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  • MySQL with Java: Open connection only if possible

    - by emempe
    I'm running a database-heavy Java application on a cluster, using Connector/J 5.1.14. Therefore, I have up to 150 concurrent tasks accessing the same MySQL database. I get the following error: Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Too many connections This happens because the server can't handle so many connections. I can't change anything on the database server. So my question is: Can I check if a connection is possible BEFORE I actually connect to the database? Something like this (pseudo code): check database for open connection slots if (slot is free) { Connection cn = DriverManager.getConnection(url, username, password); } else { wait ... } Cheers

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  • Reusing of a PreparedStatement between methods?

    - by MRalwasser
    We all know that we should rather reuse a JDBC PreparedStatement than creating a new instance within a loop. But how to deal with PreparedStatement reuse between different method invocations? Does the reuse-"rule" still count? Should I really consider using a field for the PreparedStatement or should I close and re-create the prepared statement in every invocation? (Of course an instance of such a class would be bound to a Connection which might be a disadvantage) I am aware that the ideal answer might be "it depends". But I am looking for a best practice for less experienced developers that they will do the right choice in most of the cases.

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  • What is the most "database independent" way of creating a variable length text field in a database

    - by Thibaut Colar
    I want to create a text field in the database, with no specific size (it will store text of length unknown in some case) - the particular text are serialized simple object (~ JSON) What is the most database independent way to do this : - a varchar with no size specified (don't think all db support this) - a 'text' field, this seems to be common, but I don't believe it's a standard - a blob or other object of that kind ? - a varchar of a a very large size (that's inefficient and wastes disk space probably) - Other ? I'm using JDBC, but I'd like to use something that is supported in most DB (oracle, mysql, postgresql, derby, HSQL, H2 etc...) Thanks.

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  • How to update mutual entries in DB?

    - by Sthita
    I am not able to perform mutual update to my Database. My Requirement is like this : Insert IDS UPDate DB Entries ID ConnectedTo ID connectedTo connectedVia 2 1 --- No Entry ----- 2 3 -- No Entry ----- When ID 1 Comes in to picture (Enties happened to Table) 1 4 1 3 2 1 5 2 4 1 1 2 2 5 1 When ID 3 Comes into picture (Enties happened to Table) 3 4 3 5 1 3 1 ---- 3 2 ---- Similarly when ID 4 Comes in to picture 4 9 4 2 3 4 10 4 5 1 4 3 4 2 1 4 1 1 9 4 1 10 4 Its basically Updating the mutual connections.No Duplicate entries should happen. Like for example 2 3 and 3 2 are mutually connected and 1 is associated with them so there is no need to insert (3 2 via 1). I think this is my requirement. Anything possible combinations i have missed please let me know. i will Update. Please help me writing the logic or any example using jdbc and java.

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  • AbstractMethodError when invoking createArrayOf, with postgresql 8.4 jdbc4 and JBoss 5.1GA

    - by Francesco
    Hi, when using this method public List<Field> getFieldWithoutId(List<Integer> idSections) throws Exception { try { Connection conn = this.getConnection(); Array arraySections = conn.createArrayOf("int4", idSections.toArray()); this.log.info("Recupero field"); List<Field> fields = this.getJdbcTemplate().query(getFieldWithoutIdQuery, new Object[] {arraySections},ParameterizedBeanPropertyRowMapper.newInstance(Field.class)); /*if (!conn.isClosed()) conn.close(); */ releaseConnection(conn); return fields; } catch (Exception e) { e.printStackTrace(); throw new Exception("Errore."); } } I have an exception at conn.createArrayOf("int4", idSections.toArray());. The exception is: javax.ejb.EJBException : Unexpected Error java.lang.AbstractMethodError: org.jboss.resource.adapter.jdbc.jdk5.WrappedConnectionJDK5.createArrayOf(Ljava/lang/String;[Ljava/lang/Object;)Ljava/sql/Array; postgresql-8.4-701.jdbc4.jar is in jboss/server/all/lib dir. Application is spring based with ejb3. When working locally with the same setup everything is fine. This only happens on a preproduction environment. Only difference is locally I have jboss run in default mode, in the other case there are 2 jbosses in all configuration. I can't track down the cause of this error. Could someone help me please?

