GPU Module Changelog¶

This page documents the version history of the KDB-X GPU module, including released versions, fixes, and improvements.

3.0.0¶

Release date: 2026-11-09

This release adds the .gpu.tensor API and a simpler interface through one module with virtual GPU objects, descending sorts, per-call device selection, and correctness fixes that make GPU results match q.

New

Added the .gpu.tensor API for typed tensor data on the GPU: arithmetic and broadcasting, reductions and running scans, moving windows, sorting, linear algebra (mmu, inv, chol, lsq, and principal component analysis (PCA)), concatenation, take and view, NumPy-style indexing (gather), and type conversion. Results stay on the GPU and interoperate with q data.
Added .gpu.xdesc and .gpu.idesc, the descending counterparts of .gpu.xasc and .gpu.iasc.
Added .gpu.onDev[d;f], which runs f with device d current and restores the previous device when it returns or signals, for per-call device selection under peach. The reference now documents that .gpu.setDev is per host thread.
Query expressions now support GUID columns in min, max, &, |, mins, maxs, mmin, mmax, and ordering comparisons.

Breaking changes

.gpu:use`gpu returns GPU results as virtual objects and the separate use`g module is removed. Every .gpu and .gpu.tensor function keeps its name and signature and still accepts q data; plain q select, exec, select[n], lj, ij, aj, wj, xasc, meta, cols, and xkey work on GPU tables. q primitives do not see inside a virtual object; see GPU objects.
The use`g names .gpu.qry and .gpu.device, the .gpu.tensor groups aggs, scans, moving and linear, and the aliases dve, xexp, flip, upsert, and random.rng are gone; use the .gpu/.gpu.tensor names in the reference.

Fixes and improvements

Joins and searches: Single-key .gpu.aj, .gpu.bin, .gpu.lj, .gpu.ij, .gpu.wj, and .gpu.wj1 are faster on attributed key columns, which now include byte and month. The as-of join family matches enum keys across different domains and keeps q's null-time and window behavior. Mixed-type in follows q's rules, and xbar with real, float or datetime divisors now matches q in previously divergent cases.
Floating-point fidelity: Comparisons, casts and grouped keys now match q's comparison tolerance (1f=1+2 xexp -44 is 1b), subnormal and NaN handling, signed zeros and datetime keys in grouping, `g# lookups and sorts, and rounding in float-to-integer casts.
Aggregates and scans: Aggregates of aggregates under by, constant aggregates per group, scans and moving operations of atoms, scalar booleans combined with per-row conditions, empty by grouping, seeded fills and wavg with atom operands now match q. Grouped integer sums wrap on overflow as q does.
Data transfer: A CUDA error during .gpu.to or .gpu.from now reports a q error instead of ending the session. Failed uploads and appends release their resources and leave the target intact. .j.j serializes GPU-resident columns.
Nested columns: .gpu.take and .gpu.sublist slice a nested column by rows, as q does. Operations that cannot support nested columns report an error instead of returning wrong results.
Memory and performance: Memory freed after an operation is kept for reuse, speeding up repeated queries. Empty .gpu.take and .gpu.sublist results stay on the GPU, and grouped (`g#) appends keep a correct index.
Fixes: .gpu.count of a keyed table returns the row count; the empty select phrase no longer returns row numbers for a column named i; .gpu.sublist clamps negative counts like q; datetime columns sort without aborting the q session; GUID result columns in joins are copied at the right width and grouped GUID indexes no longer crash; unknown names in query expressions error instead of being read as data.

2.9.0¶

Release date: 2026-10-20

This release skips sorting for inputs that are already sorted, adds memory compaction with .gpu.compact, and fixes several bugs.

