Good day.
If I followed Ken's line of thought correctly, I would like to expand it to
be part of the new proposal for the transaction API.
First of all, about the model, I think we came to a consensus that it
should be:
[image: image.png]
The point is that we do not have a notion of connection in TinkerPop, but
we have a notion of GraphTraversal.
So, from my perspective, this diagram can be changed to
[image: image.png]
There is a corner case for Non-TX databases that we need to discuss.
I believe Non-TX mode is not appropriate for handling graph data
structures. GQL, for example, requires serializable isolation to satisfy
the standard requirements.
Instead, we should require to have presence of a transaction, which is
started *implicitly* when GraphTraversal is created and committed once it
is closed.
I think we DO need methods for explicit transaction management, but 90% of
the cases will be covered by implicit transaction management throughout the
GraphTraversal life cycle.
1. TX is started when GraphTraversal is created.
2. TX is committed when GraphTraversal is closed (which includes terminal
operations like toList or iterate).
3. TX is rolled back in case of exceptional execution of
GraphTraversal. Users can always roll back a transaction by using the
fail() step.
We also provide in the YTDB the following methods that I hope will become
part of the framework: gSource.computeInTx(g ->{}), gSource.executeInTx(g -
{}), gSource.autoExecuteInTx(g - {}: g) (this one executes g.iterate() on
the returned GraphTraversal, which we find really handy).
Now, regarding explicit TX management.
I think that explicit TX management is still needed if you want to execute
several queries and mix them with complex logic, but I think that methods
that explicitly cause TX begin/start/commit are confusing and provide bad
DevX.
What I propose is to use lambda-controlled TXs (slightly different from the
above). I think that an explicit rollback/commit of TX by the user is
similar to the goto operator in old programming languages; it gives finer
control over TXs, but overall only adds confusion and can be completely
avoided in modern languages.
Explicit control on TXs is proposed to be implemented using methods similar
to above, with a different signature, namely:
gSource.executeInTx(graphTraversalSupplier -> {
var g = graphTraversalSupplier.get();
var v = g.V().next();
g.close()
v.property("p", "val");
int i = v.value("int");
if(i > 0) {
g = graphTraversalSupplier.get();
g.V().has("i2", i).property("i2", i + 1).iterate();
}
})
In this case, the transaction is detached from GraphTraversal, and its
lifecycle is not controlled by GraphTraversal.
Instead, TX is committed if an exception is not thrown from the lambda
method.
To inform the user if GraphTraversal controls TX or not, a simple
isTxAttached method is proposed to be introduced
gSource.<V>computeInTX(graphTraversalSupplier -> {}) works in similar way
but returns value.
So the final diagram could look like the following:
[image: image.png]
Please note that in this model, there is no need for an explicit
transaction object.
On Fri, Dec 5, 2025 at 10:18 AM Andrii Lomakin <[email protected]>
wrote:
> Good day, Ken.
>
> >This could map to multiple threads on the provider side. It's probably OK
> if something like "g.tx()..." returns the same transaction. We could
> require users to open multiple DriverRemoteConnections/Clients to achieve
> this and that would be similar to other data connectivity APIs.
>
> Unfortunately I do not follow, could you elaborate more or give me example
> how do you see it ?
>
> On Thu, Dec 4, 2025 at 7:06 PM Ken Hu <[email protected]> wrote:
>
>> I might be thinking about this too much for just the remote case and not
>> considering the embedded case enough. In my mind, there just needs to be an
>> easy way for users of the language variants (in particular JavaScript
>> because of its single threaded nature) to start multiple transactions from
>> a single thread. This could map to multiple threads on the provider side.
>> It's probably OK if something like "g.tx()..." returns the same
>> transaction. We could require users to open multiple
>> DriverRemoteConnections/Clients to achieve this and that would be similar
>> to other data connectivity APIs.
>>
>> On Thu, Dec 4, 2025 at 2:37 AM Andrii Lomakin via dev <
>> [email protected]> wrote:
>>
>>> The point about having multiple concurrent transactions within the same
>>> thread warrants a more detailed discussion.
