Develop Reference

Looking for the optimization of the below code

I have found below code buggy as it degrades the performance of extjs3 grid, i am looking for possibilities of optimization at query or code level, as per my analysis, if we extract out the query there are two nested inner queries which are responding slow, in addition, the code inside while loop trying to find the unique id, can't we have distinct in query, or joins rather than inner queries.
Please suggest me the best practice to follow in order to achieve optimization.
public boolean isSCACreditOverviewGridVisible(String sessionId) {
Connection conn = null;
ResultSet rs = null;
PreparedStatement ps = null;
boolean result = false;
try {
CommonUtility commUtil = new CommonUtility();
List<String> hmIds = new ArrayList<String>();
Map<String, String> tmStockMap = new TreeMap<String, String>();
Set<String> setRecentCertificate = new HashSet<String>();
String managerAccountId = sessionInfo.getMembershipAccount();
String stockQuery = " select memberId , RootCertficateId from stockposition sp where sp.stocktype = 'TR' and sp.memberId "
+ " IN ( select hm2.accountId from "
DATALINK
+ ".holdingmembers hm2 "
+ " where hm2.holdingId = ( select holdingId from "
DATALINK
+ ".holdingmembers hm1 where hm1.accountId = ? )) "
+ " order by sp.createdDate desc ";
conn = getChildDBConnection();
if (null != conn) {
ps = conn.prepareStatement(stockQuery);
ps.setString(1, managerAccountId);
rs = ps.executeQuery();
if (null != rs) {
while (rs.next()) {
String memberId = rs.getString("memberId");
String rootCertficateId = rs
.getString("RootCertficateId");
if (tmStockMap.containsKey(rootCertficateId)) {
continue;
}
hmIds.add(memberId);
tmStockMap.put(rootCertficateId, memberId);
}
}
rs.close();
ps.close();
if (null != hmIds && !hmIds.isEmpty()) {
String inIds = commUtil.getInStateParam(hmIds);
String mostRecentLicense = "Select RootCertificateId , memberaccountid from "
+ OctopusSchema.octopusSchema
+ ".certificate c where c.memberaccountid IN ("
+ inIds
+ ") and c.isrootcertificate=0 and c.certificationstatusid > 1 order by c.modifieddate desc";
ps = conn.prepareStatement(mostRecentLicense);
rs = ps.executeQuery();
if (null != rs) {
while (rs.next()) {
String rootCertficateId = rs
.getString("RootCertificateId");
String memberaccountid = rs
.getString("memberaccountid");
if (setRecentCertificate.contains(memberaccountid)) {
continue;
}
setRecentCertificate.add(memberaccountid);
if (tmStockMap.containsKey(rootCertficateId)) {
result = true;
break;
}
}
}
rs.close();
ps.close();
} else {
result = false;
}
}
} catch (Exception e) {
LOGGER.error(e);
} finally {
closeDBReferences(conn, ps, null, rs);
}
return result;
}
QUERY:
select RootCertficateId,memberId from stockposition sp where sp.stocktype = 'TR' and sp.memberId
IN ( select hm2.accountId from
DATALINK.holdingmembers hm2
where hm2.holdingId = ( select holdingId from
DATALINK.holdingmembers hm1 where hm1.accountId = '4937' ))
order by sp.createdDate DESC;

One quick approach would be a substition of your IN by EXISTS. If your inner queryes return a lot of rows, it would be a lot more efficient. It depends if your subquery returns a lot of results.
SQL Server IN vs. EXISTS Performance