Fixes and improvements

Fixed null and out-of-range fills in .gpu.gather and SQL column re-indexing for real, float, datetime, char, and symbol columns, including a symbol result corruption that could crash q. .gpu.gather now also accepts short and int index vectors, CPU-resident or GPU-resident.
.gpu.aj and .gpu.bin now support 4-byte columns: int, month, date, minute, second, and time as the ordered column, and int as an equality column.
.gpu.asc, .gpu.iasc, and .gpu.xasc skip the sort when the input already has the `s attribute.
Added .gpu.compact to reclaim the capacity a GPU-resident object reserved for appending. Like a global amend in q, it signals noupdate from a secondary thread.
Setting a global-scope setting of .gpu.config from a secondary thread now signals noupdate, as .gpu.compact does. Reading configuration is unaffected.
Implemented .gpu.select and .gpu.update column re-indexing, including nested re-indexing, composition with operations such as iasc, and support for where and by. Functional iasc symbol-vector arguments support arbitrary depth and follow q's right-to-left application semantics. For example, (iasc;`source`index1`index2) is interpreted as iasc source[index1[index2]].
Accelerated first-clause = and in filters in .gpu.select and .gpu.update using the grouped (`g) attribute. Supports all column types except byte, month, and deprecated datetime.

2.8.0¶

Release date: 2026-09-01

Exec form of .gpu.select.

Fixes and improvements

.gpu.select now supports exec forms: the shapes of the by and phrase arguments choose between select and exec semantics, as in native q.
Fixed some incorrect temporal casts.

2.7.0¶

Release date: 2026-08-26

Runtime configuration with .gpu.config, fby and .gpu.ungroup support, and sort, allocation, and comparison fixes.

Fixes and improvements

Added .gpu.config to get or set runtime configuration.
Added the alloc setting to .gpu.config, choosing power-of-two device allocations (`buddy, the default and previous behavior) or exact-size ones (`tight). `tight cuts VRAM for data that isn't appended to, at the cost of every append reallocating.
Added .gpu.ungroup.
Added support for fby in .gpu.select and .gpu.update.
Added support for .gpu.append taking a symbol atom naming a global as its first argument. It appends to that global and returns the symbol, similar to `t upsert y.
Added support in .gpu.select for comparing an enumerated symbol column (type 20h) to a symbol atom (type 11h) with = and <>. For example:

q)T:.gpu.to ([]s:`sym$`AAPL`MSFT`AAPL;p:150 300 152)
q).gpu.from .gpu.select[T;enlist(=;`s;enlist`AAPL);0b;()]

Deprecated .gpu.setMemRelThres and .gpu.getMemRelThres in favor of the memRelThres setting of .gpu.config.
Fixed .gpu.asc, .gpu.xasc and two-key .gpu.aj failing with an allocation error on empty input.
Fixed .gpu.asc sorting against a null buffer, and .gpu.to failing silently, on an allocation failure.
Fixed a comparison against a scalar returning wrong values in its last rows.
Fixed incorrect sort order in .gpu.xasc, .gpu.asc, and .gpu.iasc when sorting on an enumerated symbol column with a large enumeration domain.
Fixed incorrect sort order in .gpu.xasc, .gpu.asc, and .gpu.iasc when sorting on an enumerated symbol column whose enumeration domain has more entries than the table has rows.
Fixed copy-on-write semantics of .gpu.append.
Fixed a GPU_LAUNCH_FAIL error when sorting on multiple columns, seen on some GPU architectures.

2.6.2¶

Release date: 2026-08-14

Where clauses rework.

Fixes and improvements

Reworked how where clauses are applied to improve performance for highly selective queries.

2.6.1¶

Release date: 2026-08-12

Blackwell sm_120 architecture support.

Fixes and improvements

Added support for the sm_120 architecture of Blackwell.

To find the correct version for your GPU, run nvidia-smi --query-gpu=compute_cap and multiply by 10 (for example, 10.0 → 100, 12.0 → 120).

2.6.0¶

Release date: 2026-08-12

Inner join, window join, covariance, correlation, and update support, additional .gpu.select operations, and .gpu.select fixes.