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  • Accessing Unicode telugu text from Ms-Access Database in Java

    - by Ravi Chandra
    I have an MS-Access database ( A English-telugu Dictionary database) which contains a table storing English words and telugu meanings. I am writing a dictionary program in Java which queries the database for a keyword entered by the user and display the telugu meaning. My Program is working fine till I get the data from the database, but when I displayed it on some component like JTextArea/JEditorPane/ etc... the telugu text is being displayed as '????'. Why is it happening?. I have seen the solution for "1467412/reading-unicode-data-from-an-access-database-using-jdbc" which provides some workaround for Hebrew language. But it is not working for telugu. i.e I included setCharset("UTF8")before querying from the database. but still I am getting all '?'s. As soon as I got data from Resultset I am checking the individual characters, all the telugu characters are being encoded by 63 only. This is my observation. I guess this must be some type of encoding problem. I would be very glad if somebody provides some solution for this. Thanks in advance.

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  • Restrict access to connection pool in Weblogic?

    - by Andrew White
    In short, how can I restrict access to connection pool X based on application name or JAR name? A simple use case might help... A business web-app (call it WEB_APP_A) uses pool Y to do basic look-up SQL. Some users of this web-app have access to also update some sensitive data in the database. This code is provided by a JAR file (call it HR_JAR) that can be dropped in where needed. This JAR uses pool X for all of it's connections. We don't want developers of WEB_APP_A using pool X. We only want HR_JAR using pool X. This is to keep devs of WEB_APP_A from accidentally or intentionally abusing the access pool X provides. Some considerations: This is legacy code so HR_JAR is here to stay We are running on Weblogic 9.2 We can not keep passwords in any from in the source code We have researched weblogic user level authn/authz for JDBC resources but then this begs the question; how do we secure the user creds we use to become a user per app/jar? Ideas? Thoughts? I can elaborate more on what I have tried, but I wanted fresh ideas.

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  • Calling an Oracle PL/SQL procedure with Custom Object return types from 0jdbc6 JDBCthin drivers

    - by Andrew Harmel-Law
    I'm writing some JDBC code which calls a Oracle 11g PL/SQL procdedure which has a Custom Object return type. Whenever I try an register my return types, I get either ORA-03115 or PLS-00306 as an error when the statement is executed depending on the type I set. An example is below: PLSQL Code: Procedure GetDataSummary (p_my_key IN KEYS.MY_KEY%TYPE, p_recordset OUT data_summary_tab, p_status OUT VARCHAR2); Java Code: String query = "beginmanageroleviewdata.getdatasummary(?, ?, ?); end;"); CallableStatement stmt = conn.prepareCall(query); stmt.setInt(1, 83); stmt.registerOutParameter(2, OracleTypes.CURSOR); // Causes error: PLS-00306 stmt.registerOutParameter(3, OracleTypes.VARCHAR); stmt.execute(stmt); // Error mentioned above thrown here. Can anyone provide me with an example showing how I can do this? I guess it's possible. However I can't see a rowset OracleType. CURSOR, REF, DATALINK, and more fail. Apologies if this is a dumb question. I'm not a PL/SQL expert and may have used the wrong terminology in some areas of my question. (If so, please edit me). Thanks in advance. Regs, Andrew

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  • Getting a connection from a Sybase datasource in WAS 6.1 fails with message "User name property miss

    - by Abel Morelos
    I have a standalone application that needs to connect to a Sybase database via a datasource, I'm trying to connect using getConnection() and get the connection from this Sybase datasource which is hosted in WAS 6.1, sadly I'm getting an error JZ004 - Sybase(R) jConnect for JDBC(TM) Programmer's Reference: SQL Exception and Warning Messages JZ004 error message is: User name property missing in DriverManager.getConnection(..., Properties) Action: Provide the required user property. As you can see, this is not a connectivity (so we can discard JNDI or lookup problems), but rather a configuration problem. For my Sybase datasource in WAS 6.1 I have set up the proper authentication alias (Component-managed Authentication Alias), and I know the credentials are alright, "Test Connection" is successful for this datasource. Somebody had a similar problem and was because of the authentication alias- http://forum.springsource.org/showthread.php?t=39915 Next, I tried calling getConnection() but now I provided the credentials like getConnection(user, password)... and this time it worked!!! So I suspect that somehow WAS 6.1 is not picking or taking the authentication info I set in the datasource as mentioned before. If you think that maybe getConnection(user, password) should be OK for my case, well, that's not the case since I have a requirement to keep the credentials in the server, the standalone application only needs to know the JNDI information to lookup the datasource. Please let me know if have faced a similar problem, or what would you suggest me to do. Thanks.

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  • How to use SQLErrorCodeSQLExceptionTranslator and DAO class with @Repository in Spring?

