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MDEV-25080 Implement ColumnStore-side changes for pushdown of SELECT_LEX_UNITs.

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This commit is contained in:
Gagan Goel
2022-08-31 16:46:15 -04:00
parent 8671f55784
commit 45a779f743
11 changed files with 551 additions and 126 deletions
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321
dbcon/mysql/ha_mcs_pushdown.cpp
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@ -728,20 +728,22 @@ int ha_mcs_group_by_handler::end_scan()
DBUG_RETURN(rc);
}
/*@brief create_columnstore_select_handler- Creates handler*/
/************************************************************
/*@brief create_columnstore_select_handler_- Creates handler
************************************************************
* DESCRIPTION:
* Creates a select handler if there is no non-equi JOIN, e.g
* t1.c1 > t2.c2 and logical OR in the filter predicates.
* More details in server/sql/select_handler.h
* PARAMETERS:
* thd - THD pointer.
* select_lex - SELECT_LEX* that describes the query.
* sel_lex - SELECT_LEX* that describes the query.
* sel_unit - SELECT_LEX_UNIT* that describes the query.
* Only one of sel_lex and sel_unit is not null.
* RETURN:
* select_handler if possible
* NULL in other case
***********************************************************/
select_handler* create_columnstore_select_handler(THD* thd, SELECT_LEX* select_lex)
select_handler* create_columnstore_select_handler_(THD* thd, SELECT_LEX* sel_lex, SELECT_LEX_UNIT* sel_unit)
{
mcs_select_handler_mode_t select_handler_mode = get_select_handler_mode(thd);
@ -778,60 +780,96 @@ select_handler* create_columnstore_select_handler(THD* thd, SELECT_LEX* select_l
return nullptr;
}
// Iterate and traverse through the item list and the JOIN cond
// and do not create SH if the unsupported (set_user_var)
// function is present.
TABLE_LIST* table_ptr = select_lex->get_table_list();
for (; table_ptr; table_ptr = table_ptr->next_global)
std::vector<SELECT_LEX*> select_lex_vec;
if (sel_unit && !sel_lex)
{
if (check_user_var(table_ptr->select_lex))
for (SELECT_LEX* sl = sel_unit->first_select(); sl; sl = sl->next_select())
{
return nullptr;
select_lex_vec.push_back(sl);
}
}
else
{
select_lex_vec.push_back(sel_lex);
}
for (size_t i = 0; i < select_lex_vec.size(); i++)
{
SELECT_LEX* select_lex = select_lex_vec[i];
// Iterate and traverse through the item list and the JOIN cond
// and do not create SH if the unsupported (set_user_var)
// function is present.
TABLE_LIST* table_ptr = select_lex->get_table_list();
for (; table_ptr; table_ptr = table_ptr->next_global)
{
if (check_user_var(table_ptr->select_lex))
{
return nullptr;
}
}
}
// We apply dedicated rewrites from MDB here so MDB's data structures
// becomes dirty and CS has to raise an error in case of any problem
// or unsupported feature.
ha_columnstore_select_handler* handler = new ha_columnstore_select_handler(thd, select_lex);
ha_columnstore_select_handler* handler;
JOIN* join = select_lex->join;
if (select_lex->first_cond_optimization && select_lex->handle_derived(thd->lex, DT_MERGE))
if (sel_unit && sel_lex)
{
if (!thd->is_error())
{
my_printf_error(ER_INTERNAL_ERROR, "%s", MYF(0), "Error occured in select_lex::handle_derived()");
}
return handler;
handler = new ha_columnstore_select_handler(thd, sel_lex, sel_unit);
}
else if (sel_unit)
{
handler = new ha_columnstore_select_handler(thd, sel_unit);
}
else
{
handler = new ha_columnstore_select_handler(thd, sel_lex);
}
// This is partially taken from JOIN::optimize_inner() in sql/sql_select.cc
if (select_lex->first_cond_optimization)
for (size_t i = 0; i < select_lex_vec.size(); i++)
{
create_explain_query_if_not_exists(thd->lex, thd->mem_root);
Query_arena *arena, backup;
arena = thd->activate_stmt_arena_if_needed(&backup);
COND* conds = join->conds;
select_lex->where = conds;
SELECT_LEX* select_lex = select_lex_vec[i];
JOIN* join = select_lex->join;
if (isPS)
if (select_lex->first_cond_optimization && select_lex->handle_derived(thd->lex, DT_MERGE))
{
select_lex->prep_where = conds ? conds->copy_andor_structure(thd) : 0;
if (!thd->is_error())
{
my_printf_error(ER_INTERNAL_ERROR, "%s", MYF(0), "Error occured in select_lex::handle_derived()");
}
return handler;
}
select_lex->update_used_tables();
// This is partially taken from JOIN::optimize_inner() in sql/sql_select.cc
if (select_lex->first_cond_optimization)
{
create_explain_query_if_not_exists(thd->lex, thd->mem_root);
Query_arena *arena, backup;
arena = thd->activate_stmt_arena_if_needed(&backup);
COND* conds = join->conds;
select_lex->where = conds;
if (arena)
thd->restore_active_arena(arena, &backup);
if (isPS)
{
select_lex->prep_where = conds ? conds->copy_andor_structure(thd) : 0;
}
select_lex->update_used_tables();
if (arena)
thd->restore_active_arena(arena, &backup);
#ifdef DEBUG_WALK_COND
if (conds)
{
conds->traverse_cond(cal_impl_if::debug_walk, NULL, Item::POSTFIX);
}
if (conds)
{
conds->traverse_cond(cal_impl_if::debug_walk, NULL, Item::POSTFIX);
}
#endif
}
}
// Attempt to execute the query using the select handler.
