diff options
Diffstat (limited to 'storage/xtradb/pars/pars0opt.c')
| -rw-r--r-- | storage/xtradb/pars/pars0opt.c | 200 |
1 files changed, 96 insertions, 104 deletions
diff --git a/storage/xtradb/pars/pars0opt.c b/storage/xtradb/pars/pars0opt.c index 34246929c53..2e392ba4836 100644 --- a/storage/xtradb/pars/pars0opt.c +++ b/storage/xtradb/pars/pars0opt.c @@ -16,7 +16,8 @@ Place, Suite 330, Boston, MA 02111-1307 USA *****************************************************************************/ -/****************************************************** +/**************************************************//** +@file pars/pars0opt.c Simple SQL optimizer Created 12/21/1997 Heikki Tuuri @@ -47,15 +48,14 @@ Created 12/21/1997 Heikki Tuuri #define OPT_SCROLL_COND 4 -/*********************************************************************** -Inverts a comparison operator. */ +/*******************************************************************//** +Inverts a comparison operator. +@return the equivalent operator when the order of the arguments is switched */ static int opt_invert_cmp_op( /*==============*/ - /* out: the equivalent operator when the order of - the arguments is switched */ - int op) /* in: operator */ + int op) /*!< in: operator */ { if (op == '<') { return('>'); @@ -74,18 +74,18 @@ opt_invert_cmp_op( return(0); } -/*********************************************************************** +/*******************************************************************//** Checks if the value of an expression can be calculated BEFORE the nth table in a join is accessed. If this is the case, it can possibly be used in an -index search for the nth table. */ +index search for the nth table. +@return TRUE if already determined */ static ibool opt_check_exp_determined_before( /*============================*/ - /* out: TRUE if already determined */ - que_node_t* exp, /* in: expression */ - sel_node_t* sel_node, /* in: select node */ - ulint nth_table) /* in: nth table will be accessed */ + que_node_t* exp, /*!< in: expression */ + sel_node_t* sel_node, /*!< in: select node */ + ulint nth_table) /*!< in: nth table will be accessed */ { func_node_t* func_node; sym_node_t* sym_node; @@ -134,24 +134,22 @@ opt_check_exp_determined_before( return(FALSE); } -/*********************************************************************** +/*******************************************************************//** Looks in a comparison condition if a column value is already restricted by -it BEFORE the nth table is accessed. */ +it BEFORE the nth table is accessed. +@return expression restricting the value of the column, or NULL if not known */ static que_node_t* opt_look_for_col_in_comparison_before( /*==================================*/ - /* out: expression restricting the - value of the column, or NULL if not - known */ - ulint cmp_type, /* in: OPT_EQUAL, OPT_COMPARISON */ - ulint col_no, /* in: column number */ - func_node_t* search_cond, /* in: comparison condition */ - sel_node_t* sel_node, /* in: select node */ - ulint nth_table, /* in: nth table in a join (a query + ulint cmp_type, /*!< in: OPT_EQUAL, OPT_COMPARISON */ + ulint col_no, /*!< in: column number */ + func_node_t* search_cond, /*!< in: comparison condition */ + sel_node_t* sel_node, /*!< in: select node */ + ulint nth_table, /*!< in: nth table in a join (a query from a single table is considered a join of 1 table) */ - ulint* op) /* out: comparison operator ('=', + ulint* op) /*!< out: comparison operator ('=', PARS_GE_TOKEN, ... ); this is inverted if the column appears on the right side */ @@ -231,26 +229,24 @@ opt_look_for_col_in_comparison_before( return(NULL); } -/*********************************************************************** +/*******************************************************************//** Looks in a search condition if a column value is already restricted by the search condition BEFORE the nth table is accessed. Takes into account that if we will fetch in an ascending order, we cannot utilize an upper limit for -a column value; in a descending order, respectively, a lower limit. */ +a column value; in a descending order, respectively, a lower limit. +@return expression restricting the value of the column, or NULL if not known */ static que_node_t* opt_look_for_col_in_cond_before( /*============================*/ - /* out: expression restricting the - value of the column, or NULL if not - known */ - ulint cmp_type, /* in: OPT_EQUAL, OPT_COMPARISON */ - ulint col_no, /* in: column number */ - func_node_t* search_cond, /* in: search condition or NULL */ - sel_node_t* sel_node, /* in: select node */ - ulint nth_table, /* in: nth table in a join (a query + ulint cmp_type, /*!