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rewrite support alias

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This commit is contained in:
JackyWoo 2023-07-07 17:03:37 +08:00
parent 0dc1fdd67f
commit ca6905b308
2 changed files with 71 additions and 28 deletions
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2
src/Core/Settings.h
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@ -774,7 +774,7 @@ class IColumn;
M(Bool, keeper_map_strict_mode, false, "Enforce additional checks during operations on KeeperMap. E.g. throw an exception on an insert for already existing key", 0) \
M(UInt64, extract_kvp_max_pairs_per_row, 1000, "Max number pairs that can be produced by extractKeyValuePairs function. Used to safeguard against consuming too much memory.", 0) \
M(Timezone, session_timezone, "", "The default timezone for current session or query. The server default timezone if empty.", 0) \
M(Bool, optimize_uniq_to_count, false, "Rewrite uniq and other variants(except uniqUpTo) to distinct to to count, it is a RBO based optimization.", 0)
M(Bool, optimize_uniq_to_count, false, "Rewrite uniq and its variants(except uniqUpTo) to count if subquery has distinct or group by clause, it is a RBO based optimization.", 0)
// End of COMMON_SETTINGS
// Please add settings related to formats into the FORMAT_FACTORY_SETTINGS and move obsolete settings to OBSOLETE_SETTINGS.

