execute crashes server": we were deleting lex->result
after each execute, but prepared statements assumed that
it's left intact.
The fix adds cleanup() method to select_result hierarchy,
so that result objects can be reused.
Plus we now need to delete result objects more wisely.


mysql-test/r/ps.result:
  Test results fixed: test case for bug#5034
mysql-test/t/ps.test:
  A test case for bug#5034, few followups
sql/sql_class.cc:
  - fix warning in THD::THD
  - implementation of cleanup() for select_result hierarchy
  - select_export::send_eof was identical to 
    select_dump::send_eof: moved to the base class select_to_file.
  - Statement::end_statement() to end lex, free items, and
    delete possible select_result
sql/sql_class.h:
  - select_result::cleanup() declaration
  -
sql/sql_insert.cc:
  - implementation of select_insert::cleanup(): currently
    we always create a new instance of select_insert/
    select_create on each execute.
sql/sql_lex.cc:
  - with more complicated logic of freeing lex->result it's 
    easier to have it non-zero only if it points to a valid
    result.
sql/sql_lex.h:
  Now st_lex::st_lex is not empty.
sql/sql_parse.cc:
  mysql_execute_command():
  - delete select_result *result only if it was created in
    this function.
  - use end_statement() to cleanup lex and thd in the end of
    each statement.
  - no need to save THD::lock if this is explain. This save
    apparently left from times when derived tables were 
    materialized here, not in open_and_lock_tables.
sql/sql_prepare.cc:
  - call result->cleanup() in reset_stmt_for_execute
  - now Statement is responsible for freeing its lex->result.
sql/sql_select.cc:
  handle_select():
  - don't delete result, it might be needed
    for next executions
  - result is never null

into serg.mylan:/usr/home/serg/Abk/mysql-4.1

in ha_commit_trans - why it didn't crash earlier ?


mysql-test/r/null.result:
  after merge fix

sql/item_cmpfunc.h:
  Auto merged
mysql-test/r/join_outer.result:
  merged with 'ul'
mysql-test/r/null.result:
  merged with 'ul'

(cannot call it a "merge" :)

Abandoned improper use of MyISAM data.
Thanks Ingo!

cmd-line-utils/libedit/history.c:
  account for closing \0

into ice.snake.net:/Volumes/ice2/MySQL/bk/mysql-4.1

without InnoDB.

  Added test case for bug #4256.
join_outer.result:
  Fixed bug #4256.
item_cmpfunc.h:
  Fixed inconsistency of values of used_tables_cache and
  const_item_cache for Item_func_isnull objects.
  This inconsistency caused bug #4256.


sql/item_cmpfunc.h:
  Fixed inconsistency of values of used_tables_cache and
  const_item_cache for Item_func_isnull objects.
  This inconsistency caused bug #4256.
mysql-test/r/join_outer.result:
  Fixed bug #4256.
mysql-test/r/null.result:
  Added test case for bug #4256.
mysql-test/t/null.test:
  Added test case for bug #4256.

into rurik.mysql.com:/home/igor/mysql-4.1


sql/item_sum.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged

into ice.snake.net:/Volumes/ice2/MySQL/bk/mysql-4.1

into rurik.mysql.com:/home/igor/mysql-4.1

into mysql.com:/home/kostja/work/mysql-4.1-4912


sql/item_cmpfunc.cc:
  Auto merged
sql/mysql_priv.h:
  Auto merged
sql/sql_base.cc:
  Auto merged
sql/sql_class.h:
  Auto merged
sql/sql_parse.cc:
  Auto merged
sql/sql_prepare.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged

 a second time". The bug was caused by incompatibility of
negations elimination algorithm and PS: during first statement 
execute a subtree with negation was replaced with equivalent 
subtree without NOTs.
The problem was that although this transformation was permanent, 
items of the new subtree were created in execute-local memory.
The patch adds means to check if it is the first execute of a
prepared statement, and if this is the case, to allocate items
in memory of the prepared statement.
The implementation:
- backports Item_arena from 5.0
- adds Item_arena::is_stmt_prepare(), 
  Item_arena::is_first_stmt_execute().
- deletes THD::allocate_temporary_pool_for_ps_preparing(),
  THD::free_temporary_pool_for_ps_preparing(); they
  were redundant.
and adds a few invariants:
- thd->free_list never contains junk (= freed items)
- thd->current_arena is never null. If there is no
  prepared statement, it points at the thd. 
The rest of the patch contains mainly mechanical changes and
cleanups.


