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Commit184505b

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Attached is a patch that does the following:
1) improves performance of commit/rollback by reducing number of roundtrips to the server2) uses 7.1 functionality for setting the transaction isolation level3) backs out a patch from 11 days ago because that code failed tocompile under jdk1.1Details:1) The old code was doing the following for each commit: commit begin set transaction isolation level xxxthus 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 xxxIn a simple test program that performs 1000 transactions (where eachtransaction does one simple select inside that transaction) has thefollowing before and after timings:Client and Server on same machineold new--- ---1.877sec 1.405sec 25.1% improvementClient and Server on different machinesold 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 thebegining of each transaction, instead of using the new 7.1 syntax of'set session characteristics as transaction isolation level xxx' whichonly needs to be done once instead of for each transaction. This isdone conditionally (i.e. if server is 7.0 or older do the old behaviour,else do the new behaviour) to not break backward compatibility. Thisalso required the movement of some code to check/test database versionnumbers 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 forConnection.setCatalog() used Properties.setProperty() which only existsin JDK1.2 or higher. Thus compiling the JDBC1 driver failed as thismethod doesn't exist. Thus I backed out that patch.Barry Lind
1 parentdad8e41 commit184505b

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3 files changed

+112
-90
lines changed

3 files changed

+112
-90
lines changed

‎src/interfaces/jdbc/org/postgresql/Connection.java

Lines changed: 86 additions & 32 deletions
Original file line numberDiff line numberDiff line change
@@ -11,7 +11,7 @@
1111
importorg.postgresql.core.Encoding;
1212

1313
/**
14-
* $Id: Connection.java,v 1.21 2001/07/30 14:51:19 momjian Exp $
14+
* $Id: Connection.java,v 1.22 2001/08/04 19:32:04 momjian Exp $
1515
*
1616
* This abstract class is used by org.postgresql.Driver to open either the JDBC1 or
1717
* JDBC2 versions of the Connection class.
@@ -37,6 +37,9 @@ public abstract class Connection
3737
*/
3838
privateEncodingencoding =Encoding.defaultEncoding();
3939

40+
privateStringdbVersionLong;
41+
privateStringdbVersionNumber;
42+
4043
publicbooleanCONNECTION_OK =true;
4144
publicbooleanCONNECTION_BAD =false;
4245

@@ -262,18 +265,19 @@ protected void openConnection(String host, int port, Properties info, String dat
262265
// used, so we denote this with 'UNKNOWN'.
263266

264267
finalStringencodingQuery =
265-
"selectcase when pg_encoding_to_char(1) = 'SQL_ASCII' then 'UNKNOWN' else getdatabaseencoding() end";
268+
"case when pg_encoding_to_char(1) = 'SQL_ASCII' then 'UNKNOWN' else getdatabaseencoding() end";
266269

267270
// Set datestyle and fetch db encoding in a single call, to avoid making
268271
// more than one round trip to the backend during connection startup.
269272

270273
java.sql.ResultSetresultSet =
271-
ExecSQL("set datestyle to 'ISO'; " +encodingQuery);
274+
ExecSQL("set datestyle to 'ISO';select version()," +encodingQuery +";");
272275

273276
if (!resultSet.next()) {
274277
thrownewPSQLException("postgresql.con.failed","failed getting backend encoding");
275278
}
276-
dbEncoding =resultSet.getString(1);
279+
dbVersionLong =resultSet.getString(1);
280+
dbEncoding =resultSet.getString(2);
277281
encoding =Encoding.getEncoding(dbEncoding,info.getProperty("charSet"));
278282

279283
// Initialise object handling
@@ -904,8 +908,7 @@ public void setAutoCommit(boolean autoCommit) throws SQLException {
904908
if (autoCommit)
905909
ExecSQL("end");
906910
else {
907-
ExecSQL("begin");
908-
doIsolationLevel();
911+
ExecSQL("begin; " +getIsolationLevelSQL());
909912
}
910913
this.autoCommit =autoCommit;
911914
}
@@ -934,11 +937,7 @@ public boolean getAutoCommit() throws SQLException {
934937
publicvoidcommit()throwsSQLException {
935938
if (autoCommit)
936939
return;
937-
ExecSQL("commit");
938-
autoCommit =true;
939-
ExecSQL("begin");
940-
doIsolationLevel();
941-
autoCommit =false;
940+
ExecSQL("commit; begin; " +getIsolationLevelSQL());
942941
}
943942