    - by GuidoMB
    I'm using Spring 3.0.2 and I have a class called MovieDAO that uses JDBC to handle the db. I have set the @Repository annotations and I want to convert the SQLException to the Spring's DataAccessException I have the following example: @Repository public class JDBCCommentDAO implements CommentDAO { static JDBCCommentDAO instance; ConnectionManager connectionManager; private JDBCCommentDAO() { connectionManager = new ConnectionManager("org.postgresql.Driver", "postgres", "postgres"); } static public synchronized JDBCCommentDAO getInstance() { if (instance == null) instance = new JDBCCommentDAO(); return instance; } @Override public Collection<Comment> getComments(User user) throws DAOException { Collection<Comment> comments = new ArrayList<Comment>(); try { String query = "SELECT * FROM Comments WHERE Comments.userId = ?"; Connection conn = connectionManager.getConnection(); PreparedStatement stmt = conn.prepareStatement(query); stmt = conn.prepareStatement(query); stmt.setInt(1, user.getId()); ResultSet result = stmt.executeQuery(); while (result.next()) { Movie movie = JDBCMovieDAO.getInstance().getLightMovie(result.getInt("movie")); comments.add(new Comment(result.getString("text"), result.getInt("score"), user, result.getDate("date"), movie)); } connectionManager.closeConnection(conn); } catch (SQLException e) { e.printStackTrace(); //CONVERT TO DATAACCESSEXCEPTION } return comments; } } I Don't know how to get the Translator and I don't want to extends any Spring class, because that is why I'm using the @Repository annotation

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  • Problems with string parameter insertion into prepared statement

    - by c0d3x
    Hi, I have a database running on an MS SQL Server. My application communicates via JDBC and ODBC with it. Now I try to use prepared statements. When I insert a numeric (Long) parameter everything works fine. When I insert a string parameter it does not work. There is no error message, but an empty result set. WHERE column LIKE ('%' + ? + '%') --inserted "test" -> empty result set WHERE column LIKE ? --inserted "%test%" -> empty result set WHERE column = ? --inserted "test" -> works But I need the LIKE functionality. When I insert the same string directly into the query string (not as a prepared statement parameter) it runs fine. WHERE column LIKE '%test%' It looks a little bit like double quoting for me, but I never used quotes inside a string. I use preparedStatement.setString(int index, String x) for insertion. What is causing this problem? How can I fix it? Thanks in advance.

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  • JAVA Procedure Error

    - by Sam....
    java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]Procedure 'STP_Insert_tblReceipt' expects parameter '@CPVFlag', which was not supplied. I m getting error at This Point when trying to call procedure... Everything is perfect ,,,Count of Question marks are similar to parameter provided cs = conn.prepareCall("{call STP_Insert_tblReceipt(?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?, ?,?,?)}"); // cs = conn.prepareCall("{call STP_Receipt_Form_Insertion_Trial(?,?,?, ?,?,?, ?,?,?, ?,?,?, ?)}"); cs.setLong(1, Long.parseLong(txtMobileNo.getText())); cs.setString(2, String.valueOf(cboDistributor.getSelectedItem())); cs.setLong(3, Long.parseLong(txtBoxNo.getText())); cs.setInt(4, Integer.parseInt(txtFileNo.getText())); cs.setString(5, pickUp_date); cs.setString(6, rec_date); cs.setString(7, String.valueOf(cmbCtrlNo.getSelectedItem())); cs.setString(8, UserName); cs.setString(9, rec_date); cs.setString(10, RegionLocation); cs.setString(11, txtRemark.getText().trim()); cs.setString(12, txtSimNo.getText().trim()); cs.setInt(13, 2); cs.setString(14, String.valueOf(cmbAryanRegion.getSelectedItem())); cs.setString(15, String.valueOf(cboPickUpType.getSelectedItem())); cs.setString(16, String.valueOf(txtCafNo.getText())); cs.setString(17, distributorId); //cs.setString(18, circleName); cs.setString(18, cboCircle.getSelectedItem().toString()); cs.registerOutParameter(19, java.sql.Types.INTEGER); cs.setString(20, auditorName); cs.setString(21, retailerName); cs.setString(22, retailerCode); cs.setInt(23, mappedFlag); //cs.setString(24, distCode); cs.setString(24, cboDistCode.getSelectedItem().toString()); //cs.setString(25, zoneName); cs.setString(25, cboZone.getSelectedItem().toString()); cs.setString(26, comment); **cs.setInt(27, 1);** **this is for CPV Flag** After this cs.execute();

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  • Login Problem Windows Authentication