How to deal with multiple queries in a java servlet

I'm trying to send an increase count variable of a picture (which is increased by just increasing +1 everytime a new session hits a picture). I'm getting the following error message however, i'm checking for an empty result set. My thought process is that I can try to select the picturesNo that has been called and if it can't find that pictureNo we simply insert the first count to the table, and if it can find it, we then update this.
Error message:
"SQLException: Illegal operation on empty result set."
Code to increase the count for the session
HttpSession session = request.getSession() ;
Integer counter = (Integer) session.getAttribute("counter");
String accCount = (String) session.getAttribute("attributeKey") ;
String url = "http://localhost:8080/techfore";
String encodedURL = url + ";jsessionid=" + request.getSession().getId();
if (accCount == null || encodedURL == null) { // New session?
response.sendRedirect("/techfore/WelcomePage");
}
else{
if(counter == 0) {
counter = new Integer(counter.intValue() + 1);
session.setAttribute("counter", counter);
}
}
Utilities.initalCount(out, pictureName, counter);
Code to run the queries
public static void initalCount(PrintWriter out, String pictureName, int accessCount) {
Connection con = null;
try { // Connect to the database
con = openConnection(out);
}
catch (Exception e) { // Failed to open the connection
out.println("<P>" + e.getMessage());
}
try {
Statement stmt = con.createStatement();
String query0;
ResultSet rs1;
query0="SELECT PictureNo FROM Statistics WHERE PictureNo = (SELECT PictureNo FROM Pictures WHERE ShortName = '"+pictureName+"')";
rs1 = stmt.executeQuery(query0);
if(rs1.next()){
//yes exist
String description = rs1.getString("Description");
int pictureNo = rs1.getInt("PictureNo");
IncreaseCount(out, pictureNo, accessCount);
}
else {
//if rs is null insert
int pictureNo = rs1.getInt("PictureNo");
AddCount(out, pictureNo, accessCount);
}
stmt.close() ;
}
catch(SQLException ex) {
out.println("<P>SQLException: " + ex.getMessage()) ;
}
}
public static void AddCount(PrintWriter out, int pictureNo, int accessCount) {
Connection con = null;
try { // Connect to the database
con = openConnection(out);
}
catch (Exception e) { // Failed to open the connection
out.println("<P>" + e.getMessage());
return;
}
try {
Statement stmt = con.createStatement();
String query;
ResultSet rs1;
query="INSERT INTO Statistics VALUES "+pictureNo+","+accessCount+" ";
stmt.executeUpdate(query);
stmt.close() ;
}
catch(SQLException ex) {
out.println("<P>SQLException: " + ex.getMessage()) ;
}
}
public static void IncreaseCount(PrintWriter out, int pictureNo, int accessCount) {
Connection con = null;
try { // Connect to the database
con = openConnection(out);
}
catch (Exception e) { // Failed to open the connection
out.println("<P>" + e.getMessage());
return;
}
try {
Statement stmt = con.createStatement();
String query;
ResultSet rs1;
query="UPDATE Statistics SET AccessCount = "+accessCount+" + 1 WHERE PictureNo = "+pictureNo+"";
stmt.executeUpdate(query);
stmt.close() ;
}
catch(SQLException ex) {
out.println("<P>SQLException: " + ex.getMessage()) ;
}
}
New insert
query="INSERT INTO Statistics VALUES (SELECT PictureNo FROM Pictures WHERE FileName = '"+pictureName+"'),"+accessCount+" ";

