From cd8115e0090cb04380292f880adcec9c2fc2e0f3 Mon Sep 17 00:00:00 2001 From: Bruce Momjian Date: Wed, 13 Nov 2013 10:14:05 -0500 Subject: [PATCH] docs: clarify MVCC introduction to allow for per-statement snapshots --- doc/src/sgml/mvcc.sgml | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/doc/src/sgml/mvcc.sgml b/doc/src/sgml/mvcc.sgml index cefd3235a6..f56eb557b1 100644 --- a/doc/src/sgml/mvcc.sgml +++ b/doc/src/sgml/mvcc.sgml @@ -41,12 +41,12 @@ for developers to manage concurrent access to data. Internally, data consistency is maintained by using a multiversion model (Multiversion Concurrency Control, MVCC). - This means that while querying a database each transaction sees + This means that each SQL statement sees a snapshot of data (a database version) as it was some time ago, regardless of the current state of the underlying data. - This protects the transaction from viewing inconsistent data that - could be caused by (other) concurrent transaction updates on the same + This prevents statements from viewing inconsistent data produced + by concurrent transactions performing updates on the same data rows, providing transaction isolation for each database session. MVCC, by eschewing the locking methodologies of traditional database systems, -- 2.40.0