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#include <Interpreters/AddIndexConstraintsOptimizer.h>
#include <Interpreters/TreeCNFConverter.h>
#include <Parsers/IAST_fwd.h>
#include <Parsers/ASTIdentifier.h>
#include <Parsers/ASTFunction.h>
#include <Parsers/ASTConstraintDeclaration.h>
#include <Storages/StorageInMemoryMetadata.h>
#include <Parsers/ASTSelectQuery.h>
namespace DB
{
AddIndexConstraintsOptimizer::AddIndexConstraintsOptimizer(
const StorageMetadataPtr & metadata_snapshot_)
: metadata_snapshot(metadata_snapshot_)
{
}
namespace
{
bool onlyIndexColumns(const ASTPtr & ast, const std::unordered_set<std::string_view> & primary_key_set)
{
const auto * identifier = ast->as<ASTIdentifier>();
if (identifier && !primary_key_set.contains(identifier->name()))
return false;
for (auto & child : ast->children)
if (!onlyIndexColumns(child, primary_key_set))
return false;
return true;
}
bool onlyConstants(const ASTPtr & ast)
{
const auto * identifier = ast->as<ASTIdentifier>();
if (identifier)
return false;
for (auto & child : ast->children)
if (!onlyConstants(child))
return false;
return true;
}
const std::unordered_map<std::string, ComparisonGraphCompareResult> & getRelationMap()
{
const static std::unordered_map<std::string, ComparisonGraphCompareResult> relations =
{
{"equals", ComparisonGraphCompareResult::EQUAL},
{"less", ComparisonGraphCompareResult::LESS},
{"lessOrEquals", ComparisonGraphCompareResult::LESS_OR_EQUAL},
{"greaterOrEquals", ComparisonGraphCompareResult::GREATER_OR_EQUAL},
{"greater", ComparisonGraphCompareResult::GREATER},
};
return relations;
}
const std::unordered_map<ComparisonGraphCompareResult, std::string> & getReverseRelationMap()
{
const static std::unordered_map<ComparisonGraphCompareResult, std::string> relations =
{
{ComparisonGraphCompareResult::EQUAL, "equals"},
{ComparisonGraphCompareResult::LESS, "less"},
{ComparisonGraphCompareResult::LESS_OR_EQUAL, "lessOrEquals"},
{ComparisonGraphCompareResult::GREATER_OR_EQUAL, "greaterOrEquals"},
{ComparisonGraphCompareResult::GREATER, "greater"},
};
return relations;
}
bool canBeSequence(const ComparisonGraphCompareResult left, const ComparisonGraphCompareResult right)
{
using CR = ComparisonGraphCompareResult;
if (left == CR::UNKNOWN || right == CR::UNKNOWN || left == CR::NOT_EQUAL || right == CR::NOT_EQUAL)
return false;
if ((left == CR::GREATER || left == CR::GREATER_OR_EQUAL) && (right == CR::LESS || right == CR::LESS_OR_EQUAL))
return false;
if ((right == CR::GREATER || right == CR::GREATER_OR_EQUAL) && (left == CR::LESS || left == CR::LESS_OR_EQUAL))
return false;
return true;
}
ComparisonGraphCompareResult mostStrict(const ComparisonGraphCompareResult left, const ComparisonGraphCompareResult right)
{
using CR = ComparisonGraphCompareResult;
if (left == CR::LESS || left == CR::GREATER)
return left;
if (right == CR::LESS || right == CR::GREATER)
return right;
if (left == CR::LESS_OR_EQUAL || left == CR::GREATER_OR_EQUAL)
return left;
if (right == CR::LESS_OR_EQUAL || right == CR::GREATER_OR_EQUAL)
return right;
if (left == CR::EQUAL)
return left;
if (right == CR::EQUAL)
return right;
return CR::UNKNOWN;
}
/// Create OR-group for 'indexHint'.
/// Consider we have expression like A <op1> C, where C is constant.
/// Consider we have a constraint I <op2> A, where I depends only on columns from primary key.
/// Then if op1 and op2 forms a sequence of comparisons (e.g. A < C and I < A),
/// we can add to expression 'indexHint(I < A)' condition.
CNFQuery::OrGroup createIndexHintGroup(
const CNFQuery::OrGroup & group,
const ComparisonGraph<ASTPtr> & graph,
const ASTs & primary_key_only_asts)
{
CNFQuery::OrGroup result;
for (const auto & atom : group)
{
const auto * func = atom.ast->as<ASTFunction>();
if (func && func->arguments->children.size() == 2 && getRelationMap().contains(func->name))
{
auto check_and_insert = [&](const size_t index, const ComparisonGraphCompareResult need_result)
{
if (!onlyConstants(func->arguments->children[1 - index]))
return false;
for (const auto & primary_key_ast : primary_key_only_asts)
{
ComparisonGraphCompareResult actual_result;
if (index == 0)
actual_result = graph.compare(primary_key_ast, func->arguments->children[index]);
else
actual_result = graph.compare(func->arguments->children[index], primary_key_ast);
if (canBeSequence(need_result, actual_result))
{
ASTPtr helper_ast = func->clone();
auto * helper_func = helper_ast->as<ASTFunction>();
helper_func->name = getReverseRelationMap().at(mostStrict(need_result, actual_result));
helper_func->arguments->children[index] = primary_key_ast->clone();
result.insert(CNFQuery::AtomicFormula{atom.negative, helper_ast});
return true;
}
}
return false;
};
auto expected = getRelationMap().at(func->name);
if (!check_and_insert(0, expected) && !check_and_insert(1, expected))
return {};
}
}
return result;
}
}
void AddIndexConstraintsOptimizer::perform(CNFQuery & cnf_query)
{
const auto primary_key = metadata_snapshot->getColumnsRequiredForPrimaryKey();
const auto & graph = metadata_snapshot->getConstraints().getGraph();
const std::unordered_set<std::string_view> primary_key_set(std::begin(primary_key), std::end(primary_key));
ASTs primary_key_only_asts;
for (const auto & vertex : graph.getVertices())
for (const auto & ast : vertex)
if (onlyIndexColumns(ast, primary_key_set))
primary_key_only_asts.push_back(ast);
CNFQuery::AndGroup and_group;
cnf_query.iterateGroups([&](const auto & or_group)
{
auto add_group = createIndexHintGroup(or_group, graph, primary_key_only_asts);
if (!add_group.empty())
and_group.emplace(std::move(add_group));
});
if (!and_group.empty())
{
CNFQuery::OrGroup new_or_group;
new_or_group.insert(CNFQuery::AtomicFormula{false, makeASTFunction("indexHint", TreeCNFConverter::fromCNF(CNFQuery(std::move(and_group))))});
cnf_query.appendGroup(CNFQuery::AndGroup{new_or_group});
}
}
}
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