Connecting to different schemas using prepared statement

I have the following code running fine with one sql statement selectEmpShowDocs_SQL referring to schema1. In this scenario, I have hard coded the value of empID as 2 as shown in the sql below :
private String selectEmpShowDocs_SQL =
"SELECT " +
"emp_doc " +
"FROM " +
"schema1.emp_info " +
"WHERE " +
"doc_id = ? "+
"AND"+
"empID = 2";
Now, I have another sql statement which is retrieving the emp_id value and instead of hardcoding the value just like I did above for empID, I want to pass the value of emp_id obtained from the following sql statement to the above sql statement. This is the statement which is referring to schema2.
private String selectEmpIDSQL =
"SELECT " +
"emp_id " +
"FROM " +
"schema2.emp_id " +
"WHERE " +
"company_id = 435 "
I am wondering is it possible to connect with two different schemas with one prepared statement? Here someone mentioned that prepared statement is bound to a specific database and in that case if it's not possible, what would be the best approach for me?
Here is the full code that works fine for me using only the SQL query referring to schema1.
public List<EmployeeDocument> getEmployeeDocument(String docId, Integer employeeID) throws DaoException
{
StopWatch stopWatch = new StopWatch();
stopWatch.start();
DataSource ds = null;
Connection conn = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
List<EmployeeDocument> empShowDocs = new ArrayList<EmployeeDocument>();
try {
ds = jdbcTemplate.getDataSource();
conn = ds.getConnection();
pstmt = conn.prepareStatement(selectEmpShowDocs_SQL);
logger.debug("sql query :" + selectEmpShowDocs_SQL);
System.out.println(selectEmpShowDocs_SQL);
pstmt.setString(1, docId);
logger.debug("sql parameters, docId:" + docId);
rs = pstmt.executeQuery();
while(rs.next()) {
EmployeeDocument empShowDocRecord = new EmployeeDocument();
empShowDocRecord.setEmp_Content(rs.getString("emp_doc")));
empShowDocs.add(empShowDocRecord);
}
} catch(Throwable th) {
throw new DaoException(th.getMessage(), th);
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
rs = null;
}
if (pstmt != null) {
try {
pstmt.close();
} catch(SQLException sqe) {
sqe.printStackTrace();
}
pstmt = null;
}
if (conn != null) {
try {
conn.close();
} catch (SQLException sqle) {
sqle.printStackTrace();
}
conn = null;
}
if (ds != null) {
ds = null;
}
}
return empShowDocs;
}
private String selectEmpShowDocs_SQL =
"SELECT " +
"emp_doc " +
"FROM " +
"schema1.emp_info " +
"WHERE " +
"doc_id = ? "+
"AND"+
"empID = 2";
private String selectEmpIDSQL =
"SELECT " +
"emp_id " +
"FROM " +
"schema2.emp_id " +
"WHERE " +
"company_id = 435 "

java return data to java client

i have java client send to server (jetty-xmlrpc) query and receive data from server inside hashmap. sometime data is more big(e.g. 3645888 rows), when this data send to java client i have error ( java heap space ). how can i send data by 2 times for example ? or give me way to fix it
this is server function to get data and send it to client