944943
/**
@@ -952,11 +951,7 @@ public void commit() throws SQLException {
952951
publicvoidrollback()throwsSQLException {
953952
if (autoCommit)
954953
return;
955-
ExecSQL("rollback");
956-
autoCommit =true;
957-
ExecSQL("begin");
958-
doIsolationLevel();
959-
autoCommit =false;
954+
ExecSQL("rollback; begin; " +getIsolationLevelSQL());
960955
}
961956

962957
/**
@@ -988,7 +983,7 @@ else if (message.indexOf("SERIALIZABLE") != -1)
988983
/**
989984
* You can call this method to try to change the transaction
990985
* isolation level using one of the TRANSACTION_* values.
991-
*
986+
*
992987
* <B>Note:</B> setTransactionIsolation cannot be called while
993988
* in the middle of a transaction
994989
*
@@ -999,29 +994,67 @@ else if (message.indexOf("SERIALIZABLE") != -1)
999994
* @see java.sql.DatabaseMetaData#supportsTransactionIsolationLevel
1000995
*/
1001996
publicvoidsetTransactionIsolation(intlevel)throwsSQLException {
1002-
isolationLevel =level;
1003-
doIsolationLevel();
997+
//In 7.1 and later versions of the server it is possible using
998+
//the "set session" command to set this once for all future txns
999+
//however in 7.0 and prior versions it is necessary to set it in
1000+
//each transaction, thus adding complexity below.
1001+
//When we decide to drop support for servers older than 7.1
1002+
//this can be simplified
1003+
isolationLevel =level;
1004+
StringisolationLevelSQL;
1005+
switch(isolationLevel) {
1006+
casejava.sql.Connection.TRANSACTION_READ_COMMITTED:
1007+
if (haveMinimumServerVersion("7.1")) {
1008+
isolationLevelSQL ="SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL READ COMMITTED";
1009+
}else {
1010+
isolationLevelSQL =getIsolationLevelSQL();
1011+
}
1012+
break;
1013+
1014+
casejava.sql.Connection.TRANSACTION_SERIALIZABLE:
1015+
if (haveMinimumServerVersion("7.1")) {
1016+
isolationLevelSQL ="SET SESSION CHARACTERISTICS AS TRANSACTION ISOLATION LEVEL SERIALIZABLE";
1017+
}else {
1018+
isolationLevelSQL =getIsolationLevelSQL();
1019+
}
1020+
break;
1021+
1022+
default:
1023+
thrownewPSQLException("postgresql.con.isolevel",newInteger(isolationLevel));
1024+
}
1025+
ExecSQL(isolationLevelSQL);
10041026
}
10051027

10061028
/**
10071029
* Helper method used by setTransactionIsolation(), commit(), rollback()
1008-
* and setAutoCommit(). This sets the current isolation level.
1030+
* and setAutoCommit(). This returns the SQL string needed to
1031+
* set the isolation level for a transaction. In 7.1 and later it
1032+
* is possible to set a default isolation level that applies to all
1033+
* future transactions, this method is only necesary for 7.0 and older
1034+
* servers, and should be removed when support for these older
1035+
* servers are dropped
10091036
*/
1010-
protectedvoiddoIsolationLevel()throwsSQLException {
1037+
protectedStringgetIsolationLevelSQL()throwsSQLException {
1038+
//7.1 and higher servers have a default specified so
1039+
//no additional SQL is required to set the isolation level
1040+
if (haveMinimumServerVersion("7.1")) {
1041+
return"";
1042+
}
10111043
Stringq ="SET TRANSACTION ISOLATION LEVEL";
10121044

10131045
switch(isolationLevel) {
10141046
casejava.sql.Connection.TRANSACTION_READ_COMMITTED:
1015-
ExecSQL(q+" READ COMMITTED");
1016-
return;
1047+
q =q+" READ COMMITTED";
1048+
break;
10171049

