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vweevers merged 2 commits into from
Sep 24, 2021
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Add features: getMany, keyIterator, valueIterator, iteratorNextv, iteratorAll #11

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Document ecosystem support of features
vweevers Sep 24, 2021
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Add features: getMany, keyIterator, valueIterator, iteratorNextv, ite…
vweevers Sep 24, 2021
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211 changes: 207 additions & 4 deletions README.md
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Expand Up @@ -74,24 +74,118 @@ if (db.supports.streams === true)

Does the db support [Buffer](https://nodejs.org/api/buffer.html) keys? May depend on runtime environment as well. Does _not_ include support of other binary types like typed arrays (which is why this is called `bufferKeys` rather than `binaryKeys`).

<details>
<summary>Support matrix</summary>

| Module | Support |
| :------------------- | :------ |
| `abstract-leveldown` | ✅ |
| `leveldown` | ✅ |
| `rocksdb` | ✅ |
| `memdown` | ✅ |
| `level-js` | ✅ |
| `encoding-down` | ✅ |
| `deferred-leveldown` | ✅ |
| `levelup` | ✅ |
| `level-packager` | ✅ |
| `level` | ✅ |
| `level-mem` | ✅ |
| `level-rocksdb` | ✅ |
| `subleveldown` | ✅ |
| `multileveldown` | ✅ |
| `level-party` | ✅ |

</details>

### `snapshots` (boolean)

Does the db have snapshot guarantees (meaning that reads are unaffected by simultaneous writes)? Must be `false` if any of the following is true:

- Reads don't operate on a [snapshot](https://github.com/Level/abstract-leveldown#iterator)
- Snapshots are created asynchronously.

<details>
<summary>Support matrix</summary>

| Module | Snapshot guarantee |
| :------------------- | :-------------------------- |
| `abstract-leveldown` | ✅ |
| `leveldown` | ✅ |
| `rocksdb` | ✅ |
| `memdown` | ✅ |
| `level-js` | ✅ (by buffering) |
| `encoding-down` | ✅ |
| `deferred-leveldown` | ✅ |
| `levelup` | ✅ |
| `level-packager` | ✅ |
| `level` | ✅ |
| `level-mem` | ✅ |
| `level-rocksdb` | ✅ |
| `subleveldown` | ✅ |
| `multileveldown` | ✅ (unless `retry` is true) |
| `level-party` | ❌ (unless `retry` is false) |

</details>

### `permanence` (boolean)

Does data survive after process exit? Is `false` for e.g. [`memdown`](https://github.com/Level/memdown), typically `true`.

### `seek` (boolean)

Does `db.iterator()` support [`seek(..)`](https://github.com/Level/abstract-leveldown/#iteratorseektarget)?
Do iterators support [`seek(..)`](https://github.com/Level/abstract-leveldown/#iteratorseektarget)?

<details>
<summary>Support matrix</summary>

| Module | Support |
| :------------------- | :------------- |
| `abstract-leveldown` | ✅ 6.0.0 |
| `leveldown` | ✅ 1.2.0 |
| `rocksdb` | ✅ 1.0.0 |
| `memdown` | ✅ 4.1.0 |
| `level-js` | ❌ |
| `encoding-down` | ✅ 6.1.0 |
| `deferred-leveldown` | ✅ 5.1.0 |
| `levelup` | ✅ n/a |
| `level-packager` | ✅ n/a |
| `level` | ❌ (`level-js`) |
| `level-mem` | ✅ 4.0.0 |
| `level-rocksdb` | ✅ 1.0.0 |
| `subleveldown` | ✅ 4.1.0 |
| `multileveldown` | ❌ |
| `level-party` | ❌ |

</details>

#### `clear` (boolean)

Does db support [`db.clear(..)`](https://github.com/Level/abstract-leveldown/#dbclearoptions-callback)? For an overview, see [Level/community#79](https://github.com/Level/community/issues/79).
Does db support [`db.clear(..)`](https://github.com/Level/abstract-leveldown/#dbclearoptions-callback)?

<details>
<summary>Support matrix</summary>

See also [Level/community#79](https://github.com/Level/community/issues/79).

| Module | Support | Optimized |
| :------------------- | :------ | :-------------- |
| `abstract-leveldown` | ✅ 6.1.0 | n/a |
| `leveldown` | ✅ 5.2.0 | ❌ |
| `rocksdb` | ✅ 4.1.0 | ❌ |
| `memdown` | ✅ 5.0.0 | ❌ |
| `level-js` | ✅ 5.0.0 | ✅ 5.0.0 |
| `encoding-down` | ✅ 6.2.0 | n/a |
| `deferred-leveldown` | ✅ 5.2.0 | n/a |
| `levelup` | ✅ 4.2.0 | n/a |
| `level-packager` | ✅ 5.0.3 | n/a |
| `level` | ✅ 6.0.0 | ❌ (`leveldown`) |
| `level-mem` | ✅ 5.0.1 | ❌ (`memdown`) |
| `level-rocksdb` | ✅ 5.0.0 | ❌ (`rocksdb`) |
| `subleveldown` | ✅ 4.2.1 | n/a |
| `multileveldown` | ❌ | n/a |
| `level-party` | ❌ | n/a |

</details>

### `status` (boolean)

Expand Down Expand Up @@ -136,7 +230,19 @@ db.open(.., callback)

### `createIfMissing`, `errorIfExists` (boolean)

Does `db.open(options, ..)` support these (`leveldown`) options?
Does `db.open(options, ..)` support these options?

