Transactions in SQL Server’s In-Memory OLTP are rather straight forward. While there are probably optimizations that are not discussed, the basic design pattern is fairly easy to follow and could probably be reused in other projects.

Transactions in SQL Server’s In-Memory OLTP rely on a timestamp-like construct known as a Transaction ID. A transaction uses two timestamps, one for the beginning of the operation and one that is assigned when the transaction is committed. While multiple transactions can share the same start value.

Likewise each version of a row in memory has a starting and ending transaction id. The basic rule is that a transaction can only read data when RowVersion.StartingId <= Transaction.StartingId < RowVersion.EndingId.

For a DELETE operation, the row version’s ending id is initially set to the transaction’s starting id. Then a flag is set to indicate that a transaction is in process.

UPDATE operations begin like DELETE operations with the setting of an ending transaction id on the previous row version. Then a new row version is created with a starting transaction id that is equal to the transaction’s starting id. The ending id is initially set to infinity and again an active transaction flag is set. The old row version also gets a pointer to the new row version.

An INSERT operation is the same as an UPDATE without the need to delete the previous row version.

Commit and Validation

The commit phase starts by assigning a unique transaction id to current transaction. Then a validation process begins in which the affected records are checked for isolation errors. The type of errors depend on the level of transactional isolation requested. Only three levels, Snapshot, Repeatable Read, and Serializable, are supported by memory optimized tables.

Snapshot

Just like with normal tables, inserts into memory optimized tables can fail if another transaction has attempted to insert a row at the same time. But the way it fails is a bit different. Normally one transaction has to wait for the other to complete, after which the losing transaction just sees the duplicate row and never make the insertion attempt.

Here we instead see both transactions insert their row. After which they will read back the data to see if they won the race. If they don’t error 41325 is raised with the message “The current transaction failed to commit due to a repeatable read validation failure on table [name].”

Repeatable Read Transactions

MSDN has this warning about the repeatable read isolation level, “One important thing to note is that, because the repeatable read isolation level is achieved using blocking of the other transaction, the use of this isolation level greatly increases the number of locks held for the duration of the transaction.”

Since memory optimized tables don’t have locks, repeatable read works very differently for them. Rather than blocking other transactions, it rereads the rows at the end of the transaction. If any of them have changed, the transaction is aborted. This is reflected in error code 41305 with the message “The current transaction failed to commit due to a repeatable read validation failure on table [name].”

Serializable Transactions

Like Repeatable Read, Serializable Transactions traditionally relied on locks to keep other transactions from interfering with the data being examined. So instead it will check for to see if it failed to read any valid rows or encountered phantom rows. If either occurs then again the transaction will be aborted.

Post Processing

If validation is successful, the ending transaction id of each affected row version is set to the transaction’s ending id. Likewise the starting id for new row versions (e.g. from inserts and updates) is set to the transaction’s ending id. The active flags are cleared and the indexes are updated to point to the new records.

Garbage Collection

It should be noted that the indexes are not necessarily updated to remove pointers to the old row versions. Nor are the old versions deleted immediately.

Instead the Memory Optimized Tables require the use of a reference counted garbage collector. Details are not available yet, but based on the rest of the design its behavior is predictable. The GC will need to start at the indexes and check to see which of them point to out of date rows. When detected, it can decrement the reference counter and update the index to point to the most recent version of the row. If the counter reaches zero, then the row version is deleted.

The tricky part with the garbage collector is to know which rows to look at in the first place. One would speculate that simply iterating over all the rows of each index would be rather cost prohibitive.

Design Notes

When using In-Memory OLTP, developers need to be much more aware of their access patterns. If code isn’t written to avoid overlapping transactions then the resulting isolation level violations will make aborted transactions much more common than they would be using traditional tables.

