How to implement transactions in appian

Question

I have a process like this. I want to use transaction constraints on three write record nodes. Is there some easy way I can implement my require.

another question is what the functional of sync records. 
 I have read this document. https://docs.appian.com/suite/help/25.2/Sync_Records_Smart_Service.html But I don't understand the node's function and what scenario will use this node. I think when I use the write records, the data has already update into the database and sync automatically, why I need this node.

Harsha Sharma · Answer

For transaction constraints, its good to define the relationships between tables efficiently in database as well as during record type relationship configuration. You can allow the related records to be added/updated / deleted with the base records using single Write records node. You won't need three nodes and Appian will commit the transaction only if all the operations are performed without any errors. 
 I suggest to go through the below documents thoroughly to understand this : 
 docs.appian.com/.../Write_Records_Smart_Service.html 
 https://docs.appian.com/suite/help/25.2/record-type-relationships.html#allow-writes-and-deletes 
 Anyway if you want the transaction to be applied via code and logic let me know and I can share a workaround for that. 
 For sync records smart service - there are use cases when we want to sync the record deliberately to refresh data. E.g. some data manipulation is done via a store procedure call in process model and then you need to re-sync record data. Some other example use cases are mentioned here https://docs.appian.com/suite/help/25.2/Sync_Records_Smart_Service.html#examples

Shubham Aware · Answer

Constraints :- Instead of using three separate Write Records nodes, configure all three records in a single Write Records node. This automatically creates one transaction, ensuring that if any write fails, all operations roll back while maintaining all record and database relations. To understand sync record smart service first understand basics of sync record:- Sync Records synchronizes data from your database into Appian&rsquo;s record cache. What is Sync? --> Appian maintains a cache layer of your database data. Instead of querying the database every time, Appian retrieves data from this cache. Much faster data retrieval and better performance Database &larr; stores your actual data Sync Records &larr; copies/updates data from database to Appian cache Appian Cache &larr; fast, in-memory storage for quick access Record View/Queries &larr; read from cache instead of database. 
 When you make database changes (especially outside Appian or bulk operations), you use Sync Records to update Appian&rsquo;s cache with the latest database information like executing database insert script directly in database.

Shubham Aware · Answer

If you are using the latest version of Appian, you can write to different types of record types&mdash;within the same schema&mdash;using a single Write Records smart service, by passing each as a separate pv! of type Record.

Shubham Aware · Answer

Check release notes for 25.1

https://docs.appian.com/suite/help/25.1/Appian_Release_Notes.html#write-to-multiple-record-types-at-once

I tried writing multiple records of different type in single write record smart service.
For obvious reason write event will not work.