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The replay invariant in design/qwp-nack-policy-v2.md said a NACK means the server applied nothing of the rejected batch. The server's commit batch now spans every table of a receive pass and commits the tables one at a time (questdb#8195). It rejects the whole batch for every refusal it can check before committing: a read-only node, an ACL denial, or a dropped, renamed or suspended table. A storage fault on one table's commit, or a DROP, RENAME or SUSPEND WAL landing while the batch commits, can still fail a table after others committed. Their rows from frames at or after the NACKed frame are then applied, and the client's RETRIABLE replay sends them again. The invariant now states what a NACK names, when the replay duplicates nothing, and the exception with its bound: one server receive pass (http.recv.buffer.size, 2 MiB by default). DEDUP tables absorb the duplicates. The client's policy does not change: it replays rather than risk loss.
jerrinot
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The invariant packed the ack rule, the pre-commit refusals and the partial-commit exception into one long sentence chain, and it no longer matched the server: questdb#8195 now checks a table's refusals as the table joins the commit batch, and a DROP, RENAME or SUSPEND WAL can fail a table at any time while it waits for its commit, not only mid-commit. The bullet now states the ack rule, what a RETRIABLE replay normally re-sends, when it re-sends rows the server already stored, and what bounds them: one server receive pass for plain frames, or the whole group for a FLAG_DEFER_COMMIT group, which the old text left out.
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Tandem: questdb/questdb#8195.
The server commits each table on its own, so a table whose commit fails after others committed leaves their rows from the replayed frames already stored. Since questdb/questdb#8195 one commit spans the plain frames of a whole receive pass, which makes this up to one pass (
http.recv.buffer.size, 2 MiB by default); aFLAG_DEFER_COMMITgroup can re-send the whole group. The invariant now states this in place of "NACK ⇒ batch atomically not applied".