    - by user109280
    Duplicate of: http://stackoverflow.com/questions/881928/windows-authentication-trusted-connection-problem I logged in the Windows Server(Machine 1) as "abc\user1 ". Windows Server machine is in abc domain. MSSQL Server is in the "abc" domain on Machine 1 and have mixed mode.authentication. It has account "abc\user1 " and "abc\user2 ". Both has role of sysadmin and serveradmin. I logged in another machine(Machine 2) using "abc\user2 ". Same Domain. Run the ant which connect to MSSQL Server. URL is formed as follows. jdbc:sqlserver://%DB_IP%:%DB_PORT%;SelectMethod=cursor;integratedSecurity=true;DatabaseName=dbname; 1) From Machine 2, If I use "abc\user2" credential for connection, then it works fine. since integratedSecurity=true. 2) From Machine 2, If I use "abc\user1" credential for connection, then it doesn't fine, since integratedSecurity=true and take System Credentials i.e "abc\user2". Even if I make integratedSecurity=false , then also it doesn't connect using "abc\user1" What changes to URL I have make to work for "abc\user1" from Machine2 for connection. what properties to be added in url? OR Driver doesn't support to use another domain\User Credentials? What need to set on MSSQL Server ?? Deepak

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  • How to set logging level for JDBCDriverLogging

    - by Scott
    I am trying to change the logging level to stop showing millions of this: <May 26, 2010 10:26:02 AM EDT> <Debug> <JDBCDriverLogging> <000000> <2336: 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 | |> I have tried adding this to my java line: -Djava.util.logging.config.file=/foo/bar/logging.properties With this as my logging.properties file: handlers = java.util.logging.ConsoleHandler .level = OFF java.util.logging.ConsoleHandler.level = INFO No luck. I have tried this: Logger logger = Logger.getLogger("com.microsoft.sqlserver.jdbc"); Handler handler = new ConsoleHandler(); handler.setLevel(Level.INFO); logger.addHandler(handler); logger.setLevel(Level.INFO); logger.setUseParentHandlers(false); No luck. I have searched around and all ideas center around one of these two options, so I must be doing something else wrong I am using jtds-1.2.2.jar. Thanks for any suggestions.

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  • Storing Result set into an array

    - by OVERTONE
    i know this should be simpel and im probably staring straight at the problem but once again im stuck and need the help of the code gurus. im trying too take one row from a column in jdbc, and put them in an array. i do this as follows: public void fillContactList() { createConnection(); try { Statement stmt = conn.createStatement(); ResultSet namesList = stmt.executeQuery("SELECT name FROM Users"); try { while (namesList.next()) { contactListNames[1] = namesList.getString(1); System.out.println("" + contactListNames[1]); } } catch(SQLException q) { } conn.commit(); stmt.close(); conn.close(); } catch(SQLException e) { } creatConnection is an already defined method that does what it obviously does. i creat my result set while theres another one, i store the string of that column into an array. then print it out for good measure. too make sure its there. the problem is that its storing the entire column into contactListNames[1] i wanted to make it store column1 row 1 into [1] then column 1 row 2 into [2] i know i could do this with a loop. but i dont know too take only one row at a time from a single column. any ideas? p.s ive read the api, i jsut cant see anything that fits.

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  • Tomcat, Hibernate and the java.io.EOFException

    - by Marco
    Hi, My Java application, which uses Hibernate and it's hosted by Tomcat 6.0, gets the following exception after a long time of inactivity when it tries to access the DB: com.mysql.jdbc.CommunicationsException: Communications link failure due to underlying exception: ** BEGIN NESTED EXCEPTION ** java.io.EOFException STACKTRACE: java.io.EOFException at com.mysql.jdbc.MysqlIO.readFully(MysqlIO.java:1963) at com.mysql.jdbc.MysqlIO.reuseAndReadPacket(MysqlIO.java:2375) at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:2874) at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1623) at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:1715) at com.mysql.jdbc.Connection.execSQL(Connection.java:3249) at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:1268) at com.mysql.jdbc.PreparedStatement.executeQuery(PreparedStatement.java:1403) at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:208) at org.hibernate.loader.Loader.getResultSet(Loader.java:1812) at org.hibernate.loader.Loader.doQuery(Loader.java:697) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:259) at org.hibernate.loader.Loader.doList(Loader.java:2232) at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2129) at org.hibernate.loader.Loader.list(Loader.java:2124) at org.hibernate.loader.hql.QueryLoader.list(QueryLoader.java:401) at org.hibernate.hql.ast.QueryTranslatorImpl.list(QueryTranslatorImpl.java:363) at org.hibernate.engine.query.HQLQueryPlan.performList(HQLQueryPlan.java:196) at org.hibernate.impl.SessionImpl.list(SessionImpl.java:1149) at org.hibernate.impl.QueryImpl.list(QueryImpl.java:102) Any tips? Thanks

