Log Buffer #511: A Carnival of the Vanities for DBAs

This Log Buffer Edition covers Oracle, SQL Server, MySQL.

Oracle:

A Sneak Peek at Oracle’s Chatbot Cloud Service and 5 Key Factors Necessary for Bot ROI

Oracle JET Hybrid – NavDrawer Template Menu/Header Structure

Oracle Enterprise Linux 6.6 AMI Available on AWS

Datascape Podcast Episode 9 – What’s Up with Oracle These Days?

Sequential Asynchronous calls in Node.JS – using callbacks, async and ES6 Promises

SQL Server:

Fixing an SSRS Password Error while (more...)

How to make dashboard using PostgreSQL database

PostgreSQL is a powerful, open source object-relational database system. It has more than 15 years of active development and a proven architecture that has earned it a strong reputation for reliability, data integrity, and correctness. It runs on all major operating systems, including Linux, UNIX (AIX, BSD, HP-UX, SGI IRIX, macOS, Solaris, Tru64), and Windows.

Are you using PostgreSQL for your data marts or data-warehouse? If so, build your Free PostgreSQL performance dashboard software.

Read (more...)

How to create dashboard for MySQL database

MySQL is the most popular Open Source SQL database management system. Due to its reliability and easy-to-use structure, MySQL is widely used within almost any industry. It is used by both small and big businesses. Among MySQL users you can find such huge companies like Facebook, Youtube, Twitter,etc.

Using MySQL with InfoCaptor does not require any JDBC driver as it uses native PHP drivers. In case you need to use JDBC drivers, please check this (more...)

Log Buffer #508: A Carnival of the Vanities for DBAs

This Log Buffer Edition covers Oracle, SQL Server and MySQL.

Oracle:

Compiling views: When the FORCE Fails You

Goldengate 12c Troubleshooting XAGENABLE

A performance Deep Dive into Tablespace Encryption

EBS Release 12 Certified with Safari 10 and MacOS Sierra 10.12

Oracle Database 12c (12.2.0.1.0) on VirtualBox

SQL Server:

A Single-Parameter Date Range in SQL Server Reporting Services

Generating Plots Automatically From PowerShell and SQL Server Using Gnuplot

Justify the (more...)

Log Buffer #507: A Carnival of the Vanities for DBAs

This Log Buffer edition covers Oracle, SQL Server and MySQL blog posts with a touch of Cloud.

Oracle:

Provisioning EBS on Oracle Cloud: Latest Enhancements

ORA-54002 when trying to create Virtual Column using REGEXP_REPLACE on Oracle 12cR2

Business rules, common sense and query performance

Problem with V$RECOVERY_AREA_USAGE view and FRA space not being reclaimed

Updated SQLcl: 2 New Commands, Bug Fixes, and 12cR2 Oh My!

SQL Server:

Windowing Functions: Tell me (more...)

Presentation: Making MySQL highly available using Oracle Grid Infrastructure

I published my 2014 presentation “Making MySQL highly available using Oracle Grid Infrastructure” in Slideshare. You can view it here:

Wanted: RDBMS superpower summary for app developers

At last night's WWCode Cincinnati panel, I recommended that developers talk to their DBA about what advanced capabilities their RDBMS can offer, so that they don't end up reimplementing functionality in the app that are already available (better and more efficiently) in the database itself. Devs can waste a lot of effort by thinking of databases as dumb, inert data boxes.

I was asked an excellent question: "Where can a dev quickly familiarize herself with (more...)

Couchbase 4.0 and related subjects

I last wrote about Couchbase in November, 2012, around the time of Couchbase 2.0. One of the many new features I mentioned then was secondary indexing. Ravi Mayuram just checked in to tell me about Couchbase 4.0. One of the important new features he mentioned was what I think he said was Couchbase’s “first version” of secondary indexing. Obviously, I’m confused.

Now that you’re duly warned, let me remind you of aspects of (more...)

Confusion and problems with lost+found directory in MySQL/Galera cluster configuration

The lost+found directory is filesystem directory created at root level of mounted drive for ext file systems. It is used by file system check tools (fsck) for file recoveries.

In MySql world it can cause confusion or possible problems with synchronisation in Galera cluster configuration.

Let’s check some examples.

I have MySQL database with datadir=/data in configuration file. I have deleted lost+found directory and restarted MySQL service.

When I list my databases this is result:

(more...)

Test MySQL on AWS quickly

Using sysbench to performance test AWS RDS MySQL hardware is an easy three step  operation. 

Sysbench creates synthetic tests and they are done on a 1 mil row 'sbtest' table that sysbench creates in the MySQL database you indicate. The test doesn't intrude with your database schema, and it doesn't use your data, so it is quite safe. The test is an OLTP test trying to simulate event operations in the database as it (more...)

