql_[sql]_stmt_prepare, mysql_[sql]_stmt_execute.
Essentially, these functions do all the magic of preparing/executing
@ -2890,6 +2961,12 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
*/
status_var_increment(thd->status_var.com_stmt_prepare);
if (! (lex= new (mem_root) st_lex_local))
DBUG_RETURN(TRUE);
if (set_db(thd->db, thd->db_length))
DBUG_RETURN(TRUE);
/*
alloc_query() uses thd->memroot && thd->query, so we should call
both of backup_statement() and backup_query_arena() here.
@ -2917,19 +2994,6 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
lex->set_trg_event_type_for_tables();
/* Remember the current database. */
if (thd->db && thd->db_length)
{
db= this->strmake(thd->db, thd->db_length);
db_length= thd->db_length;
}
else
{
db= NULL;
db_length= 0;
}
/*
While doing context analysis of the query (in check_prepared_statement)
we allocate a lot of additional memory: for open tables, JOINs, derived
@ -2953,7 +3017,7 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
*/
if (error == 0)
error= check_prepared_statement(this, name.str != 0);
error= check_prepared_statement(this);
/*
Currently CREATE PROCEDURE/TRIGGER/EVENT are prohibited in prepared
@ -3000,6 +3064,293 @@ bool Prepared_statement::prepare(const char *packet, uint packet_len)
DBUG_RETURN(error);
}
bool
Prepared_statement::set_parameters(String *expanded_query,
uchar *packet, uchar *packet_end)
{
bool is_sql_ps= packet == NULL;
if (is_sql_ps)
{
/* SQL prepared statement */
if (set_params_from_vars(this, thd->lex->prepared_stmt_params,
expanded_query))
goto set_params_data_err;
}
else if (param_count)
{
#ifndef EMBEDDED_LIBRARY
uchar *null_array= packet;
if (setup_conversion_functions(this, &packet, packet_end) ||
set_params(this, null_array, packet, packet_end,
expanded_query))
goto set_params_data_err;
#else
/*
In embedded library we re-install conversion routines each time
we set params, and also we don't need to parse packet.
So we do it in one function.
*/
if (set_params_data(this, expanded_query))
goto set_params_data_err;
#endif
}
return FALSE;
set_params_data_err:
my_error(ER_WRONG_ARGUMENTS, MYF(0),
is_sql_ps ? "EXECUTE" : "mysql_stmt_execute");
reset_stmt_params(this);
return TRUE;
}
/**
Execute a prepared statement. Re-prepare it a limited number
of times if necessary.
Try to execute a prepared statement. If there is a metadata
validation error, prepare a new copy of the prepared statement,
swap the old and the new statements, and try again.
If there is a validation error again, repeat the above, but
perform no more than MAX_REPREPARE_ATTEMPTS.
@note We have to try several times in a loop since we
release metadata locks on tables after prepared statement
prepare. Therefore, a DDL statement may sneak in between prepare
and execute of a new statement. If this happens repeatedly
more than MAX_REPREPARE_ATTEMPTS times, we give up.
In future we need to be able to keep the metadata locks between
prepare and execute, but right now open_and_lock_tables(), as
well as close_thread_tables() are buried deep inside
execution code (mysql_execute_command()).
@return TRUE if an error, FALSE if success
@retval TRUE either MAX_REPREPARE_ATTEMPTS has been reached,
or some general error
@retval FALSE successfully executed the statement, perhaps
after having reprepared it a few times.
*/
bool
Prepared_statement::execute_loop(String *expanded_query,
bool open_cursor,
uchar *packet,
uchar *packet_end)
{
const int MAX_REPREPARE_ATTEMPTS= 3;
Execute_observer execute_observer;
bool error;
int reprepare_attempt= 0;
if (set_parameters(expanded_query, packet, packet_end))
return TRUE;
reexecute:
execute_observer.m_invalidated= FALSE;
/*
If the free_list is not empty, we'll wrongly free some externally
allocated items when cleaning up after validation of the prepared
statement.
*/
DBUG_ASSERT(thd->free_list == NULL);
/*
Install the metadata observer. If some metadata version is
different from prepare time and an observer is installed,
the observer method will be invoked to push an error into
the error stack.
*/
if (sql_command_flags[lex->sql_command] &
CF_REEXECUTION_FRAGILE)
{
thd->m_metadata_observer= &execute_observer;
}
if (!(specialflag & SPECIAL_NO_PRIOR))
my_pthread_setprio(pthread_self(),QUERY_PRIOR);
error= execute(expanded_query, open_cursor) || thd->is_error();
if (!(specialflag & SPECIAL_NO_PRIOR))
my_pthread_setprio(pthread_self(), WAIT_PRIOR);
thd->m_metadata_observer= 0;
if (error && !thd->is_fatal_error && !thd->killed &&
execute_observer.m_invalidated &&
reprepare_attempt++ < MAX_REPREPARE_ATTEMPTS)
{
thd->clear_error();
error= reprepare();
if (! error) /* Success */
goto reexecute;
}
reset_stmt_params(this);
return error;
}
/**
Reprepare this prepared statement.
