What is Mysqldumpslow?
mysqldumpslow is a tool to examine the slow query log. It parses the slow query log files, printing a summary result. Normally, mysqldumpslow groups queries that are similar except for the particular values of number and string data values. It “abstracts” these values to N and ´S´ when displaying summary output.
What is Slow_query_log?
The slow query log consists of SQL statements that take more than long_query_time seconds to execute and require at least min_examined_row_limit rows to be examined. The slow query log can be used to find queries that take a long time to execute and are therefore candidates for optimization.
What is Lock_time MySQL?
The lock_time in the slow query log is actually the amount of time the query spent waiting to acquire the lock it needs to run. For example, UPDATES queries need a write lock. The locking also depends on the storage engine you are using in the table.
Does slow query log affect performance?
It is safe to log slow queries with execution time bigger than a second without worry about performance impact in case of CPU-bound workload. The performance impact is negligibly small in IO-bound workload even if all queries are logged.
How do I use PT query digest?
To use this feature, you run pt-query-digest with the –review option. It will store the fingerprints and other information into the table you specify. Next time you run it with the same option, it will do the following: It won’t show you queries you’ve already reviewed.
What is Log_queries_not_using_indexes?
log_queries_not_using_indexes tells MySQL to additionally log all queries that do not use an index to limit the number of rows scanned. Logging on this condition happens regardless of execution time.
Why is MySQL slow?
What is it? If your database is being used in high volumes, this can slow the database down. When there are too many queries to process at once, the CPU will bottleneck, resulting in a slow database.
Is MySQL 8 faster?
Transactions Processed. As shown in the graph above, MySQL 8.0 performance shows again a huge difference in the time it takes to process transactions. The lower, the better it performs which means it’s faster to process transactions.
What is query time in MySQL?
MySQL by default shows the time taken by the query to execute. Whenever you run a valid query, you will see the time of execution in seconds. Once executed, you can check the query execution time using the below query: show profiles; You will be able to see the duration of query execution in seconds.
What is explain in MySQL?
The EXPLAIN statement provides information about how MySQL executes statements: EXPLAIN works with SELECT , DELETE , INSERT , REPLACE , and UPDATE statements. That is, MySQL explains how it would process the statement, including information about how tables are joined and in which order.
What is query digest?
DESCRIPTION. pt-query-digest is a sophisticated but easy to use tool for analyzing MySQL queries. It can analyze queries from MySQL slow, general, and binary logs. (Binary logs must first be converted to text, see –type ). When the –review option is used, all unique queries are saved to a database.
How does mysqldumpslow abstract values in a query?
Normally, mysqldumpslow groups queries that are similar except for the particular values of number and string data values. It “abstracts” these values to N and ‘S’ when displaying summary output. To modify value abstracting behavior, use the -a and -n options.
What does the slow query log in MySQL mean?
The MySQL slow query log contains information about queries that take a long time to execute (see Section 5.4.5, “The Slow Query Log” ). mysqldumpslow parses MySQL slow query log files and summarizes their contents. Normally, mysqldumpslow groups queries that are similar except for the particular values of number and string data values.
Which is the Reference Manual for MySQL 5.7?
MySQL 5.7 Reference Manual / / The MySQL slow query log contains information about queries that take a long time to execute (see Section 5.4.5, “The Slow Query Log” ). mysqldumpslow parses MySQL slow query log files and summarizes their contents.