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  • Parsing XML file using a for loop

    - by Johnny Spintel
    I have been working on this program which inserts an XML file into a MYSQL database. I'm new to the whole .jar idea by inserting packages. Im having an issue with parse(), select(), and children(). Can someone inform me how I could fix this issue? Here is my stack trace and my program below: Exception in thread "main" java.lang.Error: Unresolved compilation problems: The method select(String) is undefined for the type Document The method children() is undefined for the type Element The method children() is undefined for the type Element The method children() is undefined for the type Element The method children() is undefined for the type Element at jdbc.parseXML.main(parseXML.java:28) import java.io.*; import java.sql.*; import org.jsoup.Jsoup; import org.w3c.dom.*; import javax.xml.parsers.*; public class parseXML{ public static void main(String xml) { try{ BufferedReader br = new BufferedReader(new FileReader(new File("C:\\staff.xml"))); String line; StringBuilder sb = new StringBuilder(); while((line=br.readLine())!= null){ sb.append(line.trim()); } Document doc = Jsoup.parse(line); StringBuilder queryBuilder; StringBuilder columnNames; StringBuilder values; for (Element row : doc.select("row")) { // Start the query queryBuilder = new StringBuilder("insert into customer("); columnNames = new StringBuilder(); values = new StringBuilder(); for (int x = 0; x < row.children().size(); x++) { // Append the column name and it's value columnNames.append(row.children().get(x).tagName()); values.append(row.children().get(x).text()); if (x != row.children().size() - 1) { // If this is not the last item, append a comma columnNames.append(","); values.append(","); } else { // Otherwise, add the closing paranthesis columnNames.append(")"); values.append(")"); } } // Add the column names and values to the query queryBuilder.append(columnNames); queryBuilder.append(" values("); queryBuilder.append(values); // Print the query System.out.println(queryBuilder); } }catch (Exception err) { System.out.println(" " + err.getMessage ()); } } }

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  • How best to modernize the 2002-era J2EE app?

    - by user331465
    I have this friend.... I have this friend who works on a java ee application (j2ee) application started in the early 2000's. Currently they add a feature here and there, but have a large codebase. Over the years the team has shrunk by 70%. [Yes, the "i have this friend is". It's me, attempting to humorously inject teenage high-school counselor shame into the mix] Java, Vintage 2002 The application uses EJB 2.1, struts 1.x, DAO's etc with straight jdbc calls (mixture of stored procedures and prepared statements). No ORM. For caching they use a mixture of OpenSymphony OSCache and a home-grown cache layer. Over the last few years, they have spent effort to modernize the UI using ajax techniques and libraries. This largely involves javascript libaries (jquery, yui, etc). Client Side On the client side, the lack of upgrade path from struts1 to struts2 discouraged them from migrating to struts2. Other web frameworks became popular (wicket, spring , jsf). Struts2 was not the "clear winner". Migrating all the existing UI from Struts1 to Struts2/wicket/etc did not seem to present much marginal benefit at a very high cost. They did not want to have a patchwork of technologies-du-jour (subsystem X in Struts2, subsystem Y in Wicket, etc.) so developer write new features using Struts 1. Server Side On the server side, they looked into moving to ejb 3, but never had a big impetus. The developers are all comfortable with ejb-jar.xml, EJBHome, EJBRemote, that "ejb 2.1 as is" represented the path of least resistance. One big complaint about the ejb environment: programmers still pretend "ejb server runs in separate jvm than servlet engine". No app server (jboss/weblogic) has ever enforced this separation. The team has never deployed the ejb server on a separate box then the app server. The ear file contains multiple copies of the same jar file; one for the 'web layer' (foo.war/WEB-INF/lib) and one for the server side (foo.ear/). The app server only loads one jar. The duplications makes for ambiguity. Caching As for caching, they use several cache implementations: OpenSymphony cache and a homegrown cache. Jgroups provides clustering support Now What? The question: The team currently has spare cycles to to invest in modernizing the application? Where would the smart investor spend them? The main criteria: 1) productivity gains. Specifically reducing the time to develope new subsystems features and reduced maintenance. 2) performance/scalability. They do not care about fashion or techno-du-jour street cred. What do you all recommend? On the persistence side Switch everything (or new development only) to JPA/JPA2? Straight hibernate? Wait for Java EE 6? On the client/web-framework side: Migrate (some or all) to struts2? wicket? jsf/jsf2? As for caching: terracotta? ehcache? coherence? stick with what they have? how best to take advantage of the huge heap sizes that the 64-bit jvms offer? Thanks in advance.

