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Index messages with attachments using a boolean
When indexing message attachment metadata using numeric indexes such as:
```javascript
{
conversationId: '+12223334455',
received_at: 123,
attachments: […],
numAttachments: 2,
},
{
conversationId: '+12223334455',
received_at: 456,
attachments: [],
numAttachments: 0,
}
{
conversationId: '+12223334455',
received_at: 789,
attachments: [],
numAttachments: 1,
}
```
It creates an index as follows:
```
[conversationId, received_at, numAttachments]
['+12223334455', 123, 2]
['+12223334455', 456, 0]
['+12223334455', 789, 1]
```
This means a query such as…
```
lowerBound: ['+12223334455', 0, 1 ]
upperBound: ['+12223334455', Number.MAX_VALUE, Number.MAX_VALUE]
```
…will return all three original entries because they span the `received_at`
from `0` through `Number.MAX_VALUE`. One workaround is to index booleans using
`1 | undefined` where `1` is included in the index and `undefined` is not, but
that way we lose the ability to query for the `false` value. Instead, we flip
adjust the index to `[conversationId, hasAttachments, received_at]` and can
then query messages with attachments using
```
[conversationId, 1 /* hasAttachments */, 0 /* received_at */]
[conversationId, 1 /* hasAttachments */, Number.MAX_VALUE /* received_at */]
```
7 years ago
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/**
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* @prettier
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*/
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// IndexedDB doesn’t support boolean indexes so we map `true` to 1 and `false`
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// to `0`.
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// N.B. Using `undefined` allows excluding an entry from an index. Useful
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// when index size is a consideration or one only needs to query for `true`.
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export type IndexableBoolean = 1 | 0;
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export const toIndexableBoolean = (value: boolean): IndexableBoolean =>
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value ? 1 : 0;
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