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[CP] Fix issues related to user variables.

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This commit is contained in:
leslieyuchen
2023-11-15 07:40:18 +00:00
committed by ob-robot
parent a0695bb5e8
commit bcc15937ee
6 changed files with 87 additions and 27 deletions
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37
src/sql/code_generator/ob_static_engine_cg.cpp
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@ -7000,9 +7000,40 @@ int ObStaticEngineCG::set_other_properties(const ObLogPlan &log_plan, ObPhysical
}
if (OB_SUCC(ret) && !log_plan.get_stmt()->is_explain_stmt()) {
if (OB_FAIL(generate_rt_exprs(log_plan.get_stmt()->get_query_ctx()->var_init_exprs_,
phy_plan.var_init_exprs_))) {
LOG_WARN("generate var init exprs failed", KR(ret));
const ObIArray<ObRawExpr*> &var_init_exprs = log_plan.get_stmt()->get_query_ctx()->var_init_exprs_;
phy_plan.var_init_exprs_.set_capacity(var_init_exprs.count());
for (int i = 0; OB_SUCC(ret) && i < var_init_exprs.count(); ++i) {
const ObRawExpr *var_init_expr = var_init_exprs.at(i);
LOG_DEBUG("start to generate var init expr", KPC(var_init_expr));
/**
* What is a user variable initialization expression?
* In MySQL, the user variable assignment clause in SELECT FROM DUAL statement will always be
* executed before the statement is executed.
* However, in OceanBase, such clauses may not be executed due to short-circuit operation in the execution path,
* leading to uninitialized user variables.
* For example: SELECT * FROM t1, (SELECT @rownum:=0) AS init;
* In this statement, if t1 is an empty table, MySQL will still execute SELECT @rownum:=0,
* while OB will not.
* To accommodate this behavior,
* we collect the expressions that appear in SELECT FROM DUAL and can be executed independently,
* and execute them once as the initialization operation for user variables before the plan is executed.
**/
if (!var_init_expr->has_flag(CNT_SUB_QUERY) &&
!var_init_expr->has_flag(CNT_AGG) &&
!var_init_expr->has_flag(CNT_WINDOW_FUNC) &&
!var_init_expr->has_flag(CNT_ONETIME) &&
!var_init_expr->has_flag(CNT_ALIAS) &&
!var_init_expr->has_flag(CNT_DYNAMIC_PARAM) &&
!ObOptimizerUtil::has_psedu_column(*var_init_expr) &&
!ObOptimizerUtil::has_hierarchical_expr(*var_init_expr) &&
var_init_expr->get_relation_ids().is_empty()) {
ObExpr *var_rt_expr = nullptr;
if (OB_FAIL(generate_rt_expr(*var_init_expr, var_rt_expr))) {
LOG_WARN("generate var init expr failed", KR(ret), KPC(var_init_expr));
} else if (OB_FAIL(phy_plan.var_init_exprs_.push_back(var_rt_expr))) {
LOG_WARN("store var rt expr failed", KR(ret));
}
}
}
}