MariaDB – Measure Replicaton Lag and Check / Fix Replication Inconsistencies using Percona tools

Percona Toolkit is collection of command-line tools to perform many MySQL tasks like creating backups, finding duplicate indexes, managing replication, etc.

In this post I will talk about how to measure replication lag and check/fix replication inconsistencies with this tools:
pt-heartbeat
pt-table-checksum
pt-table-sync


I am using environment from previous blog post.
Master-Master replication with MariaDB 10.0.16 database on Debian 7.


Install Percona Toolkit on both nodes:


$ sudo wget percona.com/get/percona-toolkit.deb

$ (more...)

MariaDB(MySQL) Master-Master Replication

The simplest and probably most common replication method is master-slave replication. Basically, data is replicated from master database to the slave. In case of master database failure you must get the slave database up-to-date before failover and then promote slave to be new master.

Another method is to set up replication in both directions called master-master replication. But you must be aware that this setup brings some potential issues as data changes are happening on (more...)

MySQL Locking

Have you ever wondered if MySQL does Row Level Locking? Or wondered why are you getting the error:

ERROR 1205 (HY000) : Lock wait timeout exceeded; try restarting transaction

You get the error because your allocated time to hold a DML lock in a transaction exceeds the set limit. Usually the default limit to hold a DML row lock, set by innodb_lock_wait_timeout db parameter, is 50 seconds. If your transaction doesn't commit/rollback within 50 seconds (more...)

Thoughts and notes, Thanksgiving weekend 2014

I’m taking a few weeks defocused from work, as a kind of grandpaternity leave. That said, the venue for my Dances of Infant Calming is a small-but-nice apartment in San Francisco, so a certain amount of thinking about tech industries is inevitable. I even found time last Tuesday to meet or speak with my clients at WibiData, MemSQL, Cloudera, Citus Data, and MongoDB. And thus:

1. I’ve been sloppy in my terminology around “geo-distribution”, in (more...)

rdbms-subsetter

I've never had a tool I really liked that would extract a chunk of a large production database for testing purposes while respecting the database's foreign keys. This past week I finally got to write one: rdbms-subsetter.

rdbms-subsetter postgresql://user:passwd@host/source_db postgresql://user:passwd@host/excerpted_db 0.001

Getting it to respect referential integrity "upward" - guaranteeing every needed parent record would be included for each child row - took less than a day. Trying to get it to also guarantee (more...)

%sql: To Pandas and Back

A Pandas DataFrame has a nice to_sql(table_name, sqlalchemy_engine) method that saves itself to a database.

The only trouble is that coming up with the SQLAlchemy Engine object is a little bit of a pain, and if you're using the IPython %sql magic, your %sql session already has an SQLAlchemy engine anyway. So I created a bogus PERSIST pseudo-SQL command that simply calls to_sql with the open database connection:

%sql PERSIST mydataframe

The result is (more...)

auto-generate SQLAlchemy models

PyOhio gave my lightning talk on ddlgenerator a warm reception, and Brandon Lorenz got me thinking, and PyOhio sprints filled my with py-drenaline, and now ddlgenerator can inspect your data and spit out SQLAlchemy model definitions for you:


$ cat merovingians.yaml
-
name: Clovis I
reign:
from: 486
to: 511
-
name: Childebert I
reign:
from: 511
to: 558
$ ddlgenerator --inserts sqlalchemy merovingians.yaml

from sqlalchemy import create_engine, Column, Integer, Table, Unicode
engine (more...)

ddlgenerator

I've had it on github for a while, but I finally released ddlgenerator to PyPI.

I've been frustrated for years that there was no good open-source way to set up RDBMS tables from flat data files. Sure, you could import the data - after setting up the DDL by hand. ddlgenerator handles that; in fact, you can go from zero, setting up and populating a table in a single line. Nothing up my sleeve:


$ (more...)

ipython-sql for multi-database comparisons

For my newest ipython-sql trick, I needed to compare some queries run across different databases. How hard would it be to get side-by-side results into tidy IPython Notebook output?

Not hard at all, it turns out, if you're willing to violate basic principles of human decency.

That's an itty-bitty image, (more...)

When to consider sharding a MySQL database

Uncategorized
| Mar 13, 2013

When to consider sharding a MySQL database

 

Why should you not just design your applications from the start to account for data sharding? Sharding a database, that is horizontally partitioning tables among multiple databases, creates an added level of complexity that is not desirable in an application. However, there are times when sharding is required to maintain acceptable performance. So when is the right time to shard your database?

 

When to consider sharding a MySQL database   Why should you not just design your applications from the start to account for data sharding? Sharding a database, that is horizontally partitioning tables among multiple databases, creates an added level of complexity that is not desirable in an application. However, there are times when sharding is […]

-->