>>>
>>> To compare this behavior, consider how major SQL databases handle
>>> attempts
>>> to start a second transaction when one is already active:
>>>
>>> 1. Error out: The database prevents the operation, signaling that a
>>> transaction is already active (e.g., "Transaction already active").
>>> 2. Create a nested transaction (savepoint): The database creates a
>>> sub-scope of the first transaction, not an independent transaction. If
>>> the
>>> parent transaction fails, the child scope also fails.
>>> 3. Implicitly commit the first: The database automatically commits the
>>> first transaction to open the second one (a common behavior in MySQL
>>> DDL).
>>>
>>> As far as I know, only Firebird has historically allowed several truly
>>> independent transactions concurrently on the same thread. I suspect
>>> support
>>> for simultaneous transactions may be even more limited among graph
>>> database
>>> vendors.
>>>
>>> On Thu, Dec 4, 2025 at 10:47 AM Andrii Lomakin <
>>> [email protected]>
>>> wrote:
>>>
>>> > Good day.
>>> > As for questions from Ken
>>> > >What OGMs are you referring to here? Regular transactions are
>>> complicated
>>> > enough by itself, I would only want to introduce nested transactions if
>>> > there were well maintained OGMs that would have a demonstrable benefit
>>> from
>>> > this.
>>> >
>>> > We have such an OGM using TinkerPop that is well maintained, if you
>>> mean
>>> > by this years of support and thousands of instances running on OS
>>> version.
>>> > However, I have given it thought and believe that it is a relatively
>>> rare
>>> > case, and OGM is so complex that it can manage nested transactions
>>> itself
>>> > if needed.
>>> > I think we can support nested transactions on pause for now, till we
>>> > receive more feedback from users.
>>> >
>>> > There are many inconsistencies to discuss in the TX lifecycle, even
>>> > without nested transactions.
>>> >
>>> > >Sessions won't exist moving forward (4.x+) as they are tied to remote
>>> > Groovy execution. So let's continue this conversation as simply
>>> > transactions and not refer to sessions at all to prevent confusion,
>>> unless
>>> > you intend to have these changes in the 3.8.x line?
>>> > Yeah, we already removed Groovy support in our fork, so it is even now
>>> in
>>> > our distribution TX, and the session is the same.
>>> >
>>> >
>>> > >Could you expand a bit more on "Transaction scope is limited to the
>>> > current thread only".
>>> > I mean that TX visibility and manipulation are limited to a single
>>> thread
>>> > where it is created.
>>> > If some of the providers support TX visibility between several threads,
>>> > that will only add a bonus for them if such a need arises, of course,
>>> > without breaking the API.
>>> >
>>> > > I find it limiting that an attempt to open multiple transactions from
>>> > the same thread ends up returning the same Transaction instance
>>> > Do you propose to support several transactions in the same thread?
>>> > I am afraid not all current vendors can support this model.
>>> >
>>> > On Wed, Dec 3, 2025 at 1:23 PM Stephen Mallette <[email protected]>
>>> > wrote:
>>> >
>>> >> Andrii, I'd like to just quickly clarify Ken's point stating "
>>> Sessions
>>> >> won't exist moving forward (4.x+) ". He's saying what you said: "
>>> >> 'session'
>>> >> and 'tx' are essentially the same concepts". We acknowledged that and
>>> >> decided to stop using "session" terminology and instead use
>>> "transaction"
>>> >> terminology only to avoid confusion.
>>> >>
>>> >> Much of what you wrote is in the spirit of what has been considered
>>> for
>>> >> 4.x, so that is nice alignment. I do think the goal though is to have
>>> a
>>> >> consistent transaction API/system that works for both embedded and
>>> remote
>>> >> cases. It will be interesting to see how that is achieved.
