MySQL 8.1.0
Source Code Documentation

#include "sql/range_optimizer/tree.h"
#include <algorithm>
#include <set>
#include <utility>
#include "m_string.h"
#include "memory_debugging.h"
#include "my_dbug.h"
#include "my_sqlcommand.h"
#include "mysql/components/services/log_builtins.h"
#include "mysql/strings/m_ctype.h"
#include "mysqld_error.h"
#include "sql/handler.h"
#include "sql/key.h"
#include "sql/key_spec.h"
#include "sql/range_optimizer/internal.h"
#include "sql/range_optimizer/range_opt_param.h"
#include "sql/range_optimizer/range_optimizer.h"
#include "sql/sql_class.h"
#include "sql/sql_lex.h"
#include "sql/system_variables.h"
#include "sql/table.h"
#include "sql_string.h"
Namespaces  
namespace  anonymous_namespace{tree.cc} 
Functions  
SEL_TREE *  tree_and (RANGE_OPT_PARAM *param, SEL_TREE *tree1, SEL_TREE *tree2) 
SEL_TREE *  tree_or (RANGE_OPT_PARAM *param, bool remove_jump_scans, SEL_TREE *tree1, SEL_TREE *tree2) 
SEL_ROOT *  key_or (RANGE_OPT_PARAM *param, SEL_ROOT *key1, SEL_ROOT *key2) 
Combine two range expression under a common OR. More...  
SEL_ROOT *  key_and (RANGE_OPT_PARAM *param, SEL_ROOT *key1, SEL_ROOT *key2) 
SEL_ARG *  rb_delete_fixup (SEL_ARG *root, SEL_ARG *key, SEL_ARG *par) 
int  test_rb_tree (SEL_ARG *element, SEL_ARG *parent) 
static bool  eq_tree (const SEL_ROOT *a, const SEL_ROOT *b) 
Compare if two trees are equal, recursively (not necessarily the same elements, but in terms of structure and values in each leaf). More...  
static bool  eq_tree (const SEL_ARG *a, const SEL_ARG *b) 
static bool  get_range (SEL_ARG **e1, SEL_ARG **e2, const SEL_ROOT *root1) 
static bool  all_same (const SEL_ROOT *sa1, const SEL_ROOT *sa2) 
Helper function to compare two SEL_ROOTs. More...  
void  imerge_list_and_list (List< SEL_IMERGE > *im1, List< SEL_IMERGE > *im2) 
static int  imerge_list_or_list (RANGE_OPT_PARAM *param, bool remove_jump_scans, List< SEL_IMERGE > *im1, List< SEL_IMERGE > *im2) 
static bool  imerge_list_or_tree (RANGE_OPT_PARAM *param, bool remove_jump_scans, List< SEL_IMERGE > *im1, SEL_TREE *tree) 
int  sel_cmp (Field *field, uchar *a, uchar *b, uint8 a_flag, uint8 b_flag) 
size_t  anonymous_namespace{tree.cc}::count_elements (const SEL_ARG *arg) 
bool  sel_trees_can_be_ored (SEL_TREE *tree1, SEL_TREE *tree2, RANGE_OPT_PARAM *param) 
static bool  remove_nonrange_trees (RANGE_OPT_PARAM *param, SEL_TREE *tree) 
static SEL_ROOT *  and_all_keys (RANGE_OPT_PARAM *param, SEL_ROOT *key1, SEL_ROOT *key2) 
And key trees where key1>part < key2>part. More...  
static void  left_rotate (SEL_ARG **root, SEL_ARG *leaf) 
static void  right_rotate (SEL_ARG **root, SEL_ARG *leaf) 
static ulong  count_key_part_usage (const SEL_ROOT *root, const SEL_ROOT *key, std::set< const SEL_ROOT * > *seen) 
Count how many times SEL_ARG graph "root" refers to its part "key" via transitive closure. More...  
bool  get_sel_root_for_keypart (uint key_part_num, SEL_ROOT *keypart_tree, SEL_ROOT **cur_range) 
void  print_sel_tree (RANGE_OPT_PARAM *param, SEL_TREE *tree, Key_map *tree_map, const char *msg) 
Helper function to compare two SEL_ROOTs.

