feat: a utility for creating "permutation views" (#2552)

I'm working on a lancedb version of pytorch data loading (and hopefully
addressing https://github.com/lancedb/lance/issues/3727).

However, rather than rely on pytorch for everything I'm moving some of
the things that pytorch does into rust. This gives us more control over
data loading (e.g. using shards or a hash-based split) and it allows
permutations to be persistent. In particular I hope to be able to:

* Create a persistent permutation
* This permutation can handle splits, filtering, shuffling, and sharding
* Create a rust data loader that can read a permutation (one or more
splits), or a subset of a permutation (for DDP)
* Create a python data loader that delegates to the rust data loader

Eventually create integrations for other data loading libraries,
including rust & node
This commit is contained in:
Weston Pace
2025-10-09 18:07:31 -07:00
committed by GitHub
parent 3dcec724b7
commit 5a19cf15a6
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[**@lancedb/lancedb**](../README.md) • **Docs**
***
[@lancedb/lancedb](../globals.md) / PermutationBuilder
# Class: PermutationBuilder
A PermutationBuilder for creating data permutations with splits, shuffling, and filtering.
This class provides a TypeScript wrapper around the native Rust PermutationBuilder,
offering methods to configure data splits, shuffling, and filtering before executing
the permutation to create a new table.
## Methods
### execute()
```ts
execute(): Promise<Table>
```
Execute the permutation and create the destination table.
#### Returns
`Promise`&lt;[`Table`](Table.md)&gt;
A Promise that resolves to the new Table instance
#### Example
```ts
const permutationTable = await builder.execute();
console.log(`Created table: ${permutationTable.name}`);
```
***
### filter()
```ts
filter(filter): PermutationBuilder
```
Configure filtering for the permutation.
#### Parameters
* **filter**: `string`
SQL filter expression
#### Returns
[`PermutationBuilder`](PermutationBuilder.md)
A new PermutationBuilder instance
#### Example
```ts
builder.filter("age > 18 AND status = 'active'");
```
***
### shuffle()
```ts
shuffle(options): PermutationBuilder
```
Configure shuffling for the permutation.
#### Parameters
* **options**: [`ShuffleOptions`](../interfaces/ShuffleOptions.md)
Configuration for shuffling
#### Returns
[`PermutationBuilder`](PermutationBuilder.md)
A new PermutationBuilder instance
#### Example
```ts
// Basic shuffle
builder.shuffle({ seed: 42 });
// Shuffle with clump size
builder.shuffle({ seed: 42, clumpSize: 10 });
```
***
### splitCalculated()
```ts
splitCalculated(calculation): PermutationBuilder
```
Configure calculated splits for the permutation.
#### Parameters
* **calculation**: `string`
SQL expression for calculating splits
#### Returns
[`PermutationBuilder`](PermutationBuilder.md)
A new PermutationBuilder instance
#### Example
```ts
builder.splitCalculated("user_id % 3");
```
***
### splitHash()
```ts
splitHash(options): PermutationBuilder
```
Configure hash-based splits for the permutation.
#### Parameters
* **options**: [`SplitHashOptions`](../interfaces/SplitHashOptions.md)
Configuration for hash-based splitting
#### Returns
[`PermutationBuilder`](PermutationBuilder.md)
A new PermutationBuilder instance
#### Example
```ts
builder.splitHash({
columns: ["user_id"],
splitWeights: [70, 30],
discardWeight: 0
});
```
***
### splitRandom()
```ts
splitRandom(options): PermutationBuilder
```
Configure random splits for the permutation.
#### Parameters
* **options**: [`SplitRandomOptions`](../interfaces/SplitRandomOptions.md)
Configuration for random splitting
#### Returns
[`PermutationBuilder`](PermutationBuilder.md)
A new PermutationBuilder instance
#### Example
```ts
// Split by ratios
builder.splitRandom({ ratios: [0.7, 0.3], seed: 42 });
// Split by counts
builder.splitRandom({ counts: [1000, 500], seed: 42 });
// Split with fixed size
builder.splitRandom({ fixed: 100, seed: 42 });
```
***
### splitSequential()
```ts
splitSequential(options): PermutationBuilder
```
Configure sequential splits for the permutation.
#### Parameters
* **options**: [`SplitSequentialOptions`](../interfaces/SplitSequentialOptions.md)
Configuration for sequential splitting
#### Returns
[`PermutationBuilder`](PermutationBuilder.md)
A new PermutationBuilder instance
#### Example
```ts
// Split by ratios
builder.splitSequential({ ratios: [0.8, 0.2] });
// Split by counts
builder.splitSequential({ counts: [800, 200] });
// Split with fixed size
builder.splitSequential({ fixed: 1000 });
```