MySQL Shell 8.0.21 includes some exciting
new utilities to create a logical dump and do a logical restore,
with a focus on ease of use, performance and integration. In
MySQL Shell 8.0.17, we already introduced
a multi-threaded CSV import utility util.importTable()…
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This tutorial help to import the csv data into MySQL and export data from MySQL to csv file.The CSV file is used to import and export data for moving/exchange data information between web application.You can use rest api or web application to import/export CSV data. The web application data is stored, accessed and exchanged between […]
The post How To Import/Export CSV Data Using MySQLi and PHP 7 appeared first on Phpflow.com.
A small thing that provides a huge help.
The other day I was writing some code to process a very large amount of items coming from a social media API. My items were ending in a queue in MySQL and then needed to be processed and eventually moved.
The task was not so strange, but what I have to do is to develop a queue processor. Now when you need to process a queue you have two types of queue: static and dynamic.
The static comes in a batch of N number of items in a given time interval and is normally easier to process given you have a defined number of items that you can split in chunks and process in parallel.
The dynamic is… well… more challenging. One option is to wait to have a predefined number of items, and then process them as if they were a static queue.
But this approach is not very good, given it is possible that it will delay a lot …
[Read more]A small thing that brings huge help.
The other day I was writing some code to process a very large amount of items coming from a social media API. My items were ending in a queue in MySQL and then needed to be processed and eventually moved.
The task was not so strange, but what I have to do is to develop a queue processor. Now when you need to process a queue you have two types of queue: static and dynamic.
The static comes in a batch of N number of items in a given time interval and is normally easier to process given you have a defined number of items that you can split in chunks and process in parallel.
The dynamic is… well... more challenging. One option is to wait to have a predefined number of items, and then process them as if they were a static queue.
But this approach is not very good, given it is possible that it will delay a lot the …
[Read more]Foreign Keys are what links tables together and turns a set of tables into a model. Foreign Key Constraints are conditions that must be true for the content of the tables to be an internally consistent model. Foreign Key Constraints can be defined and enforced in InnoDB, but this comes at a considerable price, and for some it may hurt more than it is worth.
A very simple shop as a ER-model. order_id is
the primary key of the Orders table. customer_id in
the Orders table is a foreign key: The primary key of another
(“foreign”) table in this table. Foreign keys can model
relationships between tables (“entities”) in an
entity-relationship diagram.
Entities and their relationships
In Entity-Relationship modelling we are using tables in a database to model entities in the real world. Each entry in such a table is meant to represent a “thing” in the real world. For example, in our …
[Read more]
As a data architect I always ensure that for any database schema
change there a fully recoverable execution path.
I have generally advised to create a patch/revert process for
every change. For example, if a change adds a new column or
index to a table, a revert script would remove the respective
column or index.
The goal is to always have a defensive position for any changes.
The concept is that simple, it is not complex.
In its simplest form I use the following directory and file structure.
/schema
schema.sql
/patch
YYYYMMDDXX.sql where XX,ZZ are sequential 2 digit numbers, e.g. 01,02
YYYYMMDDZZ.sql
/revert
YYYYMMDDXX.sql This is the same file name in the revert sub-directory.
YYYYMMDDZZ.sql
At any commit or tag in configuration management it is possible
to create a current copy of the schema, i.e. use
schema.sql.
It is also possible to take the first …
Support Channel. “Hi, I am getting deadlocks in the database and they occur when I have to rollback the transactions but if we don’t have to roll back all transactions get executed.” Wait, what? After some back and forth it becomes clear that the Dev experiences deadlocks and has data:
mysql> pager less
mysql> show engine innodb status\G
...
MySQL thread id 142531, OS thread handle 139990258222848, query id 4799571
somehost.somedomain someuser update
INSERT into sometable (identifier_id, currency, balance ) VALUES ('d4e84cb1-4d56-4d67-9d16-1d548fd26b55', 'EUR', '0')
*** (2) HOLDS THE LOCK(S):
RECORD LOCKS space id 3523 page no 1106463 n bits 224 index PRIMARY of table `somedb`.`sometable` trx id 9843342279 lock mode S locks gap before rec
and that is weird because of the lock mode S locks
gap in the last line. We get the exact same statement with
the exact same value on the second thread, but with lock …
In a previous article we wrote data to the database
using atomic update statements, and then using transactions with
SELECT ... FOR UPDATE. In this article we will look
at what happens when we continue doing this, in a more
complicated way. Source code for this article is also available on github.com.
A simple row lock
But first let’s do things manually: We create a table
kris with an integer primary key column and a
secondary unindexed data column. We are filling it with some
records with gaps between the primary keys.
We then START TRANSACTION READ WRITE and
SELECT ... FOR UPDATE a record:
Session1> create table kris ( id serial, …[Read more]
A student question: Does JavaScript make context switching for web-based applications obsolete? Wow! I asked what that meant. He said, it means JavaScript replaces all other server-side programming languages, like PHP, C#, or Python. I asked the student why he believed that. His answer was that’s what two interviewing managers told him.
I thought it would be interesting to put the idea to a test.
Below is a Node.js script that acts as a utility that
queries the MySQL database with substitution variables in query.
It also returns a standard out (stdout) stream of
the MySQL query’s results. It also supports three flag and value
pairs as arguments, and optionally writes the results of the
MySQL query to a log file while still returning result as the
stdout value. All errors are written to the standard
error (stderr) stream.
The Node.js solution is completely portable between Windows …
[Read more]Watch this on-demand webinar to learn the right way to deploy geo-distributed databases. We look at the pitfalls of deploying a single site and passive sites, and from there we show how to provide the best user experience by leveraging geo-distributed MySQL.
Tags: MySQL Geo-Distributed mysql clustering single site passive site best practices Webinar …
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