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Pipelines & scenarios · Design & Scenarios

Horizontal vs vertical partitioning

Mediumpipe-26
partitioninghorizontalverticalshardingprivacy

Question

What is the difference between horizontal and vertical partitioning?

Solution

Horizontal partitioning splits rows into separate chunks (shards/partitions). Vertical partitioning splits columns into separate stores/tables.

Horizontal (by rows):
  orders_2026_09_01 | orders_2026_09_02 | orders_region=IN
  (same columns, different row sets)

Vertical (by columns):
  orders_core(id, user_id, amount, dt)
  orders_pii(id, email, phone)          <- separate access / storage

Why horizontal

  • Scale out, parallel jobs, partition prune by date/region
  • Common in lakes, warehouses (PARTITION BY dt), Kafka partitions

Why vertical

  • Isolate wide/rarely used columns or PII
  • Faster scans of "hot" columns
  • Different retention or encryption policies

Do not confuse with

  • Normalization (relational modeling)
  • Replication (copies for durability)

Interview tip: "Horizontal = row splits; vertical = column splits." Give date partitions vs PII column separation as examples.

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