Comments on: Using “use index” With Hibernate/MySQL http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/ Tidbits and blogs from Nicholas Hagen related to software, web design, and usability Wed, 01 Feb 2012 14:31:09 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Marc http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/comment-page-1/#comment-146 Marc Tue, 04 Jan 2011 01:05:36 +0000 http://www.znetdevelopment.com/blogs/?p=235#comment-146 Right, forget that. This is better. Hibernate does some funny things in some cases, therefore, you have to put quotes around your index name. <code> public String onPrepareStatement(String sql) { int loopCount = 0; String[] s = sql.split("\\*/"); sql = (s.length > 1)? s[1].trim() : s[0].trim(); while (true) { // check if function specified int idx = sql.indexOf("useindex("); if (idx 5) { break; } // find end of function int endidx = sql.indexOf(")=1", idx); if (endidx < idx) { throwError("expected useindex(table, index) is true"); } // get both parameters String[] params = sql.substring(idx + 9, endidx).split(","); if (params.length != 2) { throwError("expected 2 parameters to useindex(table, index)"); } // trim parameters and verify String tableId = params[0].trim(); String indexHint = params[1].trim(); if (tableId.length() == 0 || indexHint.length() == 0) { throwError("invalid parameters to useindex(table, index)"); } // find actual table name minus id int dotIdx = tableId.indexOf('.'); // if (dotIdx -1) ? tableId.substring(0,dotIdx) : tableId; int tableIdx = sql.indexOf(" " + tableName + " "); if (tableIdx < 0) { throwError("unknown table name in useindex(table, index)"); } Pattern pattern = Pattern.compile("( [^ ]+ )" + tableName + " "); Matcher m = pattern.matcher(sql); m.find(); String entity = m.group(1); String[] sqlParts = sql.split(entity); String newSql = sqlParts[0]; for (int x = 0; x < sqlParts.length - 1; x++) { // Look ahead to the name of the table int nxtSpace = sqlParts[x + 1].indexOf(" "); String localTable = sqlParts[x + 1].substring(0, nxtSpace); newSql += entity + localTable; newSql += " use index(" + indexHint.replaceAll("'","") + ")"; for(int a = x + 1;a < sqlParts.length;a++){ //remove all useindex for this table sqlParts[a] = sqlParts[a].replaceAll("useindex\\(" + localTable + "[^=]+=1 [^ ]+ ", ""); } newSql += sqlParts[x + 1].substring(nxtSpace); } sql = newSql; if(sql.indexOf("useindex") == -1) break; loopCount++; } return sql; } protected void throwError(String message) { throw new IllegalStateException(message); } </code> Right, forget that. This is better. Hibernate does some funny things in some cases, therefore, you have to put quotes around your index name.


public String onPrepareStatement(String sql) {
int loopCount = 0;
String[] s = sql.split("\\*/");
sql = (s.length > 1)? s[1].trim() : s[0].trim();

while (true) {
// check if function specified
int idx = sql.indexOf("useindex(");
if (idx 5) {
break;
}

// find end of function
int endidx = sql.indexOf(")=1", idx);
if (endidx < idx) {
throwError("expected useindex(table, index) is true");
}

// get both parameters
String[] params = sql.substring(idx + 9, endidx).split(",");
if (params.length != 2) {
throwError("expected 2 parameters to useindex(table, index)");
}

// trim parameters and verify
String tableId = params[0].trim();
String indexHint = params[1].trim();
if (tableId.length() == 0 || indexHint.length() == 0) {
throwError("invalid parameters to useindex(table, index)");
}

// find actual table name minus id
int dotIdx = tableId.indexOf('.');
// if (dotIdx -1) ? tableId.substring(0,dotIdx) : tableId;
int tableIdx = sql.indexOf(" " + tableName + " ");
if (tableIdx < 0) {
throwError("unknown table name in useindex(table, index)");
}

Pattern pattern = Pattern.compile("( [^ ]+ )" + tableName + " ");
Matcher m = pattern.matcher(sql);
m.find();
String entity = m.group(1);
String[] sqlParts = sql.split(entity);

String newSql = sqlParts[0];
for (int x = 0; x < sqlParts.length - 1; x++) {
// Look ahead to the name of the table
int nxtSpace = sqlParts[x + 1].indexOf(" ");
String localTable = sqlParts[x + 1].substring(0, nxtSpace);
newSql += entity + localTable;
newSql += " use index(" + indexHint.replaceAll("'","") + ")";
for(int a = x + 1;a < sqlParts.length;a++){
//remove all useindex for this table
sqlParts[a] = sqlParts[a].replaceAll("useindex\\(" + localTable + "[^=]+=1 [^ ]+ ", "");
}
newSql += sqlParts[x + 1].substring(nxtSpace);
}
sql = newSql;
if(sql.indexOf("useindex") == -1)
break;
loopCount++;
}

return sql;
}

protected void throwError(String message) {
throw new IllegalStateException(message);
}

