World forums support vote up/down now, and what does that mean for you

I really wanted to post this in the official blog, however we don’t have a “World” blog, and this does not really fit into “Commerce blog” which we (Commerce development team) usually use for official announcements, so I have to use my personal blog instead.

If you haven’t noticed, then you can now vote up, or down a post in World forum. Thanks to the hard work of my colleagues in World development team, that feature went on live today! (Of which I’m very excited)

If you have been using StackOverflow (as as developer, you likely have), then you know the meaning of voting up and down. The idea is the same here, there are differences in the detail implementations, such as the amount of points given (or taken) from a vote up (down), but basically:

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Loading carts in a load balancing environment

UPDATE 1: Apparently HttpContext.Current.Request.AnonymousID already uses the cookie internally, so there might be something that makes it stop working. I’ll update when I found out.

Today we received a support ticket as customers seeing corrupted carts data being lost – line items with invalid data, duplicated line items etc. “Corrupted data” is one of the alarming words that we take very seriously, so I decided to jump on it right away.

The setup is a load balancing environment, and the problem only happens with anonymous users. However, it can be “fixed” by turning on the sticky sessions mode. So basically, instead of having sessions on the memory of a server (so sessions on server A can’t be seen by server B, and vice versa), they need a mechanism (can be a database) to share sessions between servers.

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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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Lessons learned from a “boring” Black Friday

This Black Friday, I was in a task force, ready to help high profile DXC Commerce customers to cope with a peak in traffic. It turned out to be boring – there was no moment I could be a hero and “save the day”. Things went surprisingly smooth, even for websites which were struggling with last Black Friday. I went home and was little dissatisfied, but deep down, I know it was a huge success. The hard work from us (Commerce development team), them (the partner development teams), and Managed Services has been well paid off.

Use the latest version

You have heard me saying this, and you will probably hear from me again: Please, use the latest version possible. There is no reason to stay with an old version. This is a little truth: I hurt a little deep inside whenever I read a question on world asking a question about Commerce 7.5, or even 8.x. You should be using at least 10.8 by now, if not 11.x.

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Please, rebuild your database indexes, now

I will make it quick and to the point: if you are expecting a lot of customers visiting your site tomorrow (and you should) for Black Friday, you should rebuild your database indexes, now.

On average, it will help you to serve more customers and they will be happier with a more responsive, faster website. On best cases it will help prevent catastrophes.

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Read only Catalog UI – part 1

https://world.episerver.com/forum/developer-forum/Episerver-Commerce/Thread-Container/2015/6/read-only-catalog/

A while back, we had this question on World. It’s not uncommon to update the catalog data by an external system, mostly from a PIM – Product information management system. In such cases, it might not make senses to enable editing in Catalog UI. You might need the new UI for the other parts, such as Marketing UI, but you wouldn’t want the editors to accidentally update the product information – because those would be lost, anyway.

Is there away to do it? Yes, there is.

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Beware of IContentLoader.GetChildren() for CatalogContent

This is more of a self-to-note.

If you are using IContentLoader.GetChildren<T>(ContentReference), one important thing to remember is this uses the current preferred language. Normally when you get children of a catalog, or a node, that would not be a problem, because a catalog entity – node or entry, will be available in every language supported by the catalog. So if you just want to get the children references, the language is not important. (Note that, if you just need the children references, IRelationRepository should be a faster, more lightweight way to go, but that’s another story). If you want to get children in a specific language – which is the most common case, you know that you can use the other overload of GetChildren<T>(ContentReference, ILanguageSelector) , where you can specify the language you want to load.

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Super charged Episerver Commerce performance

Well, that was the title of my talk at the last week Meetup in Lund – hosted by Avensia. My first time in Lund – it is a very beautiful (small) city. It was a very nice event with about thirty developers from inside and outside Avensia, and I hope I did give some good information to make your Commerce solutions faster!

Then it comes to my attention that some of you might be interested in the talk. Unfortunately I don’t think the talk was recorded (I’d have been famous on Youtube!), but here’s the slides from the talk:

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A curious case of SQL execution plan, part 2

Recently I wrote about how to look into, identify and solve the problem with a SQL Server execution plan – as you can read here: http://vimvq1987.com/curious-case-sql-execution-plan/

I have some more time to revisit the query now, and I realized I made a “small” mistake. The “optimized” query is using a Clustered Index Scan

So it’s not as fast as it should be, and it will perform quite poorly in no cache scenario (when the buffer is empty, for example) – it takes about 40s to complete. Yes it’s still better than the original one, both in non cached and cached cases. But it’s not good enough. An index scan, even cached, is not only slower, but also more prone to deadlocks. It’s also worse in best case scenario, when the original one can use the proper index seek.

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A curious case of SQL execution plan

I said this already, and I will say it again: SQL Server optimizer is smart. I can even go further and say, it’s smarter than you and me (I have no doubt that you are smart, even very, very smart 🙂 ). So most of the cases, you leave it to do whatever it thinks is the best.

But there are cases SQL Server optimizer is fooled by the engine – it gets confused and chooses an sub-optimal plan, because it was given wrong, outdated, or incorrect information. That’s when you need to step in.

Today I face one case like that, as reported here: http://world.episerver.com/forum/developer-forum/Episerver-Commerce/Thread-Container/2017/10/database-timeout-on-productvariant-update/

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