public HashMap getFlickValues(String query,String query2){
System.out.println("Query is : "+query);
System.out.println("Query2 is: "+query2);
Connection c = null;
Connection c2 = null;
Statement st = null;
Statement st2 = null;
HashMap<String, Object[]> result = new HashMap<String, Object[]>();
ArrayList<Double> vaArrL = new ArrayList<Double>();
ArrayList<Double> vbArrL = new ArrayList<Double>();
ArrayList<Double> vcArrL = new ArrayList<Double>();
try {
Class.forName("org.postgresql.Driver");
String conString = "jdbc:postgresql://" + host + ":" + port + "/" + DBName +
"?user=" + user + "&pass=" + pass;
String conString1 = "jdbc:postgresql://" + host + ":" + port2 + "/" + DBName2 +
"?user=" + user + "&pass=" + pass;
//String conString1 = "jdbc:postgresql://127.0.0.1:5431/merkezdbram " +
// "?user=" + user + "&pass=" + pass;
/*c = DriverManager.getConnection(conString);
st = c.createStatement();
ResultSet rs = st.executeQuery(query);
while (rs.next()){
vaArrL.add(rs.getDouble("va"));
vbArrL.add(rs.getDouble("vb"));
vcArrL.add(rs.getDouble("vc"));
}*/
c = DriverManager.getConnection(conString);
//c.setAutoCommit(false);
c2 = DriverManager.getConnection(conString1);
//c2.setAutoCommit(false);
st = c.createStatement();
//st.setFetchSize(1000);
st2 = c2.createStatement();
//st2.setFetchSize(1000);
List<ResultSet> resultSets = new ArrayList<>();
resultSets.add(st.executeQuery(query));
resultSets.add(st2.executeQuery(query2));
ResultSets rs = new ResultSets(resultSets);
int count = 0;
int ResultSetSize = rs.getFetchSize();
System.out.println("ResultSetSize is "+ResultSetSize);
while (rs.next()){
//count++;
//if ( count == 2200000) { break;}
vaArrL.add(rs.getDoubleVa("va"));
vbArrL.add(rs.getDoubleVb("vb"));
vcArrL.add(rs.getDoubleVc("vc"));
}
int sz = vaArrL.size();
result.put("va", vaArrL.toArray(new Object[sz]));
result.put("vb", vbArrL.toArray(new Object[sz]));
result.put("vc", vcArrL.toArray(new Object[sz]));
//rs.close();
st.close();
c.close();
} catch ( Exception e ) {
System.out.println(e);
e.printStackTrace();
}
System.out.println("Flicker vaArrL.size = "+vaArrL.size());
return result;
}
and ResultSets class is :
class ResultSets {
private java.util.List<java.sql.ResultSet> resultSets;
private java.sql.ResultSet current;
public ResultSets(java.util.List<java.sql.ResultSet> resultSets) {
this.resultSets = new java.util.ArrayList<>(resultSets);
current = resultSets.remove(0);
}
public boolean next() throws SQLException {
if (current.next()) {
return true;
}else if (!resultSets.isEmpty()) {
current = resultSets.remove(0);
return next();
}
return false;
}
public Double getDoubleVa(String va) throws SQLException{
return current.getDouble("va");
}
public Double getDoubleVb(String vb) throws SQLException{
return current.getDouble("vb");
}
public Double getDoubleVc(String vc) throws SQLException{
return current.getDouble("vc");
}
}
i want way to return data to client without (java heap space) ?
i make -Xmx1024m for VM argument , but same problrm
i want solution in my code
thanks

