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Deduplicating Without Breaking Keys
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Deduplicating Without Breaking Keys

MediumSQL · PostgreSQL

Problem

Write a SQL query to identify and remove duplicate records from a staging table without dropping the primary key constraints.

Treat rows with identical values in source_system, external_record_id, event_type, and payload as duplicates. Retain the row with the smallest staging_id for each duplicate set, and remove the other rows.

Output

  1. Return the deleted rows with staging_id, source_system, external_record_id, event_type, and payload.
  2. Sort the returned rows by staging_id ascending.

Schema

robotics_staging
ColumnTypeDescription
staging_idPKINTEGERUnique identifier for the staged record
source_systemVARCHAR(40)System that produced the incoming record
external_record_idVARCHAR(40)Identifier assigned by the source system
event_typeVARCHAR(30)Type of robotics event
payloadTEXTRaw staged event payload
Tablesrobotics_staging
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