51 lines
1.3 KiB
Markdown
51 lines
1.3 KiB
Markdown
---
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title: Use Cursor-Based Pagination Instead of OFFSET
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impact: MEDIUM-HIGH
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impactDescription: Consistent O(1) performance regardless of page depth
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tags: pagination, cursor, keyset, offset, performance
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---
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## Use Cursor-Based Pagination Instead of OFFSET
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OFFSET-based pagination scans all skipped rows, getting slower on deeper pages. Cursor pagination is O(1).
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**Incorrect (OFFSET pagination):**
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```sql
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-- Page 1: scans 20 rows
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select * from products order by id limit 20 offset 0;
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-- Page 100: scans 2000 rows to skip 1980
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select * from products order by id limit 20 offset 1980;
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-- Page 10000: scans 200,000 rows!
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select * from products order by id limit 20 offset 199980;
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```
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**Correct (cursor/keyset pagination):**
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```sql
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-- Page 1: get first 20
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select * from products order by id limit 20;
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-- Application stores last_id = 20
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-- Page 2: start after last ID
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select * from products where id > 20 order by id limit 20;
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-- Uses index, always fast regardless of page depth
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-- Page 10000: same speed as page 1
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select * from products where id > 199980 order by id limit 20;
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```
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For multi-column sorting:
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```sql
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-- Cursor must include all sort columns
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select * from products
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where (created_at, id) > ('2024-01-15 10:00:00', 12345)
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order by created_at, id
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limit 20;
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```
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Reference: [Pagination](https://supabase.com/docs/guides/database/pagination)
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