Fixes and improvements

Added support for inner join .gpu.ij.
Added support for window joins .gpu.wj and .gpu.wj1, with sum, min, max, count, avg, first, and last aggregations.
Added support for covariance, sample covariance, and correlation with .gpu.cov, .gpu.scov, and .gpu.cor for GPU-resident float vectors.
Added support for rank and xrank in .gpu.select.
Added support for iasc with a by clause in .gpu.select.
Added support for .gpu.update.
Fixed iasc under a where clause in .gpu.select to match native q.
Fixed a bug in .gpu.select that caused some operations to fail on boolean expressions.

2.5.0¶

Release date: 2026-07-28

This release adds support for Blackwell, additional .gpu.select operations, and .gpu.lj; it also improves performance and allocation-failure handling.

Fixes and improvements

Added support for left join .gpu.lj.
Added support for ema in .gpu.select.
Improved group-by sort performance in .gpu.select.
Fixed a bug that terminated the process after an allocation failure instead of returning a recoverable error.
Fixed a crash on an empty input to .gpu.select.
Added Blackwell (sm_100) support.

2.4.0¶

Release date: 2026-07-16

Additional .gpu.select operation support and a groupby fix.

Fixes and improvements

Added support for fill (^) and fills (^\) in .gpu.select.
Added support for ratios and deltas in .gpu.select.
Added support for prev, xprev, and next in .gpu.select.
Fixed a bug in .gpu.select that manifested as missing results in a groupby operation.

2.3.0¶

Release date: 2026-06-30

Windowed scan operations & Sort performance improvements.

Fixes and improvements

Added support for msum, mmin, mmax and mdev in .gpu.select.
Improved multi-column sort performance in .gpu.xasc, .gpu.asc, and .gpu.iasc.

2.2.0¶

Release date: 2026-06-15

Scan operations, keyed tables, and performance improvements.

Fixes and improvements

Added support for prds, mins, and maxs in .gpu.select.
Added support for keyed tables, which are now returned from .gpu.select with a by clause.
Improved .gpu.select performance by avoiding casts with bit-identical input and output.

2.1.0¶

Release date: 2026-06-02

Scan operation support and fixes.

Fixes and improvements

Added support for sums and xexp in .gpu.select.
Allowed non-GPU-resident columns in .gpu.xasc. Sorting on such columns (that is, the lhs arguments) remains unsupported.
Fixed .gpu.select to broadcast atomic results to match the size of other columns.
Fixed a crash in .gpu.take when trying to create very large tables.
Fixed .gpu.gather handling of null indices to match q semantics. Null indices now produce null output values instead of incorrectly reading from index 0.

2.0.0¶

Release date: 2026-05-19

Nested data and richer .gpu.select.

Fixes and improvements

Added support for columns of lists (1 level deep only). This enables mavg inside a .gpu.select with a by clause.
Improved sorting performance.
Improved aggregate performance in .gpu.select.
Added greater operator support in .gpu.select: casting, dev, first, iasc, in, last, mavg, sqrt, var, wavg, within, and xbar.
Removed the requirement for an aggregate in the select phrase when using .gpu.select with a by clause.
Fixed integer-sum overflow.
Exposed GPU memory pool configuration through .gpu.setMemRelThres and .gpu.getMemRelThres. For more information, refer to CUDA memory pool documentation.
Exposed cudaProfilerStart and cudaProfilerStop through .gpu.profiler.start and .gpu.profiler.stop.
Renamed device management functions: ndev to cntDev, gdev to getDev, sdev to setDev, and mdev to memDev.

1.0.1¶

Release date: 2026-04-30

Release fix.

Fixes and improvements

Support for CUDA 12 alongside CUDA 13.
Fixed build issue with some 1.0.0 packages.

1.0.0¶

Release date: 2026-03-31

Initial Release

Fixes and improvements

N/A