Attachment doc in sync gateway 3.X

nagarajan_subbaraj · February 13, 2023, 1:12am

Hi Team,
we are migrating from sync-gw 2.8 to 3.x. question here is, how do we identify the binary attachment to a document. In2.8 version, we can get the sha value and prefix with _sync:att:sha then we can get the actual binary document, but 3.x version we see another sha value added(hope it is the generated based on the document values) but we do get exact document like 2.8.

Thanks.

bbrks · February 13, 2023, 10:48am

Attachments created/modified in 3.x have a 1:1 association with a regular document, rather than 1:many, so the attachment key also includes a reference to the owning document.

We do this so we’re able to automaically clean up associated attachments on document removal.

github.com

couchbase/sync_gateway/blob/44a437d701db8037730de2d65a080b3938678b3c/db/attachment.go#L427-L433


      
          // MakeAttachmentKey returns the unique for attachment storage and retrieval.
          func MakeAttachmentKey(version int, docID, digest string) string {
          	if version == AttVersion2 {
          		return base.Att2Prefix + sha256Digest([]byte(docID)) + ":" + digest
          	}
          	return base.AttPrefix + digest
          }

nagarajan_subbaraj · February 13, 2023, 2:43pm

Thanks @bbrks , so looks like we can’t directly get the binary attachment id. we have to search with suffix - meta().id like ‘%sha-id’. am i correct?