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Showing entries 1 to 10 of 85 10 Older Entries

Displaying posts with tag: performance_schema (reset)

Profiling Stored Procedures in MySQL 5.7
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With the changes to performance_schema in MySQL 5.7 Development Milestone Release it is now possible to analyze and profile the execution of stored programs. This is highly useful if you develop more complex stored procedures and try to find the bottlenecks. The "old" performance_schema up to MySQL 5.6 only reported a CALL statement with a runtime, but no information on statements that were executed WITHIN the stored procedure. Now let's try this in the latest MySQL 5.7.6 DMR release. After creating some test table and a test stored procedure we need to activate the events_statements_history_long consumer, which is OFF by default:



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Take the long view on the MySQL PERFORMANCE_SCHEMA with ps_history and sys_history
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The performance_schema is a powerful tool for analyzing MySQL performance and behavior. One aspect of the performance_schema is that the view of the data is "right now", and very little historical information is present. You can see that there are 10 threads connected right now, but what about five minutes ago?

ps_history
ps_history is a set of stored routines and events for periodically collecting the data in the performance_schema into another schema called ps_history. The ps_history schema contains a copy of each performance_schema view as a real table, and timestamp and server_id …


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Using Percona Cloud Tools to solve real-world MySQL problems
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For months when speaking with customers I have been positioning Percona Cloud Tools (PCT) as a valuable tool for the DBA/Developer/SysAdmin but only recently have I truly been able to harness the data and make a technical recommendation to a customer that I feel would have been very difficult to accomplish otherwise.

Let me provide some background: I was tasked with performing a Performance Audit for one of …

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Getting mutex information from MySQL’s performance_schema
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We have been using SHOW ENGINE INNODB MUTEX command for years. It shows us mutex and rw-lock information that could be useful during service troubleshooting in case of performance problems. As Morgan Tocker announced in his blog post the command will be removed from MySQL 5.7 and we have to use performance_schema to get that info.

The documentation of MySQL also says that most of the command output has been removed from 5.6 and that we can find similar info in performance_schema. It doesn’t show any …

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How well does your table fit in the InnoDB buffer pool in MySQL 5.6+?
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Some time ago, Peter Zaitsev posted a blog titled “How well does your table fits in innodb buffer pool?” He used some special INFORMATION_SCHEMA tables developed for Percona Server 5.1 to report how much of each InnoDB table and index resides in your buffer pool.

As Peter pointed out, you can use this view into the buffer pool to watch a buffer pool warm up with pages as you run queries. You can also use it for capacity planning. If you expect some tables need to be fully loaded in the buffer pool to be …

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Improvements for XA in MySQL 5.7
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Today I was doing some tests with XA transactions in MySQL 5.6.

The output of the XA RECOVER command to list transactions was hard to read because of the representation of the data column:

The good news is that 5.7 has transaction information in performance_schema:

mysql> select trx_id, isolation_level, state, xid, xa_state, access_mode 
-> from performance_schema.events_transactions_current; …





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Memory summary tables in Performance Schema in MySQL 5.7
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One of great innovation in MySQL 5.7 is memory summary tables в Performance Schema and corresponding views in sys schema

And as troubleshooting freak I have huge reason to greet this feature.

Before version 5.7 we had very limited abilities to diagnose memory issues in MySQL. We could use operating system tools, such as vmstat, top, free, but they only showed what MySQL server uses memory, but do not show how. In version 5.7 things changed. …



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Performance Schema memory tables and rightless users
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When I talk about troubleshooting I like to repeat: "Don't grant database access to everybody!" This can sound a bit weird having one can give very limited read-only access.

But only if ignore the fact what even minimal privileges in MySQL allows to change session variables, including those which control server resources. My favorite example is "Kill MySQL server with join_buffer_size". But before version 5.7 I could only recommend this, but not demonstrate. Now, with help of memory summary tables in Performance Schema, I can show how unprivileged user can let your server to use great amount of swap.

At first lets …



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pstop – a top-like program for MySQL (based on performance_schema)
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I have been working with MySQL for some time and it has changed significantly from what I was using in 5.0 to what we have now in 5.6. One of the biggest handicap we’ve had in the past is to not be able to see what MySQL is doing or why.

MySQL 5.5 introduced us to performance_schema. It was a good start but quite crude. MySQL 5.6 gave us a significant increase in stuff that allows you to see what is going on inside MySQL. That’s great, except it’s hard to read, the documentation is good, but not oriented at the DBA but more at the MySQL developer (that’s what it seems like at least). So most of us have ignored it. Others …

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When your query is blocked, but there is no blocking query
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When I queried information_schema.innodb_trx (introduced in 5.1 with the InnoDB Plugin) I noticed there were a few transactions in LOCK WAIT state.

Example:

mysql [information_schema] > select trx_id,trx_state 
    -> from information_schema.innodb_trx;
+--------+-----------+
| trx_id | trx_state |
+--------+-----------+
| 7974 | LOCK WAIT |
| 7962 | RUNNING |
+--------+-----------+
2 rows in set (0.00 sec)


Then I made a query to join a few information_schema and performance_schema tables to find out which query was blocking my …












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Showing entries 1 to 10 of 85 10 Older Entries

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