mapbox / mapbox/osm-wayback

Losing versions without tags

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bug
Dominant language
C++
Stars
2
Forks
1
PR merge metrics
No merged PRs in 30d

Description

Objects that lose all of their tags (example: removal of TIGER artifacts) lose a version in the current implementation.

Likewise, there are some objects that start without any tags and then get tags later. These versions cause a lookup failure in rocksdb, which is currently counted in the `add_tags` function. Current Validation stats on these missing versions are:

===================== Running Phuket =====================
5821 features processed, additional history values: 4406
301 (6.39%) Lookup failures (specific history versions probably don't have any tags)

===================== Running Cyberjaya =====================
2318 features processed, additional history values: 1733
124 (6.67%) Lookup failures (specific history versions probably don't have any tags)

===================== Running Alameda_SF =====================
32143 features processed, additional history values: 11689
619 (5.02%) Lookup failures (specific history versions probably don't have any tags)

===================== Running KualaLumpur =====================
56270 features processed, additional history values: 88783
7957 (8.22%) Lookup failures (specific history versions probably don't have any tags)

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing how untagged object versions move through the add_tags function and how those versions are looked up in RocksDB. Reproduce the missing-version counts using the Validation runs described for Phuket, Cyberjaya, Alameda_SF, or KualaLumpur. Done means versions without tags no longer cause lookup failures or get incorrectly lost.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp
Domain
databases
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
25/100

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