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								exports.run = ({ transaction, logger }) => {
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								  const messagesStore = transaction.objectStore('messages');
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								  logger.info("Create message attachment metadata index: 'hasAttachments'");
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								  messagesStore.createIndex(
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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 */]
```
											
										 
										
											8 years ago
										 
									 
								 
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								    'hasAttachments',
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								    ['conversationId', 'hasAttachments', 'received_at'],
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								    { unique: false }
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								  );
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								  ['hasVisualMediaAttachments', 'hasFileAttachments'].forEach(name => {
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								    logger.info(`Create message attachment metadata index: '${name}'`);
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								    messagesStore.createIndex(name, ['conversationId', 'received_at', name], {
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								      unique: false,
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								    });
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								  });
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								};
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