C#, SQL, Episerver/Optimizely, performance, and beyond
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.
Continue reading “Please, rebuild your database indexes, now”
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.
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.
Continue reading “Beware of IContentLoader.GetChildren() for CatalogContent”
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:
Continue reading “Super charged Episerver Commerce performance”
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.
Continue reading “A curious case of SQL execution plan, part 2”
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/
Recently I worked on a support case where a customer reported deadlocks and timeout exceptions on queries to a specific table – NodeEntryRelation. Yes, it was mentioned in this post. However, there is more to it.
Keeping the indexes healthy definitely help to improve performance and avoid deadlocks and timeout exceptions. However it can only work to a limit, because even if the indexes are in their perfect state (the fragmentation level is 0%), the query will still take time.
Looking in the query we talked about – ecf_Catalog_GetChildrenEntries – what does it do. It lists the entries which are direct children of a catalog. So normally entries belong to categories (nodes), but it’s possible (Although not recommended) to have entries that belong directly to a catalog.
Continue reading “Episerver Commerce catalog performance optimization – part 4”
Recently I stumped upon this question:
which is very interesting to me. I can see this is a real scenario – and even quite common. When a price become obsolete, you want your contents to be reindexed so the next time you query, the search result will be returned correctly. But how?
Continue reading “Reindex obsolete prices in Episerver Commerce”
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.
This is an unusual post – as I usually don’t post sample code – that should be the job of the documentation. However, I jumped upon this question http://world.episerver.com/forum/developer-forum/Episerver-Commerce/Thread-Container/2017/8/global-price-increase/, and found it to be an interesting case to demo.
It’s worth noting that as a customer, I’d like price drops, not the way around, so in this example, we will see how to cut prices of all products to 5%, instead of making them 5% more. Of course, it’s just simple mathematics, so you can change to the formula however you want.