Scale-out storage: PostgreSQL and MySQL read replicas (ST-5 to ST-15)

A data store with readReplicas becomes a replicated store. Writes, operator-written SQL and everything outside a read scope go to the primary. JMAP reads before a request's first write, IMAP LIST, STATUS, SEARCH, SORT and FETCH, POP3 RETR and TOP, DAV GET, PROPFIND and REPORT, and blob downloads run in a read scope. Only account data (properties, indexes, change logs, counters, ACLs, blobs, the search index) is read from a replica; the registry, in-memory values, the task queue and the rest stay on the primary. In a scope, the first read picks a replica round-robin among those up and under the lag limit, and only if it has every change this node has written or heard of for the scope's accounts: marks come from write results, the cluster's state-change broadcasts, a sinceState the client presents, and, with more than one node, Redis. A write inside the scope sends the rest of it to the primary. A miss on a replica is looked up on the primary, and a replica error retries the read there and marks the replica down. Each node samples lag every second (WAL positions on PostgreSQL; GTID sets or Seconds_Behind_Source on MySQL), stops reading from a replica over 5 s and starts again under 2.5 s, and probes a down replica every 10 s. At startup a replica is left out if it's the primary, isn't read-only, applies out of commit order, or doesn't show a marker written to the primary within six tries. replica_tests (postgres, STORE=PostgreSqlReplicated) runs a primary and a streaming hot standby in containers: tests 9, 10, 12, 13, 14 and 15 pass.
2026-09-19 14:05:59 -07:00
parent a635b490ec
commit 1518c69033
24 changed files with 1722 additions and 45 deletions
@@ -105,6 +105,23 @@ pub fn spawn_broadcast_subscriber(inner: Arc<Inner>, mut shutdown_rx: watch::Rec
                                            );
                                            match event {
                                                BroadcastEvent::PushNotification(notification) => {
+                                                    // inbuxa: ST-7: another node's change raises this
+                                                    // node's high-water mark for the account
+                                                    match &notification {
+                                                        common::ipc::PushNotification::StateChange(change) => inner
+                                                            .build_server()
+                                                            .core
+                                                            .storage
+                                                            .data
+                                                            .note_change(change.account_id, change.change_id),
+                                                        common::ipc::PushNotification::EmailPush(push) => inner
+                                                            .build_server()
+                                                            .core
+                                                            .storage
+                                                            .data
+                                                            .note_change(push.account_id, push.change_id),
+                                                        _ => {}
+                                                    }
                                                    if inner
                                                        .ipc
                                                        .push_tx