cleanup: Select_limit_counters rename set_unlimited to clear
The function was originally introduced by eb0804ef5e7eeb059bb193c3c6787e8a4188d34d MDEV-18553: MDEV-16327 pre-requisits part 1: isolation of LIMIT/OFFSET handling set_unlimited had an overloaded notion of both clearing the offset value and the limit value. The code is used for SQL_CALC_ROWS option to disable the limit clause after the limit is reached, while at the same time the calling code suppreses sending of rows. Proposed solution: Dedicated clear method for query initialization (to ensure no garbage remains between executions). Dedicated set_unlimited that only alters the limit value.
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@ -2910,7 +2910,7 @@ void st_select_lex_unit::init_query()
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{
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init_query_common();
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set_linkage(GLOBAL_OPTIONS_TYPE);
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lim.set_unlimited();
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lim.clear();
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union_distinct= 0;
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prepared= optimized= optimized_2= executed= 0;
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bag_set_op_optimized= 0;
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@ -37,8 +37,13 @@ class Select_limit_counters
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{
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offset_limit_cnt= offset;
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select_limit_cnt= limit;
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if (select_limit_cnt + offset_limit_cnt >=
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select_limit_cnt)
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/*
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Guard against an overflow condition, where limit + offset exceede
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ha_rows value range. This case covers unreasonably large parameter
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values that do not have any practical use so assuming in this case
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that the query does not have a limit is fine.
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*/
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if (select_limit_cnt + offset_limit_cnt >= select_limit_cnt)
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select_limit_cnt+= offset_limit_cnt;
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else
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select_limit_cnt= HA_POS_ERROR;
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@ -52,7 +57,16 @@ class Select_limit_counters
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bool is_unlimited() const
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{ return select_limit_cnt == HA_POS_ERROR; }
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/*
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Set the limit to allow returning an unlimited number of rows. Useful
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for cases when we want to continue execution indefinitely after the limit
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is reached (for example for SQL_CALC_ROWS extension).
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*/
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void set_unlimited()
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{ select_limit_cnt= HA_POS_ERROR; }
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/* Reset the limit entirely. */
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void clear()
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{ select_limit_cnt= HA_POS_ERROR; offset_limit_cnt= 0; }
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bool check_offset(ha_rows sent) const
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@ -7761,8 +7761,8 @@ void mysql_init_multi_delete(LEX *lex)
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{
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lex->sql_command= SQLCOM_DELETE_MULTI;
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mysql_init_select(lex);
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lex->first_select_lex()->limit_params.select_limit= 0;
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lex->unit.lim.set_unlimited();
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lex->first_select_lex()->limit_params.clear();
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lex->unit.lim.clear();
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lex->first_select_lex()->table_list.
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save_and_clear(&lex->auxiliary_table_list);
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lex->query_tables= 0;
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@ -1340,7 +1340,7 @@ bool st_select_lex_unit::prepare(TABLE_LIST *derived_arg,
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else
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{
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sl->join->result= result;
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lim.set_unlimited();
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lim.clear();
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if (!sl->join->procedure &&
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result->prepare(sl->join->fields_list, this))
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{
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