Hi dev's, I am currently creating the Confluence page for this proposal.
I noticed that FIP-35 is not currently listed on the wiki. Could you please confirm if this number is available for use, or if I should assigned a different one? Best regards, Prajwal Banakar On Wed, 11 Mar 2026 at 22:56, Prajwal Banakar <[email protected]> wrote: > Hi Keith, > > Thank you for the follow-up. > > You are correct that FieldRoaringBitmap64Agg already exists in > fluss-server. I have updated the proposal accordingly. To clarify, the > 32-bit scope is intended to keep the initial type system and SQL function > surface focused and deliverable, rather than being a limitation of the > aggregator itself. Since the server-side aggregator is already in place, > RBM64 will be a natural, low-risk follow-on once the type system and > pushdown infrastructure are established. > > I have also removed the misleading motivation paragraph as you suggested. > The updated document is available at the same link. Additionally, I would > welcome Yang's input on the alignment with FIP-21. > > Best regards, > Prajwal Banakar > > On Wed, 11 Mar 2026 at 17:37, Keith Lee <[email protected]> > wrote: > >> Hi Prajwal, >> >> Thank you for addressing / answering the questions. >> >> > This proposal adds the missing bridge: a proper BITMAP DDL type, SQL >> functions (BITMAP_BUILD, BITMAP_OR_AGG, BITMAP_CARDINALITY), and pushdown >> via applyAggregates(). The storage-side aggregation logic already exists; >> this proposal makes it accessible end-to-end >> >> 1. That makes sense. I think the motivation section should lead with that >> and remove the following as it can be misleading given that rbm is >> supported by aggregation merge engine: “users requiring high-cardinality >> unique counting (e.g., UV analytics) must execute Client-Side Aggregation. >> The TabletServer is forced to send massive amounts of raw LogRecordBatch >> rows over the network to a Flink cluster for evaluation. This results in >> unnecessary network transfer and prevents efficient utilization of the >> existing aggregation merge engine.” >> >> 2. That makes sense. Thank you for the context. >> >> 3. >> >> > RBM64 requires a fundamentally different internal structure; a map of >> RBM32 chunks which increases implementation and serialization complexity >> significantly. >> >> My understanding is that the proposal wires existing >> FieldRoaringBitmap32Agg to support rbm32. FieldRoaringBitmap64Agg should >> already exist and handle the complexity that you mentioned? >> >> Additionally, it might be good for Yang to review / provide input on this >> given his work on FIP-21. >> >> Best regards >> >> Keith Lee >> >> >> On Wed, 11 Mar 2026 at 05:49, Prajwal Banakar <[email protected] >> > >> wrote: >> >> > Hi Keith, thank you for the detailed feedback. >> > >> > 1. On motivation vs existing aggregation merge engine: The aggregation >> > merge engine in 0.9 supports rbm32/rbm64 at the storage level, but >> BITMAP >> > is not yet a first-class type in the DDL or type system. Users today >> must >> > declare the column as BYTES (as shown in the 0.9 release example: >> uv_bitmap >> > BYTES), and there are no SQL functions to build, merge, or query bitmaps >> > from Flink SQL. This proposal adds the missing bridge: a proper BITMAP >> DDL >> > type, SQL functions (BITMAP_BUILD, BITMAP_OR_AGG, BITMAP_CARDINALITY), >> and >> > pushdown via applyAggregates(). The storage-side aggregation logic >> already >> > exists; this proposal makes it accessible end-to-end. >> > >> > 2. On NULL semantics: BITMAP_OR(bitmap, NULL) returns NULL following >> > standard SQL scalar function semantics where NULL inputs propagate to >> NULL >> > outputs. BITMAP_OR_AGG follows aggregate function convention consistent >> > with how SUM and AVG behave, where NULLs in individual rows are skipped >> and >> > only a fully NULL input set returns NULL. This distinction follows >> FLIP-556 >> > and StarRocks semantics. >> > >> > 3. On 32-bit scope: The proposal is scoped to 32-bit initially because >> > RoaringBitmap32 covers integer values up to 2^32 (~4 billion), which is >> > sufficient for most user ID and session ID use cases. RBM64 requires a >> > fundamentally different internal structure; a map of RBM32 chunks which >> > increases implementation and