Today, I will write about How to fix Error:  “The specified instance of SQL Server is hosted by a system that is not a Windows Server Failover Cluster(WSFC) node" on SQL Server 2012. And this is the error message:

The specified instance of SQL Server is hosted by a system that is not a Windows Server Failover Cluster(WSFC) node. (Microsoft.SqlServer.Management.HadrTasks)

The local node is not part of quorum and is therefore unable to process this operation. This may be due to one of the following reasons:

• The local node is not able to communicate with the WSFC cluster.
• No quorum set across the WSFC cluster.

The local node isn’t part of quorum and so unable to process that operation.This prompt me that perhaps the second instance doesn't understand itself its HADR enable. thus I qery sys.dm_hadr_cluster_members and sys.dm_hadr_cluster for both nodes.

On node1, it will come correct information. On node2, the result's empty.
SELECT *
FROM sys.dm_hadr_cluster_members;
Go
select * from sys.dm_hadr_cluster

The way to fix it's disable the HADR from SQL Server configuration manager . Bounce SQL Server and SQL agent. rentable HADR and bounce SQL server and SQL agent. The issue was resolved after second bounce

.

Today, I want to write about Change the Password Directly from Database on Joomla 3.4 Hosting. First, If the admin user is already defined, the best way is to vary the password within the database to a known password. This method requires that you just have direct access to the MySQL database using phpMyAdmin or another client.

Cautions: change your password after login

Following steps show how to manually reset a password to the word - "Admin"

1. Open phpMyAdmin and choose the database of your Joomla web site. On the Left Top side of the dropdown list will appear. It'll show all the database tables.
2. Find a table  " prefix_users" in the list of tables (note: prefix can depend upon your prefix value.).
3. Click on the "Browse" button in the top toolbar. it'll show all of the users for this web site.
4. Click on the " Edit icon " for user whose word you would like to change.
5. Modify password value to the following 
09b135d0d2022f04d1d679afec90cfc6:9z78xfHz0TFnmI8d4jHtvmk0QxayQJUv 

into the password field and press the Go button.
6. Log in with this user and password (Admin).
7. Then, after you logging again, change password from user Manager for this user.
8. Now, Select all of the users in User manager and also modify the password of others if your website was hacked.

Today, I will show you how to manage product attributes in PrestaShop 1.6. Attributes on PrestaShoip are the basis of product variations. You can only create variations of a product if at least one of its attributes changes and you can add multiple attributes.

1. First, You must Log Into your Prestashop 1.6  admin panel and Click on Catalog -> Product Attributes

2. Click the Add New Attributes button within the top right corner

3. On the Catalog -Attributes and Values - Add new Attribute web page enter the subsequent fields:

• name: for instance, shade (the name is perhaps not visible to the web page visitors)
• Public identify: e.g. shade (visible to your website visitors)
• URL: specific url layout in block layered generation
• Meta title: specific format for meta title
• Indexable: Use this attribute in url generated through the layered navigation module
• Attribute type: create a choice the type of the attribute

4. Then, Click Save. You're getting to see the attribute you only added in the list.

Now, We’ll Add the Attribute Values on Prestashop 1.6

1. On Catalog select Product Attributes, then click Add New Value.

2. Enter the fields as below:

• Attribute group: Select the type of the attribute, example: Color, etc.
• Value: The name of the value itself, for instance for Color.
• Meta title: The Specific format for your meta title.
• Color: You can Select a color with the color picker, or enter an HTML color code.
• Texture: Upload color texture from your PC.
  

  

4. Click on Save button at the bottom right or Save then add another value to feature additional values.
5. You may see all the values you added if you click Edit button for the attribute you added the values to under Catalog -> Product Attributes . You'll additionally edit or delete them from there.

Here are some tips and tricks you'll be able to use for Umbraco 7.2 CMS related developments. You'll be ready to use the following techniques to organise your Umbraco page URLs.

NiceUrl
This is the most common method for us to return a "Friendly URL" for a given node within the Umbraco content section. As explained in Umbraco, a 'Friendly url' is the complete encoded URL excluding the domain. however this relies on the settings you tack in UmbracoSettings.config file. If you set useDomainPrefixes=true in UmbracoSettings.config, NiceUrl returns the url as well as the domain.

