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MCOL-4282 Follow up version 2.

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Mutate the optimizer flags for prepared statements in:
  1. ha_mcs::open
  2. ha_mcs::discover_check_version

This is done to ensure the optimizer flags are disabled before
JOIN::prepare() is called during "PREPARE stmt FROM ...".
This commit is contained in:
Gagan Goel
2020-09-25 01:29:21 -04:00
parent 5646164a46
commit a1ea633a19
3 changed files with 51 additions and 2 deletions
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29
dbcon/mysql/ha_mcs.cpp
View File

@ -220,6 +220,20 @@ int ha_mcs::open(const char* name, int mode, uint32_t test_if_locked)
{
DBUG_ENTER("ha_mcs::open");
bool isPS = current_thd->stmt_arena &&
(current_thd->stmt_arena->is_stmt_prepare() ||
current_thd->stmt_arena->is_stmt_execute());
// MCOL-4282 See the description for discover_check_version() in ha_mcs.h
// for why we need to mutate optimizer flags here. Sequence of SQL
// statements that will lead to this execution path for prepared
// statements:
// CREATE TABLE t1 (a int, b int) engine=columnstore;
// PREPARE stmt1 FROM "SELECT * FROM t1";
// EXECUTE stmt1;
if (isPS)
mutate_optimizer_flags(current_thd);
int rc;
try
{
@ -234,6 +248,17 @@ int ha_mcs::open(const char* name, int mode, uint32_t test_if_locked)
DBUG_RETURN(rc);
}
int ha_mcs::discover_check_version()
{
bool isPS = current_thd->stmt_arena &&
(current_thd->stmt_arena->is_stmt_prepare() ||
current_thd->stmt_arena->is_stmt_execute());
if (isPS)
mutate_optimizer_flags(current_thd);
return 0;
}
/**
@brief
@ -1096,6 +1121,10 @@ int ha_mcs::reset()
condStack.clear();
}
// Restore the optimizer flags which were mutated earlier in
// ha_mcs::open/ha_mcs::discover_check_version
restore_optimizer_flags(current_thd);
DBUG_RETURN(0);
}

14
dbcon/mysql/ha_mcs.h
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@ -138,6 +138,20 @@ public:
*/
int open(const char* name, int mode, uint32_t test_if_locked); // required
// MCOL-4282 This function is called by open_tables in sql_base.cc.
// We mutate the optimizer flags here for prepared statements as this
// handler function is called before JOIN::prepare, and we need to
// disable the default optimizer flags before JOIN::prepare (which is
// called during "PREPARE stmt FROM ..." SQL) is called.
// Sequence of SQL statements that will lead to this execution path
// for prepared statements:
// CREATE TABLE t1 (a int, b int) engine=columnstore;
// INSERT INTO t1 VALUES (1, 2), (2, 4), (3, 1);
// PREPARE stmt1 FROM "SELECT * FROM t1";
// EXECUTE stmt1;
int discover_check_version() override;
/** @brief
We implement this in ha_example.cc; it's a required method.
*/

10
dbcon/mysql/ha_mcs_pushdown.cpp
View File

@ -47,10 +47,16 @@ void mutate_optimizer_flags(THD *thd_)
// MCOL-2178 Disable all optimizer flags as it was in the fork.
// CS restores it later in SH::scan_end() and in case of an error
// in SH::scan_init()
set_original_optimizer_flags(thd_->variables.optimizer_switch, thd_);
thd_->variables.optimizer_switch = OPTIMIZER_SWITCH_IN_TO_EXISTS |
ulonglong flags_to_set = OPTIMIZER_SWITCH_IN_TO_EXISTS |
OPTIMIZER_SWITCH_COND_PUSHDOWN_FOR_DERIVED |
OPTIMIZER_SWITCH_COND_PUSHDOWN_FROM_HAVING;
if (thd_->variables.optimizer_switch == flags_to_set)
return;
set_original_optimizer_flags(thd_->variables.optimizer_switch, thd_);
thd_->variables.optimizer_switch = flags_to_set;
}
void restore_optimizer_flags(THD *thd_)