database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-08-01 03:47:19 +03:00
Code Activity

MDEV-19956 Queries with subqueries containing UNION are not parsed

Browse Source 
Shift-Reduce conflicts prevented parsing some queries with subqueries that
used set operations when the subqueries occurred in expressions or in IN
predicands.
The grammar rules for query expression were transformed in order to avoid
these conflicts. New grammar rules employ an idea taken from MySQL 8.0.
This commit is contained in:
Igor Babaev
2019-09-20 09:03:38 -07:00
parent e3da362c03
commit b44171428a
21 changed files with 7212 additions and 593 deletions
Download Patch File Download Diff File Expand all files Collapse all files

48
sql/sql_union.cc
View File

@ -831,8 +831,8 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
bool is_union_select;
bool have_except= FALSE, have_intersect= FALSE;
bool instantiate_tmp_table= false;
bool single_tvc= !first_sl->next_select() && first_sl->tvc &&
!fake_select_lex;
bool single_tvc= !first_sl->next_select() && first_sl->tvc;
bool single_tvc_wo_order= single_tvc && !first_sl->order_list.elements;
DBUG_ENTER("st_select_lex_unit::prepare");
DBUG_ASSERT(thd == current_thd);
@ -924,8 +924,9 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
if (is_union_select || is_recursive)
{
if ((is_unit_op() && !union_needs_tmp_table() &&
!have_except && !have_intersect) || single_tvc)
if ((single_tvc_wo_order && !fake_select_lex) ||
(is_unit_op() && !union_needs_tmp_table() &&
!have_except && !have_intersect && !single_tvc))
{
SELECT_LEX *last= first_select();
while (last->next_select())
@ -940,7 +941,7 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
else
{
if (!is_recursive)
union_result= new (thd->mem_root) select_unit(thd);
union_result= new (thd->mem_root) select_unit(thd);
else
{
with_element->rec_result=
@ -986,17 +987,40 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
if (sl->tvc && sl->order_list.elements &&
!sl->tvc->to_be_wrapped_as_with_tail())
{
SELECT_LEX_UNIT *unit= sl->master_unit();
if (thd->lex->context_analysis_only & CONTEXT_ANALYSIS_ONLY_VIEW)
{
sl->master_unit()->fake_select_lex= 0;
sl->master_unit()->saved_fake_select_lex= 0;
unit->fake_select_lex= 0;
unit->saved_fake_select_lex= 0;
}
else
{
sl->order_list.empty();
sl->explicit_limit= 0;
sl->select_limit= 0;
sl->offset_limit= 0;
if (!unit->first_select()->next_select())
{
if (!unit->fake_select_lex)
{
Query_arena *arena, backup_arena;
arena= thd->activate_stmt_arena_if_needed(&backup_arena);
bool rc= unit->add_fake_select_lex(thd);
if (arena)
thd->restore_active_arena(arena, &backup_arena);
if (rc)
goto err;
}
SELECT_LEX *fake= unit->fake_select_lex;
fake->order_list= sl->order_list;
fake->explicit_limit= sl->explicit_limit;
fake->select_limit= sl->select_limit;
fake->offset_limit= sl->offset_limit;
sl->order_list.empty();
sl->explicit_limit= 0;
sl->select_limit= 0;
sl->offset_limit= 0;
if (describe)
fake->options|= SELECT_DESCRIBE;
}
else if (!sl->explicit_limit)
sl->order_list.empty();
}
}
@ -1021,7 +1045,7 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
goto err;
}
else if (sl->tvc->prepare(thd, sl, tmp_result, this))
goto err;
goto err;
}
else if (prepare_join(thd, sl, tmp_result, additional_options,
is_union_select))