NiceUrl with XSLT
Code for Return current page URL

<xsl:value-of select="umbraco.library:NiceUrl($currentPage/@id)" />
This code will return hyperlink to parent page
<a href="{umbraco.library:NiceUrl($currentPage/../@id)}">
  <xsl:value-of select="$currentPage/../@nodeName" />
</a>

NiceUrl with Razor
Return current page URL
@umbraco.library.NiceUrl(Model.Id)Hyperlink to parent page;
<a href="@umbraco.library:NiceUrl(Model.Parent.Id)">
  @Model.Parent.Name
</a>
Model is basically Razors equivalent of "$currentPage" in XSLT.

NiceUrl with C#
This will get the current page URL to a string
var currentNode = umbraco.presentation.nodeFactory.Node.GetCurrent();
string pageURL = umbraco.library.NiceUrl(currentNode.Id);
This will get the parent page URL to a string;
var currentNode = umbraco.presentation.nodeFactory.Node.GetCurrent();
string parentPageURL = umbraco.library.NiceUrl(currentNode.Parent.Id);

umbracoUrlAlias
As Umbraco explains, using the "umbracoUrlAlias" alias with a text-string property can change you to supply multiple URLs for a content node. For example if we were to enter "news,events/upcoming-events", this is able to resolve the following URLs to the same page
./news.aspx
/events/upcoming-events.aspx
Things to note: you must perpetually use umbracoUrlAlias field value in lowercase letters, not use a leading slash and not use a trailing ".aspx".

SQL 2014 is a great release from Microsoft and in this post I will describe information about Buffer pool extension in SQL Server 2014. In previous article, we have anylize new feature in SQL 2014.

As you know, the Buffer Pool is one of the main memory consumers in SQL Server. When you read data from your storage, the data is cached in the Buffer Pool. SQL Server caches Execution Plans in the Plan Cache, which is also part of the Buffer Pool. The more physical memory you have, the larger your Buffer Pool will be (configured through the Max Server Memory setting).

A lot of SQL Server customers are dealing with the problem that physical memory is restricted in database servers: all memory slots are already occupied, so how do you want to add additional memory to the physical server? Of course, you can migrate to a larger server, but that’s another story… The solution to this specific problem is the introduction of Buffer Pool Extensions in SQL Server 2014. 

Before I’m talking about the configuration and the concrete use of the Buffer Pool Extensions, I want to talk a little bit about the architecture and design behind the Buffer Pool Extensions. The traditional Buffer Pool of SQL Server always differentiates between clean and dirty pages. A clean page is a page which has the same content as the page in the storage. A dirty page is changed in memory, but hasn’t yet written to the storage. Around every minute the so-called CHECKPOINT process writes dirty pages out to the storage, means that our dirty page becomes a clean page

The Buffer Pool Extensions itself are only used if the Buffer Pool of SQL Server get’s into memory pressure. Memory pressure means that SQL Server needs more memory than currently available. In that case the Buffer evicts pages from the Buffer Pool, which were least recently used. SQL Server uses here a Least Recently Used Policy (LRU). If you have now configured an Extension File, then SQL Server will write these pages into it, instead of writing them directly out to our slow storage. If the page is a dirty one, then the page will be also concurrently written to the physical storage (through an asynchronous I/O operation). Therefore you can’t loose any data when you are dealing with the Buffer Pool Extensions. At some point in time your Extension File will be also completely full. In that case SQL Server has to evict older pages from the Extension File (again through a LRU policy), and finally writes them to the physical storage. The Extension File just acts as an additional layer between the Buffer Pool and the storage itself.