@ -840,69 +878,45 @@ select_handler* create_columnstore_select_handler(THD* thd, SELECT_LEX* select_l
// Skip execution for EXPLAIN queries
if (!thd->lex->describe)
{
// This is taken from JOIN::optimize()
join->fields = &select_lex->item_list;
// Instantiate handler::table, which is the place for the result set.
if (handler->prepare())
for (size_t i = 0; i < select_lex_vec.size(); i++)
{
// check fallback
if (select_handler_mode == mcs_select_handler_mode_t::AUTO) // columnstore_select_handler=AUTO
SELECT_LEX* select_lex = select_lex_vec[i];
JOIN* join = select_lex->join;
// This is taken from JOIN::optimize()
join->fields = &select_lex->item_list;
// Instantiate handler::table, which is the place for the result set.
if ((i == 0) && handler->prepare())
{
push_warning(thd, Sql_condition::WARN_LEVEL_WARN, 9999,
"MCS select_handler execution failed. Falling back to server execution");
restore_query_state(handler);
delete handler;
return nullptr;
// check fallback
if (select_handler_mode == mcs_select_handler_mode_t::AUTO) // columnstore_select_handler=AUTO
{
push_warning(thd, Sql_condition::WARN_LEVEL_WARN, 9999,
"MCS select_handler execution failed. Falling back to server execution");
restore_query_state(handler);
delete handler;
return nullptr;
}
// error out
if (!thd->is_error())
{
my_printf_error(ER_INTERNAL_ERROR, "%s", MYF(0), "Error occured in handler->prepare()");
}
return handler;
}
// error out
if (!thd->is_error())
{
my_printf_error(ER_INTERNAL_ERROR, "%s", MYF(0), "Error occured in handler->prepare()");
}
// Prepare query execution
// This is taken from JOIN::exec_inner()
if (!select_lex->outer_select() && // (1)
select_lex != select_lex->master_unit()->fake_select_lex) // (2)
thd->lex->set_limit_rows_examined();
return handler;
}
// Prepare query execution
// This is taken from JOIN::exec_inner()
if (!select_lex->outer_select() && // (1)
select_lex != select_lex->master_unit()->fake_select_lex) // (2)
thd->lex->set_limit_rows_examined();
if (!join->tables_list && (join->table_count || !select_lex->with_sum_func) &&
!select_lex->have_window_funcs())
{
if (!thd->is_error())
{
restore_query_state(handler);
delete handler;
return nullptr;
}
return handler;
}
if (!join->zero_result_cause && join->exec_const_cond && !join->exec_const_cond->val_int())
join->zero_result_cause = "Impossible WHERE noticed after reading const tables";
// We've called exec_const_cond->val_int(). This may have caused an error.
if (unlikely(thd->is_error()))
{
// error out
handler->pushdown_init_rc = 1;
return handler;
}
if (join->zero_result_cause)
{
if (join->select_lex->have_window_funcs() && join->send_row_on_empty_set())
{
join->const_tables = join->table_count;
join->first_select = sub_select_postjoin_aggr;
}
else
if ((!sel_unit || sel_lex) && !join->tables_list &&
(join->table_count || !select_lex->with_sum_func) &&
!select_lex->have_window_funcs())
{
if (!thd->is_error())
{
@ -913,23 +927,56 @@ select_handler* create_columnstore_select_handler(THD* thd, SELECT_LEX* select_l
return handler;
}
}
if ((join->select_lex->options & OPTION_SCHEMA_TABLE) &&
get_schema_tables_result(join, PROCESSED_BY_JOIN_EXEC))
{
if (!thd->is_error())
if (!join->zero_result_cause && join->exec_const_cond && !join->exec_const_cond->val_int())
join->zero_result_cause = "Impossible WHERE noticed after reading const tables";
// We've called exec_const_cond->val_int(). This may have caused an error.
