Shulou(Shulou.com)05/31 Report--

What is the state of insert..selcet sending data in RR mode? in view of this problem, this article introduces the corresponding analysis and solution in detail, hoping to help more partners who want to solve this problem to find a more simple and feasible way.

For example:

What does the word sending data mean? The isolation level is RR and the statement is insert..select.

II. About sending data

I've talked about this before, but in fact, sending data may include the following:

The location of Innodb layer data is returned to MySQL layer.

The query of the Innodb layer data is returned to the MySQL layer

Modification of Innodb layer data (if insert..select)

Innodb layer locking and waiting

Wait to enter the Innodb layer (innodb_thread_concurrency parameter)

The MySQL layer sends data to the client

III. Summary of the reasons why insert..selcet is in sending data in RR mode

In RR mode, the select table of insert..select will have an S row lock, and if the row is in an X lock, the sending data state will appear.

If the insert record in insert..selcet is blocked (uniqueness check), it will be in sending data state

If the whole process needs to operate a large amount of data, it is in the state of sending data.

IV. | | THD::enter_stage: 'Sending data' / cdh/mysqldebug/percona-server-5.7.29-32/sql/sql_executor.cc:202 930Troup4: | | > PROFILING::status_change 931Troup4: | | do_select 934Troup4: | > sub_select 935Thum4: | | | | > init_read_record 936Troup4: | info: using rr_sequential 937Troup4: | > ha_rnd_init 938Troup4: | > change_active_index 939Troup4: | > innobase_get_index 940Troup4: | index_read 950Thum4: | | | | | > row_search_mvcc 951Troup4: | > row_sel_store_mysql_rec 952Troup4: | | > row_sel_store_mysql_field_func 953Troup4: | | row_sel_store_mysql_field_func 955Troup4: | | | | ha_innobase::write_row 981 Tester 4: | | > row_ins 982 Tester 4: | row_ins: table: test/testbb 983 Tester 4: | > row_ins_index_entry_step 984 Tester 4: | | > row_ | Ins_clust_index_entry 985 Tester 4: | > row_ins_clust_index_entry_low 986 Tester 4: | | > btr_cur_search_to_nth_level 987 Tester 4: | | thd_report_row_lock_wait 989 Tester 4: | | | |

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