< in: OPT_EQUAL, OPT_COMPARISON */ + ulint col_no, /*!< in: column number */ + func_node_t* search_cond, /*!< in: search condition or NULL */ + sel_node_t* sel_node, /*!< in: select node */ + ulint nth_table, /*!< in: nth table in a join (a query from a single table is considered a join of 1 table) */ - ulint* op) /* out: comparison operator ('=', + ulint* op) /*!< out: comparison operator ('=', PARS_GE_TOKEN, ... ) */ { func_node_t* new_cond; @@ -309,24 +305,24 @@ opt_look_for_col_in_cond_before( return(exp); } -/*********************************************************************** +/*******************************************************************//** Calculates the goodness for an index according to a select node. The goodness is 4 times the number of first fields in index whose values we already know exactly in the query. If we have a comparison condition for an additional field, 2 point are added. If the index is unique, and we know all the unique fields for the index we add 1024 points. For a clustered index -we add 1 point. */ +we add 1 point. +@return goodness */ static ulint opt_calc_index_goodness( /*====================*/ - /* out: goodness */ - dict_index_t* index, /* in: index */ - sel_node_t* sel_node, /* in: parsed select node */ - ulint nth_table, /* in: nth table in a join */ - que_node_t** index_plan, /* in/out: comparison expressions for + dict_index_t* index, /*!< in: index */ + sel_node_t* sel_node, /*!< in: parsed select node */ + ulint nth_table, /*!< in: nth table in a join */ + que_node_t** index_plan, /*!< in/out: comparison expressions for this index */ - ulint* last_op) /* out: last comparison operator, if + ulint* last_op) /*!< out: last comparison operator, if goodness > 1 */ { que_node_t* exp; @@ -393,30 +389,29 @@ opt_calc_index_goodness( return(goodness); } -/*********************************************************************** -Calculates the number of matched fields based on an index goodness. */ +/*******************************************************************//** +Calculates the number of matched fields based on an index goodness. +@return number of excatly or partially matched fields */ UNIV_INLINE ulint opt_calc_n_fields_from_goodness( /*============================*/ - /* out: number of excatly or partially matched - fields */ - ulint goodness) /* in: goodness */ + ulint goodness) /*!< in: goodness */ { return(((goodness % 1024) + 2) / 4); } -/*********************************************************************** +/*******************************************************************//** Converts a comparison operator to the corresponding search mode PAGE_CUR_GE, -... */ +... +@return search mode */ UNIV_INLINE ulint opt_op_to_search_mode( /*==================*/ - /* out: search mode */ - ibool asc, /* in: TRUE if the rows should be fetched in an + ibool asc, /*!< in: TRUE if the rows should be fetched in an ascending order */ - ulint op) /* in: operator '=', PARS_GE_TOKEN, ... */ + ulint op) /*!< in: operator '=', PARS_GE_TOKEN, ... */ { if (op == '=') { if (asc) { @@ -443,15 +438,15 @@ opt_op_to_search_mode( return(0); } -/*********************************************************************** -Determines if a node is an argument node of a function node. */ +/*******************************************************************//** +Determines if a node is an argument node of a function node. +@return TRUE if is an argument */ static ibool opt_is_arg( /*=======*/ - /* out: TRUE if is an argument */ - que_node_t* arg_node, /* in: possible argument node */ - func_node_t* func_node) /* in: function node */ + que_node_t* arg_node, /*!< in: possible argument node */ + func_node_t* func_node) /*!< in: function node */ { que_node_t* arg; @@ -469,7 +464,7 @@ opt_is_arg( return(FALSE); } -/*********************************************************************** +/*******************************************************************//** Decides if the fetching of rows should be made in a descending order, and also checks that the chosen query plan produces a result which satisfies the order-by. */ @@ -477,7 +472,7 @@ static void opt_check_order_by( /*===============*/ - sel_node_t* sel_node) /* in: select node; asserts an error + sel_node_t* sel_node) /*!