mirror of https://gitee.com/bigwinds/arangodb
265 lines
12 KiB
C++
265 lines
12 KiB
C++
////////////////////////////////////////////////////////////////////////////////
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/// @brief rules for the query optimizer
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///
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/// @file arangod/Aql/OptimizerRules.h
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///
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/// DISCLAIMER
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///
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/// Copyright 2010-2014 triagens 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 triAGENS GmbH, Cologne, Germany
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///
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/// @author Max Neunhoeffer
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/// @author Copyright 2014, triagens GmbH, Cologne, Germany
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////////////////////////////////////////////////////////////////////////////////
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#ifndef ARANGOD_AQL_OPTIMIZER_RULES_H
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#define ARANGOD_AQL_OPTIMIZER_RULES 1
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#include <Basics/Common.h>
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#include "Aql/Optimizer.h"
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namespace triagens {
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namespace aql {
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// -----------------------------------------------------------------------------
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// --SECTION-- rules for the optimizer
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// -----------------------------------------------------------------------------
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove redundant sorts
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/// this rule modifies the plan in place:
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/// - sorts that are covered by earlier sorts will be removed
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////////////////////////////////////////////////////////////////////////////////
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int removeRedundantSortsRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove all unnecessary filters
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/// this rule modifies the plan in place:
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/// - filters that are always true are removed completely
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/// - filters that are always false will be replaced by a NoResults node
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////////////////////////////////////////////////////////////////////////////////
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int removeUnnecessaryFiltersRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief specialize the variables used in a COLLECT INTO
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////////////////////////////////////////////////////////////////////////////////
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int specializeCollectVariables (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove INTO of a COLLECT if not used
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////////////////////////////////////////////////////////////////////////////////
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int removeCollectIntoRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief propagate constant attributes in FILTERs
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////////////////////////////////////////////////////////////////////////////////
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int propagateConstantAttributesRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove SORT RAND() if appropriate
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////////////////////////////////////////////////////////////////////////////////
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int removeSortRandRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief move calculations up in the plan
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/// this rule modifies the plan in place
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/// it aims to move up calculations as far up in the plan as possible, to
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/// avoid redundant calculations in inner loops
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////////////////////////////////////////////////////////////////////////////////
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int moveCalculationsUpRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief move calculations down in the plan
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/// this rule modifies the plan in place
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/// it aims to move down calculations as far down in the plan as possible,
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/// beyond FILTER and LIMIT statements
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////////////////////////////////////////////////////////////////////////////////
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int moveCalculationsDownRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief fuse multiple calculations into a single one
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/// this rule modifies the plan in place
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////////////////////////////////////////////////////////////////////////////////
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int fuseCalculationsRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief determine the "right" type of AggregateNode and
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/// add a sort node for each COLLECT (may be removed later)
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/// this rule cannot be turned off (otherwise, the query result might be wrong!)
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////////////////////////////////////////////////////////////////////////////////
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int specializeCollectRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief split and-combined filters and break them into smaller parts
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////////////////////////////////////////////////////////////////////////////////
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int splitFiltersRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief move filters up in the plan
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/// this rule modifies the plan in place
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/// filters are moved as far up in the plan as possible to make result sets
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/// as small as possible as early as possible
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/// filters are not pushed beyond limits
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////////////////////////////////////////////////////////////////////////////////
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int moveFiltersUpRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove redundant CalculationNodes
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////////////////////////////////////////////////////////////////////////////////
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int removeRedundantCalculationsRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove CalculationNodes and SubqueryNodes that are never needed
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////////////////////////////////////////////////////////////////////////////////
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int removeUnnecessaryCalculationsRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief prefer IndexRange nodes over EnumerateCollection nodes
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////////////////////////////////////////////////////////////////////////////////
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int useIndexRangeRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief try to use the index for sorting
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////////////////////////////////////////////////////////////////////////////////
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int useIndexForSortRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief try to remove filters which are covered by indexes
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////////////////////////////////////////////////////////////////////////////////
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int removeFiltersCoveredByIndexRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief interchange adjacent EnumerateCollectionNodes in all possible ways
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////////////////////////////////////////////////////////////////////////////////
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int interchangeAdjacentEnumerationsRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief scatter operations in cluster - send all incoming rows to all remote
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/// clients
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////////////////////////////////////////////////////////////////////////////////
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int scatterInClusterRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief distribute operations in cluster - send each incoming row to every
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/// remote client precisely once. This happens in queries like:
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///
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/// FOR x IN coll1 [SOME FILTER/CALCULATION STATEMENTS] REMOVE f(x) in coll2
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///
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/// where coll2 is sharded by _key, but not if it is sharded by anything else.
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/// The collections coll1 and coll2 do not have to be distinct for this.
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////////////////////////////////////////////////////////////////////////////////
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int distributeInClusterRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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int distributeFilternCalcToClusterRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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int distributeSortToClusterRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief try to get rid of a RemoteNode->ScatterNode combination which has
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/// only a SingletonNode and possibly some CalculationNodes as dependencies
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////////////////////////////////////////////////////////////////////////////////
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int removeUnnecessaryRemoteScatterRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief this rule removes Remote-Gather-Scatter/Distribute-Remote nodes from
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/// plans arising from queries of the form:
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///
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/// FOR x IN coll [SOME FILTER/CALCULATION STATEMENTS] REMOVE x IN coll
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///
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/// when coll is any collection sharded by any attributes, and
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///
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/// FOR x IN coll [SOME FILTER/CALCULATION STATEMENTS] REMOVE x._key IN coll
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///
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/// when the coll is sharded by _key.
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///
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/// This rule dues not work for queries like:
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///
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/// FOR x IN coll [SOME FILTER/CALCULATION STATEMENTS] REMOVE y IN coll
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///
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/// [different variable names], or
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///
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/// FOR x IN coll1 [SOME FILTER/CALCULATION STATEMENTS] REMOVE x in coll2
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///
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/// when coll1 and coll2 are not the same, or
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///
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/// FOR x IN coll [SOME FILTER/CALCULATION STATEMENTS] REMOVE f(x) in coll
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///
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/// where f is some function.
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///
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////////////////////////////////////////////////////////////////////////////////
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int undistributeRemoveAfterEnumCollRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief this rule replaces expressions of the type:
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/// x.val == 1 || x.val == 2 || x.val == 3
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// with
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// x.val IN [1,2,3]
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// when the OR conditions are present in the same FILTER node, and refer to the
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// same (single) attribute.
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////////////////////////////////////////////////////////////////////////////////
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int replaceOrWithInRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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int removeRedundantOrRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief remove $OLD and $NEW variables from data-modification statements
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/// if not required
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////////////////////////////////////////////////////////////////////////////////
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int removeDataModificationOutVariablesRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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////////////////////////////////////////////////////////////////////////////////
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/// @brief patch UPDATE statement on single collection that iterates over the
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/// entire collection to operate in batches
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////////////////////////////////////////////////////////////////////////////////
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int patchUpdateStatementsRule (Optimizer*, ExecutionPlan*, Optimizer::Rule const*);
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} // namespace aql
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} // namespace triagens
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#endif
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// Local Variables:
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// mode: outline-minor
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// outline-regexp: "^\\(/// @brief\\|/// {@inheritDoc}\\|/// @addtogroup\\|// --SECTION--\\|/// @\\}\\)"
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// End:
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