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  • "FOR UPDATE" v/s "LOCK IN SHARE MODE" : Allow concurrent threads to read updated "state" value of locked row

    - by shadesco
    I have the following scenario: User X logs in to the application from location lc1: call it Ulc1 User X (has been hacked, or some friend of his knows his login credential, or he just logs in from a different browser on his machine,etc.. u got the point) logs in at the same time from location lc2: call it Ulc2 I am using a main servlet which : - gets a connection from database pooling - sets autocommit to false - executes a command that goes through app layers: if all successful, set autocommit to true in a "finally" statement, and closes connection. Else if an exception happens, rollback(). In my database (mysql/innoDb) i have a "history" table, with row columns: id(primary key) |username | date | topic | locked The column "locked" has by default value "false" and it serves as a flag that marks if a specific row is locked or not. Each row is specific to a user (as u can see from the username column) So back to the scenario: --Ulc1 sends the command to update his history from the db for date "D" and topic "T". --Ulc2 sends the same command to update history from the db for the same date "D" and same topic "T" at the exact same time. I want to implement an mysql/innoDB locking system that will enable whichever thread arriving to do the following check: Is column "locked" for this row true or not? if true, return a message to the user that " he is already updating the same data from another location" if not true (ie not locked) : flag it as locked and update then reset locked to false once finished. Which of these two mysql locking techniques, will actually allow the 2nd arriving thread from reading the "updated" value of the locked column to decide wt action to take?Should i use "FOR UPDATE" or "LOCK IN SHARE MODE"? This scenario explains what i want to accomplish: - Ulc1 thread arrives first: column "locked" is false, set it to true and continue updating process - Ulc2 thread arrives while Ulc1's transaction is still in process, and even though the row is locked through innoDb functionalities, it doesn't have to wait but in fact reads the "new" value of column locked which is "true", and so doesn't in fact have to wait till Ulc1 transaction commits to read the value of the "locked" column(anyway by that time the value of this column will already have been reset to false). I am not very experienced with the 2 types of locking mechanisms, what i understand so far is that LOCK IN SHARE MODE allow other transaction to read the locked row while FOR UPDATE doesn't even allow reading. But does this read gets on the updated value? or the 2nd arriving thread has to wait the first thread to commit to then read the value? Any recommendations about which locking mechanism to use for this scenario is appreciated. Also if there's a better way to "check" if the row has been locked (other than using a true/false column flag) please let me know about it. thank you SOLUTION (Jdbc pseudocode example based on @Darhazer's answer) Table : [ id(primary key) |username | date | topic | locked ] connection.setautocommit(false); //transaction-1 PreparedStatement ps1 = "Select locked from tableName for update where id="key" and locked=false); ps1.executeQuery(); //transaction 2 PreparedStatement ps2 = "Update tableName set locked=true where id="key"; ps2.executeUpdate(); connection.setautocommit(true);// here we allow other transactions threads to see the new value connection.setautocommit(false); //transaction 3 PreparedStatement ps3 = "Update tableName set aField="Sthg" where id="key" And date="D" and topic="T"; ps3.executeUpdate(); // reset locked to false PreparedStatement ps4 = "Update tableName set locked=false where id="key"; ps4.executeUpdate(); //commit connection.setautocommit(true);

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  • Connection drop problem with Hibernate-mysql-c3p0