< in: select node; asserts an error if the plan does not agree with the order-by */ { @@ -521,7 +516,7 @@ opt_check_order_by( } } -/*********************************************************************** +/*******************************************************************//** Optimizes a select. Decides which indexes to tables to use. The tables are accessed in the order that they were written to the FROM part in the select statement. */ @@ -529,9 +524,9 @@ static void opt_search_plan_for_table( /*======================*/ - sel_node_t* sel_node, /* in: parsed select node */ - ulint i, /* in: this is the ith table */ - dict_table_t* table) /* in: table */ + sel_node_t* sel_node, /*!< in: parsed select node */ + ulint i, /*!< in: this is the ith table */ + dict_table_t* table) /*!< in: table */ { plan_t* plan; dict_index_t* index; @@ -617,22 +612,19 @@ opt_search_plan_for_table( btr_pcur_init(&(plan->clust_pcur)); } -/*********************************************************************** +/*******************************************************************//** Looks at a comparison condition and decides if it can, and need, be tested for -a table AFTER the table has been accessed. */ +a table AFTER the table has been accessed. +@return OPT_NOT_COND if not for this table, else OPT_END_COND, +OPT_TEST_COND, or OPT_SCROLL_COND, where the last means that the +condition need not be tested, except when scroll cursors are used */ static ulint opt_classify_comparison( /*====================*/ - /* out: OPT_NOT_COND if not for this - table, else OPT_END_COND, - OPT_TEST_COND, or OPT_SCROLL_COND, - where the last means that the - condition need not be tested, except - when scroll cursors are used */ - sel_node_t* sel_node, /* in: select node */ - ulint i, /* in: ith table in the join */ - func_node_t* cond) /* in: comparison condition */ + sel_node_t* sel_node, /*!< in: select node */ + ulint i, /*!< in: ith table in the join */ + func_node_t* cond) /*!< in: comparison condition */ { plan_t* plan; ulint n_fields; @@ -713,15 +705,15 @@ opt_classify_comparison( return(OPT_TEST_COND); } -/*********************************************************************** +/*******************************************************************//** Recursively looks for test conditions for a table in a join. */ static void opt_find_test_conds( /*================*/ - sel_node_t* sel_node, /* in: select node */ - ulint i, /* in: ith table in the join */ - func_node_t* cond) /* in: conjunction of search + sel_node_t* sel_node, /*!< in: select node */ + ulint i, /*!< in: ith table in the join */ + func_node_t* cond) /*!< in: conjunction of search conditions or NULL */ { func_node_t* new_cond; @@ -758,7 +750,7 @@ opt_find_test_conds( } } -/*********************************************************************** +/*******************************************************************//** Normalizes a list of comparison conditions so that a column of the table appears on the left side of the comparison if possible. This is accomplished by switching the arguments of the operator. */ @@ -766,9 +758,9 @@ static void opt_normalize_cmp_conds( /*====================*/ - func_node_t* cond, /* in: first in a list of comparison + func_node_t* cond, /*!< in: first in a list of comparison conditions, or NULL */ - dict_table_t* table) /* in: table */ + dict_table_t* table) /*!< in: table */ { que_node_t* arg1; que_node_t* arg2; @@ -800,7 +792,7 @@ opt_normalize_cmp_conds( } } -/*********************************************************************** +/*******************************************************************//** Finds out the search condition conjuncts we can, and need, to test as the ith table in a join is accessed. The search tuple can eliminate the need to test some conjuncts. */ @@ -808,8 +800,8 @@ static void opt_determine_and_normalize_test_conds( /*===================================*/ - sel_node_t* sel_node, /* in: select node */ - ulint i) /* in: ith table in the join */ + sel_node_t* sel_node, /*!< in: select node */ + ulint i) /*!