database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-07-29 05:21:33 +03:00
Code Activity

Backport of subquery optimizations to 5.3.

Browse Source 
There are still test failures because of:
- Wrong query results in outer join + semi join
- EXPLAIN output differences
This commit is contained in:
Sergey Petrunya
2010-01-17 17:51:10 +03:00
parent 1a490f2da4
commit b83cb52e9e
57 changed files with 30727 additions and 504 deletions
Download Patch File Download Diff File Expand all files Collapse all files

291
sql/sql_select.h
View File

@ -28,6 +28,10 @@
#include "procedure.h"
#include <myisam.h>
/* Values in optimize */
#define KEY_OPTIMIZE_EXISTS 1
#define KEY_OPTIMIZE_REF_OR_NULL 2
typedef struct keyuse_t {
TABLE *table;
Item *val; /**< or value if no field */
@ -51,6 +55,11 @@ typedef struct keyuse_t {
NULL - Otherwise (the source equality can't be turned off)
*/
bool *cond_guard;
/*
0..64 <=> This was created from semi-join IN-equality # sj_pred_no.
MAX_UINT Otherwise
*/
uint sj_pred_no;
} KEYUSE;
class store_key;
@ -122,8 +131,11 @@ typedef enum_nested_loop_state
(*Next_select_func)(JOIN *, struct st_join_table *, bool);
typedef int (*Read_record_func)(struct st_join_table *tab);
Next_select_func setup_end_select_func(JOIN *join);
int rr_sequential(READ_RECORD *info);
class JOIN_CACHE;
class SJ_TMP_TABLE;
typedef struct st_join_table {
st_join_table() {} /* Remove gcc warning */
@ -212,13 +224,55 @@ typedef struct st_join_table {
Item *cache_idx_cond;
SQL_SELECT *cache_select;
JOIN *join;
/** Bitmap of nested joins this table is part of */
nested_join_map embedding_map;
/*
Embedding SJ-nest (may be not the direct parent), or NULL if none.
This variable holds the result of table pullout.
*/
TABLE_LIST *emb_sj_nest;
/* FirstMatch variables (final QEP) */
struct st_join_table *first_sj_inner_tab;
struct st_join_table *last_sj_inner_tab;
/* Variables for semi-join duplicate elimination */
SJ_TMP_TABLE *flush_weedout_table;
SJ_TMP_TABLE *check_weed_out_table;
/*
If set, means we should stop join enumeration after we've got the first
match and return to the specified join tab. May point to
join->join_tab[-1] which means stop join execution after the first
match.
*/
struct st_join_table *do_firstmatch;
/*
ptr - We're doing a LooseScan, this join tab is the first (i.e.
"driving") join tab), and ptr points to the last join tab
handled by the strategy. loosescan_match_tab->found_match
should be checked to see if the current value group had a match.
NULL - Not doing a loose scan on this join tab.
*/
struct st_join_table *loosescan_match_tab;
/* Buffer to save index tuple to be able to skip duplicates */
uchar *loosescan_buf;
/* Length of key tuple (depends on #keyparts used) to store in the above */
uint loosescan_key_len;
/* Used by LooseScan. TRUE<=> there has been a matching record combination */
bool found_match;
/*
Used by DuplicateElimination. tab->table->ref must have the rowid
whenever we have a current record.
*/
int keep_current_rowid;
/* NestedOuterJoins: Bitmap of nested joins this table is part of */
nested_join_map embedding_map;
void cleanup();
inline bool is_using_loose_index_scan()
{
@ -1141,6 +1195,8 @@ enum_nested_loop_state sub_select_cache(JOIN *join, JOIN_TAB *join_tab, bool
end_of_records);
enum_nested_loop_state sub_select(JOIN *join,JOIN_TAB *join_tab, bool
end_of_records);
enum_nested_loop_state sub_select_sjm(JOIN *join, JOIN_TAB *join_tab,
bool end_of_records);
/**
Information about a position of table within a join order. Used in join
@ -1171,6 +1227,89 @@ typedef struct st_position
/* If ref-based access is used: bitmap of tables this table depends on */
table_map ref_depend_map;
bool use_join_buffer;
/* These form a stack of partial join order costs and output sizes */
COST_VECT prefix_cost;
double prefix_record_count;
/*
Current optimization state: Semi-join strategy to be used for this
and preceding join tables.
Join optimizer sets this for the *last* join_tab in the
duplicate-generating range. That is, in order to interpret this field,
one needs to traverse join->[best_]positions array from right to left.
When you see a join table with sj_strategy!= SJ_OPT_NONE, some other
field (depending on the strategy) tells how many preceding positions
this applies to. The values of covered_preceding_positions->sj_strategy
must be ignored.
