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------------------------------------------------------------
revno: 2630.13.16
committer: Davi Arnaut <Davi.Arnaut@Sun.COM>
branch nick: WL#4284
timestamp: Sat 2008-07-26 13:38:20 -0300
message:
WL#4284: Transactional DDL locking

SQL statements' effect on transactions.

Currently the MySQL server and its storage engines are not
capable of rolling back operations that define or modify data
structures (also known as DDL statements) or operations that
alter any of the system tables (the mysql database). Allowing
these group of statements to participate in transactions
is unfeasible at this time (since rollback has no effect
whatsoever on them) and goes against the design of our metadata
locking subsystem.

The solution is to issue implicit commits before and after
those statements execution. This effectively confines each of
those statements to its own special transaction and ensures
that metadata locks taken during this special transaction
are not leaked into posterior statements/transactions.
This commit is contained in:
Konstantin Osipov
2009-12-03 18:47:20 +03:00
parent 37edcc7e26
commit 4ae05129dc
12 changed files with 2484 additions and 153 deletions
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47
sql/sql_class.h
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@ -3152,6 +3152,36 @@ public:
joins are currently prohibited in these statements.
*/
#define CF_REEXECUTION_FRAGILE (1U << 5)
/**
Implicitly commit before the SQL statement is executed.
Statements marked with this flag will cause any active
transaction to end (commit) before proceeding with the
command execution.
This flag should be set for statements that probably can't
be rolled back or that do not expect any previously metadata
locked tables.
*/
#define CF_IMPLICT_COMMIT_BEGIN (1U << 6)
/**
Implicitly commit after the SQL statement.
Statements marked with this flag are automatically committed
at the end of the statement.
This flag should be set for statements that will implicitly
open and take metadata locks on system tables that should not
be carried for the whole duration of a active transaction.
*/
#define CF_IMPLICIT_COMMIT_END (1U << 7)
/**
CF_IMPLICT_COMMIT_BEGIN and CF_IMPLICIT_COMMIT_END are used
to ensure that the active transaction is implicitly committed
before and after every DDL statement and any statement that
modifies our currently non-transactional system tables.
*/
#define CF_AUTO_COMMIT_TRANS (CF_IMPLICT_COMMIT_BEGIN | CF_IMPLICIT_COMMIT_END)
/**
Diagnostic statement.
@ -3163,6 +3193,23 @@ public:
*/
#define CF_DIAGNOSTIC_STMT (1U << 8)
/* Bits in server_command_flags */
/**
Skip the increase of the global query id counter. Commonly set for
commands that are stateless (won't cause any change on the server
internal states).
*/
#define CF_SKIP_QUERY_ID (1U << 0)
/**
Skip the increase of the number of statements that clients have
sent to the server. Commonly used for commands that will cause
a statement to be executed but the statement might have not been
sent by the user (ie: stored procedure).
*/
#define CF_SKIP_QUESTIONS (1U << 1)
/* Functions in sql_class.cc */
void add_to_status(STATUS_VAR *to_var, STATUS_VAR *from_var);