Google Drive

01What are the table stakes — what can a user do with a file?

Upload and download files of any type: upload writes bytes to blob storage plus a metadata row; download checks permission first, then hands back a short-lived signed URL.

02Is a folder a real container, or just a label?

Folders form a tree via parent pointers, so organizing and moving are metadata operations — moving a 100K-file folder rewrites one pointer and no bytes move.

03How does sharing actually work — who can see what?

Owners grant viewer/commenter/editor roles to users or groups on files or folders; a folder grant inherits down the subtree, so one grant shares a thousand files.

04What does “anyone with the link” really mean?

A share link carries a random token mapped to a server-side grant (anyone-with-link or domain-only, with a role) — the server still checks every request, and revoking the grant kills every copy of the URL.

05Does saving over a file destroy the old contents?

No: each save creates a version — a small metadata row pointing at an immutable blob — so history browsing and restore are cheap, and retention rules prune old versions.

06I edit on my laptop — what happens on my phone?

Changes propagate to every device via a change log and sync clients — the chunking and delta machinery is the file-sync sibling’s design; here the sync client is one more consumer of metadata changes.

01How much latency can the permission check add to every read?

The permission check adds single-digit milliseconds at roughly 350K checks/s: reads hit a cache of computed effective access; only a miss walks the folder chain.

02I remove someone from a folder — when does their access actually die?

Revoke takes effect within seconds everywhere: it invalidates cached access explicitly instead of waiting out a TTL — stale access for a removed user is a security incident, not a staleness bug.

03Can search ever show me a file I am not allowed to open?

No read path — search, folder listing, or API — ever returns a file the requester cannot open; permission filtering runs at the query layer, never only in the UI.

04What are we promising about never losing a file?

Bytes sit in replicated blob storage built for eleven-nines durability; metadata changes like a move commit atomically, so a subtree is never half-moved.

05Does moving a giant folder block the user who dragged it?

Folder operations feel instant regardless of subtree size: the synchronous work is one pointer flip and a tuple write; cache invalidation and reindexing fan out asynchronously.