Getting SQL error 1078 Before start of result set in Java program [duplicate]

This question already has answers here:
ResultSet exception - before start of result set
(6 answers)
Closed 5 years ago.
I have a Java method that is supposed to get column values from one MySQL row and create a string with the values. When run, it generates a SQL error 1078 "Before start of result set."
Here is the the class in which the error is occuring (Problem is in listPosesInSection method:
/** Class used to access the database */
import java.sql.*;
import java.util.ArrayList;
import javax.swing.JOptionPane;
public class YogaDatabaseAccess {
String dbUrl = "jdbc:mysql://localhost/yoga";
private Connection connection;
private ResultSet rset;
private ResultSetMetaData rsMetaData;
private Statement statement;
private PreparedStatement pStatementAll = null;
private PreparedStatement pStatementPartial = null;
// Strings for queries and updates
String strListPosesNotPrimary;
String strInsertNewClass;
String strInsertNewSection;
String strInsertNewPose;
String strUpdateClass;
String strUpdateSection;
String strUpdatePose;
String strArrangePoseOrder;
private String[] poseArray;
// Constructor
YogaDatabaseAccess() {
connectToDatabase();
}
// Method that connects to database
private void connectToDatabase() {
try {
connection = DriverManager.getConnection(dbUrl, "Kyle", "Kullerstrand#2");
System.out.println("Database connected");
}
catch(SQLException e) {
System.out.println(e.getMessage());
}
}
// Query that returns lists to be used with combo boxes
public String listForBoxes(String listName) {
// List to be returned
String strList = "";
// Determine name of the database table for this list
String listTableName;
if (listName == "pose")
listTableName = listName + "s";
else if (listName == "class")
listTableName = listName + "es";
else
listTableName = listName;
// Determine the database column name for this list
String listColumnName = listName + "_name";
// Run the query
try {
statement = connection.createStatement();
rset = statement.executeQuery("SELECT DISTINCT " + listColumnName + " FROM " + listTableName +
" ORDER BY " + listColumnName);
while (rset.next()){
strList = strList + rset.getString(listColumnName) + ", ";
}
} catch (SQLException e) {
e.printStackTrace();
}
return strList;
}
// Query that returns list of primary poses for a section
public String listPrimaryPoses(String sectionName) {
// List to be returned
String strList = "";
// Run the query
try {
statement = connection.createStatement();
rset = statement.executeQuery("SELECT DISTINCT pose_name FROM poses WHERE primarily_suitable_for = '" + sectionName +
"' OR primarily_suitable_for = 'Anything' ORDER BY pose_name");
while (rset.next()){
strList = strList + rset.getString("pose_name") + ", ";
}
} catch (SQLException e) {
e.printStackTrace();
}
return strList;
}
// Query that returns list of secondary poses for a section
public String listSecondaryPoses(String sectionName) {
// List to be returned
String strList = "";
// Run the query
try {
statement = connection.createStatement();
rset = statement.executeQuery("SELECT DISTINCT pose_name FROM poses WHERE sometimes_suitable_for = '" + sectionName + "' ORDER BY pose_name");
while (rset.next()){
strList = strList + rset.getString("pose_name") + ", ";
}
} catch (SQLException e) {
e.printStackTrace();
}
return strList;
}
// Query that returns the poses within a specific section
public String listPosesInSection(String tableName, String sectionName) {
String strList;
StringBuilder strBuilderList = new StringBuilder("");
// Run the query
try {
statement = connection.createStatement();
// Query will collect all columns from one specific row
rset = statement.executeQuery("SELECT * FROM " + tableName + " WHERE " + tableName + "_name = '" + sectionName + "'");
while (rset.next()) {
for (int i = 2; i <= countColumnsInTable(tableName); i++) // First value (0) is always null, skip section name (1)
if (rset.getString(i) != null) // If column has a value
strBuilderList.append(rset.getString(i) + "\n");
}
} catch (SQLException e) {
e.printStackTrace();
}
strList = strBuilderList.toString();
return strList.replaceAll(", $",""); // Strips off the trailing comma
}
// Insert statement that inserts a new class into the classes table
public void insertNewClass(String className) {
/** String insert = "INSERT INTO poses (pose_name, primarily_suitable_for, sometimes_suitable_for) values(?, ?, ?)";
System.out.println("About to create the prepared statement");
// Run the insert
try {
pStatement = connection.prepareStatement(insert);
// statement.execute("INSERT IGNORE INTO poses VALUES ('" + poseName + "', '" + suitableFor + "', '" + suitableForSometimes + "')");
pStatement.setString(1, poseName);
pStatement.setString(2, suitableFor);
pStatement.setString(3, suitableForSometimes);
System.out.println("Created the prepared statement");
// execute query, and return number of rows created
pStatement.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
} */
}
// Insert statement that inserts a new pose into poses table
public void insertNewPose(String poseName, String suitableFor, String suitableForSometimes) {
String insertAll = "INSERT INTO poses (pose_name, primarily_suitable_for, sometimes_suitable_for) values(?, ?, ?)";
String insertPartial = "INSERT INTO poses (pose_name, primarily_suitable_for) values(?, ?)";