>>> >>
>>> >> On Tue, Dec 2, 2025 at 3:53 PM Ken Hu <[email protected]> wrote:
>>> >>
>>> >> > Hi Andrii,
>>> >> >
>>> >> > Good day to you as well. I have a couple questions about this that I
>>> >> would
>>> >> > like some more details on.
>>> >> >
>>> >> > 1. What OGMs are you referring to here? Regular transactions are
>>> >> > complicated enough by itself, I would only want to introduce nested
>>> >> > transactions if there were well maintained OGMs that would have a
>>> >> > demonstrable benefit from this.
>>> >> > 2. I like some of your ideas about removing Transaction as its own
>>> >> class,
>>> >> > but I'm not sure GraphTraversalSource is where it should be
>>> instead. Do
>>> >> you
>>> >> > have some more details about what you think the Transaction API
>>> should
>>> >> look
>>> >> > like?
>>> >> > 3. Could you expand a bit more on "Transaction scope is limited to
>>> the
>>> >> > current thread only". I always get confused by TinkerPop's threaded
>>> vs
>>> >> > multithreaded transaction. I find it limiting that an attempt to
>>> open
>>> >> > multiple transactions from the same thread ends up returning the
>>> same
>>> >> > Transaction instance. Maybe I didn't quite understand what you
>>> meant by
>>> >> > this.
>>> >> > 4. Sessions won't exist moving forward (4.x+) as they are tied to
>>> remote
>>> >> > Groovy execution. So let's continue this conversation as simply
>>> >> > transactions and not refer to sessions at all to prevent confusion,
>>> >> unless
>>> >> > you intend to have these changes in the 3.8.x line?
>>> >> >
>>> >> > Regards,
>>> >> > Ken
>>> >> >
>>> >> >
>>> >> > On Tue, Dec 2, 2025 at 3:33 AM Andrii Lomakin via dev <
>>> >> > [email protected]> wrote:
>>> >> >
>>> >> > > Small clarification.
>>> >> > > Implementation notes are related to changes in the remote
>>> protocol.
>>> >> > >
>>> >> > > On Tue, Dec 2, 2025 at 8:55 AM Andrii Lomakin <
>>> >> > > [email protected]>
>>> >> > > wrote:
>>> >> > >
>>> >> > > > To clarify: in this model, 'session' and 'tx' are essentially
>>> the
>>> >> same
>>> >> > > > concepts.
>>> >> > > >
>>> >> > > > I also think it is essential to have a common denominator that
>>> >> makes TP
>>> >> > > > applications portable across implementations.
>>> >> > > > That is why I also propose to restrict transaction scope to the
>>> >> thread
>>> >> > > > scope. It will be a common denominator that will not harm user
>>> >> > experience
>>> >> > > > but will ensure uniform and expected API behavior.
>>> >> > > > There should not be both `begin` and `open` methods because the
>>> >> > contract
>>> >> > > > of the beginning method is vague and unpredictable.
>>> >> > > >
>>> >> > > > On Tue, Dec 2, 2025 at 8:18 AM Andrii Lomakin <
>>> >> > > > [email protected]> wrote:
>>> >> > > >
>>> >> > > >> Good day,
>>> >> > > >>
>>> >> > > >> I have a proposal to enhance the transaction handling logic in
>>> TP,
>>> >> > > >> specifically regarding nested transaction calls, which are
>>> common
>>> >> in
>>> >> > EE
>>> >> > > >> development, particularly when utilizing OGM.
>>> >> > > >>
>>> >> > > >> Currently, calling open multiple times causes an exception.
>>> This
>>> >> > > behavior
>>> >> > > >> is restrictive, and the term "open" can be confusing.
>>> >> > > >>
>>> >> > > >> I propose a design that improves the developer experience by
>>> using
>>> >> an
>>> >> > > >> internal counter for transaction calls:
>>> >> > > >>
>>> >> > > >> Proposed transaction counter logic
>>> >> > > >> 1. begin/commit counter:
>>> >> > > >> - begin would increment an internal counter.
