demo · v134
Dedup on vs off: the overcounting problem
The whole point of reading interest groups in a Shared Storage worklet is to avoid double-counting users who qualify for multiple campaigns. Without deduplication the reach histogram overcounts; with deduplication each user is counted once. Toggle between the two modes and watch the histogram change.
Shared Storage API: checking…
Simulated audience — interest group memberships:
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Unique users
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Raw count (no dedup)
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Deduped count (v134)
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Overcount factor
Per-campaign reach count:
Simulated worklet logic
why this matters
Without interestGroups(), a Shared Storage worklet counts every qualifying impression event once per campaign. A user who was shown ads for three campaigns gets counted three times in the aggregate reach report. With v134’s interestGroups() call, the worklet can identify overlapping group memberships and emit a single contribution per user.