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A quick tip for optimizing TCP performance on linux.

edit /etc/sysctl.conf add the lines:

If using gigabit ethernet:

net.ipv4.tcp_mem= 98304 131072 196608
net.ipv4.tcp_window_scaling=1
net.core.wmem_default = 65536
net.core.rmem_default = 65536
net.core.wmem_max=8388608

To reload these use:

# sysctl -p

If using infiniband:

net.ipv4.tcp_window_scaling=1
net.ipv4.tcp_timestamps=0
net.ipv4.tcp_sack=0
net.ipv4.tcp_rmem=10000000 10000000 10000000
net.ipv4.tcp_wmem=10000000 10000000 10000000
net.ipv4.tcp_mem=10000000 10000000 10000000
net.core.rmem_max=524287
net.core.wmem_max=524287
net.core.rmem_default=524287
net.core.wmem_default=524287
net.core.optmem_max=524287
net.core.netdev_max_backlog=300000

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In this article Barry Mavin, CEO and Chief Software Architect for Recital provides details on how the Recital Database Server can be used to provide a solution for Universal Data Integration.

Overview

The Recital Database Server handles universal cross-platform data access to a wide range of data sources. The database server natively handles full remote SQL data access to Recital, Visual FoxPro, FoxPro, FoxBASE, Clipper and older dBase data. Using Bridges, it handles full remote SQL data access to C-ISAM and OpenVMS RMS. Using gateway connections, it handles full remote SQL data access to Oracle, MySQL, PostgreSQL, SQL Server, server-side ODBC, server-side JDBC and server-side OLE DB data sources. With its ability to access data using server-side ODBC, JDBC and OLE DB drivers from clients on all supported operating systems (Windows, Linux, Unix, OpenVMS), the Recital Database Server is an ideal Data Integration Solution for applications of all sizes and complexity.

Universal Data Integration Solutions

There are several ways in which data may be accessed by the Database Server.

Table 1:

Client Universal Data Access solutions for accessing local or remote data.


Client Solution
Recital Use remote gateway connections
Visual FoxPro Use the Universal ODBC Driver
Java (all platforms) Use the Universal JDBC Driver
.NET Framework Use the Universal .NET Data Provider
Microsoft Office Use the Universal ODBC Driver
Windows Mobile Use the Universal Compact Framework .NET Data Provider
PHP on Linux Use the Universal ODBC Driver for Linux
Mono on Linux Use the Universal .NET Data Provider
Others If the data source you want to access is not in the list above, then you can use a remote ODBC, JDBC or OLE DB gateway.
You can find examples of connection strings for most ODBC and OLE DB data sources by clicking here.

Table 2:

Windows Server Universal Data Access solutions accessible from any remote client running on Windows, Linux, Unix or OpenVMS:


Data Source Solution
Recital Native support (See table 1)
Visual FoxPro Native support (See table 1)
FoxPro Native support (See table 1)
FoxBASE Native support (See table 1)
Clipper Native support (See table 1)
dBase Native support (See table 1)
C-ISAM Use a bridge (See table 1)
Access Use a gateway connection
gateway="oledb:Provider=Microsoft.Jet.OLEDB.4.0;Data Source=\somepath\mydb.mdb;User Id=admin;Password=;"
Exchange Use a gateway connection
gateway="oledb:Provider=ExOLEDB.DataSource;Data Source=http://servername/publicstore"
Excel Use a gateway connection
gateway="oledb:Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\MyExcel.xls;"
Oracle Use a gateway connection
gateway="oledb:Provider=msdaora;Data Source=TheOracleDB;User Id=xxxxx;Password=xxxxx;"
SQL Server Use a gateway connection
gateway="oledb:Provider=sqloledb;Data Source=Aron1;Initial Catalog=pubs;User Id=sa;Password=asdasd;"
MySQL Use a gateway connection
gateway="oledb:Provider=MySQLProv;Data Source=mydb;User Id=xxxxx;Password=xxxxx;"
IBM DB2 Use a gateway connection
gateway="oledb:Provider=DB2OLEDB;Network Transport Library=TCPIP;Network Address=XXX.XXX.XXX.XXX;Initial Catalog=MyCtlg;Package Collection=MyPkgCol;Default Schema=Schema;User ID=MyUser;Password=MyPW"
Sybase ASA Use a gateway connection
gateway="oledb:Provider=ASAProv;Data source=myASA"
Sybase ASE Use a gateway connection
gateway="oledb:Provider=Sybase.ASEOLEDBProvider;Srvr=myASEserver,5000;Catalog=myDBname;User Id=username;Password=password"
IBM Informix Use a gateway connection
gateway="oledb:Provider=Ifxoledbc.2;password=myPw;User ID=myUser;Data Source=dbName@serverName;Persist Security Info=true"
Ingres Use a gateway connection
gateway="odbc:dsn=data_source_name"
Firebird Use a gateway connection
gateway="odbc:dsn=data_source_name"
IBM AS400 iSeries Use a gateway connection
gateway="oledb:PROVIDER=IBMDA400; DATA SOURCE=MY_SYSTEM_NAME;USER ID=myUserName;PASSWORD=myPwd"
Interbase Use a gateway connection
gateway="oledb:provider=sibprovider;location=localhost:;data source=c:\databases\gdbs\mygdb.gdb;user id=xxxxx;password=xxxxx"
Others