Currently this is implemented by creating a new prepared
statement, preparing it with the original query and then
swapping the new statement and the original one.
@retval TRUE an error occurred. Possible errors include
incompatibility of new and old result set
metadata
@retval FALSE success, the statement has been reprepared
*/
bool
Prepared_statement::reprepare()
{
char saved_cur_db_name_buf[NAME_LEN+1];
LEX_STRING saved_cur_db_name=
{ saved_cur_db_name_buf, sizeof(saved_cur_db_name_buf) };
LEX_STRING stmt_db_name= { db, db_length };
Prepared_statement *copy;
bool cur_db_changed;
bool error= TRUE;
status_var_increment(thd->status_var.com_stmt_reprepare);
copy= new Prepared_statement(thd, &thd->protocol_text);
if (! copy)
return TRUE;
if (mysql_opt_change_db(thd, &stmt_db_name, &saved_cur_db_name, TRUE,
&cur_db_changed))
goto end;
error= (name.str && copy->set_name(&name) ||
copy->prepare(query, query_length) ||
validate_metadata(copy));
if (cur_db_changed)
mysql_change_db(thd, &saved_cur_db_name, TRUE);
if (! error)
{
swap_prepared_statement(copy);
swap_parameter_array(param_array, copy->param_array, param_count);
is_reprepared= TRUE;
/*
Clear possible warnigns during re-prepare, it has to be completely
transparent to the user. We use mysql_reset_errors() since
there were no separate query id issued for re-prepare.
*/
mysql_reset_errors(thd, TRUE);
}
end:
delete copy;
return error;
}
/**
Validate statement result set metadata (if the statement returns
a result set).
Currently we only check that the number of columns of the result
set did not change.
This is a helper method used during re-prepare.
@param[in] copy the re-prepared prepared statement to verify
the metadata of
@retval TRUE error, ER_PS_NEED_REBIND is reported
@retval FALSE statement return no or compatible metadata
*/
bool Prepared_statement::validate_metadata(Prepared_statement *copy)
{
List_iterator_fast<Item> it_org(lex->select_lex.item_list);
List_iterator_fast<Item> it_new(copy->lex->select_lex.item_list);
Item *item_org;
Item *item_new;
/**
If this is an SQL prepared statement or EXPLAIN,
return FALSE -- the metadata of the original SELECT,
if any, has not been sent to the client.
*/
if (is_protocol_text() || lex->describe)
return FALSE;
if (lex->select_lex.item_list.elements !=
copy->lex->select_lex.item_list.elements)
{
/** Column counts mismatch. */
my_error(ER_PS_REBIND, MYF(0));
return TRUE;
}
return FALSE;
}
/**
Replace the original prepared statement with a prepared copy.
This is a private helper that is used as part of statement
reprepare
@return This function does not return any errors.
*/
void
Prepared_statement::swap_prepared_statement(Prepared_statement *copy)
{
Statement tmp_stmt;
/* Swap memory roots. */
swap_variables(MEM_ROOT, main_mem_root, copy->main_mem_root);
/* Swap the arenas */
tmp_stmt.set_query_arena(this);
set_query_arena(copy);
copy->set_query_arena(&tmp_stmt);
/* Swap the statement parent classes */
tmp_stmt.set_statement(this);
set_statement(copy);
copy->set_statement(&tmp_stmt);
/* Swap ids back, we need the original id */
swap_variables(ulong, id, copy->id);
/* Swap mem_roots back, they must continue pointing at the main_mem_roots */
swap_variables(MEM_ROOT *, mem_root, copy->mem_root);
/*
Swap the old and the new parameters array. The old array
is allocated in the old arena.
*/
swap_variables(Item_param **, param_array, copy->param_array);
/* Swap flags: this is perhaps unnecessary */
swap_variables(uint, flags, copy->flags);
/* Swap names, the old name is allocated in the wrong memory root */
swap_variables(LEX_STRING, name, copy->name);
/* Ditto */
swap_variables(char *, db, copy->db);
DBUG_ASSERT(db_length == copy->db_length);
DBUG_ASSERT(param_count == copy->param_count);
DBUG_ASSERT(thd == copy->thd);
last_error[0]= '\0';
last_errno= 0;
/* Do not swap protocols, the copy always has protocol_text */
}
/**
Execute a prepared statement.
