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PostgreSQL does not have in-place update in the first place, on every UPDATE it does a DELETE+INSERT. So "partial update" does not make much sense, because you'
by tomiko_nakamura 12y ago
PostgreSQL does not have in-place update in the first place, on every UPDATE it does a DELETE+INSERT. So "partial update" does not make much sense, because you'll create a new copy of the row anyway.
- NickNameNick 12y agoThat's not quite how PostgreSQL's Multi-value-Concurrency system works.
- tomiko_nakamura 12y agoMVCC means "Multiversion Concurrency Control" and yes, that's pretty much exactly how it works (creating copies of the rows, so that different snapshots see different rows). In practice it's more complicated of course. A nice intro to MVCC is available here: http://momjian.us/main/writings/pgsql/mvcc.pdf http://momjian.us/main/writings/pgsql/mvcc.pdf (and in the Bruce's other talks http://momjian.us/main/presentations/internals.html http://momjian.us/main/presentations/internals.html). Or maybe you mean something else by Multi-value-Concurrency. In that case please elaborate.