<details>
<summary>Support matrix</summary>

| Module | Support |
| :---------- | :------ |
| `leveldown` | ✅ |
| `rocksdb` | ✅ |
| `memdown` | ❌ |
| `level-js` | ❌ |

</details>

### `promises` (boolean)

Expand All @@ -147,18 +253,115 @@ db.put('key', 'value', callback)
await db.put('key', 'value')
```

_Note: iterators are currently exonerated because they, at the time of writing, don't support promises anywhere._
<details>
<summary>Support matrix</summary>

| Module | Support |
| :------------------- | :------------------- |
| `abstract-leveldown` | ❌ (except iterators) |
| `leveldown` | ❌ (except iterators) |
| `rocksdb` | ❌ (except iterators) |
| `memdown` | ❌ (except iterators) |
| `level-js` | ❌ (except iterators) |
| `encoding-down` | ❌ (except iterators) |
| `deferred-leveldown` | ❌ (except iterators) |
| `levelup` | ✅ |
| `level-packager` | ✅ |
| `level` | ✅ |
| `level-mem` | ✅ |
| `level-rocksdb` | ✅ |
| `subleveldown` | ❌ |
| `multileveldown` | ❌ |
| `level-party` | ❌ |

</details>

### `streams` (boolean)

Does db have the methods `createReadStream`, `createKeyStream` and `createValueStream`, following the API currently documented in `levelup`?

<details>
<summary>Support matrix</summary>

| Module | Support |
| :------------------- | :------ |
| `abstract-leveldown` | ❌ |
| `leveldown` | ❌ |
| `rocksdb` | ❌ |
| `memdown` | ❌ |
| `level-js` | ❌ |
| `encoding-down` | ❌ |
| `deferred-leveldown` | ❌ |
| `levelup` | ✅ |
| `level-packager` | ✅ |
| `level` | ✅ |
| `level-mem` | ✅ |
| `level-rocksdb` | ✅ |
| `subleveldown` | ✅ |
| `multileveldown` | ✅ |
| `level-party` | ✅ |

</details>

### `encodings` (boolean)

Do all relevant db methods take `keyEncoding` and `valueEncoding` options?

_TBD: what this means for `*asBuffer` options._

<details>
<summary>Support matrix</summary>

| Module | Support |
| :------------------- | :------ |
| `abstract-leveldown` | ❌ |
| `leveldown` | ❌ |
| `rocksdb` | ❌ |
| `memdown` | ❌ |
| `level-js` | ❌ |
| `encoding-down` | ✅ |
| `deferred-leveldown` | ❌ |
| `levelup` | ✅ |
| `level-packager` | ✅ |
| `level` | ✅ |
| `level-mem` | ✅ |
| `level-rocksdb` | ✅ |
| `subleveldown` | ✅ |
| `multileveldown` | ✅ |
| `level-party` | ✅ |

</details>

### `getMany` (boolean)

Does the db have a `getMany(keys[, options][, callback])` method?

_At the time of writing this is a new feature, subject to change, zero modules support it._

### `keyIterator` (boolean)

Does the `db` have a `keys([options])` method that returns a key iterator? Also implies support of `iterator#mode`.

_At the time of writing this is a new feature, subject to change, zero modules support it._

### `valueIterator` (boolean)

Does the `db` have a `values([options])` method that returns a key iterator? Also implies support of `iterator#mode`.

_At the time of writing this is a new feature, subject to change, zero modules support it._

### `iteratorNextv` (boolean)

Do iterators have a `nextv(size[, options][, callback])` method?

_At the time of writing this is a new feature, subject to change, zero modules support it._

### `iteratorAll` (boolean)

Do iterators have a `all([options][, callback])` method?

_At the time of writing this is a new feature, subject to change, zero modules support it._

### `additionalMethods` (object)

In the form of:
Expand Down
5 changes: 5 additions & 0 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,11 @@ module.exports = function supports (...manifests) {
permanence: manifest.permanence || false,
seek: manifest.seek || false,
clear: manifest.clear || false,
getMany: manifest.getMany || false,
keyIterator: manifest.keyIterator || false,
valueIterator: manifest.valueIterator || false,
iteratorNextv: manifest.iteratorNextv || false,
iteratorAll: manifest.iteratorAll || false,

// Features of abstract-leveldown that levelup doesn't have
status: manifest.status || false,
Expand Down