Hi Dimitri, Thanks for raising this. I'd prefer email so it's async and easier for everyone to participate at their own pace. A dedicated sync can come later if email gets stuck.
My understanding is that BasePersistence already extends PolicyMappingPersistence and MetricsPersistence, plus has event persistence folded in directly. That's because AtomicOperationMetaStoreManager operates against a single BasePersistence instance per realm, and each backend (in-memory, JDBC, NoSQL) has one factory chain producing it. So to follow the current architecture, we need to make BasePersistence extend IdempotencyPersistence too. Splitting IdempotencyPersistence out as a top-level SPI would mean adding parallel factory plumbing in every backend. Happy to discuss the broader SPI shape on this thread. I'd prefer to land #4269 with the current shape since it follows the agreed-upon architecture, and revisit the layering uniformly in a follow-up once we converge — that broader discussion may take a while. Thanks, Huaxin On Tue, May 5, 2026 at 2:29 PM Dmitri Bourlatchkov <[email protected]> wrote: > Hi Huaxin, Yufei, > > I left some comments on [4269] mostly about SPI design concerns. > > Since we wanted to reopen a more general SPI discussion anyway, it might be > worth having a dedicated sync about that... > > Alternatively, we could have that discussion by email now, if you prefer. I > have some starting points to share for discussion. > > WDYT? > > [4269] https://github.com/apache/polaris/pull/4269 > > Thanks, > Dmitri. > > On Fri, Apr 17, 2026 at 7:07 PM huaxin gao <[email protected]> wrote: > > > Hi Robert, > > > > Thanks, and I’m glad we’re aligned on the handler-level direction. I also > > appreciate the detailed review and feedback throughout this discussion. > > > > Since the old implementation is going away and the handler-level > > implementation will be in a fresh PR, would you be OK removing the -1 > from > > PR #3803 <https://github.com/apache/polaris/pull/3803>? If so, I’ll > close > > the old PR and open a new one for the handler-level approach. > > > > Best, > > > > Huaxin > > > > On Thu, Apr 16, 2026 at 12:57 AM Robert Stupp <[email protected]> wrote: > > > > > i Yufei, Huaxin, > > > > > > Thanks for the thoughtful replies, and for opening the issue for > > > `createTableStaged` [1]. I’m glad we’re converging on the handler-level > > > direction. > > > > > > I agree benchmarking can run in parallel with implementation. For my > own > > > review, I’d prefer to wait until reproducible benchmark results are > > posted > > > (using the scope from my April 14 note, or with any scope changes > called > > > out). > > > > > > Happy to review once that is available. > > > > > > Best, > > > Robert > > > > > > [1] https://github.com/apache/polaris/issues/4200 > > > > > > > > > On Tue, Apr 14, 2026 at 7:54 PM huaxin gao <[email protected]> > > wrote: > > > > > > > Hi Robert, > > > > > > > > Thanks for the feedback. Glad the handler-level design addresses the > > > > concerns. > > > > > > > > I also feel we should converge on the design and implementation > first, > > > and > > > > run benchmarks in parallel. The access patterns will be different > with > > > the > > > > handler-level approach, so benchmarking the current filter-based code > > > > wouldn't be representative. > > > > > > > > I'll open a GitHub issue to track createTableStaged support, and I'll > > > open > > > > a fresh PR for the handler-level implementation. > > > > > > > > Best, > > > > > > > > Huaxin > > > > > > > > On Tue, Apr 14, 2026 at 10:30 AM Yufei Gu <[email protected]> > > wrote: > > > > > > > > > Hi Robert, > > > > > > > > > > Thanks for the thorough review and for clearly laying out the > > concerns, > > > > > this is very helpful. > > > > > > > > > > For point 1(Q3), I do not think this needs to be a hard > prerequisite > > > > before > > > > > looking at the implementation. > > > > > > > > > > The handler level design and correctness concerns are largely > > > independent > > > > > from the exact performance characteristics. It would be more > > productive > > > > to > > > > > first converge on the right architecture, then validate and iterate > > on > > > > > performance with concrete measurements. Also, while