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How are unique queries calculated in PT-query-Digest?
To calculate unique queries, pt-query-digest strips down values passed in the WHERE condition, removes all whitespaces (among others) and calculates a hash for a query. Such hash, called a ‘Query ID’ is used in pt-query-digest to differentiate between queries.
How to analyze your SQL workload using Pt-query Digest?
Using tcpdump, you can grab network traffic data – a good and low-impact method of collecting basic metrics for slow queries. So, now that you are sitting on top of a large pile of data, perhaps tens of gigabytes of logs, how do you get a whole picture of the workload?
How to collect data about slow SQL queries?
In our previous post, we discussed the different ways to collect data about slow queries – MySQL offers slow log, general log and binary log. Using tcpdump, you can grab network traffic data – a good and low-impact method of collecting basic metrics for slow queries.
How to calculate the number of queries executed in Percona?
For example, in this case we can see that the query executed 2 times, which is 13% of the total number of queries in the file. The min, max and avg columns are self-explanatory. The 95% column shows the 95th percentile; 95% of the values are less than or equal to this value.
What is the purpose of PT-query-Digest Percona?
By default pt-query-digest merely collects and aggregates data from the files specified. It is designed to be as efficient as possible, but depending on the input you give it, it can use a lot of CPU and memory.
What’s the cost of a commit in MySQL?
The main cost in COMMIT is flushing one write to the rollback log, regardless of how much went on in the transaction. Hardware — SSD – drops the 10ms to 1ms (or something like that); RAID with battery backed write cache – makes writes take virtually 0 ms, even without loss of safety.