>>> >> > > >> - commit would decrement the internal counter, causing the
>>> actual
>>> >> > > >> transaction commit only when the counter reaches zero.
>>> >> > > >> 2. rollback behavior:
>>> >> > > >> - rollback would immediately force a transaction rollback and
>>> >> > > decrements
>>> >> > > >> the internal counter
>>> >> > > >> - the subsequent calls to rollback on the same transaction
>>> object
>>> >> > > should
>>> >> > > >> be allowed until the stack trace reaches the initial begin
>>> method
>>> >> > call,
>>> >> > > >> after which further rollback calls would throw an exception.
>>> >> > > >> 3. Error handling:
>>> >> > > >> - A commit without a matching begin (e.g., counter is already
>>> zero)
>>> >> > > >> should throw an exception.
>>> >> > > >> - A rollback without a matching begin should throw an exception
>>> >> > > >>
>>> >> > > >> I would also consider hiding the Transaction object altogether
>>> and
>>> >> > > >> delegating the logic of transaction management to
>>> >> GraphTraversalSource
>>> >> > > it
>>> >> > > >> will simplify the API a lot, both for users and vendors.
>>> >> > > >>
>>> >> > > >> I also propose to restrict transaction scope to the thread
>>> scope,
>>> >> it
>>> >> > > will
>>> >> > > >> be a common denominator that will not harm user experience but
>>> will
>>> >> > > ensure
>>> >> > > >> uniform and expected API behavior across all implementations.
>>> >> > > >>
>>> >> > > >> Proposed API changes
>>> >> > > >> - I propose deprecating open and using begin with the
>>> semantics
>>> >> > > >> described above to avoid confusion.
>>> >> > > >> - Transaction object is deprecated, and TX control
>>> functionality is
>>> >> > > >> delegated to the GraphTraversal/Graph instances.
>>> >> > > >> - tx() method is deprecated.
>>> >> > > >> - Transaction scope is limited to the current thread only.
>>> >> > > >>
>>> >> > > >> Behavior for non-direct calls
>>> >> > > >> When begin/commit/rollback methods are not called directly, the
>>> >> > > >> transaction should be automatically committed by a terminal
>>> >> operation
>>> >> > > >> (e.g., when hasNext returns false) in both remote and embedded
>>> >> modes.
>>> >> > > >>
>>> >> > > >> Implementation notes:
>>> >> > > >> 1. The begin command should be added. Relying on the implicit
>>> >> start of
>>> >> > > TX
>>> >> > > >> by traversal can lead to non-controlled side effects.
>>> >> > > >> 2. For the sake of optimization of the remote protocol, while
>>> >> multiple
>>> >> > > >> calls of begin/commit/rollback are allowed in the remote
>>> protocol,
>>> >> > > >> practically, it will mean that we will track the counter
>>> locally on
>>> >> > the
>>> >> > > >> client and will send begin/commit/rollback only once for the TX
>>> >> > > lifecycle.
>>> >> > > >>
>>> >> > > >> This model should be uniform across all deployment types.
>>> >> > > >> What are your thoughts on this approach?
>>> >> > > >>
>>> >> > > >> -----
>>> >> > > >> Andrii Lomakin
>>> >> > > >> YouTrackDB development lead
>>> >> > > >>
>>> >> > > >
>>> >> > > >
>>> >> > > > --
>>> >> > > > Andrii Lomakin
>>> >> > > > YouTrackDB development lead
>>> >> > > >
>>> >> > >
>>> >> > >
>>> >> > > --
>>> >> > > Andrii Lomakin
>>> >> > > YouTrackDB development lead
>>> >> > >
>>> >> >
>>> >>
>>> >
>>> >
>>> > --
>>> > Andrii Lomakin
>>> > YouTrackDB development lead
>>> >
>>>
>>>
>>> --
>>> Andrii Lomakin
>>> YouTrackDB development lead
>>>
>>
>
> --
> Andrii Lomakin
> YouTrackDB development lead
>
--
Andrii Lomakin
YouTrackDB development lead
