mirror of https://gitee.com/bigwinds/arangodb
102 lines
4.7 KiB
C++
102 lines
4.7 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// DISCLAIMER
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///
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/// Copyright 2018 ArangoDB GmbH, Cologne, Germany
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///
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/// Licensed under the Apache License, Version 2.0 (the "License");
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/// you may not use this file except in compliance with the License.
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/// You may obtain a copy of the License at
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///
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/// http://www.apache.org/licenses/LICENSE-2.0
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///
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/// Unless required by applicable law or agreed to in writing, software
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/// distributed under the License is distributed on an "AS IS" BASIS,
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/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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/// See the License for the specific language governing permissions and
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/// limitations under the License.
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///
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/// Copyright holder is ArangoDB GmbH, Cologne, Germany
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///
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/// @author Jan Steemann
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_INDEXES_SORTED_INDEX_ATTRIBUTE_MATCHER_H
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#define ARANGOD_INDEXES_SORTED_INDEX_ATTRIBUTE_MATCHER_H 1
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#include "Basics/Common.h"
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#include "Containers/HashSet.h"
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#include "Indexes/Index.h"
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namespace arangodb {
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namespace aql {
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class Ast;
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struct AstNode;
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class SortCondition;
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struct Variable;
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} // namespace aql
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class Index;
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namespace SortedIndexAttributeMatcher {
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Index::FilterCosts supportsFilterCondition(std::vector<std::shared_ptr<arangodb::Index>> const& allIndexes,
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arangodb::Index const* index,
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arangodb::aql::AstNode const* node,
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arangodb::aql::Variable const* reference,
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size_t itemsInIndex);
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Index::SortCosts supportsSortCondition(arangodb::Index const* index,
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arangodb::aql::SortCondition const* sortCondition,
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arangodb::aql::Variable const* reference,
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size_t itemsInIndex);
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/// @brief specializes the condition for use with the index
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arangodb::aql::AstNode* specializeCondition(arangodb::Index const* index,
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arangodb::aql::AstNode* node,
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arangodb::aql::Variable const* reference);
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/// @brief matches which index attributes of index are supported by the filter
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/// condition represented by the passed-in AST node.
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/// For example, if the query is
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///
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/// FOR doc IN <collection-with-index>
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/// FILTER doc.value1 == 2 && doc.value2 == 3
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///
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/// then "reference" will point to the variable "doc" (this is the variable we are
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/// looking for inside the filter condition(s). The filter condition will be an n-ary
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/// AND consisting of the two sub-conditions "doc.value1 == 2" && "doc.value2 == 3".
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/// the function will walk through all subconditions and will put the index attribute
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/// that is used by the subcondition into the outvariable "found".
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/// if a subcondition is not covered by the index, it will increase the counter
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/// "postFilterConditions", so the caller can see how many subconditions need to be
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/// handled afterwards even when using the index. this is useful when comparing different
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/// indexes, and to estimate the amount of post-filtering work left when picking a
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/// particular index.
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/// "values" is a counter variable and is increased by one for every equality condition,
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/// and increased by the number of IN values for IN lookups. the counter is used to
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/// estimate the number of items coming out of the index later.
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/// while walking over the subconditions, the function will also populate "nonNullAttributes"
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/// if it can prove a specific attribute for the search variable (e.g. "doc") cannot become
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/// null. this can be useful later when looking at sparse indexes.
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void matchAttributes(arangodb::Index const* index, arangodb::aql::AstNode const* node,
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arangodb::aql::Variable const* reference,
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std::unordered_map<size_t, std::vector<arangodb::aql::AstNode const*>>& found,
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size_t& postFilterConditions, size_t& values,
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std::unordered_set<std::string>& nonNullAttributes, bool isExecution);
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/// @brief whether or not the access fits
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bool accessFitsIndex(
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arangodb::Index const* idx, arangodb::aql::AstNode const* access,
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arangodb::aql::AstNode const* other, arangodb::aql::AstNode const* op,
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arangodb::aql::Variable const* reference,
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std::unordered_map<size_t, std::vector<arangodb::aql::AstNode const*>>& found,
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std::unordered_set<std::string>& nonNullAttributes, bool isExecution);
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bool isDuplicateOperator(arangodb::aql::AstNode const* node,
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::arangodb::containers::HashSet<int> const& operatorsFound);
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}; // namespace SortedIndexAttributeMatcher
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} // namespace arangodb
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#endif
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