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Deduplicate and Keep Latest
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Deduplicate and Keep Latest

EasySQL · PostgreSQL

Problem

Gartner Peer Insights receives review records from periodic ingestion jobs, and the same review can appear multiple times as it is updated. Write a PostgreSQL query that returns one latest valid record for each (source_system, source_review_id) key.

Requirements

  1. Exclude rows with a missing source_review_id or source_updated_at.
  2. Use ROW_NUMBER() to rank records by the most recent source_updated_at within each key.
  3. Use ingestion_id descending as a deterministic tie-breaker when timestamps match.
  4. Return the retained records ordered by source_system, then source_review_id.

Schema

peer_insight_reviews
ColumnTypeDescription
ingestion_idPKINTUnique ingestion record identifier
source_systemVARCHAR(40)Originating Gartner review surface
source_review_idVARCHAR(30)Review identifier from the source system
source_updated_atTIMESTAMPLast update time reported by the source
statusVARCHAR(20)Review lifecycle status
ratingINTReview rating from 0 to 5
review_titleVARCHAR(120)Review title
Tablespeer_insight_reviews
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CodePostgreSQL
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