// Run the insert
try {
if (suitableForSometimes == "NULL") { // Insert statement contains a null value for sometimes suitable column
pStatementPartial = connection.prepareStatement(insertPartial);
pStatementPartial.setString(1, poseName);
pStatementPartial.setString(2, suitableFor);
pStatementPartial.executeUpdate();
} else { // Insert statement contains values for all three columns
pStatementAll = connection.prepareStatement(insertAll);
pStatementAll.setString(1, poseName);
pStatementAll.setString(2, suitableFor);
pStatementAll.setString(3, suitableForSometimes);
pStatementAll.executeUpdate();
}
} catch (SQLException e) {
System.err.println("SQLException: " + e.getMessage() + ":" + e.getSQLState());
JOptionPane.showMessageDialog(null, "This pose already exists.");
} finally {
SQLWarning w;
try {
for (w = connection.getWarnings(); w != null; w = w.getNextWarning())
System.err.println("WARNING: " + w.getMessage() + ":" + w.getSQLState());
} catch (SQLException e) {
e.printStackTrace();
JOptionPane.showMessageDialog(null, "An unknown error in the yoga design program has occurred.");
}
}
}
// Insert statement that inserts a new section into warmup, work or restore sections
public void insertNewSection(String sectionType, String sectionName, ArrayList<String> poses) {
System.out.println("insertNewSection method was called");
int maxColumns = countColumnsInTable(sectionType);
poseArray = new String[poses.size()];
poseArray = poses.toArray(poseArray);
if (poseArray.length == 0)
JOptionPane.showMessageDialog(null, "There are no poses in this section. Please add poses.");
// Create a list of columns of the table for the INSERT statement
StringBuilder columns = new StringBuilder(sectionType + "_name");
for (int c = 1; c < maxColumns; c++)
columns.append(", pose_" + c);
// Create a string list of poses, separated by commas, from the array
StringBuilder values = new StringBuilder();
values.append("'" + poseArray[0] + "'");
for (int v = 1; v < poseArray.length - 1; v++)
values.append(", '" + poseArray[v] + "'");
// make sure query uses correct number of columns by padding the query with NULL
for (int i = poseArray.length; i < maxColumns; i++)
values.append(", NULL");
String posesToAddToSection = values.toString();
// The string containing the entire insert statement
String insert = "INSERT INTO " + sectionType + " (" + columns + ") VALUES ('" + sectionName + "', " + posesToAddToSection + ")";
// Run the insert
try {
statement = connection.createStatement();
statement.executeUpdate(insert);
} catch (SQLException e) {
System.err.println("SQLException: " + e.getMessage() + ":" + e.getSQLState());
JOptionPane.showMessageDialog(null, "An error in the yoga design program has occurred. SQLException: " +
e.getMessage() + ":" + e.getSQLState());
} finally {
SQLWarning w;
try {
for (w = connection.getWarnings(); w != null; w = w.getNextWarning())
System.err.println("WARNING: " + w.getMessage() + ":" + w.getSQLState());
} catch (SQLException e) {
e.printStackTrace();
JOptionPane.showMessageDialog(null, "An unknown error in the yoga design program has occurred.");
}
}
}
// Statement that deletes rows from tables
public void deleteRow(String tableName, String columnName, String rowName) {
String delete = "DELETE FROM " + tableName + " WHERE " + columnName + " = '" + rowName + "'";
// Run the insert
try {
statement = connection.createStatement();
statement.executeUpdate(delete);
System.out.println("Delete statement was run on Java's end.");
} catch (SQLException e) {
System.err.println("SQLException: " + e.getMessage() + ":" + e.getSQLState());
JOptionPane.showMessageDialog(null, "Sorry, something went wrong: SQLException: " +
e.getMessage() + ":" + e.getSQLState());
} finally {
SQLWarning w;
try {
for (w = connection.getWarnings(); w != null; w = w.getNextWarning())
System.err.println("WARNING: " + w.getMessage() + ":" + w.getSQLState());
} catch (SQLException e) {
e.printStackTrace();
}
}
}
// Method for getting the number of columns in a table using metadata
public int countColumnsInTable(String sectionType) {
int count = 16;
try {
// System.out.println(sectionType);
statement = connection.createStatement();
rset = statement.executeQuery("SELECT * FROM " + sectionType);
rsMetaData = rset.getMetaData();
count = rsMetaData.getColumnCount();
// System.out.println("Column count is " + count);
} catch (SQLException e) {
e.printStackTrace();
}
return count;
}
// Close the database and release resources
public void closeDatabase() {
try {
connection.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
And here is the beginning of the error list:
java.sql.SQLException: Before start of result set
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1078)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:975)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:920)
at com.mysql.jdbc.ResultSetImpl.checkRowPos(ResultSetImpl.java:855)
at com.mysql.jdbc.ResultSetImpl.getStringInternal(ResultSetImpl.java:5773)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5693)
at YogaDatabaseAccess.listPosesInSection(YogaDatabaseAccess.java:125)
at YogaSectionDesigner$5.actionPerformed(YogaSectionDesigner.java:229)

May be you can check this out:
ResultSet exception - before start of result set
Had the same Problem. Solved it that way.