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184505bbfc
1) improves performance of commit/rollback by reducing number of round trips to the server 2) uses 7.1 functionality for setting the transaction isolation level 3) backs out a patch from 11 days ago because that code failed to compile under jdk1.1 Details: 1) The old code was doing the following for each commit: commit begin set transaction isolation level xxx thus a call to commit was performing three round trips to the database. The new code does this in one round trip as: commit; begin; set transaction isolation level xxx In a simple test program that performs 1000 transactions (where each transaction does one simple select inside that transaction) has the following before and after timings: Client and Server on same machine old new --- --- 1.877sec 1.405sec 25.1% improvement Client and Server on different machines old new --- --- 4.184sec 2.927sec 34.3% improvement (all timings are an average of four different runs) 2) The driver was using 'set transaction isolation level xxx' at the begining of each transaction, instead of using the new 7.1 syntax of 'set session characteristics as transaction isolation level xxx' which only needs to be done once instead of for each transaction. This is done conditionally (i.e. if server is 7.0 or older do the old behaviour, else do the new behaviour) to not break backward compatibility. This also required the movement of some code to check/test database version numbers from the DatabaseMetaData object to the Connection object. 3) Finally while testing, I discovered that the code that was checked in 11 days ago actually didn't compile. The code in the patch for Connection.setCatalog() used Properties.setProperty() which only exists in JDK1.2 or higher. Thus compiling the JDBC1 driver failed as this method doesn't exist. Thus I backed out that patch. Barry Lind |
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PostgreSQL Data Base Management System (formerly known as Postgres, then as Postgres95). This directory contains the development version of 7.2 of the PostgreSQL database server. The server is not 100% ANSI SQL compliant, but it gets closer with every release. After you unzip and untar the distribution file, look at file INSTALL for the installation notes and file HISTORY for the changes. The latest version of this software may be obtained at ftp://ftp.postgresql.org/pub/. For more information look at our WWW home page located at http://www.postgreSQL.org/. PostgreSQL is not public domain software. It is copyrighted by the University of California but may be used according to the licensing terms of the the copyright below: ------------------------------------------------------------------------ POSTGRES95 Data Base Management System (formerly known as Postgres, then as Postgres95). Copyright (c) 1994-7 Regents of the University of California Permission to use, copy, modify, and distribute this software and its documentation for any purpose, without fee, and without a written agreement is hereby granted, provided that the above copyright notice and this paragraph and the following two paragraphs appear in all copies. IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.