mysql-test/r/ps.result:
  Test results updated (test case for Bug#4912)
mysql-test/t/ps.test:
  A test case for Bug#4912 "mysqld crashs in case a statement is 
  executed a second time"
sql/item_cmpfunc.cc:
  current_statement -> current_arena
sql/item_subselect.cc:
  Statement -> Item_arena, current_statement -> current_arena
sql/item_subselect.h:
  Item_subselect does not need to save thd->current_statement.
sql/item_sum.cc:
  Statement -> Item_arena
sql/item_sum.h:
  Statement -> Item_arena
sql/mysql_priv.h:
  Statement -> Item_arena
sql/sql_base.cc:
  current_statement -> current_arena
sql/sql_class.cc:
  - Item_arena
  - convenient set_n_backup_statement, restore_backup_statement
  (nice idea, Sanja)
sql/sql_class.h:
  - Item_arena: backport from 5.0
  - allocate_temporary_pool_for_ps_preparing,
    free_temporary_pool_for_ps_preparing removed.
sql/sql_derived.cc:
  current_statement -> current_arena
sql/sql_lex.cc:
  current_statement -> current_arena
sql/sql_parse.cc:
  Deploy invariant that thd->free_list never contains junk items
  (backport from 5.0).
sql/sql_prepare.cc:
  - backporting Item_arena
  - no need to allocate_temporary_pool_for_ps_preparing().
sql/sql_select.cc:
  Fix for bug#4912 "mysqld crashs in case a statement is 
  executed a second time": if this is the first execute of
  a prepared statement, negation elimination is
  done in memory of the prepared statement.
sql/sql_union.cc:
  Backporting Item_arena from 5.0.

  Fixed it to work, added function to fix include/mysql_version.h LICENSE tag from GPL to Commercial


Build-tools/mysql-copyright:
  Fixed it to work, added function to fix include/mysql_version.h LICENSE tag from GPL to Commercial

into rurik.mysql.com:/home/igor/mysql-4.1


sql/sql_select.cc:
  Auto merged

myisam/Makefile.am:
  put zlib at the end (libtool adds the whole bunch of dependencies right after that)
sql/Makefile.am:
  put zlib at the end (libtool adds the whole bunch of dependencies right after that)

into serg.mylan:/usr/home/serg/Abk/mysql-4.1


sql/mysql_priv.h:
  Auto merged

sql/lock.cc:
  Auto merged
sql/mysql_priv.h:
  Auto merged
sql/sql_db.cc:
  Auto merged

into mysql.com:/home/jonas/src/mysql-4.1

into build.mysql.com:/users/rburnett/mysql-4.1


sql/mysql_priv.h:
  Auto merged

into rurik.mysql.com:/home/igor/dev/mysql-4.1-0


sql/item_sum.cc:
  Auto merged
sql/sql_select.cc:
  Auto merged

into mysql.com:/home/jonas/src/mysql-4.1

sql/sql_select.cc:
  why cannot I compare (type) to (const type) ?????

into ice.snake.net:/Volumes/ice2/MySQL/bk/mysql-4.1


sql/mysqld.cc:
  Auto merged
sql/set_var.cc:
  Auto merged

Fix for MyISAM. Tests for MyISAM and HASH+BTREE.

into mysql.com:/home/jonas/src/mysql-4.1

into brandersnatch.localdomain:/home/dlenev/src/mysql-4.1-bg4302

into poseidon.(none):/home/tomas/mysql-4.1

into brandersnatch.localdomain:/home/dlenev/src/mysql-4.1-bg4302


sql/sql_select.cc:
  Auto merged

into mysql.com:/space/my/mysql-4.1

into poseidon.(none):/home/tomas/mysql-4.1

into mysql.com:/home/mysql_src/mysql-4.0