From 11d8138ca36221c328ea3df5e9e5318384d21ecd Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Sat, 14 Aug 2004 22:17:08 +0000 Subject: [PATCH] Minor editorializing. --- doc/src/sgml/ref/set_transaction.sgml | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) diff --git a/doc/src/sgml/ref/set_transaction.sgml b/doc/src/sgml/ref/set_transaction.sgml index 50a8908825..d57792ee3d 100644 --- a/doc/src/sgml/ref/set_transaction.sgml +++ b/doc/src/sgml/ref/set_transaction.sgml @@ -1,4 +1,4 @@ - + SET TRANSACTION @@ -34,9 +34,9 @@ where transaction_mode is one of: characteristics of the current transaction. It has no effect on any subsequent transactions. SET SESSION CHARACTERISTICS sets the default transaction - characteristics for subsequent transactions of a session. SET - TRANSACTION can override it for an individual - transaction. + characteristics for subsequent transactions of a session. These + defaults can be overridden by SET TRANSACTION for an + individual transaction. @@ -68,14 +68,6 @@ where transaction_mode is one of: before the first query or data-modification statement was executed in this transaction. - - - Intuitively, serializable means that two concurrent - transactions will leave the database in the same state as if - the two had been executed strictly one after the other (in one - order or the other). - - @@ -111,7 +103,7 @@ where transaction_mode is one of: TRUNCATE; and EXPLAIN ANALYZE and EXECUTE if the command they would execute is among those listed. This is a high-level notion of read-only that - does not prevent writes to disk. + does not prevent all writes to disk. @@ -138,8 +130,9 @@ where transaction_mode is one of: and . (In fact SET SESSION CHARACTERISTICS is just a verbose equivalent for setting these variables with SET.) - This allows them to be set in the configuration file. Consult for more information. + This means the defaults can be set in the configuration file, via + ALTER DATABASE, etc. Consult + for more information. @@ -149,10 +142,10 @@ where transaction_mode is one of: Both commands are defined in the SQL standard. SERIALIZABLE is the default transaction - isolation level in the standard; in + isolation level in the standard. In PostgreSQL the default is ordinarily READ COMMITTED, but you can change it as - mentioned above. Because of multiversion concurrency control, the + mentioned above. Because of lack of predicate locking, the SERIALIZABLE level is not truly serializable. See for details. -- 2.40.0