itopiz

itopiz

Are you using in-memory projections with CQRS/ES commanded?

Hi,

I am working on an application using CQRS and Event Sourcing with the help of the commanded library.

I am interesting in using in-memory projections for some of my read models instead of persisting them to a database (for example).

Does anyone (@slashdotdash? ) have experience with this and feedback to share?

Thank you

Marked As Solved

slashdotdash

slashdotdash

The next version of EventStore has support for transient subscriptions (#215). These subscriptions won’t persist the last seen event so if you restart the subscription it will replay all the events from wherever you configure it to start from (origin, current, or specific event number). You could use this feature to have projections replay their events each time they start.

The downside of this approach is that it will take longer to build the projection as more events are stored. For this reason I always prefer to use persistent read model projections and not rebuild them from scratch. A hyrbid approach might be to snapshot the projection after a certain number of events and then rebuild the projection starting with the latest snaphot and creating a subscription from the next event after the snapshot’s version.

Also Liked

slashdotdash

slashdotdash

I have now published EventStore v1.2.0 to Hex so you can start using transient subscriptions.

Last Post!

slashdotdash

slashdotdash

I have now published EventStore v1.2.0 to Hex so you can start using transient subscriptions.

Where Next?

Popular in Questions Top

rms.mrcs
Hi, I need to transform a list of numbers into a map where the keys are the indexes and the values are the original values of the list. ...
New
jononomo
I am trying to figure out how Mix knows whether the environment is test, dev, or prod – where is this set? Thanks.
New
Qqwy
Original source of discussion: This topic on the Pragmatic Programmers’ Functional Web Development with Elixir, OTP, and Phoenix forum. ...
New
Lily
In templates/appointment/index.html.eex: <%= for appointment <- @appointments do %> <tr> <td><%= appoi...
New
WestKeys
Currently suffering from paralysis by [HTTP client] analysis. This is rather unusual in Elixirland as there tends to be consensus on the ...
New
Harrisonl
We have an ECS cluster with 4 services, where each task joins a single cluster, via discovery ECS discovery service. Currently when I de...
New
jason.o
In the code below, if the create action is not set to accept “extra_key” as an input, it errors out with a message shown above. Is there ...
New

Other popular topics Top

electic
Hi, I am new to Elixir. I am trying to use the DateTime component to insert a date into MySQL however the there seems to be no way to fo...
New
stefanchrobot
What’s the safe way to decode a JSON string into a struct? I want to avoid calling String.to_atom. Jason.decode can give me a map with st...
New
Darmani72
If I have a post route which an argument: post /my_post_route/:my_param1, MyController.my_post_handler How would get the post params ...
New
joeerl
Hello again - after a longish gap I’ve decided I really must dig into Elixir and see what’s been happening here - so I have a few questio...
New
gshaw
What is the idiomatic way of matching for not nil in Elixir? E.g., First way: defp halt_if_not_signed_in(conn, signed_in_account) when...
New
AstonJ
Posting this to see if we can make things easier for people to get into Neovim. If you use Neovim and have a favourite distro please let ...
New

We're in Beta

About us Mission Statement