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Merge

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This commit is contained in:
Igor Babaev
2010-12-27 14:22:05 -08:00
parent 1eb5e0e603 7d68e1ead7
commit 0dc5ef87d4
62 changed files with 9350 additions and 760 deletions
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131
sql/opt_range.h
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@ -283,12 +283,13 @@ public:
virtual void need_sorted_output() = 0;
enum {
QS_TYPE_RANGE = 0,
QS_TYPE_INDEX_MERGE = 1,
QS_TYPE_RANGE_DESC = 2,
QS_TYPE_FULLTEXT = 3,
QS_TYPE_ROR_INTERSECT = 4,
QS_TYPE_ROR_UNION = 5,
QS_TYPE_GROUP_MIN_MAX = 6
QS_TYPE_INDEX_INTERSECT = 1,
QS_TYPE_INDEX_MERGE = 2,
QS_TYPE_RANGE_DESC = 3,
QS_TYPE_FULLTEXT = 4,
QS_TYPE_ROR_INTERSECT = 5,
QS_TYPE_ROR_UNION = 6,
QS_TYPE_GROUP_MIN_MAX = 7
};
/* Get type of this quick select - one of the QS_TYPE_* values */
@ -314,6 +315,10 @@ public:
Save ROWID of last retrieved row in file->ref. This used in ROR-merging.
*/
virtual void save_last_pos(){};
void add_key_and_length(String *key_names,
String *used_lengths,
bool *first);
/*
Append comma-separated list of keys this quick select uses to key_names;
@ -323,13 +328,16 @@ public:
virtual void add_keys_and_lengths(String *key_names,
String *used_lengths)=0;
void add_key_name(String *str, bool *first);
/*
Append text representation of quick select structure (what and how is
merged) to str. The result is added to "Extra" field in EXPLAIN output.
This function is implemented only by quick selects that merge other quick
selects output and/or can produce output suitable for merging.
*/
virtual void add_info_string(String *str) {};
virtual void add_info_string(String *str) {}
/*
Return 1 if any index used by this quick select
uses field which is marked in passed bitmap.
@ -458,12 +466,23 @@ private:
uint mrr_buf_size,
MEM_ROOT *alloc);
friend class QUICK_SELECT_DESC;
friend class QUICK_INDEX_SORT_SELECT;
friend class QUICK_INDEX_MERGE_SELECT;
friend class QUICK_ROR_INTERSECT_SELECT;
friend class QUICK_INDEX_INTERSECT_SELECT;
friend class QUICK_GROUP_MIN_MAX_SELECT;
friend bool quick_range_seq_next(range_seq_t rseq, KEY_MULTI_RANGE *range);
friend range_seq_t quick_range_seq_init(void *init_param,
uint n_ranges, uint flags);
friend
int read_keys_and_merge_scans(THD *thd, TABLE *head,
List<QUICK_RANGE_SELECT> quick_selects,
QUICK_RANGE_SELECT *pk_quick_select,
READ_RECORD *read_record,
bool intersection,
key_map *filtered_scans,
Unique **unique_ptr);
};
@ -481,40 +500,44 @@ public:
/*
QUICK_INDEX_MERGE_SELECT - index_merge access method quick select.
QUICK_INDEX_SORT_SELECT is the base class for the common functionality of:
- QUICK_INDEX_MERGE_SELECT, access based on multi-index merge/union
- QUICK_INDEX_INTERSECT_SELECT, access based on multi-index intersection
QUICK_INDEX_MERGE_SELECT uses
QUICK_INDEX_SORT_SELECT uses
* QUICK_RANGE_SELECTs to get rows
* Unique class to remove duplicate rows
* Unique class
- to remove duplicate rows for QUICK_INDEX_MERGE_SELECT
- to intersect rows for QUICK_INDEX_INTERSECT_SELECT
INDEX MERGE OPTIMIZER
Current implementation doesn't detect all cases where index_merge could
Current implementation doesn't detect all cases where index merge could
be used, in particular:
* index_merge will never be used if range scan is possible (even if
range scan is more expensive)
* index_merge+'using index' is not supported (this the consequence of
* index merge+'using index' is not supported (this the consequence of
the above restriction)
* If WHERE part contains complex nested AND and OR conditions, some ways
to retrieve rows using index_merge will not be considered. The choice
to retrieve rows using index merge will not be considered. The choice
of read plan may depend on the order of conjuncts/disjuncts in WHERE
part of the query, see comments near imerge_list_or_list and
SEL_IMERGE::or_sel_tree_with_checks functions for details.
