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 
- Last fixes

sql/item.cc:
  MWL#17: Table elimination
  - Don't make multiple calls of ::walk(check_column_usage_processor),
    call once and cache the value
sql/item.h:
  MWL#17: Table elimination
  - s/KEYUSE::usable/KEYUSE::type/, more comments
sql/opt_table_elimination.cc:
  MWL#17: Table elimination
  - Don't make multiple calls of ::walk(check_column_usage_processor),
    call once and cache the value
sql/sql_select.cc:
  MWL#17: Table elimination
  - s/KEYUSE::usable/KEYUSE::type/, more comments
sql/sql_select.h:
  MWL#17: Table elimination
  - s/KEYUSE::usable/KEYUSE::type/, more comments
sql/table.h:
  MWL#17: Table elimination
  - Better comments
This commit is contained in:
Sergey Petrunya
2009-06-30 17:11:00 +04:00
parent 9fa1bce436
commit 8156d9eb0a
6 changed files with 138 additions and 65 deletions
Download Patch File Download Diff File Expand all files Collapse all files

36
sql/sql_select.h
View File

@ -33,6 +33,40 @@
#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 */
@ -64,7 +98,7 @@ typedef struct keyuse_t {
This equality cannot be used for index access but is useful
for table elimination.
*/
int usable;
enum keyuse_type type;
} KEYUSE;
class store_key;