mariadb/mysql-test/main/log_slow_innodb.result
Sergei Petrunia 513c827041 MDEV-34190: r_engine_stats.pages_read_count is unrealistically low
The symptoms were: take a server with no activity and a table that's
not in the buffer pool. Run a query that reads the whole table and
observe that r_engine_stats.pages_read_count shows about 2% of the table
was read. Who reads the rest?

The cause was that page prefetching done inside InnoDB was not counted.

This counts page prefetch requests made in buf_read_ahead_random() and
buf_read_ahead_linear() and makes them visible in:

- ANALYZE: r_engine_stats.pages_prefetch_read_count
- Slow Query Log: Pages_prefetched:

This patch intentionally doesn't attempt to count the time to read the
prefetched pages:
* there's no obvious place where one can do it
* prefetch reads may be done in parallel (right?), it is not clear how
  to count the time in this case.
2024-07-04 15:24:49 +03:00

94 lines
5.8 KiB
Text

CREATE TABLE t1(a INT primary key, b int) ENGINE=InnoDB;
INSERT INTO t1 select seq, seq from seq_1_to_1000;
SET SESSION min_examined_row_limit=0;
SET SESSION long_query_time=0;
SET SESSION log_slow_verbosity='innodb,query_plan';
[slow_log_start.inc] log_slow_innodb-verbosity_1
SELECT sum(a+b) FROM t1;
sum(a+b)
1001000
UPDATE t1 set b=b+1 where a=1 or a=999;
[log_slow_stop.inc] log_slow_innodb-verbosity_1
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Thread_id: .+ Schema: .+ QC_hit: (Yes|No)$ expected_matches: 3
[log_grep.inc] found expected match count: 3
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Query_time: \d+\.\d+ Lock_time: \d+\.\d+ Rows_sent: \d+ Rows_examined: \d+$ expected_matches: 3
[log_grep.inc] found expected match count: 3
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Rows_affected: \d+ Bytes_sent: \d+$ expected_matches: 3
[log_grep.inc] found expected match count: 3
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Full_scan: (Yes|No) Full_join: (Yes|No) Tmp_table: (Yes|No) Tmp_table_on_disk: (Yes|No)$
[log_grep.inc] lines: 1
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Filesort: (Yes|No) Filesort_on_disk: (Yes|No) Merge_passes: \d+\ Priority_queue: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Filesort: (Yes|No) Filesort_on_disk: (Yes|No) Merge_passes: \d+\ Priority_queue: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Tmp_tables: \d+ Tmp_disk_tables: \d+$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Pages_accessed: \d+ Pages_read: \d+ Pages_prefetched: \d+ Pages_updated: \d+ Old_rows_read: \d+$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_1 pattern: ^# Pages_read_time: \d+\.\d+ Engine_time: \d+\.\d+$ expected_matches: 2
[log_grep.inc] found expected match count: 2
SET SESSION log_slow_verbosity='innodb,query_plan';
[slow_log_start.inc] log_slow_innodb-verbosity_2
SELECT 1;
1
1
[log_slow_stop.inc] log_slow_innodb-verbosity_2
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Thread_id: .+ Schema: .+ QC_hit: (Yes|No)$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Query_time: \d+\.\d+ Lock_time: \d+\.\d+ Rows_sent: \d+ Rows_examined: \d+$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Rows_affected: \d+ Bytes_sent: \d+$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Full_scan: (Yes|No) Full_join: (Yes|No) Tmp_table: (Yes|No) Tmp_table_on_disk: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Filesort: (Yes|No) Filesort_on_disk: (Yes|No) Merge_passes: \d+\ Priority_queue: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Filesort: (Yes|No) Filesort_on_disk: (Yes|No) Merge_passes: \d+\ Priority_queue: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Tmp_tables: \d+ Tmp_disk_tables: \d+$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Pages_accessed: \d+ Pages_read: \d+ Pages_prefetched: \d+ Pages_updated: \d+ Old_rows_read: \d+$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_2 pattern: ^# Pages_read_time: \d+\.\d+ Engine_time: \d+\.\d+$
[log_grep.inc] lines: 0
SET SESSION log_slow_verbosity='query_plan';
[log_slow_stop.inc] log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000)
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Thread_id: .+ Schema: .+ QC_hit: (Yes|No)$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Query_time: \d+\.\d+ Lock_time: \d+\.\d+ Rows_sent: \d+ Rows_examined: \d+$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Rows_affected: \d+ Bytes_sent: \d+$ expected_matches: 2
[log_grep.inc] found expected match count: 2
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Full_scan: (Yes|No) Full_join: (Yes|No) Tmp_table: (Yes|No) Tmp_table_on_disk: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Filesort: (Yes|No) Filesort_on_disk: (Yes|No) Merge_passes: \d+\ Priority_queue: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Filesort: (Yes|No) Filesort_on_disk: (Yes|No) Merge_passes: \d+\ Priority_queue: (Yes|No)$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Tmp_tables: \d+ Tmp_disk_tables: \d+$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Pages_accessed: \d+ Pages_read: \d+ Pages_prefetched: \d+ Pages_updated: \d+ Old_rows_read: \d+$
[log_grep.inc] lines: 0
[log_grep.inc] file: log_slow_innodb-verbosity_3
--source include/log_slow_start.inc
INSERT INTO t1 VALUE(1000) pattern: ^# Pages_read_time: \d+\.\d+ Engine_time: \d+\.\d+$
[log_grep.inc] lines: 0
DROP TABLE t1;