Let’s have now a look on how we can configure the Buffer Pool Extensions in SQL Server 2014. SQL Server offers you here the command ALTER SERVER CONFIGURATION SET BUFFER POOL EXTENSION. Let’s have a more detailed look on how you use it:

ALTER SERVER CONFIGURATION
SET BUFFER POOL EXTENSION ON
(
   FILENAME = 'd:\ExtensionFile.BPE',
   SIZE = 10 GB
)
GO

The first restriction that you are hitting here is the fact that the Extension File must have at least the same size as the Buffer Pool itself. If you are specifying a smaller file size, you will get a lovely error message from SQL Server:

Msg 868, Level 16, State 1, Line 1
Buffer pool extension size must be larger than the current memory allocation threshold 1596 MB. Buffer pool extension is not enabled.

The next restriction that you will definitely hit is that you can’t change the size of the Extension File during the runtime of SQL Server. For example, when you want to change the Extension File to a larger size, you have to disable the Buffer Pool Extensions, and re-enable them again. You will have of course a performance degradation in the time of this operation, because you are just disabling one important caching layer used by SQL Server!

Be aware of this fact, when you are planning a deployment of the Buffer Pool Extensions for your production environment!!!

And in addition you are also not able to reduce the size of the Extension File, the file must be always larger than previously. Otherwise you are again getting an error message:

Msg 868, Level 16, State 1, Line 3
Buffer pool extension size must be larger than the current memory allocation threshold 4096 MB. Buffer pool extension is not enabled.

The whole configuration of the Buffer Pool Extensions can be also retrieved through the Dynamic Management View sys.dm_os_buffer_pool_extension_configuration.

When should you use the Buffer Pool Extensions? Microsoft makes the recommendation that your workload should be write-heavy, e.g. a OLTP workload. You should not have a look on the Buffer Pool Extensions, when you are dealing with a DWH/BI related workload – an Extension File doesn’t make sense here. And when we are talking about the Extension File itself, you should spend a very fast SSD for it! Traditional rotational hard disks are a No-Go for it!

HostForLIFE.eu, a leading Windows web hosting provider with innovative technology solutions and a dedicated professional services team, today announced the support for PrestaShop 1.6 Hosting plan due to high demand of PrestaShop 1.6 users in Europe. HostForLIFE.eu hosts its servers in top class data centers that is located in Amsterdam, London and Seattle (US) to guarantee 99.9% network uptime. All data center feature redundancies in network connectivity, power, HVAC, security, and fire suppression. All hosting plans from HostForLIFE.eu include 24×7 support and 30 days money back guarantee.

PrestaShop 1.6 is a free and open-source e-commerce web application, committed to providing the best shopping cart experience for both merchants and customers. It is written in PHP, is highly customizable, supports all the major payment services, is translated in many languages and localized for many countries, is fully responsive (both front- and back-office), etc. PrestaShop 1.6 offers new and improved navigation elements making navigating your online shop easier and more effective than ever.

PrestaShop 1.6 presents a comprehensive, intuitive user administration panel, and gives you hundreds of standard functions that can be adapted or personalized in order to respond to all of customer needs. The front office template on PrestaShop 1.6 is now mobile responsive, allowing customer online shop to display perfectly when accessed from a mobile and tablet device.

At the forefront of the latest innovative web technology, PrestaShop 1.6 integrates with Bootstrap 3.0, FontAwesome, Sass Compass and D3 Data Driven Documents. Online Shopping has never been so technologically brilliant. A unique e-commerce feature you will only find in PrestaShop 1.6, Net Profit Margin is automatically updated in real-time.

Further information and the full range of features PrestaShop 1.6 Hosting can be viewed here http://hostforlife.eu/European-PrestaShop-16-Hosting

About HostForLIFE.eu
HostForLIFE.eu is an European Windows Hosting Provider which focuses on the Windows Platform only. HostForLIFE.eu deliver on-demand hosting solutions including Shared hosting, Reseller Hosting, Cloud Hosting, Dedicated Servers, and IT as a Service for companies of all sizes.

