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MCOL-4282 Enable Select Handler for Prepared Statements

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This patch enables select handler for executing prepared
statements. Most importantly, we are now activating a
persistent arena which will allocate any new items in a
permanent MEMROOT for prepared statements and stored procedures.
Refer to JOIN::optimize_inner() for details.

In processWhere(), we now use SELECT_LEX::prep_where in case
we are executing a prepared statement, as this is where the saved
WHERE clause is stored for prepared statement processing.

In addition, we also disable derived handler for prepared
statements.
This commit is contained in:
Gagan Goel
2020-09-11 16:35:51 -04:00
parent 1a214aee1a
commit a117786027
4 changed files with 114 additions and 14 deletions
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41
dbcon/mysql/ha_mcs_pushdown.cpp
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@ -476,6 +476,10 @@ create_columnstore_derived_handler(THD* thd, TABLE_LIST *derived)
return handler;
}
// Disable derived handler for prepared statements
if (thd->stmt_arena && thd->stmt_arena->is_stmt_execute())
return handler;
SELECT_LEX_UNIT *unit= derived->derived;
SELECT_LEX *sl= unit->first_select();
@ -748,11 +752,15 @@ create_columnstore_select_handler(THD* thd, SELECT_LEX* select_lex)
return handler;
}
// Flag to indicate if this is a prepared statement
bool isPS = thd->stmt_arena && thd->stmt_arena->is_stmt_execute();
// Disable processing of select_result_interceptor classes
// which intercept and transform result set rows. E.g.:
// select a,b into @a1, @a2 from t1;
if (((thd->lex)->result &&
!((select_dumpvar *)(thd->lex)->result)->var_list.is_empty()))
!((select_dumpvar *)(thd->lex)->result)->var_list.is_empty()) &&
(!isPS))
{
return handler;
}
@ -800,8 +808,34 @@ create_columnstore_select_handler(THD* thd, SELECT_LEX* select_lex)
COND *conds = nullptr;
if (!unsupported_feature)
{
conds= simplify_joins_mcs(join, select_lex->join_list,
join->conds, TRUE, FALSE);
SELECT_LEX *sel= select_lex;
// Rewrite once for PS
// Refer to JOIN::optimize_inner() in sql/sql_select.cc
// for details on the optimizations performed in this block.
if (sel->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);
sel->first_cond_optimization= false;
conds= simplify_joins_mcs(join, select_lex->join_list,
join->conds, TRUE, FALSE);
build_bitmap_for_nested_joins_mcs(select_lex->join_list, 0);
sel->where= conds;
if (isPS)
sel->prep_where= conds;
select_lex->update_used_tables();
if (arena)
thd->restore_active_arena(arena, &backup);
// Unset SL::first_cond_optimization
opt_flag_unset_PS(sel);
}
}
if (!unsupported_feature && conds)
@ -825,7 +859,6 @@ create_columnstore_select_handler(THD* thd, SELECT_LEX* select_lex)
// We shouldn't raise error now so set an error to raise it later in init_SH.
handler->rewrite_error= unsupported_feature;
// Return SH even if init fails b/c CS changed SELECT_LEX structures
// with simplify_joins_mcs()
return handler;