10181050
casejava.sql.Connection.TRANSACTION_SERIALIZABLE:
1019-
ExecSQL(q+" SERIALIZABLE");
1020-
return;
1051+
q =q+" SERIALIZABLE";
1052+
break;
10211053

10221054
default:
10231055
thrownewPSQLException("postgresql.con.isolevel",newInteger(isolationLevel));
10241056
}
1057+
returnq;
10251058
}
10261059

10271060
/**
@@ -1033,13 +1066,7 @@ protected void doIsolationLevel() throws SQLException {
10331066
*/
10341067
publicvoidsetCatalog(Stringcatalog)throwsSQLException
10351068
{
1036-
if(catalog!=null && !catalog.equals(PG_DATABASE)) {
1037-
close();
1038-
Propertiesinfo=newProperties();
1039-
info.setProperty("user",PG_USER);
1040-
info.setProperty("password",PG_PASSWORD);
1041-
openConnection(PG_HOST,PG_PORT,info,catalog,this_url,this_driver);
1042-
}
1069+
//no-op
10431070
}
10441071

10451072
/**
@@ -1095,4 +1122,31 @@ public String EscapeSQL(String sql) {
10951122
returnsql;
10961123
}
10971124

1125+
/**
1126+
* What is the version of the server
1127+
*
1128+
* @return the database version
1129+
* @exception SQLException if a database access error occurs
1130+
*/
1131+
publicStringgetDBVersionNumber()throwsSQLException
1132+
{
1133+
if(dbVersionNumber ==null) {
1134+
StringTokenizerversionParts =newStringTokenizer(dbVersionLong);
1135+
versionParts.nextToken();/* "PostgreSQL" */
1136+
dbVersionNumber =versionParts.nextToken();/* "X.Y.Z" */
1137+
}
1138+
returndbVersionNumber;
1139+
}
1140+
1141+
publicbooleanhaveMinimumServerVersion(Stringver)throwsSQLException
1142+
{
1143+
if (getDBVersionNumber().compareTo(ver)>=0)
1144+
returntrue;
1145+
else
1146+
returnfalse;
1147+
}
1148+
1149+
1150+
10981151
}
1152+

‎src/interfaces/jdbc/org/postgresql/jdbc1/DatabaseMetaData.java

Lines changed: 13 additions & 29 deletions
Original file line numberDiff line numberDiff line change
@@ -47,15 +47,6 @@ public class DatabaseMetaData implements java.sql.DatabaseMetaData
4747
privatestaticfinalbytedefaultRemarks[]="no remarks".getBytes();
4848

4949

50-
privatebooleanhaveMinimumServerVersion(Stringver)throwsSQLException
51-
{
52-
if (getDatabaseProductVersion().compareTo(ver)>=0)
53-
returntrue;
54-
else
55-
returnfalse;
56-
}
57-
58-
5950
publicDatabaseMetaData(Connectionconn)
6051
{
6152
this.connection =conn;
@@ -126,7 +117,7 @@ public boolean isReadOnly() throws SQLException
126117
*/
127118
publicbooleannullsAreSortedHigh()throwsSQLException
128119
{
129-
returnhaveMinimumServerVersion("7.2");
120+
returnconnection.haveMinimumServerVersion("7.2");
130121
}
131122

132123
/**
@@ -159,7 +150,7 @@ public boolean nullsAreSortedAtStart() throws SQLException
159150
*/
160151
publicbooleannullsAreSortedAtEnd()throwsSQLException
161152
{
162-
return !haveMinimumServerVersion("7.2");
153+
return !connection.haveMinimumServerVersion("7.2");
163154
}
164155

165156
/**
@@ -182,14 +173,7 @@ public String getDatabaseProductName() throws SQLException
182173
*/
183174
publicStringgetDatabaseProductVersion()throwsSQLException
184175
{
185-
java.sql.ResultSetresultSet =connection.ExecSQL("select version()");
186-
resultSet.next();
187-
188-
StringTokenizerversionParts =newStringTokenizer(resultSet.getString(1));
189-
versionParts.nextToken();/* "PostgreSQL" */
190-
StringversionNumber =versionParts.nextToken();/* "X.Y.Z" */
191-
192-
returnversionNumber;
176+
returnconnection.getDBVersionNumber();
193177
}
194178

