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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/field_ref.h"
#include "mongo/db/index/multikey_paths.h"
#include "mongo/db/query/index_bounds_builder.h"
#include "mongo/db/query/index_entry.h"
#include "mongo/db/query/interval_evaluation_tree.h"
#include "mongo/db/query/query_solution.h"
namespace mongo {
namespace wildcard_planning {
using BoundsTightness = IndexBoundsBuilder::BoundsTightness;
/**
* Specifies the maximum depth of nested array indices through which a query may traverse before a
* $** index declines to answer it, due to the exponential complexity of the bounds required.
*/
static constexpr size_t kWildcardMaxArrayIndexTraversalDepth = 8u;
/**
* Given a single wildcard index, and a set of fields which are being queried, create a 'mock'
* IndexEntry for each of the query fields and add them into the provided vector.
*/
void expandWildcardIndexEntry(const IndexEntry& wildcardIndex,
const stdx::unordered_set<std::string>& fields,
std::vector<IndexEntry>* out);
/**
* Determines if any of the expanded index entries in the input 'ixscanNodes' can satisfy a query on
* a wildcard field with a FETCH (for e.g., it may only be able to answer a query on the prefix if
* the wildcard field is being queried with an incompatible $not predicate).
*/
bool canOnlyAnswerWildcardPrefixQuery(
const std::vector<std::unique_ptr<QuerySolutionNode>>& ixscanNodes);
/**
* In certain circumstances, it is necessary to adjust the bounds and tightness generated by the
* planner for $** indexes. For instance, if the query traverses through one or more arrays via
* specific indices, then we must enforce INEXACT_FETCH to ensure correctness, regardless of the
* predicate. Given an IndexEntry representing an expanded $** index, we apply any necessary
* changes to the bounds, tightness, and interval evaluation tree here.
*/
BoundsTightness translateWildcardIndexBoundsAndTightness(
const IndexEntry& index,
BoundsTightness tightnessIn,
OrderedIntervalList* oil,
interval_evaluation_tree::Builder* ietBuilder);
/**
* During planning, the expanded $** IndexEntry's keyPattern and bounds are in the format with
* expanded field path, like {..., 'path': 1, ...}. Once planning is complete, it is necessary to
* call this method in order to prepare the IndexEntry and bounds for execution. This function
* performs the following actions:
* - Converts the keyPattern to the {..., $_path: 1, "path": 1, ...} format expected by the $**
* index.
* - Adds a new entry '$_path' to the bounds vector, and computes the necessary intervals on it.
* - Adds a new, empty entry to 'multikeyPaths' for '$_path'.
* - Updates shouldDedup for index scan node.
*/
void finalizeWildcardIndexScanConfiguration(
IndexScanNode* scan, std::vector<interval_evaluation_tree::Builder>* ietBuilders);
/**
* Returns true if the given IndexScanNode is a $** scan whose bounds overlap the object type
* bracket. Scans whose bounds include the object bracket have certain limitations for planning
* purposes; for instance, they cannot provide covered results or be converted to DISTINCT_SCAN.
*/
bool isWildcardObjectSubpathScan(const IndexScanNode* node);
/**
* It's not obvious which element is the wildcard element in a compound wildcard index key pattern.
* This helper can give you the wildcard element based on the position tracked in 'IndexEntry'.
* 'index' must be a WILDCARD index.
*/
BSONElement getWildcardField(const IndexEntry& index);
} // namespace wildcard_planning
} // namespace mongo
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