MongoJournal
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Defined in: src/persistence/journals/MongoJournal.ts:76
Journal backed by MongoDB via the mongodb driver.
Optimistic concurrency rests on a unique index. append reads the
current head and then inserts; the unique compound index on
(persistenceId, sequenceNr) rejects a racing writer with server error
11000, which is translated back into JournalConcurrencyError. That is the
same two-layer scheme the relational backends use — the head check for the
ordinary case, a conditional write for the race — with the unique index
playing the part a primary key plays there.
No transaction, deliberately. Appends are contiguous from the head, so
two writers that agree on the head both try the same first sequence number:
the loser’s insertMany fails on its first document and writes nothing, with
ordered: true stopping the batch there. A partial append is therefore not
reachable through contention, which is what a transaction would have been for
— and skipping it keeps the backend usable on a standalone mongod, since
MongoDB transactions require a replica set. A mid-batch infrastructure
failure (a dropped connection after the second of five events) can still
persist a prefix; the stream stays gap-free and the next append continues from
the new head, so recovery is consistent, but the caller’s error does not mean
“nothing was written”. Single-event appends — the common case — are
atomic outright.
Payloads are stored as JSON text, not as native BSON. It costs the
ability to query inside a payload, which the framework never does (it queries
by persistence id, sequence number and tags), and it buys exact round-trip
fidelity: BSON would reject or mangle a payload with dotted or $-prefixed
keys, and would quietly change how undefined and dates come back. The
other backends store JSON text too, so an event stream means the same thing
everywhere.
Being a cross-process store, it exposes no in-process event bus, so the query
layer polls — same as Postgres and Cassandra. Tag queries do use an index:
see MongoQuery.
Extends
Section titled “Extends”Implements
Section titled “Implements”Constructors
Section titled “Constructors”Constructor
Section titled “Constructor”new MongoJournal(
options?):MongoJournal
Defined in: src/persistence/journals/MongoJournal.ts:82
Parameters
Section titled “Parameters”options?
Section titled “options?”MongoJournalOptions = {}
Returns
Section titled “Returns”MongoJournal
Overrides
Section titled “Overrides”MongoStore.constructor
Accessors
Section titled “Accessors”serializer
Section titled “serializer”Get Signature
Section titled “Get Signature”get serializer():
Serializer<unknown> |undefined
Defined in: src/persistence/journals/MongoJournal.ts:97
The configured payload serializer — read by MongoQuery so tag reads decode like the journal.
Returns
Section titled “Returns”Serializer<unknown> | undefined
Methods
Section titled “Methods”append()
Section titled “append()”append<
E>(persistenceId,events,expectedSeq,tags?):Promise<PersistentEvent<E>[]>
Defined in: src/persistence/journals/MongoJournal.ts:107
Append events to the stream of persistenceId, enforcing optimistic
concurrency: the current highest sequence number MUST equal expectedSeq
or the call throws JournalConcurrencyError. Returns the written events
with their assigned sequence numbers.
Type Parameters
Section titled “Type Parameters”E
Parameters
Section titled “Parameters”persistenceId
Section titled “persistenceId”string
events
Section titled “events”readonly E[]
expectedSeq
Section titled “expectedSeq”number
readonly string[]
Returns
Section titled “Returns”Promise<PersistentEvent<E>[]>
Implementation of
Section titled “Implementation of”close()
Section titled “close()”close():
Promise<void>
Defined in: src/persistence/LazyStore.ts:66
Best-effort teardown; idempotent.
Returns
Section titled “Returns”Promise<void>
Implementation of
Section titled “Implementation of”Inherited from
Section titled “Inherited from”delete()
Section titled “delete()”delete(
persistenceId,toSeq):Promise<void>
Defined in: src/persistence/journals/MongoJournal.ts:185
Delete events up to and including toSeq — used when compacting past
a snapshot. Only ever a prefix, so what survives is a suffix that
read still returns contiguously, and sequence numbers never rewind:
highestSeq keeps reporting the high-water mark afterwards.
Parameters
Section titled “Parameters”persistenceId
Section titled “persistenceId”string
number
Returns
Section titled “Returns”Promise<void>
Implementation of
Section titled “Implementation of”highestSeq()
Section titled “highestSeq()”highestSeq(
persistenceId):Promise<number>
Defined in: src/persistence/journals/MongoJournal.ts:176
Current highest sequence number for persistenceId — 0 if no events exist.
Parameters
Section titled “Parameters”persistenceId
Section titled “persistenceId”string
Returns
Section titled “Returns”Promise<number>
Implementation of
Section titled “Implementation of”openForQuery()
Section titled “openForQuery()”openForQuery():
Promise<{events:MongoCollectionLike<EventDocument>; }>
Defined in: src/persistence/journals/MongoJournal.ts:251
Open the store and hand the query layer the collection it needs — the one
seam MongoQuery needs into an otherwise private surface.
Returns
Section titled “Returns”Promise<{ events: MongoCollectionLike<EventDocument>; }>
persistenceIds()
Section titled “persistenceIds()”persistenceIds():
Promise<string[]>
Defined in: src/persistence/journals/MongoJournal.ts:213
No persistenceIdsPaginated counterpart, deliberately. distinct is the
only way to reach the id set through this driver shim and it has no
cursor, so a “page” would still be the whole distinct result sliced in
JS — the fallback in the query layer already does exactly that, and doing
it here would only hide that no work was pushed down. A real push-down
wants a $group/$sort/$limit pipeline, which means widening
MongoCollectionLike with aggregate; that is a change worth making on
its own evidence, not as a side effect of #156.
Returns
Section titled “Returns”Promise<string[]>
Implementation of
Section titled “Implementation of”read()
Section titled “read()”read<
E>(persistenceId,fromSeq,toSeq?):Promise<PersistentEvent<E>[]>
Defined in: src/persistence/journals/MongoJournal.ts:160
Return the events in [fromSeq, …, toSeq], ascending by sequence
number. toSeq defaults to the current highest sequence number.
Both bounds are inclusive — fromSeq is the first event returned,
not an “after” cursor.
Ordering and contiguity are part of the contract, and replay
enforces them (#122). Consecutive entries must differ by exactly
one, every sequenceNr must be a safe integer ≥ 1, and nothing may
fall outside the requested window. delete compacts a prefix,
never a hole in the middle, so a gap inside the returned slice can
only mean a defect — a missing ORDER BY, a half-written append, a
store someone else can write. replayState raises
JournalIntegrityError instead of folding it, because an actor
that recovers from a shuffled or holed stream reaches a state that
never existed and then fails every later persist with a
JournalConcurrencyError that has no visible cause.
Type Parameters
Section titled “Type Parameters”E
Parameters
Section titled “Parameters”persistenceId
Section titled “persistenceId”string
fromSeq
Section titled “fromSeq”number
toSeq?
Section titled “toSeq?”number
Returns
Section titled “Returns”Promise<PersistentEvent<E>[]>