the store is > > > reused, > > > > > the access pattern and critical sections change with the handler > > level > > > > > approach. Measuring the current implementation in isolation may not > > > > reflect > > > > > the actual behavior of the final design. > > > > > > > > > > We already have a similar situation with the NoSQL benchmark, where > > the > > > > > code has been merged for a while but the benchmarking work is still > > in > > > > > progress. That has not blocked design or code review, and we are > > > > iterating > > > > > on performance as we go. > > > > > > > > > > I agree that realistic benchmarking is important. But I would > suggest > > > we > > > > > treat this as a parallel track, not a gate. Otherwise we risk > > blocking > > > > > progress on the design without knowing whether the measured > overhead > > is > > > > > even representative of the final system. > > > > > > > > > > Happy to help define a benchmark plan once the design is settled. > > > > > > > > > > Yufei > > > > > > > > > > > > > > > On Tue, Apr 14, 2026 at 6:28 AM Robert Stupp <[email protected]> > wrote: > > > > > > > > > > > Hi Huaxin, > > > > > > > > > > > > yeah, the handler-level approach is the right call, I'm glad you > > went > > > > > with > > > > > > it. > > > > > > > > > > > > To be explicit about what your proposal aims to resolve: > > > > > > > > > > > > - Authorization bypass is fixed. The check now runs after > > > > resource-level > > > > > > authorization. > > > > > > - No credentials in the database. Fresh credentials re-vended on > > > replay > > > > > via > > > > > > the normal vending path. > > > > > > - Phase 2 architecture problem gone. The handler has the > principal, > > > > > storage > > > > > > config, and IAM access that the filter never could have. > > > > > > - Caller identity is in the binding. > > > > > > > > > > > > Three things still need adressing: > > > > > > > > > > > > First, and this is a hard prerequisite before I look at any > > > > > implementation > > > > > > code: Q3 from April 5 is still open. The store is being reused > > as-is, > > > > so > > > > > > the overhead can be measured right now without new handler code. > 3+ > > > DB > > > > > > round-trips per mutation on the catalog connection pool, > write-hot > > > > table, > > > > > > polling loops under duplicate traffic - those numbers need to > come > > > > from a > > > > > > realistic setup: networked database under concurrent load, not a > > > local > > > > > > Postgres. The latency concerns are specifically about Aurora and > > > > > > CockroachDB, and the polling storm only shows up under concurrent > > > > > duplicate > > > > > > traffic. Please share the methodology so the results are > > > reproducible. > > > > > > > > > > > > Second: please open a GitHub issue for the createTableStaged > > > deferral. > > > > > > > > > > > > Third: since the filter is going away entirely and the critical > > > > sections > > > > > > move to the handlers, does it make sense to close #3803 and open > a > > > > fresh > > > > > > PR? The old diff is mostly code that's being deleted, and it > > carries > > > a > > > > > lot > > > > > > of review history. A clean PR would be easier for everyone to > > review > > > - > > > > > just > > > > > > reference the old one for context. > > > > > > > > > > > > Happy to do a fresh review once the new implementation is up. > > > > > > > > > > > > Best, > > > > > > Robert > > > > > > > > > > > > > > > > > > On Tue, Apr 14, 2026 at 1:44 AM huaxin gao < > [email protected] > > > > > > > > wrote: > > > > > > > > > > > > > Hi Robert, > > > > > > > > > > > > > > Here is a revised design proposal for the idempotency replay > > > > mechanism. > > > > > > I'd > > > > > > > appreciate your feedback. Thanks! > > > > > > > > > > > > > > *Moving idempotency to handler level* > > > > > > > > > > > > > > The idempotency check moves from the HTTP filter into the > handler > > > > > > methods, > > > > > > > after authorization. The filter is removed. The caller's > > principal > > > > hash > > > > > > is > > > > > > > included in the idempotency binding and checked on replay. > > > > > > > > > > > > > > *Credential-bearing mutations (createTable)* > > > > > > > > > > > > > > On