*/
uint sj_strategy;
/*
Valid only after fix_semijoin_strategies_for_picked_join_order() call:
if sj_strategy!=SJ_OPT_NONE, this is the number of subsequent tables that
are covered by the specified semi-join strategy
*/
uint n_sj_tables;
/* LooseScan strategy members */
/* The first (i.e. driving) table we're doing loose scan for */
uint first_loosescan_table;
/*
Tables that need to be in the prefix before we can calculate the cost
of using LooseScan strategy.
*/
table_map loosescan_need_tables;
/*
keyno - Planning to do LooseScan on this key. If keyuse is NULL then
this is a full index scan, otherwise this is a ref+loosescan
scan (and keyno matches the KEUSE's)
MAX_KEY - Not doing a LooseScan
*/
uint loosescan_key; // final (one for strategy instance )
uint loosescan_parts; /* Number of keyparts to be kept distinct */
/* FirstMatch strategy */
/*
Index of the first inner table that we intend to handle with this
strategy
*/
uint first_firstmatch_table;
/*
Tables that were not in the join prefix when we've started considering
FirstMatch strategy.
*/
table_map first_firstmatch_rtbl;
/*
Tables that need to be in the prefix before we can calculate the cost
of using FirstMatch strategy.
*/
table_map firstmatch_need_tables;
/* Duplicate Weedout strategy */
/* The first table that the strategy will need to handle */
uint first_dupsweedout_table;
/*
Tables that we will need to have in the prefix to do the weedout step
(all inner and all outer that the involved semi-joins are correlated with)
*/
table_map dupsweedout_tables;
/* SJ-Materialization-Scan strategy */
/* The last inner table (valid once we're after it) */
uint sjm_scan_last_inner;
/*
Tables that we need to have in the prefix to calculate the correct cost.
Basically, we need all inner tables and outer tables mentioned in the
semi-join's ON expression so we can correctly account for fanout.
*/
table_map sjm_scan_need_tables;
} POSITION;
@ -1183,6 +1322,87 @@ typedef struct st_rollup
List<Item> *fields;
} ROLLUP;
/*
Temporary table used by semi-join DuplicateElimination strategy
This consists of the temptable itself and data needed to put records
into it. The table's DDL is as follows:
CREATE TABLE tmptable (col VARCHAR(n) BINARY, PRIMARY KEY(col));
where the primary key can be replaced with unique constraint if n exceeds
the limit (as it is always done for query execution-time temptables).
The record value is a concatenation of rowids of tables from the join we're
executing. If a join table is on the inner side of the outer join, we
assume that its rowid can be NULL and provide means to store this rowid in
the tuple.
*/
class SJ_TMP_TABLE : public Sql_alloc
{
public:
/*
Array of pointers to tables whose rowids compose the temporary table
record.
*/
class TAB
{
public:
JOIN_TAB *join_tab;
uint rowid_offset;
ushort null_byte;
uchar null_bit;
};
TAB *tabs;
TAB *tabs_end;
/*
is_confluent==TRUE means this is a special case where the temptable record
has zero length (and presence of a unique key means that the temptable can
have either 0 or 1 records).
In this case we don't create the physical temptable but instead record
its state in SJ_TMP_TABLE::have_confluent_record.
*/
bool is_confluent;
/*
When is_confluent==TRUE: the contents of the table (whether it has the
record or not).
*/
bool have_confluent_row;
/* table record parameters */
uint null_bits;
uint null_bytes;
uint rowid_len;
/* The temporary table itself (NULL means not created yet) */
TABLE *tmp_table;
/*
These are the members we got from temptable creation code. We'll need
them if we'll need to convert table from HEAP to MyISAM/Maria.
*/
ENGINE_COLUMNDEF *start_recinfo;
ENGINE_COLUMNDEF *recinfo;
/* Pointer to next table (next->start_idx > this->end_idx) */
SJ_TMP_TABLE *next;
};
#define SJ_OPT_NONE 0
#define SJ_OPT_DUPS_WEEDOUT 1
#define SJ_OPT_LOOSE_SCAN 2
#define SJ_OPT_FIRST_MATCH 3
#define SJ_OPT_MATERIALIZE 4
#define SJ_OPT_MATERIALIZE_SCAN 5
inline bool sj_is_materialize_strategy(uint strategy)
{
return strategy >= SJ_OPT_MATERIALIZE;
}
class JOIN :public Sql_alloc
{
@ -1192,8 +1412,17 @@ public:
JOIN_TAB *join_tab,**best_ref;
JOIN_TAB **map2table; ///< mapping between table indexes and JOIN_TABs
JOIN_TAB *join_tab_save; ///< saved join_tab for subquery reexecution
TABLE **table,**all_tables,*sort_by_table;
uint tables,const_tables;
TABLE **table;
TABLE **all_tables;
/**
The table which has an index that allows to produce the requried ordering.