97
src/Interpreters/RewriteUniqToCountVisitor.cpp
View File

@ -14,16 +14,49 @@
namespace DB
{
using Aliases = std::unordered_map<String, ASTPtr>;
namespace
{
bool matchFnUniq(String func_name)
{
auto name = Poco::toLower(func_name);
return name == "uniq" || name == "uniqHLL12" || name == "uniqExact" || name == "uniqTheta" || name == "uniqCombined" || name == "uniqCombined64";
return name == "uniq" || name == "uniqHLL12" || name == "uniqExact" || name == "uniqTheta" || name == "uniqCombined"
|| name == "uniqCombined64";
}
bool expressionListEquals(ASTExpressionList * lhs, ASTExpressionList * rhs)
bool expressionEquals(const ASTPtr & lhs, const ASTPtr & rhs, Aliases & alias)
{
if (lhs->getTreeHash() == rhs->getTreeHash())
{
return true;
}
else
{
auto * lhs_idf = lhs->as<ASTIdentifier>();
auto * rhs_idf = rhs->as<ASTIdentifier>();
if (lhs_idf && rhs_idf)
{
/// compound identifiers, such as: <t.name, name>
if (lhs_idf->shortName() == rhs_idf->shortName())
return true;
/// translate alias
if (alias.find(lhs_idf->shortName()) != alias.end())
lhs_idf = alias.find(lhs_idf->shortName())->second->as<ASTIdentifier>();
if (alias.find(rhs_idf->shortName()) != alias.end())
rhs_idf = alias.find(rhs_idf->shortName())->second->as<ASTIdentifier>();
if (lhs_idf->shortName() == rhs_idf->shortName())
return true;
}
}
return false;
}
bool expressionListEquals(ASTExpressionList * lhs, ASTExpressionList * rhs, Aliases & alias)
{
if (!lhs || !rhs)
return false;
@ -31,27 +64,23 @@ bool expressionListEquals(ASTExpressionList * lhs, ASTExpressionList * rhs)
return false;
for (size_t i = 0; i < lhs->children.size(); i++)
{
if (lhs->children[i]->formatForLogging() != rhs->children[i]->formatForLogging()) // TODO not a elegant way
if (!expressionEquals(lhs->children[i], rhs->children[i], alias))
return false;
}
return true;
}
/// Test whether lhs contains all expr in rhs.
bool expressionListContainsAll(ASTExpressionList * lhs, ASTExpressionList * rhs)
/// Test whether lhs contains all expressions in rhs.
bool expressionListContainsAll(ASTExpressionList * lhs, ASTExpressionList * rhs, Aliases alias)
{
if (!lhs || !rhs)
return false;
if (lhs->children.size() < rhs->children.size())
return false;
std::vector<String> lhs_strs;
for (const auto & le : lhs->children)
{
lhs_strs.emplace_back(le->formatForLogging());
}
for (const auto & re : rhs->children)
{
if (std::find(lhs_strs.begin(), lhs_strs.end(), re->formatForLogging()) != lhs_strs.end())
auto predicate = [&re, &alias](ASTPtr & le) { return expressionEquals(le, re, alias); };
if (std::find_if(lhs->children.begin(), lhs->children.end(), predicate) == lhs->children.end())
return false;
}
return true;
@ -72,46 +101,60 @@ void RewriteUniqToCountMatcher::visit(ASTPtr & ast, Data & /*data*/)
return;
if (selectq->tables()->as<ASTTablesInSelectQuery>()->children[0]->as<ASTTablesInSelectQueryElement>()->children.size() != 1)
return;
auto * table_expr = selectq->tables()->as<ASTTablesInSelectQuery>()->children[0]->as<ASTTablesInSelectQueryElement>()->children[0]->as<ASTTableExpression>();
auto * table_expr = selectq->tables()
->as<ASTTablesInSelectQuery>()
->children[0]
->as<ASTTablesInSelectQueryElement>()
->children[0]
->as<ASTTableExpression>();
if (!table_expr || table_expr->children.size() != 1 || !table_expr->subquery)
return;
auto * subquery = table_expr->subquery->as<ASTSubquery>();
if (!subquery)
return;
auto * sub_selectq = subquery->children[0]->as<ASTSelectWithUnionQuery>()->children[0]->as<ASTExpressionList>()->children[0]->as<ASTSelectQuery>();
auto * sub_selectq = subquery->children[0]
->as<ASTSelectWithUnionQuery>()->children[0]
->as<ASTExpressionList>()->children[0]
->as<ASTSelectQuery>();
if (!sub_selectq)
return;
auto sub_expr_list = sub_selectq->select();
if (!sub_expr_list)
return;
auto match_distinct = [&]() -> bool
/// collect subquery select expressions alias
std::unordered_map<String, ASTPtr> alias;
for (auto expr : sub_expr_list->children)
{
if (!expr->tryGetAlias().empty())
alias.insert({expr->tryGetAlias(), expr});
}
auto match_subquery_with_distinct = [&]() -> bool
{
if (!sub_selectq->distinct)
return false;
auto sub_expr_list = sub_selectq->select();
if (!sub_expr_list)
return false;
/// uniq expression list == subquery group by expression list
if (!expressionListEquals(func->children[0]->as<ASTExpressionList>(), sub_expr_list->as<ASTExpressionList>()))
if (!expressionListEquals(func->children[0]->as<ASTExpressionList>(), sub_expr_list->as<ASTExpressionList>(), alias))
return false;
return true;
};
auto match_group_by = [&]() -> bool
auto match_subquery_with_group_by = [&]() -> bool
{
auto group_by = sub_selectq->groupBy();
auto group_by = sub_selectq->groupBy(); // TODO group by type
if (!group_by)
return false;
auto sub_expr_list = sub_selectq->select();
if (!sub_expr_list)
return false;
/// uniq expression list == subquery group by expression list
if (!expressionListEquals(func->children[0]->as<ASTExpressionList>(), group_by->as<ASTExpressionList>()))
/// uniq expression list == subquery group by expression list
if (!expressionListEquals(func->children[0]->as<ASTExpressionList>(), group_by->as<ASTExpressionList>(), alias))
return false;
/// subquery select expression list must contain all columns in uniq expression list
expressionListContainsAll(sub_expr_list->as<ASTExpressionList>(), func->children[0]->as<ASTExpressionList>());
if (!expressionListContainsAll(sub_expr_list->as<ASTExpressionList>(), func->children[0]->as<ASTExpressionList>(), alias))
return false;
return true;
};
if (match_distinct() || match_group_by())
if (match_subquery_with_distinct() || match_subquery_with_group_by())
expr_list->children[0] = makeASTFunction("count");
}