Category: Uncategorized

Useful T-SQL snippets for development and troubleshooting

This post is more of a note-to-self. These are the useful T-SQL statements which can be incredibly useful in development and troubleshooting

SET STATISTICS IO ON

Turn on the IO statistics for statements run after that until set to OFF explicitly. We then switch to Messages tab to see how many IO operations were done on each table.

SET STATISTICS TIME ON

Find out about the statements were executed: which statements, its texts, how many reads (logical), how many time was spent on CPU and how many time was spent total

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Choose your battles

This is the third part of the series: How to survive and thrive – a series for new developers to become better at their jobs. You can read the first two parts here and here.

In military, there is a term of “uphill battle”. That when you have to fight your way up a hill, when you enemy controls the top. It’s a very difficult fight and your chance of success is low. Any experienced military leader knows uphill battles are something you should avoid until there are no other options.

That also applies with any jobs. Including programming.

The truth is, you shouldn’t fight the battles you can’t win.
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Mass update catalog entries

This is something you don’t do daily, but you will probably need one day, so it might come in handy.

Recently we got a question on how to update the code of all entries in the catalog. This is interesting, because even thought you don’t update the codes that often (if at all, as the code is the identity to identify the entries with external system, such as ERPs or PIMs), it raises a question on how to do mass update on catalog entries.

    • Update the code directly via database query. It is supposedly the fastest to do such thing. If you have been following my posts closely, you must be familiar with my note regarding how Episerver does not disclose the database schema. I list it here because it’s an option, but not the good one. It easily goes wrong (and cause catastrophes), you have to deal with versions and cache, and those can be hairy to get right. Direct data manipulation should be only used as the last resort when no other option is available.

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The art of paging

No this is not really “art” – I’m just trying to have a more clickbait title. It’s more about understanding what you have at your disposal and use them for your benefits – in this case – how new SQL statement can drastically improve your performance.

In this blogpost we will look into paging feature of SQL Server. in Commerce we usually work with large set of data – millions of rows are fairly common, and it’s natural to load data by page. There is no point loading thousands, or even millions of rows in one go. First it’s not practical to display all of them. Second you’ll likely end up with an timeout exception and/or an out of memory exception. Even if you are lucky enough to get through, it’s still able to take your SQL Server instance to a knee, and transferring that much data over network will be another bottleneck for your system. So my friends, the best practice for loading data is to do it by batches, and to not load everything at once.

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Fixing a stored procedure

At Episerver development team, we understand the importance of good performance. Who would not like a lightning fast website? We work hard to ensure the framework is fast, and we seize (almost) every opportunity to make it faster.

You know in Commerce 10.2 we introduced a new cart mode – serializable cart, and it’s proven to bring great performance compared to the “old/traditional” approach. Our own tests showed an improvement of 3-5x times faster. But can it be even faster? Probably yes.

And actually we did some improvements in later versions. In the scope of this blog post, we will just focus into a specific aspect – and to learn a little more about SQL Server performance optimization.

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Maintaining your indexes

Indexes are crucial to SQL Server performance. Having the right indexes might make the difference of day and night with your application performance – as I once talked here.

However, even having the right indexes is not everything. You have to keep them healthy. Indexes, as any other kinds of storage, is subjected to fragmentation. SQL Server works best if the index structure is compact and continuous, but with all of the inserts/updates/deletes, it’s inevitable to get fragmented. When the fragmentation grows, it starts affecting the performance of SQL Server: Instead of having to read just one page, it now have to read two, which increases both time and resource needed, and so on and so forth.

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Episerver caching issue with .NET 4.7

Update 1: The bug is fixed in .NET 4.7.1 (thanks to Pascal van der Horst for the information)

Update 2: The related bug is fixed in CMS Core 10.10.2 and 9.12.5. If upgrading to that version is not an option, you can contact Episerver support service for further assistance.

Original post:

If you are using Episerver and update to .NET 4.7 (even involuntarily, such as you are using DXC/Azure to host your websites. Microsoft updated Azure to .NET 4.7 on June 26th) , you might notice some weird performance issues. If your servers are in Europe, Asia or Australia, then you can see a peak in memory usage. If your servers in North America, then you can see the number of database calls increased. In both cases, your website performance is affected, the former can cause your websites to constantly restarts as memory usage reaches a threshold limit, and even more obvious in the latter. Why?

It was a known issue in .NET 4.7, as mentioned here: https://support.microsoft.com/en-us/help/4035412/fix-expiration-time-issue-when-you-insert-items-by-using-the-cache-ins

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Import a bacpac to SQL Server

This is more of a note-to-self.

I sometimes have to import a bacpac file from customer’s database (usually from Azure SQL database) to my local machine – . For most of the time it’ll be very easy when the databases are in .bak format, but for .bacpac file it can be pretty complicated.

Sqlpackage.exe is the standard tool to import the .bacpac file, and it can be found with the installation of Visual Studio (for example `C:\Program Files (x86)\Microsoft Visual Studio\2017\Professional\Common7\IDE\Extensions\Microsoft\SQLDB\DAC\130`) or SQL Server ( `C:\Program Files (x86)\Microsoft SQL Server\130\DAC\bin` ). Latest version should be used because they can support the older formats (.bacpac exported from older SQL Server version), but not the way around (older version might not support .bacpac files exported from newer SQL Server versions)

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Price optimizing: to be or not to be

It can be quite confusing when you first edit prices in Episerver Commerce. To your surprises, some of the prices you imported or edited might disappear, or change, without your consent! What happened?

To answer that question, it’s essential to know there are two pricing system in Commerce: IPriceService and IPriceDetailService.

They have some different characteristics, and one of them is very important: the default implementation of IPriceDetailService saves prices as-is, while the default implementation of IPriceService does not: it optimizes prices before saving. Prices which are best for customers will be favored over the “less good” ones.

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Episerver CMS performance optimization – part 1

Update: In Episerver CMS 11, released today (November 21st 2017), the simpleaddress router has been moved to the last of the route table.

Original post:

This is an unusual post – it is not about Commerce – my area of expertise, but about CMS. Recently I’ve been working on some support cases where SQL Server instance is on high utilization, and in some scenarios it eventually slows down the site. After investigation, it’s likely to come from a small, simple and helpful feature: Simple address.

CMS content can have a property named “Simple address”, which allows you to create a “shortcut” url for that content. So if you have one page with “name in url” as “contact-us” under a page name “about-us” under Home page, you can access it via https://mysupercoolsite.com/en/about-us/contact-us. Or you can set the Simple address for that page as “contact-us”, and then you can access it directly via https://mysupercoolsite.com/contact-us.

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