@ -3162,10 +3513,7 @@ bool Prepared_statement::execute(String *expanded_query, bool open_cursor)
DBUG_ASSERT(! (error && cursor));
if (! cursor)
{
cleanup_stmt();
reset_stmt_params(this);
}
thd->set_statement(&stmt_backup);
thd->stmt_arena= old_stmt_arena;

130
sql/table.h
View File

@ -437,6 +437,105 @@ typedef struct st_table_share
return table_map_id;
}
/**
Convert unrelated members of TABLE_SHARE to one enum
representing its metadata type.
@todo perhaps we need to have a member instead of a function.
*/
enum enum_metadata_type get_metadata_type() const
{
if (is_view)
return METADATA_VIEW;
switch (tmp_table) {
case NO_TMP_TABLE:
return METADATA_BASE_TABLE;
case SYSTEM_TMP_TABLE:
return METADATA_I_S_TABLE;
default:
return METADATA_TMP_TABLE;
}
}
/**
Return a table metadata version.
* for base tables, we return table_map_id.
It is assigned from a global counter incremented for each
new table loaded into the table definition cache (TDC).
* for temporary tables it's table_map_id again. But for
temporary tables table_map_id is assigned from
thd->query_id. The latter is assigned from a thread local
counter incremented for every new SQL statement. Since
temporary tables are thread-local, each temporary table
gets a unique id.
* for everything else (views, information schema tables),
the version id is zero.
This choice of version id is a large compromise
to have a working prepared statement validation in 5.1. In
future version ids will be persistent, as described in WL#4180.
Let's try to explain why and how this limited solution allows
to validate prepared statements.
Firstly, spaces (in mathematical sense) of version numbers
never intersect for different metadata types. Therefore,
version id of a temporary table is never compared with
a version id of a view or a temporary table, and vice versa.
Secondly, for base tables, we know that each DDL flushes the
respective share from the TDC. This ensures that whenever
a table is altered or dropped and recreated, it gets a new
version id.
Unfortunately, since elements of the TDC are also flushed on
LRU basis, this choice of version ids leads to false positives.
E.g. when the TDC size is too small, we may have a SELECT
* FROM INFORMATION_SCHEMA.TABLES flush all its elements, which
in turn will lead to a validation error and a subsequent
reprepare of all prepared statements. This is
considered acceptable, since as long as prepared statements are
automatically reprepared, spurious invalidation is only
a performance hit. Besides, no better simple solution exists.
For temporary tables, using thd->query_id ensures that if
a temporary table was altered or recreated, a new version id is
assigned. This suits validation needs very well and will perhaps
never change.
Metadata of information schema tables never changes.
Thus we can safely assume 0 for a good enough version id.
Views are a special and tricky case. A view is always inlined
into the parse tree of a prepared statement at prepare.
Thus, when we execute a prepared statement, the parse tree
will not get modified even if the view is replaced with another
view. Therefore, we can safely choose 0 for version id of
views and effectively never invalidate a prepared statement
when a view definition is altered. Note, that this leads to
wrong binary log in statement-based replication, since we log
prepared statement execution in form Query_log_events
containing conventional statements. But since there is no
metadata locking for views, the very same problem exists for
conventional statements alone, as reported in Bug#25144. The only
difference between prepared and conventional execution is,
effectively, that for prepared statements the race condition
window is much wider.
In 6.0 we plan to support view metadata locking (WL#3726) and
extend table definition cache to cache views (WL#4298).
When this is done, views will be handled in the same fashion
as the base tables.
Finally, by taking into account metadata type, we always
track that a change has taken place when a view is replaced
with a base table, a base table is replaced with a temporary
table and so on.
@sa TABLE_LIST::is_metadata_version_equal()
*/
ulong get_metadata_version() const
{
return tmp_table == SYSTEM_TMP_TABLE || is_view ? 0 : table_map_id;
}
} TABLE_SHARE;
@ -1232,6 +1331,33 @@ struct TABLE_LIST
child_def_version= ~0UL;
}
/**
Compare the version of metadata from the previous execution
(if any) with values obtained from the current table
definition cache element.
@sa check_and_update_metadata_version()
*/
inline
bool is_metadata_version_equal(TABLE_SHARE *s) const
{
return (m_metadata_type == s->get_metadata_type() &&
m_metadata_version == s->get_metadata_version());
}
/**
Record the value of metadata version of the corresponding
table definition cache element in this parse tree node.