A special value of 0x1 means that the ordering will be produced by
passing 1st non-const table to filesort(). NULL means no such table exists.
*/
TABLE *sort_by_table;
uint tables; /**< Number of tables in the join */
uint outer_tables; /**< Number of tables that are not inside semijoin */
uint const_tables;
uint send_group_parts;
bool sort_and_group,first_record,full_join, no_field_update;
bool group; /**< If query contains GROUP BY clause */
@ -1227,14 +1456,47 @@ public:
- on each fetch iteration we add num_rows to fetch to fetch_limit
*/
ha_rows fetch_limit;
POSITION positions[MAX_TABLES+1],best_positions[MAX_TABLES+1];
/* Finally picked QEP. This is result of join optimization */
POSITION best_positions[MAX_TABLES+1];
/******* Join optimization state members start *******/
/*
pointer - we're doing optimization for a semi-join materialization nest.
NULL - otherwise
*/
TABLE_LIST *emb_sjm_nest;
/* *
/* Current join optimization state */
POSITION positions[MAX_TABLES+1];
/*
Bitmap of nested joins embedding the position at the end of the current
partial join (valid only during join optimizer run).
*/
nested_join_map cur_embedding_map;
/*
Bitmap of inner tables of semi-join nests that have a proper subset of
their tables in the current join prefix. That is, of those semi-join
nests that have their tables both in and outside of the join prefix.
*/
table_map cur_sj_inner_tables;
/*
Bitmap of semi-join inner tables that are in the join prefix and for
which there's no provision for how to eliminate semi-join duplicates
they produce.
*/
table_map cur_dups_producing_tables;
/* We also maintain a stack of join optimization states in * join->positions[] */
/******* Join optimization state members end *******/
Next_select_func first_select;
/*
The cost of best complete join plan found so far during optimization,
after optimization phase - cost of picked join order (not taking into
account the changes made by test_if_skip_sort_order()).
*/
double best_read;
List<Item> *fields;
List<Cached_item> group_fields, group_fields_cache;
@ -1322,6 +1584,12 @@ public:
bool union_part; ///< this subselect is part of union
bool optimized; ///< flag to avoid double optimization in EXPLAIN
Array<Item_in_subselect> sj_subselects;
/* Temporary tables used to weed-out semi-join duplicates */
List<TABLE> sj_tmp_tables;
List<SJ_MATERIALIZATION_INFO> sjm_info_list;
/*
storage for caching buffers allocated during query execution.
These buffers allocations need to be cached as the thread memory pool is
@ -1339,7 +1607,7 @@ public:
JOIN(THD *thd_arg, List<Item> &fields_arg, ulonglong select_options_arg,
select_result *result_arg)
:fields_list(fields_arg)
:fields_list(fields_arg), sj_subselects(thd_arg->mem_root, 4)
{
init(thd_arg, fields_arg, select_options_arg, result_arg);
}
@ -1401,6 +1669,7 @@ public:
rollup.state= ROLLUP::STATE_NONE;
no_const_tables= FALSE;
first_select= sub_select;
}
int prepare(Item ***rref_pointer_array, TABLE_LIST *tables, uint wind_num,
@ -1413,6 +1682,8 @@ public:
int destroy();
void restore_tmp();
bool alloc_func_list();
bool flatten_subqueries();
bool setup_subquery_materialization();
bool make_sum_func_list(List<Item> &all_fields, List<Item> &send_fields,
bool before_group_by, bool recompute= FALSE);
@ -1498,8 +1769,10 @@ bool setup_copy_fields(THD *thd, TMP_TABLE_PARAM *param,
uint elements, List<Item> &fields);
void copy_fields(TMP_TABLE_PARAM *param);
void copy_funcs(Item **func_ptr);
bool create_internal_tmp_table_from_heap(THD *thd, TABLE *table, TMP_TABLE_PARAM *param,
int error, bool ignore_last_dupp_error);
bool create_internal_tmp_table_from_heap(THD *thd, TABLE *table,
ENGINE_COLUMNDEF *start_recinfo,
ENGINE_COLUMNDEF **recinfo,
int error, bool ignore_last_dupp_key_error);
uint find_shortest_key(TABLE *table, const key_map *usable_keys);
Field* create_tmp_field_from_field(THD *thd, Field* org_field,
const char *name, TABLE *table,