⚡️ Sort get() by visible
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At the moment, when calling `get()`, we: - query on `deleted` and `visible` - sort on `_id` We have indexes for both of these things, but separately, which results in an inefficient query, since MongoDB will have to check both indexes and can result in a complete index scan, which isn't particularly great. We sort by `_id` presumably to get the oldest job (since `_id` is an `ObjectId` whose sort order correlates to creation time). However, we probably actually want the job that was visible first. This change updates to sort to use `visible`, which also means that the query and sort can use the same index.
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dawidreedsy
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| visible: {$lte: now()}, | ||
| }; | ||
| const sort: Sort = { | ||
| _id: 1, |
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I guess we would have to change our index for it to work best
mongodb-queue/mongodb-queue.ts
Line 93 in 772580d
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this.col.createIndex({visible: 1, deleted: 1}),There was a problem hiding this comment.
Not sure it it belongs to this PR though
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Definitely a different change, which will need an index regeneration.
I'm also not sure it's needed, since I think in theory MongoDB can still leverage the index for a non-prefix sort since deleted: {$exists: false} counts as an equality condition.
dawidreedsy
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Oct 23, 2024
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At the moment, when calling
get(), we:deletedandvisible_idWe have indexes for both of these things, but separately, which results in an inefficient query, since MongoDB will have to check both indexes and can result in a complete index scan, which isn't particularly great.
We sort by
_idpresumably to get the oldest job (since_idis anObjectIdwhose sort order correlates to creation time).However, we probably actually want the job that was visible first.
This change updates to sort to use
visible, which also means that the query and sort can use the same index.