if (unlikely(thd->is_error()))
{
my_printf_error(ER_INTERNAL_ERROR, "%s", MYF(0), "Error occured in get_schema_tables_result()");
// error out
handler->pushdown_init_rc = 1;
return handler;
}
return handler;
if (join->zero_result_cause)
{
if (join->select_lex->have_window_funcs() && join->send_row_on_empty_set())
{
join->const_tables = join->table_count;
join->first_select = sub_select_postjoin_aggr;
}
else
{
if (!thd->is_error())
{
restore_query_state(handler);
delete handler;
return nullptr;
}
return handler;
}
}
if ((join->select_lex->options & OPTION_SCHEMA_TABLE) &&
get_schema_tables_result(join, PROCESSED_BY_JOIN_EXEC))
{
if (!thd->is_error())
{
my_printf_error(ER_INTERNAL_ERROR, "%s", MYF(0), "Error occured in get_schema_tables_result()");
}
return handler;
}
}
handler->scan_initialized = true;
mcs_handler_info mhi(reinterpret_cast<void*>(handler), SELECT);
if ((handler->pushdown_init_rc = ha_mcs_impl_pushdown_init(&mhi, handler->table)))
bool isSelectLexUnit = (sel_unit && !sel_lex) ? true : false;
if ((handler->pushdown_init_rc = ha_mcs_impl_pushdown_init(&mhi, handler->table, isSelectLexUnit)))
{
// check fallback
if (select_handler_mode == mcs_select_handler_mode_t::AUTO)
@ -967,31 +1014,83 @@ select_handler* create_columnstore_select_handler(THD* thd, SELECT_LEX* select_l
return handler;
}
// Unset select_lex::first_cond_optimization
if (select_lex->first_cond_optimization)
for (size_t i = 0; i < select_lex_vec.size(); i++)
{
first_cond_optimization_flag_toggle(select_lex, &first_cond_optimization_flag_unset);
SELECT_LEX* select_lex = select_lex_vec[i];
// Unset select_lex::first_cond_optimization
if (select_lex->first_cond_optimization)
{
first_cond_optimization_flag_toggle(select_lex, &first_cond_optimization_flag_unset);
}
}
}
return handler;
}
select_handler* create_columnstore_select_handler(THD* thd, SELECT_LEX* select_lex, SELECT_LEX_UNIT* sel_unit)
{
return create_columnstore_select_handler_(thd, select_lex, sel_unit);
}
select_handler* create_columnstore_unit_handler(THD* thd, SELECT_LEX_UNIT* sel_unit)
{
return create_columnstore_select_handler_(thd, 0, sel_unit);
}
/***********************************************************
* DESCRIPTION:
* select_handler constructor
* PARAMETERS:
* thd - THD pointer.
* select_lex - sematic tree for the query.
* sel_lex - semantic tree for the query.
***********************************************************/
ha_columnstore_select_handler::ha_columnstore_select_handler(THD* thd, SELECT_LEX* select_lex)
: select_handler(thd, mcs_hton)
ha_columnstore_select_handler::ha_columnstore_select_handler(THD* thd, SELECT_LEX* sel_lex)
: select_handler(thd, mcs_hton, sel_lex)
, prepared(false)
, scan_ended(false)
, scan_initialized(false)
, pushdown_init_rc(0)
{
const char* timeZone = thd->variables.time_zone->get_name()->ptr();
dataconvert::timeZoneToOffset(timeZone, strlen(timeZone), &time_zone);
}
/***********************************************************
* DESCRIPTION:
* select_handler constructor
* PARAMETERS:
* thd - THD pointer.
* sel_unit - semantic tree for the query.
***********************************************************/
ha_columnstore_select_handler::ha_columnstore_select_handler(THD* thd, SELECT_LEX_UNIT* sel_unit)
: select_handler(thd, mcs_hton, sel_unit)
, prepared(false)
, scan_ended(false)
, scan_initialized(false)
, pushdown_init_rc(0)
{
const char* timeZone = thd->variables.time_zone->get_name()->ptr();
dataconvert::timeZoneToOffset(timeZone, strlen(timeZone), &time_zone);
}
/***********************************************************
* DESCRIPTION:
* select_handler constructor
* PARAMETERS:
* thd - THD pointer.
* sel_lex - semantic tree for the query.
* sel_unit - unit containing SELECT_LEX's
***********************************************************/
ha_columnstore_select_handler::ha_columnstore_select_handler(THD* thd, SELECT_LEX* sel_lex,
SELECT_LEX_UNIT* sel_unit)
: select_handler(thd, mcs_hton, sel_lex, sel_unit)
, prepared(false)
, scan_ended(false)
, scan_initialized(false)
, pushdown_init_rc(0)
{
select = select_lex;
const char* timeZone = thd->variables.time_zone->get_name()->ptr();
dataconvert::timeZoneToOffset(timeZone, strlen(timeZone), &time_zone);
}
@ -1074,7 +1173,7 @@ bool ha_columnstore_select_handler::prepare()
prepared = true;
if ((!table && !(table = create_tmp_table(thd, select))) || table->fill_item_list(&result_columns))
if ((!table && !(table = create_tmp_table(thd))) || table->fill_item_list(&result_columns))
{
pushdown_init_rc = 1;
DBUG_RETURN(true);