HostForLIFE.eu is awarded Top No#1 SPOTLIGHT Recommended Hosting Partner by Microsoft (see http://www.microsoft.com/web/hosting/HostingProvider/Details/953). Their service is ranked the highest top #1 spot in several European countries, such as: Germany, Italy, Netherlands, France, Belgium, United Kingdom, Sweden, Finland, Switzerland and other European countries. Besides this award, they have also won several awards from reputable organizations in the hosting industry and the detail can be found on their official website.

Previously, we have discussed about new features in SQL 2014. Now, in this article, I will discuss further about SQL 2014. What’s more interesting in newest SQL 2014?

Cache frequently used data on SSDs

You can specify an SSD (or an SSD array) to be used to extend memory. SQL Server 2014 will automatically cache data there with zero risk of data loss. (Only clean pages, not dirty pages, are stored there.) The best use case is for read-heavy OLTP workloads. This works with local SSDs in clusters, too – each node can have its own local SSDs (just like you would with TempDB) and preserve the SAN throughput for the data and log files.

AlwaysOn Availability Groups get more secondaries 

If you really need to scale out your reads, SQL 2014 gives you up to 8 secondaries (up from 4). Of course, you’ll be paying for Enterprise Edition licensing on these, but if you were already going to replicate data out to various reporting or BI servers, now your life is easier.

AlwaysOn AG readable secondaries will be more reliable

In SQL 2012, if your primary drops offline or the cluster loses quorum, the readable replica databases drop offline. In SQL 2014, the secondaries remain online and readable when the primaries aren’t available. However, keep in mind that typical AlwaysOn AG connections go through the AG listener name, and then fetch the list of readable replicas from the primary. This just means that in order to keep your report queries online, you can’t use the AG listener – you have to connect directly to the replica’s server name. I like using a separate set of DNS records for readable replicas, like readonly.mydomainname.com, and have my report servers point at those.

Failover Cluster Support for Clustered Shared Volumes

With regular volumes, only one node can own the volume at any given time. He owns the entire volume, and no other node can see/read/write files on that volume. However, Windows Server clusters have a type of drive volume called Clustered Shared Volumes with much more flexibility. Multiple cluster nodes can be connected to the same volume at the same time, but each node can access different files on the drive independently. Windows and Hyper-V have supported this for a while (see the BOL section on the benefits), and now SQL Server supports it too. The big benefit here is that if one node of the SQL Server cluster loses connectivity to the storage, it can still read and write data over the network to a different node’s SAN connection.

Hekaton: specialized in-memory OLTP tables

If your application is facing serious concurrency issues with thousands of simultaneous connections trying to lock data, Hekaton offers an intriguing solution. I’m not even going to try to type out an explanation here, but I’ll point out a few challenges with it:

You’ll probably need to change your data model. For example, identity fields aren’t supported – you’ll need to use a GUID as a primary clustered key.

You’ll also probably need to change your code. Hekaton works best with stored procedures, and specifically stored procs that it can compile into native code.

It’s memory-only. If you experience sudden data growth in your Hekaton tables, that means you can cache less of your other tables. If you run out of memory – well, let’s just say you’d better pray you don’t run out of memory, because hello, downtime.

Conclusion

Any question about newest SQL 2014? Or want to test the new SQL 2014 feature? Looking for SQL 2014 hosting? Try us as your SQL 2014 hosting solution.

Moodle 2.7.2 is a learning platform designed to provide educators, administrators and learners with a single robust, secure and integrated system to create personalised learning environments. Moodle 2.7.2 is a free, open source learning management system developed by educators for educators. In this secure, password protected environment, faculty can upload documents, assignment instructions, links to web sites and media. Learning can be extended beyond the limits of a traditional classroom setting through chat sessions, discussions, collaboration spaces, quizzes, surveys and more.