static 
And key trees where key1>part < key2>part.
key2 will be connected to every key in key1, and thus have its use_count incremented many times. The returned node will not have its use_count increased; you are supposed to do that yourself when you connect it to a root.
param  Range analysis context (needed to track if we have allocated too many SEL_ARGs) 
key1  Root of first tree to AND together 
key2  Root of second tree to AND together 

static 
Count how many times SEL_ARG graph "root" refers to its part "key" via transitive closure.
root  An RBRoot node in a SEL_ARG graph. 
key  Another RBRoot node in that SEL_ARG graph. 
seen  Which SEL_ARGs we have already seen in this traversal. Used for deduplication, so that we only count each SEL_ARG once. 
The passed "root" node may refer to "key" node via root>next_key_part, root>next>n
This function counts how many times the node "key" is referred (via SEL_ARG::next_key_part) by
Here is an example (horizontal links represent next_key_part pointers, vertical links  next/prev prev pointers):
++ $ root+ ++ $   $   $  ++ ++ $  ++ Here the return value   ...  $++>key will be 4. ++ ++ $   ++  $   ... $    $   ++ ++ $     +  ++ ++ $    $  ... ++ $   + ++ $
Compare if two trees are equal, recursively (not necessarily the same elements, but in terms of structure and values in each leaf).
NOTE: The demand for the same structure means that some trees that are equivalent could be deemed inequal by this function, depending on insertion order.
a  First tree to compare. 
b  Second tree to compare. 
Check if the SEL_ARG tree for 'field' is identical for all ranges in 'keypart_tree'.

inline 

static 

static 
SEL_ROOT * key_and  (  RANGE_OPT_PARAM *  param, 
SEL_ROOT *  key1,  
SEL_ROOT *  key2  
) 
SEL_ROOT * key_or  (  RANGE_OPT_PARAM *  param, 
SEL_ROOT *  key1,  
SEL_ROOT *  key2  
) 
Combine two range expression under a common OR.
On a logical level, the transformation is key_or( expr1, expr2 ) => expr1 OR expr2.
Both expressions are assumed to be in the SEL_ARG format. In a logic sense, the format is reminiscent of DNF, since an expression such as the following
( 1 < kp1 < 10 AND p1 ) OR ( 10 <= kp2 < 20 AND p2 )
where there is a key consisting of keyparts ( kp1, kp2, ..., kpn ) and p1 and p2 are valid SEL_ARG expressions over keyparts kp2 ... kpn, is a valid SEL_ARG condition. The disjuncts appear ordered by the minimum endpoint of the first range and ranges must not overlap. It follows that they are also ordered by maximum endpoints. Thus
( 1 < kp1 <= 2 AND ( kp2 = 2 OR kp2 = 3 ) ) OR kp1 = 3
Is a a valid SER_ARG expression for a key of at least 2 keyparts.
For simplicity, we will assume that expr2 is a single range predicate, i.e. on the form ( a < x < b AND ... ). It is easy to generalize to a disjunction of several predicates by subsequently call key_or for each disjunct.
The algorithm iterates over each disjunct of expr1, and for each disjunct where the first keypart's range overlaps with the first keypart's range in expr2:
If the predicates are equal for the rest of the keyparts, or if there are no more, the range in expr2 has its endpoints copied in, and the SEL_ARG node in expr2 is deallocated. If more ranges became connected in expr1, the surplus is also dealocated. If they differ, two ranges are created.
Finally, there may be one more range if expr2's first keypart's range has a greater maximum endpoint than the last range in expr1.
For the overlapping subrange, we recursively call key_or. Thus in order to compute key_or of
(1) ( 1 < kp1 < 10 AND 1 < kp2 < 10 )
(2) ( 2 < kp1 < 20 AND 4 < kp2 < 20 )
We create the ranges 1 < kp <= 2, 2 < kp1 < 10, 10 <= kp1 < 20. For the first one, we simply hook on the condition for the second keypart from (1) : 1 < kp2 < 10. For the second range 2 < kp1 < 10, key_or( 1 < kp2 < 10, 4 < kp2 < 20 ) is called, yielding 1 < kp2 < 20. For the last range, we reuse the range 4 < kp2 < 20 from (2) for the second keypart. The result is thus
( 1 < kp1 <= 2 AND 1 < kp2 < 10 ) OR ( 2 < kp1 < 10 AND 1 < kp2 < 20 ) OR ( 10 <= kp1 < 20 AND 4 < kp2 < 20 )
key_or() does not modify key1 nor key2 if they are in use by other roots (although typical use is that key1 has been disconnected from its root and thus can be modified inplace). Thus, it does not change their use_count.
The returned node will not have its use_count increased; you are supposed to do that yourself when you connect it to a root.
param  RANGE_OPT_PARAM from test_quick_select 
key1  Root of RBtree of SEL_ARGs to be ORed with key2 
key2  Root of RBtree of SEL_ARGs to be ORed with key1 
void print_sel_tree  (  RANGE_OPT_PARAM *  param, 
SEL_TREE *  tree,  
Key_map *  tree_map,  
const char *  msg  
) 

static 
bool sel_trees_can_be_ored  (  SEL_TREE *  tree1, 
SEL_TREE *  tree2,  
RANGE_OPT_PARAM *  param  
) 
SEL_TREE * tree_and  (  RANGE_OPT_PARAM *  param, 
SEL_TREE *  tree1,  
SEL_TREE *  tree2  
) 
SEL_TREE * tree_or  (  RANGE_OPT_PARAM *  param, 
bool  remove_jump_scans,  
SEL_TREE *  tree1,  
SEL_TREE *  tree2  
) 