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Database Indexing · Database Indexing Costs: Write Overhead, Bloat and When Not to Index

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Trick to keep in mind+3 XP

One insert, many writes: every index adds a step to every row.

Inserting a row writes it to the table and also adds an entry to each index on that table, and any of those can force a page to split. This is write amplification. A bulk load that was fine with no extra indexes can slow dramatically after a few are added, because each row now fans out into several physical writes.

Read it once, then a question tests whether the trick stuck.