Moodle Hosting 2.7.2 Feature Improvements

1. Improve “Atto, a new, simple-to-use editor”
Neither formchangechecker, nor quiz autosave detects changes in Atto editors
2. Mathjax default SSL CDN address is down causing atto to fail to load, , has been updated in Moodle 2.7.2
3. Gradebook Sum of grades shows wrong total if items are hidden
4. URL parameter injection in CAS authentication
5. Identity information revealed early in Q&A forum
6. For Multiple choices questions in the quiz / question bank, the options "Clear incorrect responses" and "Show the number of correct responses" did not make sense for "One answer only" questions. It is now impossible to select that combination of options on the form.
7. Warning given when the same memcached instance is used for both sessions and MUC
8. Weekly stats now working again
9. Automatic emails now sent after users import from CSV
10. Parent role only sees course total and no longer individual grades

Moodle 2.7.2 Hosting FAQs

How do I install Moodle 2.7.2 in hosting account? - You can install Moodle 2.7.2 manually by uploading the package to hosting account or simply use the auto installer in hosting Plesk Control panel. By using auto installer, you will get latest update notification if you install Moodle 2.7.2 via auto installer.

How much should I pay for Moodle 2.7.2 hosting? - Depends your requirements, the shared hosting for moodle should be less than Є5.00/mo. If you need higher hosting requirements, we highly suggest you check out our page.

How much server resource do I need? - Moodle 2.7.2 is a little server resource sensitive because the more course you add and the more users you have, the more server resources will be used. 100MB memory is needed for regualar moodle 2.7.2 site smooth running.

On this occasion, I will explain you how change the default grid settings. In Prestashop 1.6, by default uses grid of 3 products at the category page and 4 products at the homepage.  Here are the steps that you must follow. PrestaShop 1.6 is a free and open-source e-commerce web application, committed to providing the best shopping cart experience for both merchants and customers. It is written in PHP, is highly customizable, supports all the major payment services, is translated in many languages and localized for many countries, is fully responsive (both front- and back-office), etc.

Prestashop 1.6 using Bootstrap, so we can change the class of the field. So, in this case changing default product display method to grid is in this version a bit different than method used in prestashop 1.5. Don’t Forget to Open file product-list.tpl and find this code:

<li class="ajax_block_product{if $page_name == 'index' || $page_name == 'product'} col-xs-12 col-sm-4
col-md-3{else} col-xs-12 col-sm-6 col-md-4{/if}{if
smarty.foreach.products.iteration%$nbItemsPerLine
== 0} last-in-line{elseif $smarty.foreach.products.iteration%$nbItemsPerLine == 1} first-in-line{/if}{if
$smarty.foreach.products.iteration > ($smarty.foreach.products.total - $totModulo)} last-line{/if}{if
$smarty.foreach.products.iteration%$nbItemsPerLineTablet == 0} last-item-of-tablet-line{elseif $smarty.foreach.products.iteration%$nbItemsPerLineTablet == 1} first-item-of-tablet-line{/if}{if
$smarty.foreach.products.iteration%$nbItemsPerLineMobile == 0} last-item-of-mobile-line{elseif
$smarty.foreach.products.iteration%$nbItemsPerLineMobile == 1} first-item-of-mobile-line{/if}{if
$smarty.foreach.products.iteration > ($smarty.foreach.products.total - $totModuloMobile)} last-mobile- line{/if}">

Find this columns classes:
{if $page_name == 'index' || $page_name == 'product'} col-xs-12 col-sm-4 col-md-3{else}
col-xs-12 col-sm-6 col-md-4{/if}
For homepage change class col-md-3 to col-md-2, and you will get 6 columns grid. For category page change class col-md-4 to class col-md-3, and you will get 4 columns grid. Change column class to any you need. Don’t forget to change number of products per line:

{*define numbers of product per line in other page for desktop*}
    {if $page_name !='index' && $page_name !='product'}       
    {assign var='nbItemsPerLine' value=4}      
    {assign var='nbItemsPerLineTablet' value=2}       
    {assign var='nbItemsPerLineMobile' value=3}

    {else}

        {assign var='nbItemsPerLine' value=6}

        {assign var='nbItemsPerLineTablet' value=3}

        {assign var='nbItemsPerLineMobile' value=2}

    {/if}