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Showing entries 1 to 10 of 1013 10 Older Entries

Displaying posts with tag: sql (reset)

Lowercase Table Names
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A student posed the question about why table names are case sensitive. That’s because case sensitive table names are the default installation, as qualified in the MySQL documentation. You can verify that with the following query:

SELECT CASE
         WHEN @@lower_case_table_names = 1 THEN
           'Case insensitive tables'
         ELSE
           'Case sensitive tables.'
         END AS "Table Name Status";

The default value returned on Linux is:

  [Read more...]
PostgreSQL Auto IDs
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PostgreSQL’s approach to automatic numbering is as simple as Oracle but different than MySQL, and Microsoft SQL Server. For example, you have a two-step process with Oracle, PostgreSQL, MySQL, and Microsoft SQL Server. First, you create an Oracle table with the GENERATED AS IDENTITY clause, a PostgreSQL table with the SERIAL data type, a MySQL table with the AUTO_INCREMENT clause, and a Microsoft SQL Server table with the IDENTITY(1,1) clause. Then, you need to write an INSERT statement for Oracle, MySQL, or Microsoft SQL Server like:

  1. Oracle’s INSERT statement …
  [Read more...]
5 free handy tools for monitoring and managing MySQL replication
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MySQL Replication is very simple to set up. In this post I’ll discuss its importance and five handy tools for monitoring and managing MySQL replication.

What is MySQL Replication? It’s the process of copying the (real-time events) data from one master instance to another slave instance and maintaining the redundant consistent data in a different machine. This enables a distributed database system that shares the same level of information.

In MySQL the replication works based on the three threads as shown below.

1) I/O thread on the slave server:  To start on receiving replication events, …

  [Read more...]
MySQL Cluster 7.4 is GA!
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The General Availability of MySQL Cluster 7.4 has just been announced by Oracle.

The MySQL team at Oracle are excited to announce the General Availability of MySQL Cluster 7.4, ready for production workloads.

MySQL Cluster 7.4.4 can be downloaded from mysql.com and the …

  [Read more...]
Popular Programming Languages
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First of all, Happy New Year!

IEEE Spectrum published a ranking of the most popular programming languages. Computational journalist Nick Diakopoulos wrote the article. While it may surprise some, I wasn’t surprised to find SQL in the top ten.

Nick weighted and combined 12 metrics from 10 sources (including IEEE Xplore, Google, and GitHub) to rank the most popular programming languages.

  • Compiled …
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Querying InnoDB Tables
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Somebody ran into the following error message trying to query the innodb_sys_foreign and innodb_sys_foreign_cols tables from the information_schema database:

ERROR 1227 (42000): Access denied; you need (at least one of) the PROCESS privilege(s) for this operation

It’s easy to fix the error, except you must grant the PROCESS privilege. It’s a global privilege and it should only be granted to super users. You grant the privilege global PROCESS privilege to the student user with the following command:

…  [Read more...]
MySQL Non-unique Indexes
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Somebody wanted to know how to find any non-unique indexes in information_schema of the MySQL. The query takes a session variable with the table name and returns the non-unique indexes by column names. It uses a correlated subquery to exclude the table constraints. A similar query lets you find unique indexes in MySQL. Both queries are in this post.

You set the session variable like this:

SET @sv_table_name := 'member_lab';

You can query the indexes result with the following query:

SELECT   s.table_name
,        s.index_name
, …
  [Read more...]
How much memory should we assign to MariaDB?
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How much memory should we assign to MariaDB?

Before answering, I’ll show you a procedure I use to get the amount of memory I’m using. See the comments to make it work on Oracle MySQL.

CREATE PROCEDURE _.show_buffers()
        CONTAINS SQL
        COMMENT 'Show information about buffers size'
BEGIN
        SET @memory_per_thread := (
                          @@global.read_buffer_size
                        + @@global.read_rnd_buffer_size
                        + @@global.sort_buffer_size
                        + @@global.thread_stack
                        + @@global.join_buffer_size
                        + …

  [Read more...]
Creating JSON documents with MariaDB
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You probably know about two MariaDB great features: Dynamic Columns and Virtual Colums. I don’t think that we already found all possible use cases for them: more ideas will come in the future, and hopefully someone will write about them. Here, I will describe a use case which involves both Virtual Columns and Dynamic Columns.

Now, suppose that we have relational data in MariaDB, and we want to …

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On Hadoop RDBMS. Interview with Monte Zweben.
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“HBase and Hadoop are the only technologies proven to scale to dozens of petabytes on commodity servers, currently being used by companies such as Facebook, Twitter, Adobe and Salesforce.com.”–Monte Zweben.

Is it possible to turn Hadoop into a RDBMS? On this topic, I have interviewed Monte Zweben, Co-Founder and Chief Executive Officer of Splice Machine.

RVZ

Q1. What are the main challenges of applications and operational analytics that support real-time, interactive queries on data updated in real-time for Big Data?

…  [Read more...]
Showing entries 1 to 10 of 1013 10 Older Entries

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