195179
/**
@@ -558,7 +542,7 @@ public boolean supportsExpressionsInOrderBy() throws SQLException
558542
*/
559543
publicbooleansupportsOrderByUnrelated()throwsSQLException
560544
{
561-
returnhaveMinimumServerVersion("6.4");
545+
returnconnection.haveMinimumServerVersion("6.4");
562546
}
563547

564548
/**
@@ -581,7 +565,7 @@ public boolean supportsGroupBy() throws SQLException
581565
*/
582566
publicbooleansupportsGroupByUnrelated()throwsSQLException
583567
{
584-
returnhaveMinimumServerVersion("6.4");
568+
returnconnection.haveMinimumServerVersion("6.4");
585569
}
586570

587571
/**
@@ -608,7 +592,7 @@ public boolean supportsGroupByBeyondSelect() throws SQLException
608592
*/
609593
publicbooleansupportsLikeEscapeClause()throwsSQLException
610594
{
611-
returnhaveMinimumServerVersion("7.1");
595+
returnconnection.haveMinimumServerVersion("7.1");
612596
}
613597

614598
/**
@@ -749,7 +733,7 @@ public boolean supportsIntegrityEnhancementFacility() throws SQLException
749733
*/
750734
publicbooleansupportsOuterJoins()throwsSQLException
751735
{
752-
returnhaveMinimumServerVersion("7.1");
736+
returnconnection.haveMinimumServerVersion("7.1");
753737
}
754738

755739
/**
@@ -761,7 +745,7 @@ public boolean supportsOuterJoins() throws SQLException
761745
*/
762746
publicbooleansupportsFullOuterJoins()throwsSQLException
763747
{
764-
returnhaveMinimumServerVersion("7.1");
748+
returnconnection.haveMinimumServerVersion("7.1");
765749
}
766750

767751
/**
@@ -976,7 +960,7 @@ public boolean supportsPositionedUpdate() throws SQLException
976960
*/
977961
publicbooleansupportsSelectForUpdate()throwsSQLException
978962
{
979-
returnhaveMinimumServerVersion("6.5");
963+
returnconnection.haveMinimumServerVersion("6.5");
980964
}
981965

982966
/**
@@ -1053,7 +1037,7 @@ public boolean supportsSubqueriesInQuantifieds() throws SQLException
10531037
*/
10541038
publicbooleansupportsCorrelatedSubqueries()throwsSQLException
10551039
{
1056-
returnhaveMinimumServerVersion("7.1");
1040+
returnconnection.haveMinimumServerVersion("7.1");
10571041
}
10581042

10591043
/**
@@ -1075,7 +1059,7 @@ public boolean supportsUnion() throws SQLException
10751059
*/
10761060
publicbooleansupportsUnionAll()throwsSQLException
10771061
{
1078-
returnhaveMinimumServerVersion("7.1");
1062+
returnconnection.haveMinimumServerVersion("7.1");
10791063
}
10801064

10811065
/**
@@ -1303,7 +1287,7 @@ public int getMaxCatalogNameLength() throws SQLException
13031287
*/
13041288
publicintgetMaxRowSize()throwsSQLException
13051289
{
1306-
if (haveMinimumServerVersion("7.1"))
1290+
if (connection.haveMinimumServerVersion("7.1"))
13071291
return1073741824;// 1 GB
13081292
else
13091293
return8192;// XXX could be altered
@@ -1329,7 +1313,7 @@ public boolean doesMaxRowSizeIncludeBlobs() throws SQLException
13291313
*/
13301314
publicintgetMaxStatementLength()throwsSQLException
13311315
{
1332-
if (haveMinimumServerVersion("7.0"))
1316+
if (connection.haveMinimumServerVersion("7.0"))
13331317
return0;// actually whatever fits in size_t
13341318
else
13351319
return16384;

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