Storage and Recovery
Trace a write into storage and learn how to recover after failures without inventing certainty.
Pages, Buffers and the Storage Engine
SQL describes logical records, but a storage engine moves and manages physical units. This chapter connects rows to pages, memory buffers, free space and…
3,804 words/17 min read28Write-Ahead Logs and Recovery
A crash can erase memory while leaving only part of the recent work in storage. Recovery needs a protocol for deciding what those surviving bytes mean.…
3,742 words/16 min read29LSM Trees and Compaction
Some storage engines accept new writes into memory and later produce sorted immutable files instead of continually updating one in-place search tree.…
3,714 words/16 min read30Durability From Application to Device
“Saved” can mean copied into an application buffer, accepted by the operating system, acknowledged by a storage device or preserved across a specified…
3,693 words/16 min read31Backups, Restore and Point-in-Time Recovery
A backup is a copy kept for a recovery purpose. Its value depends on whether the required state can actually be restored, validated and made usable…
3,556 words/15 min read32Corruption, Reconciliation and Repair
A wrong answer can come from damaged bytes, an invalid relationship, a faulty query, a mistaken business entry or a misunderstanding of the report. These…
3,555 words/15 min read