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Showing entries 1 to 10 of 217 10 Older Entries

Displaying posts with tag: MySQL 5.6 (reset)

Is MySQL X faster than MySQL Y? – Ask queryprofiler
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When trying out new software there are many other questions you may ask and one of those is going to be the one above. The answer requires you to have built your software to capture and record low level database metrics and often the focus of application developers is slightly different: they focus on how … Continue reading Is MySQL X faster than MySQL Y? – Ask queryprofiler

Which accounts can access this data?
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Knowing which privileges a given account has is easy – just issue SHOW GRANTS FOR user@host.  But what about when you need visibility into privileges from the other direction – which accounts can access specific data?  If you’re a DBA – or perform DBA duties, regardless of your title – you may have been asked this question.  It’s an important question to ask in an audit or compliance review – but it can be a difficult question to answer.    This post will walk through how to assess this, but if you’re impatient and need answers to this question immediately, jump to the end – there’s a simple …

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Practical P_S: Find Client JRE Version Using SQL
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MySQL Connector/Java supports connection attributes since version 5.1.25.  This projects useful metadata about the client environment into the database, where MySQL administrators can query PERFORMANCE_SCHEMA tables to remotely survey application deployment environments.  One useful piece of information exposed is the version and vendor of the JVM in use by the client.  This very short blog demonstrates how to get this information from PERFORMANCE_SCHEMA.

The metadata including the Java runtime environment version and vendor can be found in PERFORMANCE_SCHEMA.SESSION_CONNECT_ATTRS table.  Here’s the full …

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State of Percona Server 5.6, MySQL 5.6 and MySQL 5.7 RC
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This week Oracle will release MySQL 5.7 GA, so it’s a perfect time to do a quick review of the current state of Percona Server 5.6.26, MySQL 5.6.26 and MySQL-5.7.8 RC. We used two boxes from our benchmark lab for this:
– Box 1: 16 Cores+HT (32 virt cores)/fast PCIe ssd card/RAM: 192GB
– Box 2: 24 Cores+HT(48 virt cores)/fast PCIe ssd card/RAM: 128GB

Dataset: sysbench/uniform, 32 tables with 12M rows each, ~95GB
Tests: sysbench – point select, oltp read only, oltp read/write
Test …



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Do not run those commands with MariaDB GTIDs - part # 2
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Update 2016-01-30: restarting the IO_THREAD might be considered useful in some situations (avoiding MDEV-9138).  Look for "in contrast, if the IO thread was also stopped first" in MDEV-6589 for more information.

In a previous post, I listed some sequences of commands that you should not run on a MariaDB slave that is lagging and which is using the GTID protocol.  Those are the following (do not

Create MySQL Index
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Indexes are separate data structures that provide alternate pathways to finding data. They can and do generally speed up the processing of queries and other DML commands, like the INSERT, UPDATE, REPLACE INTO, and DELETE statements. Indexes are also called fast access paths.

In the scope of the InnoDB Database Engine, the MySQL database maintains the integrity of indexes after you create them. The upside of indexes is that they can improve SQL statement performance. The downside is that they impose overhead on every INSERT, UPDATE, REPLACE INTO, and …

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Unexpected Memory Consumption for Bulk Index Creation in InnoDB (MySQL)
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In my last Booking.com Hackathon, I worked on MyISAM vs InnoDB for data loading (LOAD DATA IN FILE) and bulk index creation.  My motivation was the following: knowing that some are still using MyISAM for this particular use-case, I wanted to verify/understand if/why InnoDB is slower than MyISAM.  I do not yet have complete results on this specific subject but I found some interesting things that

Advanced Query Tuning in MySQL 5.6 and MySQL 5.7 Webinar: Q&A
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Thank you for attending my July 22 webinar titled “Advanced Query Tuning in MySQL 5.6 and 5.7” (my slides and a replay available here). As promised here is the list of questions and my answers (thank you for your great questions).

Q: Here is the explain example:

mysql> explain extended select id, site_id from test_index_id where site_id=1
*************************** 1. row ***************************
           id: 1
  select_type: SIMPLE
        table: test_index_id
         type: ref …
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How much could you benefit from MySQL 5.6 parallel replication?
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I have heard this question quite often: “At busy times, our replicas start lagging quite frequently. We are using N schemas, so which performance boost could we expect from MySQL 5.6 parallel replication?” Here is a quick way to give you a rough estimate of the potential benefit.

General idea

In MySQL 5.6, parallelism is added at the schema level. So in theory, if you have N schemas and if you use N parallel threads, replication could be up to N times faster. This assumes at least 2 things:

  • Replication throughput scales linearly with the number of parallel threads.
  • Writes are …
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SSL/TLS Connections to Recent MySQL Servers in Java
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Recent changes to support better security by increasing strength of Diffie-Hellman cipher suites from 512-bit to 2048-bit were introduced to MySQL Server 5.7. While this change enhances security, it is an aggressive change in that 2048-bit DH ciphers are not universally supported. This has become a problem specifically for Java users, as only Java 8 JRE (currently) supports DH ciphers greater than 1024 bits. Making the problem more acute, this change was back-ported from MySQL Server 5.7 to the recent …

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Showing entries 1 to 10 of 217 10 Older Entries

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