< in: ith table in the join */ { plan_t* plan; @@ -828,7 +820,7 @@ opt_determine_and_normalize_test_conds( ut_a(UT_LIST_GET_LEN(plan->end_conds) >= plan->n_exact_match); } -/*********************************************************************** +/*******************************************************************//** Looks for occurrences of the columns of the table in the query subgraph and adds them to the list of columns if an occurrence of the same column does not already exist in the list. If the column is already in the list, puts a value @@ -839,13 +831,13 @@ UNIV_INTERN void opt_find_all_cols( /*==============*/ - ibool copy_val, /* in: if TRUE, new found columns are + ibool copy_val, /*!< in: if TRUE, new found columns are added as columns to copy */ - dict_index_t* index, /* in: index of the table to use */ - sym_node_list_t* col_list, /* in: base node of a list where + dict_index_t* index, /*!< in: index of the table to use */ + sym_node_list_t* col_list, /*!< in: base node of a list where to add new found columns */ - plan_t* plan, /* in: plan or NULL */ - que_node_t* exp) /* in: expression or condition or + plan_t* plan, /*!< in: plan or NULL */ + que_node_t* exp) /*!< in: expression or condition or NULL */ { func_node_t* func_node; @@ -937,7 +929,7 @@ opt_find_all_cols( } } -/*********************************************************************** +/*******************************************************************//** Looks for occurrences of the columns of the table in conditions which are not yet determined AFTER the join operation has fetched a row in the ith table. The values for these column must be copied to dynamic memory for @@ -946,9 +938,9 @@ static void opt_find_copy_cols( /*===============*/ - sel_node_t* sel_node, /* in: select node */ - ulint i, /* in: ith table in the join */ - func_node_t* search_cond) /* in: search condition or NULL */ + sel_node_t* sel_node, /*!< in: select node */ + ulint i, /*!< in: ith table in the join */ + func_node_t* search_cond) /*!< in: search condition or NULL */ { func_node_t* new_cond; plan_t* plan; @@ -985,7 +977,7 @@ opt_find_copy_cols( } } -/*********************************************************************** +/*******************************************************************//** Classifies the table columns according to whether we use the column only while holding the latch on the page, or whether we have to copy the column value to dynamic memory. Puts the first occurrence of a column to either list in the @@ -994,8 +986,8 @@ static void opt_classify_cols( /*==============*/ - sel_node_t* sel_node, /* in: select node */ - ulint i) /* in: ith table in the join */ + sel_node_t* sel_node, /*!< in: select node */ + ulint i) /*!< in: ith table in the join */ { plan_t* plan; que_node_t* exp; @@ -1029,15 +1021,15 @@ opt_classify_cols( sel_node->search_cond); } -/*********************************************************************** +/*******************************************************************//** Fills in the info in plan which is used in accessing a clustered index record. The columns must already be classified for the plan node. */ static void opt_clust_access( /*=============*/ - sel_node_t* sel_node, /* in: select node */ - ulint n) /* in: nth table in select */ + sel_node_t* sel_node, /*!< in: select node */ + ulint n) /*!< in: nth table in select */ { plan_t* plan; dict_table_t* table; @@ -1101,7 +1093,7 @@ opt_clust_access( } } -/*********************************************************************** +/*******************************************************************//** Optimizes a select. Decides which indexes to tables to use. The tables are accessed in the order that they were written to the FROM part in the select statement. */ @@ -1109,7 +1101,7 @@ UNIV_INTERN void opt_search_plan( /*============*/ - sel_node_t* sel_node) /* in: parsed select node */ + sel_node_t* sel_node) /*!< in: parsed select node */ { sym_node_t* table_node; dict_table_t* table; @@ -1176,13 +1168,13 @@ opt_search_plan( #endif } -/************************************************************************ +/********************************************************************//** Prints info of a query plan. */ UNIV_INTERN void opt_print_query_plan( /*=================*/ - sel_node_t* sel_node) /* in: select node */ + sel_node_t* sel_node) /*!< in: select node */ { plan_t* plan; ulint n_fields; |