    - by user344788
    hi all, This is an issue which I have seen all across the web. I will bring it up again as till now I don't have a fix for the same. I am using hibernate 3. mysql 5 and latest c3p0 jar. I am getting a broken pipe exception. Following is my hibernate.cfg file. com.mysql.jdbc.Driver org.hibernate.dialect.MySQLDialect <property name="hibernate.show_sql">true</property> <property name="hibernate.use_sql_comments">true</property> <property name="hibernate.current_session_context_class">thread</property> <property name="connection.autoReconnect">true</property> <property name="connection.autoReconnectForPools">true</property> <property name="connection.is-connection-validation-required">true</property> <!--<property name="c3p0.min_size">5</property> <property name="c3p0.max_size">20</property> <property name="c3p0.timeout">1800</property> <property name="c3p0.max_statements">50</property> --><property name="hibernate.connection.provider_class">org.hibernate.connection.C3P0ConnectionProvider </property> <property name="hibernate.c3p0.acquireRetryAttempts">30</property> <property name="hibernate.c3p0.acquireIncrement">5</property> <property name="hibernate.c3p0.automaticTestTable">C3P0TestTable</property> <property name="hibernate.c3p0.idleConnectionTestPeriod">36000</property> <property name="hibernate.c3p0.initialPoolSize">20</property> <property name="hibernate.c3p0.maxPoolSize">100</property> <property name="hibernate.c3p0.maxIdleTime">1200</property> <property name="hibernate.c3p0.maxStatements">50</property> <property name="hibernate.c3p0.minPoolSize">10</property>--> My connection pooling is occurring fine. During the day it is fine , but once i keep it idle over the night ,next day I find it giving me broken connection error. public class HibernateUtil { private static Logger log = Logger.getLogger(HibernateUtil.class); //private static Log log = LogFactory.getLog(HibernateUtil.class); private static Configuration configuration; private static SessionFactory sessionFactory; static { // Create the initial SessionFactory from the default configuration files try { log.debug("Initializing Hibernate"); // Read hibernate.properties, if present configuration = new Configuration(); // Use annotations: configuration = new AnnotationConfiguration(); // Read hibernate.cfg.xml (has to be present) configuration.configure(); // Build and store (either in JNDI or static variable) rebuildSessionFactory(configuration); log.debug("Hibernate initialized, call HibernateUtil.getSessionFactory()"); } catch (Throwable ex) { // We have to catch Throwable, otherwise we will miss // NoClassDefFoundError and other subclasses of Error log.error("Building SessionFactory failed.", ex); throw new ExceptionInInitializerError(ex); } } /** * Returns the Hibernate configuration that was used to build the SessionFactory. * * @return Configuration */ public static Configuration getConfiguration() { return configuration; } /** * Returns the global SessionFactory either from a static variable or a JNDI lookup. * * @return SessionFactory */ public static SessionFactory getSessionFactory() { String sfName = configuration.getProperty(Environment.SESSION_FACTORY_NAME); System.out.println("Current s name is "+sfName); if ( sfName != null) { System.out.println("Looking up SessionFactory in JNDI"); log.debug("Looking up SessionFactory in JNDI"); try { System.out.println("Returning new sssion factory"); return (SessionFactory) new InitialContext().lookup(sfName); } catch (NamingException ex) { throw new RuntimeException(ex); } } else if (sessionFactory == null) { System.out.println("calling rebuild session factory now"); rebuildSessionFactory(); } return sessionFactory; } /** * Closes the current SessionFactory and releases all resources. * <p> * The only other method that can be called on HibernateUtil * after this one is rebuildSessionFactory(Configuration). */ public static void shutdown() { log.debug("Shutting down Hibernate"); // Close caches and connection pools getSessionFactory().close(); // Clear static variables sessionFactory = null; } /** * Rebuild the SessionFactory with the static Configuration. * <p> * Note that this method should only be used with static SessionFactory * management, not with JNDI or any other external registry. This method also closes * the old static variable SessionFactory before, if it is still open. */ public static void rebuildSessionFactory() { log.debug("Using current Configuration to rebuild SessionFactory"); rebuildSessionFactory(configuration); } /** * Rebuild the SessionFactory with the given Hibernate Configuration. * <p> * HibernateUtil does not configure() the given Configuration object, * it directly calls buildSessionFactory(). This method also closes * the old static variable SessionFactory before, if it is still open. * * @param cfg */ public static void rebuildSessionFactory(Configuration cfg) { log.debug("Rebuilding the SessionFactory from given Configuration"); if (sessionFactory != null && !sessionFactory.isClosed()) sessionFactory.close(); if (cfg.getProperty(Environment.SESSION_FACTORY_NAME) != null) { log.debug("Managing SessionFactory in JNDI"); cfg.buildSessionFactory(); } else { log.debug("Holding SessionFactory in static variable"); sessionFactory = cfg.buildSessionFactory(); } configuration = cfg; } } Above is my code for the session factory. And I have only select operations . And below is the method which is used most often to execute my select queries. One tricky thing which I am not understanding is in my findById method i am using this line of code getSession().beginTransaction(); without which it gives me an error saying that this cannot happpen without a transaction. But nowhere I am closing this transaction. And thers no method to close a transaction apart from commit or rollback (as far as i know) which are not applicable for select statements. public T findById(ID id, boolean lock) throws HibernateException, DAOException { log.debug("findNyId invoked with ID ="+id+"and lock ="+lock); T entity; getSession().beginTransaction(); if (lock) entity = (T) getSession().load(getPersistentClass(), id, LockMode.UPGRADE); else entity = (T) getSession().load(getPersistentClass(), id); return entity; } Can anyone please suggest what can I do ? I have tried out almost every solution available via googling, on stackoverlow or on hibernate forums with no avail. (And increasing wait_timeout on mysql is not a valid option in my case).

