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Better approach for prelocking of tables for stored routines execution

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and some SP-related cleanups.

- We don't have separate stage for calculation of list of tables
  to be prelocked and doing implicit LOCK/UNLOCK any more.
  Instead we calculate this list at open_tables() and do implicit
  LOCK in lock_tables() (and UNLOCK in close_thread_tables()).
  Also now we support cases when same table (with same alias) is
  used several times in the same query in SP.

- Cleaned up execution of SP. Moved all common code which handles
  LEX and does preparations before statement execution or complex
  expression evaluation to auxilary sp_lex_keeper class. Now 
  all statements in SP (and corresponding instructions) that
  evaluate expression which can contain subquery have their
  own LEX.
This commit is contained in:
dlenev@brandersnatch.localdomain
2005-03-04 16:35:28 +03:00
parent 6611d3d2f8
commit 5a6c7027f0
29 changed files with 1804 additions and 877 deletions
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44
sql/sql_class.h
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@ -777,6 +777,15 @@ struct Item_change_record;
typedef I_List<Item_change_record> Item_change_list;
/*
Type of prelocked mode.
See comment for THD::prelocked_mode for complete description.
*/
enum prelocked_mode_type {NON_PRELOCKED= 0, PRELOCKED= 1,
PRELOCKED_UNDER_LOCK_TABLES= 2};
/*
For each client connection we create a separate thread with THD serving as
a thread/connection descriptor
@ -877,7 +886,13 @@ public:
See also lock_tables() for details.
*/
MYSQL_LOCK *lock; /* Current locks */
MYSQL_LOCK *locked_tables; /* Tables locked with LOCK */
/*
Tables that were locked with explicit or implicit LOCK TABLES.
(Implicit LOCK TABLES happens when we are prelocking tables for
execution of statement which uses stored routines. See description
THD::prelocked_mode for more info.)
*/
MYSQL_LOCK *locked_tables;
HASH handler_tables_hash;
/*
One thread can hold up to one named user-level lock. This variable
@ -1032,8 +1047,6 @@ public:
sp_rcontext *spcont; // SP runtime context
sp_cache *sp_proc_cache;
sp_cache *sp_func_cache;
bool shortcut_make_view; /* Don't do full mysql_make_view()
during pre-opening of tables. */
/*
If we do a purge of binary logs, log index info of the threads
@ -1049,6 +1062,31 @@ public:
long long_value;
} sys_var_tmp;
/*
prelocked_mode_type enum and prelocked_mode member are used for
indicating whenever "prelocked mode" is on, and what type of
"prelocked mode" is it.
Prelocked mode is used for execution of queries which explicitly
or implicitly (via views or triggers) use functions, thus may need
some additional tables (mentioned in query table list) for their
execution.
First open_tables() call for such query will analyse all functions
used by it and add all additional tables to table its list. It will
also mark this query as requiring prelocking. After that lock_tables()
will issue implicit LOCK TABLES for the whole table list and change
thd::prelocked_mode to non-0. All queries called in functions invoked
by the main query will use prelocked tables. Non-0 prelocked_mode
will also surpress mentioned analysys in those queries thus saving
cycles. Prelocked mode will be turned off once close_thread_tables()
for the main query will be called.
Note: Since not all "tables" present in table list are really locked
thd::relocked_mode does not imply thd::locked_tables.
*/
prelocked_mode_type prelocked_mode;
THD();
~THD();