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CBG-5170 change listener: don't process docs without xattr #8064

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CBG-5170 change listener: don't process docs without xattr #8064

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024e328
CBG-5170 don't process docs without xattr
torcolvin Feb 12, 2026
2a7cbcd
Add back debug output
torcolvin Feb 17, 2026
9940a36
remove unused code
torcolvin Feb 17, 2026
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16 changes: 6 additions & 10 deletions db/change_cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -364,27 +364,23 @@ func (c *changeCache) DocChanged(event sgbucket.FeedEvent, docType DocumentType)

ctx = collection.AddCollectionContext(ctx)

// If this is a delete and there are no xattrs (no existing SG revision), we can ignore
if event.Opcode == sgbucket.FeedOpDeletion && len(docJSON) == 0 {
base.DebugfCtx(ctx, base.KeyCache, "Ignoring delete mutation for %s - no existing Sync Gateway metadata.", base.UD(docID))
// If the document has no xattrs, it can not have a _sync xattr
if event.DataType&base.MemcachedDataTypeXattr == 0 {
return
}

// If this is a binary document (and not one of the above types), we can ignore. Currently only performing this check when xattrs
// are enabled, because walrus doesn't support DataType on feed.
if collection.UseXattrs() && event.DataType == base.MemcachedDataTypeRaw {
// If this is a binary document, we can ignore.
if event.DataType == base.MemcachedDataTypeRaw {
Comment on lines +372 to +373
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Copilot AI Feb 17, 2026

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The binary document check will not correctly filter out binary documents that have xattrs. Since the xattr check at line 368 returns early for documents without xattrs, only documents WITH xattrs reach this check. For a binary document with xattrs, the DataType would be MemcachedDataTypeXattr (4), not MemcachedDataTypeRaw (0), so this equality check will fail and binary documents with xattrs will continue to be processed. The correct check should verify that the JSON flag is not set using a bitwise operation: event.DataType&base.MemcachedDataTypeJSON == 0.

Suggested change
// If this is a binary document, we can ignore.
if event.DataType == base.MemcachedDataTypeRaw {
// If this is not a JSON document (e.g. binary, with or without xattrs), we can ignore.
if event.DataType&base.MemcachedDataTypeJSON == 0 {

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return
}

// First unmarshal the doc (just its metadata, to save time/memory):
doc, syncData, err := UnmarshalDocumentSyncDataFromFeed(docJSON, event.DataType, collection.UserXattrKey(), false)
if err != nil {
// Avoid log noise related to failed unmarshaling of binary documents.
if event.DataType != base.MemcachedDataTypeRaw {
base.DebugfCtx(ctx, base.KeyCache, "Unable to unmarshal sync metadata for feed document %q. Will not be included in channel cache. Error: %v", base.UD(docID), err)
}
if errors.Is(err, sgbucket.ErrEmptyMetadata) {
base.WarnfCtx(ctx, "Unexpected empty metadata when processing feed event. docid: %s opcode: %v datatype:%v", base.UD(event.Key), event.Opcode, event.DataType)
} else {
base.DebugfCtx(ctx, base.KeyCache, "Unable to unmarshal sync metadata for feed document %q. Will not be included in channel cache. Error: %v", base.UD(docID), err)
}
return
}
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