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  • create and insert values using mysql JDBC

    - by S.PRATHIBA
    Hi all, I have the sample code. public void UpdateTable1() { for(int t=0;t<20;t++) { if(consumer==1 && number==1 && provider1==31 && feedback==1) { try{ Class.forName(driverName); con = DriverManager.getConnection(url+dbName,"root","mysql"); try { Statement st = con.createStatement(); int val = st.executeUpdate("INSERT Consumer1 VALUES ("+31+","+"'Printer'"+", "+1+" "+")"); System.out.println("1 row affected"); } catch (SQLException s) { System.out.println("SQL statement is not executed!"); } con.close(); } I want to insert the same set of values(31,printer,1) into the table consumer2,consumer3.Is it possible without using another try catch statements...Please help me.

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  • Hibernate: how to call a stored function returning a varchar?

    - by Péter Török
    I am trying to call a legacy stored function in an Oracle9i DB from Java using Hibernate. The function is declared like this: create or replace FUNCTION Transferlocation_Fix (mnemonic_code IN VARCHAR2) RETURN VARCHAR2 After several failed tries and extensive googling, I found this thread on the Hibernate forums which suggested a mapping like this: <sql-query name="TransferLocationFix" callable="true"> <return-scalar column="retVal" type="string"/> select Transferlocation_Fix(:mnemonic) as retVal from dual </sql-query> My code to execute it is Query query = session.getNamedQuery("TransferLocationFix"); query.setParameter("mnemonic", "FC3"); String result = (String) query.uniqueResult(); and the resulting log is DEBUG (org.hibernate.jdbc.AbstractBatcher:366) - - about to open PreparedStatement (open PreparedStatements: 0, globally: 0) DEBUG (org.hibernate.SQL:401) - - select Transferlocation_Fix(?) as retVal from dual TRACE (org.hibernate.jdbc.AbstractBatcher:484) - - preparing statement TRACE (org.hibernate.type.StringType:133) - - binding 'FC3' to parameter: 2 TRACE (org.hibernate.type.StringType:133) - - binding 'FC3' to parameter: 2 java.lang.NullPointerException at oracle.jdbc.ttc7.TTCAdapter.newTTCType(TTCAdapter.java:300) at oracle.jdbc.ttc7.TTCAdapter.createNonPlsqlTTCColumnArray(TTCAdapter.java:270) at oracle.jdbc.ttc7.TTCAdapter.createNonPlsqlTTCDataSet(TTCAdapter.java:231) at oracle.jdbc.ttc7.TTC7Protocol.doOall7(TTC7Protocol.java:1924) at oracle.jdbc.ttc7.TTC7Protocol.parseExecuteDescribe(TTC7Protocol.java:850) at oracle.jdbc.driver.OracleStatement.doExecuteQuery(OracleStatement.java:2599) at oracle.jdbc.driver.OracleStatement.doExecuteWithTimeout(OracleStatement.java:2963) at oracle.jdbc.driver.OraclePreparedStatement.executeUpdate(OraclePreparedStatement.java:658) at oracle.jdbc.driver.OraclePreparedStatement.execute(OraclePreparedStatement.java:736) at com.mchange.v2.c3p0.impl.NewProxyCallableStatement.execute(NewProxyCallableStatement.java:3044) at org.hibernate.dialect.Oracle8iDialect.getResultSet(Oracle8iDialect.java:379) at org.hibernate.jdbc.AbstractBatcher.getResultSet(AbstractBatcher.java:193) at org.hibernate.loader.Loader.getResultSet(Loader.java:1784) at org.hibernate.loader.Loader.doQuery(Loader.java:674) at org.hibernate.loader.Loader.doQueryAndInitializeNonLazyCollections(Loader.java:236) at org.hibernate.loader.Loader.doList(Loader.java:2220) at org.hibernate.loader.Loader.listIgnoreQueryCache(Loader.java:2104) at org.hibernate.loader.Loader.list(Loader.java:2099) at org.hibernate.loader.custom.CustomLoader.list(CustomLoader.java:289) at org.hibernate.impl.SessionImpl.listCustomQuery(SessionImpl.java:1695) at org.hibernate.impl.AbstractSessionImpl.list(AbstractSessionImpl.java:142) at org.hibernate.impl.SQLQueryImpl.list(SQLQueryImpl.java:152) at org.hibernate.impl.AbstractQueryImpl.uniqueResult(AbstractQueryImpl.java:811) at com.my.project.SomeClass.method(SomeClass.java:202) ... Any clues what am I doing wrong? Or any better ways to call this stored function?

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