]]> By: Marc http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/comment-page-1/#comment-144 Marc Mon, 03 Jan 2011 17:32:09 +0000 http://www.znetdevelopment.com/blogs/?p=235#comment-144 Ok, that basically didn't work for me. My code generates some cross joins that consequently don't get parsed. I decided to use a more brute force approach. Because I made this change I was also able to eliminate the cross joins so I ended up not being able to test that but check this out: [code] public String onPrepareStatement(String sql) { String newSql = ""; // check if function specified int idx = sql.indexOf("useindex(", 0); if (idx < 0) { return sql; } // find end of function int endidx = sql.indexOf(")", idx); if (endidx < idx) { throwError("expected useindex(table, index) is true"); } // get both parameters String[] params = sql.substring(idx + 9, endidx).split(","); if (params.length != 2) { throwError("expected 2 parameters to useindex(table, index)"); } // trim parameters and verify String tableId = params[0].trim(); String indexHint = params[1].trim(); if (tableId.length() == 0 || indexHint.length() == 0) { throwError("invalid parameters to useindex(table, index)"); } // find actual table name minus id int dotIdx = tableId.indexOf('.'); // if (dotIdx -1) ? tableId.substring(0, dotIdx) : tableId; Pattern pattern = Pattern.compile(" " + tableName + " ", Pattern.CASE_INSENSITIVE); String[] sqlParts = pattern.split(sql); newSql += sqlParts[0]; for (int x = 0; x < sqlParts.length - 1; x++) { // Look ahead to the name of the table int nxtSpace = sqlParts[x + 1].indexOf(" "); String localTable = sqlParts[x + 1].substring(0, nxtSpace); newSql += " " + tableName + " " + localTable; newSql += " use index(" + indexHint + ")"; newSql += sqlParts[x + 1].substring(nxtSpace).replaceAll( "useindex[^1]+1 [^ ]+ ", ""); } return newSql; } [/code] Ok, that basically didn’t work for me. My code generates some cross joins that consequently don’t get parsed. I decided to use a more brute force approach. Because I made this change I was also able to eliminate the cross joins so I ended up not being able to test that but check this out:
[code]
public String onPrepareStatement(String sql) {
String newSql = "";

// check if function specified
int idx = sql.indexOf("useindex(", 0);
if (idx < 0) {
return sql;
}

// find end of function
int endidx = sql.indexOf(")", idx);
if (endidx < idx) {
throwError("expected useindex(table, index) is true");
}

// get both parameters
String[] params = sql.substring(idx + 9, endidx).split(",");
if (params.length != 2) {
throwError("expected 2 parameters to useindex(table, index)");
}

// trim parameters and verify
String tableId = params[0].trim();
String indexHint = params[1].trim();
if (tableId.length() == 0 || indexHint.length() == 0) {
throwError("invalid parameters to useindex(table, index)");
}

// find actual table name minus id
int dotIdx = tableId.indexOf('.');
// if (dotIdx -1) ? tableId.substring(0,
dotIdx) : tableId;
Pattern pattern = Pattern.compile(" " + tableName + " ",
Pattern.CASE_INSENSITIVE);
String[] sqlParts = pattern.split(sql);

newSql += sqlParts[0];
for (int x = 0; x < sqlParts.length - 1; x++) {
// Look ahead to the name of the table
int nxtSpace = sqlParts[x + 1].indexOf(" ");
String localTable = sqlParts[x + 1].substring(0, nxtSpace);
newSql += " " + tableName + " " + localTable;
newSql += " use index(" + indexHint + ")";
newSql += sqlParts[x + 1].substring(nxtSpace).replaceAll(
"useindex[^1]+1 [^ ]+ ", "");
}

return newSql;

}
[/code]

]]> By: Flavian http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/comment-page-1/#comment-101 Flavian Wed, 12 May 2010 10:30:43 +0000 http://www.znetdevelopment.com/blogs/?p=235#comment-101 Hi,, Im using Core Hibernate 3... I tried using your stuff.. Created package com.citizen.hibernate.dialect Added Class : MySQL5InnoDBDialect Created package com.citizen.hibernate.interceptor Added Class : IndexInterceptor In my hibernate.cfg i updated the line from : org.hibernate.dialect.MySQL5InnoDBDialect To : com.citizen.hibernate.dialect.MySQL5InnoDBDialect Im stuck in registering IndexInterceptor How do i do that Please help... im in despo need of forcing index... Hi,,

Im using Core Hibernate 3…

I tried using your stuff..

Created package com.citizen.hibernate.dialect
Added Class : MySQL5InnoDBDialect

Created package com.citizen.hibernate.interceptor
Added Class : IndexInterceptor

In my hibernate.cfg i updated the line
from : org.hibernate.dialect.MySQL5InnoDBDialect
To : com.citizen.hibernate.dialect.MySQL5InnoDBDialect

Im stuck in registering IndexInterceptor

How do i do that

Please help… im in despo need of forcing index…

]]> By: nix http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/comment-page-1/#comment-87 nix Wed, 03 Mar 2010 15:35:01 +0000 http://www.znetdevelopment.com/blogs/?p=235#comment-87 the setting for enabling comments in persistence.xml: property name="hibernate.use_sql_comments" value="true" the setting for enabling comments in persistence.xml:

property name=”hibernate.use_sql_comments” value=”true”

]]> By: nix http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/comment-page-1/#comment-86 nix Wed, 03 Mar 2010 15:14:40 +0000 http://www.znetdevelopment.com/blogs/?p=235#comment-86 Thanks a lot. Works great! Instead of creating an own hibernate dialect, you could use the jpa function query.setHint("org.hibernate.comment","xyz"). Then you can parse the generated comment (e.g. "/* xyz */ select ... ") in your interceptor class. Attention: if have to enable the comment-function in persistence.xml ( ). Thanks a lot. Works great!

Instead of creating an own hibernate dialect, you could use the jpa function query.setHint(“org.hibernate.comment”,”xyz”).
Then you can parse the generated comment (e.g. “/* xyz */ select … “) in your interceptor class.

Attention: if have to enable the comment-function in persistence.xml ( ).

]]> By: bravocharlie http://www.znetdevelopment.com/blogs/2009/10/07/using-use-index-with-hibernatemysql/comment-page-1/#comment-80 bravocharlie Sat, 02 Jan 2010 10:00:15 +0000 http://www.znetdevelopment.com/blogs/?p=235#comment-80 Nicely done, works like a charm! Nicely done, works like a charm!

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