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- Committer: Jay Pipes
- Date: 2009-08-20 18:28:11 UTC
- mfrom: (1108.6.52 optimizer)
- mto: This revision was merged to the branch mainline in revision 1120.
- Revision ID: jpipes@serialcoder-20090820182811-akpzlv3042dyyui7
Merge Padraig's optimizer refactoring around pulling structs into real classes...
- files added:
- drizzled/optimizer
- files modified:
- drizzled/Makefile.am
added
removed
drizzled/optimizer/key_field.h
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/* -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
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* vim:expandtab:shiftwidth=2:tabstop=2:smarttab:
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*
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* Copyright (C) 2009 Sun Microsystems
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef DRIZZLED_OPTIMIZER_KEY_FIELD_H
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#define DRIZZLED_OPTIMIZER_KEY_FIELD_H
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#include <drizzled/server_includes.h>
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#include <drizzled/sql_select.h>
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#include <vector>
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namespace drizzled
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{
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namespace optimizer
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{
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/**
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* Class used when finding key fields
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*/
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class KeyField
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{
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public:
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KeyField()
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:
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field(NULL),
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val(NULL),
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level(0),
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optimize(0),
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eq_func(false),
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null_rejecting(false),
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cond_guard(NULL)
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{}
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Field *field;
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Item *val; /**< May be empty if diff constant */
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uint32_t level;
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uint32_t optimize; /**< KEY_OPTIMIZE_* */
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bool eq_func;
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/**
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If true, the condition this class represents will not be satisfied
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when val IS NULL.
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*/
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bool null_rejecting;
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bool *cond_guard; /**< @see KeyUse::cond_guard */
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};
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void add_key_fields(JOIN *join,
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KeyField **key_fields,
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uint32_t *and_level,
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COND *cond,
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table_map usable_tables,
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std::vector<SargableParam> &sargables);
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void add_key_part(DYNAMIC_ARRAY *keyuse_array, KeyField *key_field);
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/**
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* Add to KeyField array all 'ref' access candidates within nested join.
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*
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* This function populates KeyField array with entries generated from the
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* ON condition of the given nested join, and does the same for nested joins
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* contained within this nested join.
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*
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* @param[in] nested_join_table Nested join pseudo-table to process
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* @param[in,out] end End of the key field array
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* @param[in,out] and_level And-level
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* @param[in,out] sargables std::vector of found sargable candidates
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*
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*
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* @note
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* We can add accesses to the tables that are direct children of this nested
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* join (1), and are not inner tables w.r.t their neighbours (2).
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*
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* Example for #1 (outer brackets pair denotes nested join this function is
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* invoked for):
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* @code
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* ... LEFT JOIN (t1 LEFT JOIN (t2 ... ) ) ON cond
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* @endcode
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* Example for #2:
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* @code
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* ... LEFT JOIN (t1 LEFT JOIN t2 ) ON cond
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* @endcode
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* In examples 1-2 for condition cond, we can add 'ref' access candidates to
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* t1 only.
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* Example #3:
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* @code
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* ... LEFT JOIN (t1, t2 LEFT JOIN t3 ON inner_cond) ON cond
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* @endcode
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* Here we can add 'ref' access candidates for t1 and t2, but not for t3.
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*/
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void add_key_fields_for_nj(JOIN *join,
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TableList *nested_join_table,
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KeyField **end,
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uint32_t *and_level,
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std::vector<SargableParam> &sargables);
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/**
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* Merge new key definitions to old ones, remove those not used in both.
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*
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* This is called for OR between different levels.
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*
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* To be able to do 'ref_or_null' we merge a comparison of a column
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* and 'column IS NULL' to one test. This is useful for sub select queries
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* that are internally transformed to something like:.
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*
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* @code
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* SELECT * FROM t1 WHERE t1.key=outer_ref_field or t1.key IS NULL
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* @endcode
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*
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* KeyField::null_rejecting is processed as follows: @n
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* result has null_rejecting=true if it is set for both ORed references.
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* for example:
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* - (t2.key = t1.field OR t2.key = t1.field) -> null_rejecting=true
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* - (t2.key = t1.field OR t2.key <=> t1.field) -> null_rejecting=false
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*
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* @todo
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* The result of this is that we're missing some 'ref' accesses.
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* OptimizerTeam: Fix this
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*/
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KeyField *merge_key_fields(KeyField *start,
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KeyField *new_fields,
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KeyField *end,
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uint32_t and_level);
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/**
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* Add a possible key to array of possible keys if it's usable as a key
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*
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* @param key_fields Pointer to add key, if usable
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* @param and_level And level, to be stored in KeyField
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* @param cond Condition predicate
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* @param field Field used in comparision
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* @param eq_func True if we used =, <=> or IS NULL
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* @param value Value used for comparison with field
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* @param usable_tables Tables which can be used for key optimization
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* @param sargables IN/OUT std::vector of found sargable candidates
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*
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* @note
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* If we are doing a NOT NULL comparison on a NOT NULL field in a outer join
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* table, we store this to be able to do not exists optimization later.
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*
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* @returns
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* *key_fields is incremented if we stored a key in the array
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*/
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void add_key_field(KeyField **key_fields,
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uint32_t and_level,
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Item_func *cond,
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Field *field,
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bool eq_func,
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Item **value,
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uint32_t num_values,
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table_map usable_tables,
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std::vector<SargableParam> &sargables);
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/**
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* Add possible keys to array of possible keys originated from a simple
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* predicate.
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*
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* @param key_fields Pointer to add key, if usable
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* @param and_level And level, to be stored in KeyField
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* @param cond Condition predicate
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* @param field Field used in comparision
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* @param eq_func True if we used =, <=> or IS NULL
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* @param value Value used for comparison with field
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* Is NULL for BETWEEN and IN
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* @param usable_tables Tables which can be used for key optimization
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* @param sargables IN/OUT std::vector of found sargable candidates
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*
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* @note
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* If field items f1 and f2 belong to the same multiple equality and
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* a key is added for f1, the the same key is added for f2.
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*
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* @returns
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* *key_fields is incremented if we stored a key in the array
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*/
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void add_key_equal_fields(KeyField **key_fields,
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uint32_t and_level,
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Item_func *cond,
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Item_field *field_item,
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bool eq_func,
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Item **val,
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uint32_t num_values,
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table_map usable_tables,
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std::vector<SargableParam> &sargables);
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} /* end namespace optimizer */
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} /* end namespace drizzled */
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#endif /* DRIZZLED_OPTIMIZER_KEY_FIELD_H */
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