replay, instead of returning a stored response, the handler > > > calls > > > > > > > buildLoadTableResponseWithDelegationCredentials with the > existing > > > > > table's > > > > > > > metadata. This vends fresh credentials for the current caller > > > through > > > > > the > > > > > > > normal credential vending path. No credentials are stored in > the > > > > > > database — > > > > > > > the idempotency record only stores the key, principal hash, > table > > > > > > > identifier, and status code. > > > > > > > > > > > > > > *Non-credential mutations (dropTable, renameTable, > namespace/view > > > > > > > operations)* > > > > > > > > > > > > > > These do not vend credentials, so there is no leakage concern. > On > > > > > replay, > > > > > > > the handler returns the stored status code and minimal response > > > body. > > > > > > > > > > > > > > *createTableStaged* > > > > > > > > > > > > > > Staged tables are not persisted to the catalog, so the method > can > > > > > safely > > > > > > > re-run on retry. Idempotency support for this endpoint can be > > > > deferred. > > > > > > > > > > > > > > *What is reused from the current implementation* > > > > > > > > > > > > > > The IdempotencyStore interface, database schema, configuration, > > and > > > > > > > background purge logic are reused. The main change is moving > the > > > > > > > check/finalize logic from the filter into the handler. > > > > > > > > > > > > > > Best, > > > > > > > > > > > > > > Huaxin > > > > > > > > > > > > > > On Sun, Apr 5, 2026 at 11:53 AM huaxin gao < > > [email protected] > > > > > > > > > > wrote: > > > > > > > > > > > > > > > Hi Robert, > > > > > > > > > > > > > > > > Thanks for the follow-up. > > > > > > > > > > > > > > > > I appreciate the clarification. I read the listed items as > fix > > > > > options > > > > > > > and > > > > > > > > picked option 2, and the Phase 1/Phase 2 split was purely to > > keep > > > > the > > > > > > PR > > > > > > > at > > > > > > > > a reviewable size, not a design choice. > > > > > > > > > > > > > > > > I agree that the caller's identity should be part of the > > binding. > > > > > That > > > > > > is > > > > > > > > straightforward to add. > > > > > > > > > > > > > > > > On the architecture question, whether re-vending can work > > within > > > > the > > > > > > > > filter or needs a handler-level approach, I want to give this > > > > proper > > > > > > > > thought rather than rush an answer. I may not be able to get > > back > > > > to > > > > > > you > > > > > > > on > > > > > > > > this until next week (the week of 4/13). > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > > > > > > > Huaxin > > > > > > > > > > > > > > > > On Sat, Apr 4, 2026 at 11:42 PM Robert Stupp <[email protected] > > > > > > wrote: > > > > > > > > > > > > > > > >> Hi Huaxin, > > > > > > > >> > > > > > > > >> Thanks for responding. A few corrections and clarifications. > > > > > > > >> > > > > > > > >> My PR review described three consequences of the missing > > caller > > > > > > > >> identity binding and the credential leakage attack vector. > > Those > > > > > > > >> were not suggestions for a Phase 1/Phase 2 split. The > offline > > > > > > > >> decision to split into phases, and what each phase contains, > > was > > > > > > > >> yours [1]. > > > > > > > >> > > > > > > > >> On the phasing: the concern is not PR size. The concern is > > that > > > > > > > >> Phase 1 alone ships a full authorization bypass. The filter > > > > replays > > > > > > > >> cached responses before Polaris's resource-level > authorization > > > > > > > >> runs. Stripping credentials does not fix that. Any > > authenticated > > > > > > > >> user with a valid idempotency key can receive a cached > > response > > > > > > > >> for a resource they are not authorized to access. That is > the > > > case > > > > > > > >> with or without credentials in the response. > > > > > > > >> > > > > > > > >> "We will not release it until entire idempotency coding is > > > > > > > >> finished" is reassuring, but the architecture question > > remains: > > > > > > > >> can the generic filter approach support re-vending at all? > My > > > > > > > >> email explained why I believe it cannot, since it would > > require > > > > > > > >> the filter to authorize the caller, resolve storage > locations, > > > > > > > >> call cloud IAM, and manage credential caching. That is the > > > catalog > > > > > > > >> handler's job, not a filter's. > > > > > > > >> > > > > > > > >> The questions from my original email that still need > answers: > > > > > > > >> > > > > > > > >> How does the binding prevent cross-principal cache hits > > without > > > > > > > >> including the caller's identity? > > > > > > > >> > > > > > > > >> How does Phase 2 re-vend credentials from a generic HTTP > > filter > > > > > > > >> without reimplementing the catalog handler's authorization > and > > > > > > > >> credential vending logic? > > > > > > > >> > > > > > > > >> Has the operational overhead (3 DB round-trips per mutation > on > > > > > > > >> the catalog's connection pool) been benchmarked on any > > backend? > > > > > > > >> > > > > > > > >> I'd like to resolve these on this thread before more code is > > > > > > > >> written. > > > > > > > >> > > > > > > > >> Best, > > > > > > > >> Robert > > > > > > > >> > > > > > > > >> [1] > > > > > > > > https://github.com/apache/polaris/pull/3803#issuecomment-4180969838 > > > > > > > >> > > > > > > > >> On Sun, Apr 5, 2026 at 7:55 AM huaxin gao < > > > [email protected] > > > > > > > > > > > > wrote: > > > > > > > >> > > > > > > > >> > Hi Robert, > > > > > > > >> > > > > > > > > >> > Thanks for raising this on the mailing list. I acknowledge > > the > > > > > > design > > > > > > > >> > concerns you listed. > > > > > > > >> > > > > > > > > >> > To clarify: I picked your option 2 (strip credentials and > > > > re-vend > > > > > on > > > > > > > >> > replay) you suggested in the PR review. The offline > > discussion > > > > > with > > > > > > > >> Yufei > > > > > > > >> > and Prashant was simply to verify that I picked the best > > > option > > > > > from > > > > > > > all > > > > > > > >> > the three suggestions you listed in the review. > > > > > > > >> > > > > > > > > >> > The reason I split it into two phases is that the current > PR > > > is > > > > > > > already > > > > > > > >> > around 3000 lines. Adding re-vending logic on top would > make > > > it > > > > > very > > > > > > > >> hard > > > > > > > >> > to review. This is a big feature and we need to do it > piece > > by > > > > > > piece. > > > > > > > We > > > > > > > >> > will not release it until entire idempotency coding is > > > finished. > > > > > > > >> > > > > > > > > >> > I'm happy to discuss the architecture further on this > > thread, > > > > > > whether > > > > > > > >> the > > > > > > > >> > filter approach can support re-vending, or whether we > need a > > > > > > > >> handler-level > > > > > > > >> > design. I may be slow to respond next week but I'll follow > > up > > > > > after > > > > > > > >> that. > > > > > > > >> > > > > > > > > >> > Thanks, > > > > > > > >> > > > > > > > > >> > Huaxin > > > > > > > >> > > > > > > > > >> > On Sat, Apr 4, 2026 at 9:34 AM Robert Stupp < > [email protected] > > > > > > > > wrote: > > > > > > > >> > > > > > > > > >> > > Hi all, > > > > > > > >> > > > > > > > > > >> > > I need to raise some fundamental design concerns with > the > > > > > current > > > > > > > >> > > Idempotency-Key implementation in PR #3803 [1]. Some of > > > these > > > > > were > > > > > > > >> > > raised in November 2025 [2] and were acknowledged [3] > but > > > > never > > > > > > > >> > > addressed in the implementation. > > > > > > > >> > > > > > > > > > >> > > I raised the caller identity concern on the > > > > > > > >> > > mailing list in November 2025 [2]. In December 2025 > [4], I > > > > > > > >> > > reiterated that all existing implementations I could > find > > do > > > > > > > >> > > request fingerprinting including the request body, and > > > warned > > > > > that > > > > > > > >> > > the idempotency subsystem itself must not become a > source > > of > > > > > > > >> > > failures. The PR was opened in February 2026 without > > > > addressing > > > > > > > >> > > either point. > > > > > > > >> > > > > > > > > > >> > > The credential leakage consequences surfaced during code > > > > review > > > > > > > >> > > [5]. The response was an offline decision between three > > > > > > > contributors, > > > > > > > >> > > without mailing list discussion [6]. The decision was to > > > split > > > > > > > >> > > into Phase 1 (strip credentials, which produces broken > > > > responses > > > > > > > >> > > but does not fix the authorization bypass) and Phase 2 > > > > (re-vend > > > > > > > >> > > on replay, which would require a complete redesign and > > > > > > > >> > > reimplementation). Details below. > > > > > > > >> > > > > > > > > > >> > > I think we need to resolve these at the design level > > before > > > > more > > > > > > > >> > > code is written. > > > > > > > >> > > > > > > > > > >> > > I will not do further code reviews on this PR until > these > > > > design > > > > > > > >> > > concerns are resolved. > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > 1. Caller identity is not part of the idempotency > binding > > > > > > > >> > > > > > > > > > >> > > The caller's identity is not part of the binding. The > > > > > > > >> > > filter replays cached responses before Polaris's > > > > resource-level > > > > > > > >> > > authorization runs. Any authenticated user with a valid > > > > > > idempotency > > > > > > > >> > > key can receive a cached response for a resource they > are > > > not > > > > > > > >> > > authorized to access, including vended storage > > credentials. > > > > This > > > > > > > >> > > is a full authorization bypass. > > > > > > > >> > > > > > > > > > >> > > Idempotency keys are HTTP headers that end up in access > > > logs, > > > > > > > >> > > observability tooling, debug output. They cannot be a > > > security > > > > > > > >> > > boundary. I described the attack vector in my PR review > > [5]. > > > > > > > >> > > > > > > > > > >> > > The proposed Phase 2 [6] says it will "re-authorize the > > user > > > > and > > > > > > > >> > > re-vend fresh credentials on replay." That addresses > > > > credentials > > > > > > > >> > > but not the binding itself. > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > 2. Credential stripping breaks Polaris's deployment > model > > > > > > > >> > > > > > > > > > >> > > Without mailing list discussion, the decision was made > > > offline > > > > > > > >> > > to strip credentials before storing ("Phase 1") [6]. > > > > > > > >> > > > > > > > > > >> > > Polaris's purpose is to vend down-scoped credentials. > > > Clients > > > > > have > > > > > > > >> > > no ambient storage access. > > > > > > > >> > > > > > > > > > >> > > A stripped response returns a successful response > ("table > > > > > > created") > > > > > > > >> > > to the client, which then fails hard because it cannot > > > access > > > > > the > > > > > > > >> > > object storage. Query engines (Spark, Trino, etc.) will > > fail > > > > on > > > > > > > >> > > the first storage operation against that table. Query > > engine > > > > > users > > > > > > > >> > > have no way to resolve this, they don't control the REST > > > > catalog > > > > > > > >> > > interaction. For stage-create, the client gets a > > successful > > > > > > > >> > > response telling it to write data but has no credentials > > to > > > > > write > > > > > > > >> > > with. No fallback exists. > > > > > > > >> > > > > > > > > > >> > > The stripped response is spec-compliant, but > > spec-compliant > > > > and > > > > > > > >> > > operationally correct are not the same thing. > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > 3. Phase 2 is architecturally incompatible with Phase 1 > > > > > > > >> > > > > > > > > > >> > > The filter is a generic HTTP filter below the > application > > > > layer. > > > > > > It > > > > > > > >> > > treats responses as opaque JSON. Credential vending > > happens > > > > deep > > > > > > > >> > > inside IcebergCatalogHandler, scoped to specific table > > > > locations > > > > > > > >> > > and principals, through cloud IAM calls (STS AssumeRole, > > GCS > > > > > token > > > > > > > >> > > exchange). > > > > > > > >> > > > > > > > > > >> > > Re-vending on replay would require the filter to resolve > > the > > > > > > > >> > > table's storage location, authorize the caller, call > cloud > > > IAM > > > > > to > > > > > > > >> > > mint scoped credentials, and manage credential caching. > > That > > > > is > > > > > > > >> > > not a filter, that is reimplementing the catalog > handler's > > > > > > > >> > > authorization and credential vending logic. > > > > > > > >> > > > > > > > > > >> > > Phase 1 and Phase 2 need to be designed and shipped > > > together. > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > 4. Operational overhead > > > > > > > >> > > > > > > > > > >> > > Every idempotent mutation adds 3 database round-trips > > > (INSERT, > > > > > > > UPDATE, > > > > > > > >> > > heartbeat UPDATEs), each borrowing its own connection > > > > > > > >> > > (autoCommit=true, no reuse), sharing the catalog's > > > connection > > > > > pool > > > > > > > >> > > and RDBMS. This added latency increases the probability > of > > > > > client > > > > > > > >> > > timeouts, which are exactly the transient failures that > > > > > > idempotency > > > > > > > >> > > is supposed to prevent. > > > > > > > >> > > > > > > > > > >> > > The idempotency table is high-churn and write-hot, > > competing > > > > > with > > > > > > > >> > > catalog operations for connection pool capacity. The > > > overhead > > > > > gets > > > > > > > >> > > worse on managed and distributed database backends. > > > Duplicate > > > > > > > >> > > requests trigger polling loops with repeated database > > reads. > > > > > > > >> > > > > > > > > > >> > > No benchmark data has been presented for any backend. > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > What needs to change > > > > > > > >> > > > > > > > > > >> > > The current generic-filter approach cannot support these > > > > > > > >> > > requirements. This needs a different design. > > > > > > > >> > > > > > > > > > >> > > A new design must address the following: > > > > > > > >> > > > > > > > > > >> > > a) The idempotency binding MUST include the caller's > > > principal > > > > > > > >> > > identity. > > > > > > > >> > > b) Credential-bearing responses must not be stored > as-is. > > On > > > > > > > >> > > replay, the handler must build a fresh response with > > > fresh > > > > > > > >> > > credentials for the current caller. > > > > > > > >> > > c) The operational overhead needs to be benchmarked. > > > > > > > >> > > > > > > > > > >> > > I am happy to review code once the design addresses > these > > > > > points. > > > > > > > >> > > > > > > > > > >> > > Best, > > > > > > > >> > > Robert > > > > > > > >> > > > > > > > > > >> > > [1] https://github.com/apache/polaris/pull/3803 > > > > > > > >> > > [2] > > > > > > > > https://lists.apache.org/thread/qqrgr2bzsp69629jdj8kf39m10pzwy6l > > > > > > > >> > > (Nov 24, 2025: "Building a service-internal key from > > the > > > > > > client > > > > > > > >> > > provided idempotency key plus more data from the > > request > > > > > gives > > > > > > > >> > > better uniqueness. That more data can come from: > > > operation > > > > > id, > > > > > > > >> > > all operation parameters, including the whole > payload, > > > > > quite a > > > > > > > >> > > few HTTP request headers like user-agent, > > authorization, > > > > > host, > > > > > > > >> > > accept-* and also the client's address.") > > > > > > > >> > > [3] > > > > > > > > https://lists.apache.org/thread/7vy44mxsq2cgtp8gsj0r8pk8blp37h5b > > > > > > > >> > > (Dec 8, 2025: "I agree that a bare Idempotency-Key + > > > > entity > > > > > > > >> > > identifier is not enough to protect against buggy or > > > > > malicious > > > > > > > >> > > clients; fingerprinting the full request would be > > > > > stronger.") > > > > > > > >> > > [4] > > > > > > > > https://lists.apache.org/thread/jt3gmpnjh6z490dvxorjs6ms00kvo264 > > > > > > > >> > > (Dec 8, 2025: "We should avoid failing Polaris if > this > > > > > > subsystem > > > > > > > >> > > fails, or letting this subsystem be a reason for its > > > > > existence > > > > > > > >> > > (aka retry due to timeouts because the > > > idempotent-request > > > > > > > >> > > subsystem hangs).") > > > > > > > >> > > [5] > > > > > > > >> > > > > > > > > > >> > > > > > > > > > > > > > > > > https://github.com/apache/polaris/pull/3803#pullrequestreview-4051690055 > > > > > > > >> > > [6] > > > > > > > >> > > > > https://github.com/apache/polaris/pull/3803#issuecomment-4180969838 > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