* There is no "index_merge_ref" method (but index_merge on non-first
* There is no "index_merge_ref" method (but index merge on non-first
table in join is possible with 'range checked for each record').
See comments around SEL_IMERGE class and test_quick_select for more
details.
ROW RETRIEVAL ALGORITHM
index_merge uses Unique class for duplicates removal. index_merge takes
advantage of Clustered Primary Key (CPK) if the table has one.
The index_merge algorithm consists of two phases:
index merge/intersection uses Unique class for duplicates removal.
index merge/intersection takes advantage of Clustered Primary Key (CPK)
if the table has one.
The index merge/intersection algorithm consists of two phases:
Phase 1
(implemented by a QUICK_INDEX_MERGE_SELECT::read_keys_and_merge call):
Phase 1 (implemented in QUICK_INDEX_MERGE_SELECT::prepare_unique):
prepare()
{
activate 'index only';
@ -528,33 +551,32 @@ public:
deactivate 'index only';
}
Phase 2 (implemented as sequence of QUICK_INDEX_MERGE_SELECT::get_next
calls):
Phase 2
(implemented as sequence of QUICK_INDEX_MERGE_SELECT::get_next calls):
fetch()
{
retrieve all rows from row pointers stored in Unique;
retrieve all rows from row pointers stored in Unique
(merging/intersecting them);
free Unique;
retrieve all rows for CPK scan;
if (! intersection)
retrieve all rows for CPK scan;
}
*/
class QUICK_INDEX_MERGE_SELECT : public QUICK_SELECT_I
class QUICK_INDEX_SORT_SELECT : public QUICK_SELECT_I
{
protected:
Unique *unique;
public:
QUICK_INDEX_MERGE_SELECT(THD *thd, TABLE *table);
~QUICK_INDEX_MERGE_SELECT();
QUICK_INDEX_SORT_SELECT(THD *thd, TABLE *table);
~QUICK_INDEX_SORT_SELECT();
int init();
void need_sorted_output() { DBUG_ASSERT(0); /* Can't do it */ }
int reset(void);
int get_next();
bool reverse_sorted() { return false; }
bool unique_key_range() { return false; }
int get_type() { return QS_TYPE_INDEX_MERGE; }
void add_keys_and_lengths(String *key_names, String *used_lengths);
void add_info_string(String *str);
bool is_keys_used(const MY_BITMAP *fields);
#ifndef DBUG_OFF
void dbug_dump(int indent, bool verbose);
@ -562,24 +584,57 @@ public:
bool push_quick_back(QUICK_RANGE_SELECT *quick_sel_range);
/* range quick selects this index_merge read consists of */
/* range quick selects this index merge/intersect consists of */
List<QUICK_RANGE_SELECT> quick_selects;
/* quick select that uses clustered primary key (NULL if none) */
QUICK_RANGE_SELECT* pk_quick_select;
/* true if this select is currently doing a clustered PK scan */
bool doing_pk_scan;
MEM_ROOT alloc;
THD *thd;
int read_keys_and_merge();
virtual int read_keys_and_merge()= 0;
/* used to get rows collected in Unique */
READ_RECORD read_record;
};
class QUICK_INDEX_MERGE_SELECT : public QUICK_INDEX_SORT_SELECT
{
private:
/* true if this select is currently doing a clustered PK scan */
bool doing_pk_scan;
protected:
int read_keys_and_merge();
public:
QUICK_INDEX_MERGE_SELECT(THD *thd, TABLE *table)
:QUICK_INDEX_SORT_SELECT(thd, table) {}
int get_next();
int get_type() { return QS_TYPE_INDEX_MERGE; }
void add_keys_and_lengths(String *key_names, String *used_lengths);
void add_info_string(String *str);
};
class QUICK_INDEX_INTERSECT_SELECT : public QUICK_INDEX_SORT_SELECT
{
protected:
int read_keys_and_merge();
public:
QUICK_INDEX_INTERSECT_SELECT(THD *thd, TABLE *table)
:QUICK_INDEX_SORT_SELECT(thd, table) {}
key_map filtered_scans;
int get_next();
int get_type() { return QS_TYPE_INDEX_INTERSECT; }
void add_keys_and_lengths(String *key_names, String *used_lengths);
void add_info_string(String *str);
};
/*
Rowid-Ordered Retrieval (ROR) index intersection quick select.
This quick select produces intersection of row sequences returned