serialization complexity significantly. >> > Starting with 32-bit keeps the initial scope focused and deliverable. >> RBM64 >> > support is listed as a Could-Have in the MoSCoW deliverables and can >> follow >> > in a subsequent iteration. >> > >> > Best regards, >> > >> > Prajwal Banakar >> > >> > >> > On Wed, 11 Mar 2026 at 01:34, Keith Lee <[email protected]> >> > wrote: >> > >> > > Hello Prajwal, >> > > >> > > Thank you for the detailed proposal. I enjoyed reading it and have a >> few >> > > questions/comments. >> > > >> > > 1. On motivation, can you provide context on how this differs with >> > > aggregation merge engine’s roaring bitmap implementation [1]? >> > Specifically, >> > > motivation part states that “users requiring high cardinality unique >> > > counting … must execute client-side aggregation”. Aggregation merge >> > engine >> > > performs aggregation on server-side. The motivation section should >> > clarify >> > > how the proposed changes improve or complement aggregation merge >> engine, >> > > which seems to have been considered as Section 2 references FIP-21 >> > > Aggregation Merge Engine. Adding this context will help readers >> > understand >> > > the motivation of the proposal better. >> > > >> > > 2. Can you clarify the NULL semantics section specifically on the >> > decision >> > > on why BITMAP_OR(bitmap, NULL) returns NULL but BITMAP_OR_AGG only >> > returns >> > > null when all rows are NULL? >> > > >> > > 3. Why is the scope limited to 32 bit bitmaps? Adding the rationale >> > behind >> > > these e.g. how (if any) support of 64bit bitmaps would increase >> > > implementation complexity. Articulating these may help other >> contributors >> > > understand the complexity and perhaps come up with suggestions on how >> to >> > > address them. >> > > >> > > Best regards >> > > >> > > Keith Lee >> > > >> > > [1] >> > > >> > > >> > >> https://fluss.apache.org/blog/releases/0.9/#2-storage-level-processing--semantics >> > > >> > > >> > > On Mon, 9 Mar 2026 at 05:31, Prajwal Banakar < >> [email protected] >> > > >> > > wrote: >> > > >> > > > Hi Devs, >> > > > >> > > > I have pushed a working prototype to my public fork demonstrating >> the >> > > > BitmapType integrated with FieldRoaringBitmap32Agg. This includes >> four >> > > > passing unit tests. >> > > > >> > > > The link to the prototype is available in the Google Doc, and you >> can >> > > also >> > > > find it here: >> > > > >> https://github.com/Prajwal-banakar/fluss/tree/RoaringBitmap-prototype >> > > > >> > > > The Google Doc link remains the same. I look forward to your >> feedback. >> > > > >> > > > Best regards, >> > > > >> > > > Prajwal Banakar >> > > > >> > > > >> > > > On Sun, 1 Mar, 2026, 11:49 am Prajwal Banakar, < >> > > [email protected] >> > > > > >> > > > wrote: >> > > > >> > > > > Hi everyone, >> > > > > >> > > > > I would like to start a discussion on the proposal for Native >> Bitmap >> > > > > Integration & Stateless Pushdown Aggregation. >> > > > > >> > > > > This proposal enables end-to-end native support for the BITMAP >> type >> > in >> > > > > Fluss and integrates it with the existing aggregation merge >> engine to >> > > > > support server-side bitmap union pushdown. The goal is to reduce >> > > network >> > > > > transfer and offload DISTINCT-style aggregation from Flink to the >> > > > > TabletServer. >> > > > > >> > > > > Key highlights of the proposal include: >> > > > > >> > > > > - Type System: Promoting BITMAP to a first-class logical type. >> > > > > - UDF Suite: Introducing BITMAP_BUILD, BITMAP_OR_AGG, and >> > > > > BITMAP_CARDINALITY (aligned with FLIP-556 and StarRocks >> semantics). >> > > > > - Optimizer: Planner-based pushdown via applyAggregates in the >> Flink >> > > > > connector. >> > > > > - Safety: No changes to LogRecordBatch or WAL, making this >> strictly >> > > > > additive and migration-free. >> > > > > >> > > > > You can find the full proposal document here: >> > > > > >> > > > > >> > > > >> > > >> > >> https://docs.google.com/document/d/1sDhfkmo-w-UTvo2n3rsY1lytSSryswfkI83cSdka8s0/edit?usp=sharing >> > > > > >> > > > > I would appreciate feedback on the public interfaces, pushdown >> > > > > constraints, and overall scope. >> > > > > >> > > > > Best regards, >> > > > > Prajwal Banakar >> > > > > >> > > > >> > > >> > >> >
