I have a full deployment of couchbase (server, sync gateway and lite) and have an API, mobile app and web app all using it.
It works very well, but I was wondering if there are any advantages to using the Sync Gateway API over the Couchbase SDK? Specifically I would like to know if Sync Gateway would handle larger numbers of operations better than the SDK, perhaps an internal queue/cache system, but can't seem to find definitive documentation for this.
At the moment the API uses the C# Couchbase SDK and we use SyncGateway very little (only really for synchronising the mobile app).
First, some relevant background info :
Every document that needs to be synced over to Couchbase Lite(CBL) clients needs to be processed by the Sync Gateway (SGW). This is true whether a doc is written via the SGW API or whether it comes in via server write (N1QL or SDK). The latter case is referred to as "import processing” wherein the document that is written to the bucket (via N1QL) is read by SGW via DCP feed. The document is then processed by SGW and written back to the bucket with the relevant sync metadata.
Prerequisite :
In order for the SGW to import documents written directly via N1QL/SDK, you must enable “shared bucket access” and import processing as discussed here
Non-mobile documents :
If you have documents that are never going to be synced to the CBL clients, then choice is obvious. Use server SDKs or N1QL
Mobile documents (docs to sync to CBL clients) :
Assuming you are on SGW 2.x syncing with CBL 2.x clients
If you have documents written at server end that need to be synced to CBL clients, then consider the following
If you are looking at writes on server side coming in at sustained rates significantly exceeding 1.5K/sec (lets say 5K/sec), then you should go the SGW API route. While it's easy enough to do a bulk update via server N1QL query, remember that SGW still needs to keep up and do the import processing (what's discussed in the background).
Which means, if you are doing high volume updates through the SDK/N1QL, then you will have to rate limit it so the SGW can keep up (do batched updates via SDK)
That said, it is important to consider the fact that if SGW can't keep up with the write throughput on the DCP feed, it's going to result in latency, no matter how the writes are happening (SGW API or N1QL)
If your sustained write rate on server isn’t excepted to be significantly high, then go with N1QL.
Does not matter. Under shared-bucket-access, deletes coming in via SDK or SGW API will result in a tombstone. Read more about it here
Naturally, if you are dealing with SGW specific config, creating SGW users, roles, then you will use the SGW API for that.
In 2.x, it does not matter. Conflicts are handled on CBL side.
Challenge with SGW API