database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-30 16:24:05 +03:00
Code Activity

MWL#17: Table elimination

Browse Source 
- Continue addressing review feedback: remove "unusable KEYUSEs" 
  extension as it is no longer needed.

sql/item.h:
  MWL#17: Table elimination
  - Code cleanup
sql/opt_table_elimination.cc:
  MWL#17: Table elimination
  - Code cleanup
This commit is contained in:
Sergey Petrunya
2009-08-13 03:43:02 +04:00
parent 854bb82bd8
commit b032c7d833
4 changed files with 21 additions and 139 deletions
Download Patch File Download Diff File Expand all files Collapse all files

50
sql/sql_select.h
View File

@ -28,45 +28,6 @@
#include "procedure.h"
#include <myisam.h>
#define FT_KEYPART (MAX_REF_PARTS+10)
/* Values in optimize */
#define KEY_OPTIMIZE_EXISTS 1
#define KEY_OPTIMIZE_REF_OR_NULL 2
/* KEYUSE element types */
enum keyuse_type
{
/*
val refers to the same table, this is either KEYUSE_BIND or KEYUSE_NO_BIND
type, we didn't determine which one yet.
*/
KEYUSE_UNKNOWN= 0,
/*
'regular' keyuse, i.e. it represents one of the following
* t.keyXpartY = func(constants, other-tables)
* t.keyXpartY IS NULL
* t.keyXpartY = func(constants, other-tables) OR t.keyXpartY IS NULL
and can be used to construct ref acces
*/
KEYUSE_USABLE,
/*
The keyuse represents a condition in form:
t.uniq_keyXpartY = func(other parts of uniq_keyX)
This can't be used to construct uniq_keyX but we could use it to determine
that the table will produce at most one match.
*/
KEYUSE_BIND,
/*
Keyuse that's not usable for ref access and doesn't meet the criteria of
KEYUSE_BIND. Examples:
t.keyXpartY = func(t.keyXpartY)
t.keyXpartY = func(column of t that's not covered by keyX)
*/
KEYUSE_NO_BIND
};
typedef struct keyuse_t {
TABLE *table;
Item *val; /**< or value if no field */
@ -90,15 +51,6 @@ typedef struct keyuse_t {
NULL - Otherwise (the source equality can't be turned off)
*/
bool *cond_guard;
/*
1 <=> This keyuse can be used to construct key access.
0 <=> Otherwise. Currently unusable KEYUSEs represent equalities
where one table column refers to another one, like this:
t.keyXpartA=func(t.keyXpartB)
This equality cannot be used for index access but is useful
for table elimination.
*/
enum keyuse_type type;
} KEYUSE;
class store_key;
@ -258,7 +210,7 @@ typedef struct st_join_table {
JOIN *join;
/** Bitmap of nested joins this table is part of */
nested_join_map embedding_map;
void cleanup();
inline bool is_using_loose_index_scan()
{