PostgreSQL · 2 levels · 2 questions

PostgreSQL Internals

From reading a row to writing with WAL and MVCC — how Postgres really works.

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Fundamentals1 question

PostgreSQL

Reading a Row in PostgreSQL — From Query to shared_buffers

Chronological read path: Server → Postgres, heap pages on disk, index vs sequential scan to find the page, then shared_buffers hit/miss and row read.

11 min
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Level

Intermediate1 question

PostgreSQL

The Life of a Row — PostgreSQL's Write Path, in Order

One UPDATE statement followed second by second, in strict chronological order: new row versions, WAL-first writes, LSNs and segments, CLOG, the single synchronous commit fsync, MVCC visibility, checkpoints, VACUUM and freezing, crash recovery, and isolation levels.

15 min
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