@sa check_and_update_metadata_version()
*/
inline
void set_metadata_version(TABLE_SHARE *s)
{
m_metadata_type= s->get_metadata_type();
m_metadata_version= s->get_metadata_version();
}
private:
bool prep_check_option(THD *thd, uint8 check_opt_type);
bool prep_where(THD *thd, Item **conds, bool no_where_clause);
@ -1242,6 +1368,10 @@ private:
/* Remembered MERGE child def version. See top comment in ha_myisammrg.cc */
ulong child_def_version;
/** See comments for set_metadata_version() */
enum enum_metadata_type m_metadata_type;
/** See comments for set_metadata_version() */
ulong m_metadata_version;
};
class Item;

120
tests/mysql_client_test.c
View File

@ -11132,7 +11132,7 @@ static void test_bug4236()
int rc;
MYSQL_STMT backup;
myheader("test_bug4296");
myheader("test_bug4236");
stmt= mysql_stmt_init(mysql);
@ -17383,6 +17383,123 @@ static void test_bug28386()
DBUG_VOID_RETURN;
}
static void test_wl4166()
{
MYSQL_STMT *stmt;
int int_data;
char str_data[50];
char tiny_data;
short small_data;
longlong big_data;
float real_data;
double double_data;
ulong length[7];
my_bool is_null[7];
MYSQL_BIND my_bind[7];
int rc;
int i;
myheader("test_wl4166");
rc= mysql_query(mysql, "DROP TABLE IF EXISTS table_4166");
myquery(rc);
rc= mysql_query(mysql, "CREATE TABLE table_4166(col1 tinyint NOT NULL, "
"col2 varchar(15), col3 int, "
"col4 smallint, col5 bigint, "
"col6 float, col7 double, "
"colX varchar(10) default NULL)");
myquery(rc);
stmt= mysql_simple_prepare(mysql,
"INSERT INTO table_4166(col1, col2, col3, col4, col5, col6, col7) "
"VALUES(?, ?, ?, ?, ?, ?, ?)");
check_stmt(stmt);
verify_param_count(stmt, 7);
/* tinyint */
my_bind[0].buffer_type= MYSQL_TYPE_TINY;
my_bind[0].buffer= (void *)&tiny_data;
/* string */
my_bind[1].buffer_type= MYSQL_TYPE_STRING;
my_bind[1].buffer= (void *)str_data;
my_bind[1].buffer_length= 1000; /* Max string length */
/* integer */
my_bind[2].buffer_type= MYSQL_TYPE_LONG;
my_bind[2].buffer= (void *)&int_data;
/* short */
my_bind[3].buffer_type= MYSQL_TYPE_SHORT;
my_bind[3].buffer= (void *)&small_data;
/* bigint */
my_bind[4].buffer_type= MYSQL_TYPE_LONGLONG;
my_bind[4].buffer= (void *)&big_data;
/* float */
my_bind[5].buffer_type= MYSQL_TYPE_FLOAT;
my_bind[5].buffer= (void *)&real_data;
/* double */
my_bind[6].buffer_type= MYSQL_TYPE_DOUBLE;
my_bind[6].buffer= (void *)&double_data;
for (i= 0; i < (int) array_elements(my_bind); i++)
{
my_bind[i].length= &length[i];
my_bind[i].is_null= &is_null[i];
is_null[i]= 0;
}
rc= mysql_stmt_bind_param(stmt, my_bind);
check_execute(stmt, rc);
int_data= 320;
small_data= 1867;
big_data= 1000;
real_data= 2;
double_data= 6578.001;
/* now, execute the prepared statement to insert 10 records.. */
for (tiny_data= 0; tiny_data < 10; tiny_data++)
{
length[1]= my_sprintf(str_data, (str_data, "MySQL%d", int_data));
rc= mysql_stmt_execute(stmt);
check_execute(stmt, rc);
int_data += 25;
small_data += 10;
big_data += 100;
real_data += 1;
double_data += 10.09;
}
/* force a re-prepare with some DDL */
rc= mysql_query(mysql,
"ALTER TABLE table_4166 change colX colX varchar(20) default NULL");
myquery(rc);
/*
execute the prepared statement again,
without changing the types of parameters already bound.
*/
for (tiny_data= 50; tiny_data < 60; tiny_data++)
{
length[1]= my_sprintf(str_data, (str_data, "MySQL%d", int_data));
rc= mysql_stmt_execute(stmt);
check_execute(stmt, rc);
int_data += 25;
small_data += 10;
big_data += 100;
real_data += 1;
double_data += 10.09;
}
mysql_stmt_close(stmt);
rc= mysql_query(mysql, "DROP TABLE table_4166");
myquery(rc);
}
/*
Read and parse arguments and MySQL options from my.cnf
*/
@ -17689,6 +17806,7 @@ static struct my_tests_st my_tests[]= {
{ "test_bug31418", test_bug31418 },
{ "test_bug31669", test_bug31669 },
{ "test_bug28386", test_bug28386 },
{ "test_wl4166", test_wl4166 },
{ 0, 0 }
};