If the data source you want to access is not in the list above, then you can use server-side ODBC, JDBC or OLE DB.
You can find examples of connection strings for most ODBC and OLE DB data sources by clicking here.
Full details on using server-side JDBC drivers can be found here.
Full details on using server-side ODBC drivers can be found here.
Full details on using server-side OLE DB drivers can be found here.


Table 3:

Linux and Unix Server Universal Data Access solutions accessible from any remote client running on Windows, Linux, Unix or OpenVMS:


Data Source Solution
Recital Native support (See table 1)
Visual FoxPro Native support (See table 1)
FoxPro Native support (See table 1)
FoxBASE Native support (See table 1)
Clipper Native support (See table 1)
dBase Native support (See table 1)
C-ISAM Use a bridge (See table 1)
Oracle Use a gateway connection
gateway="oracle:Connection_String"
MySQL Use a gateway connection
gateway="mysql:Connection_String"
IBM DB2 Use a gateway connection
gateway="db2:Connection_String"
PostgreSQL Use a gateway connection
gateway="postgres:Connection_String"
Others

If the data source you want to access is not in the list above, then you can use a server-side JDBC driver.
Full details on using server-side JDBC drivers can be found here.


Table 4:

OpenVMS Server Universal Data Access solutions accessible from any remote client running on Windows, Linux, Unix or OpenVMS:


Data Source Solution
Recital Native support (See table 1)
Visual FoxPro Native support (See table 1)
FoxPro Native support (See table 1)
FoxBASE Native support (See table 1)
Clipper Native support (See table 1)
dBase Native support (See table 1)
RMS Use a bridge (See table 1)
Others

If the data source you want to access is not in the list above, then you can use a server-side JDBC driver.

Supported Data Sources

Native Data Access

The Recital Database Server has native built-in support for the following data sources:

  • Recital
  • Visual FoxPro
  • FoxPro
  • FoxBASE
  • Clipper
  • dBase

You can setup tables to work with using the Database Administration Tool in Recital Enterprise Studio.

Bridges

Using Bridges, you can access the following data sources as if they were standard Recital/FoxPro tables:

  • CISAM
  • OpenVMS RMS

You can setup bridges using the Database Administration Tool in Recital Enterprise Studio.

Gateways/Connections

Using Gateways, you can transparently access the following local or remote data sources:

  • Recital
  • Oracle
  • ODBC (Server-side ODBC data sources)
  • JDBC (Server-side JDBC data sources)
  • OLEDB Use this to connect to SQL Server and other Windows OLE DB data sources)
  • MySQL
  • PostgreSQL

Remote Data Object functions

Recital 10 includes a complete and robust set of data source independent functions for accession MySQL, Oracle, DB2 and Postgres. This article explains how to use them.

Client Data Access drivers

Included with the Recital Database Server are three Client drivers. These Client drivers can access any data sources supported by the Recital Database Server. They are not restricted to accessing only Recital data. They can be used to access server-side ODBC, JDBC and OLE DB data sources also.

Recital Universal .NET Data Provider

Use this client driver when building .NET applications with Visual Studio .NET. A data provider in the .NET Framework serves as a bridge between an application and a data source. A data provider is used to retrieve data from a data source and to reconcile changes to that data back to the data source.

Key features of the Recital Universal .NET Data Provider:

  • Fully Internet enabled
    The Recital Universal .NET Data Provider works across the internet providing access to a wide range of data sources located on remote servers running Windows, Linux, Unix and OpenVMS.
  • SQL Server compatible
    The Recital Universal .NET Data Provider is plug compatible with the .NET Framework SQL Server Data Provider.
  • Cross-platform Data Integration
    Using the Recital Universal .NET Data Provider, you can connect to remote Windows, Linux, Unix or OpenVMS servers and access any data source supported by the Recital Database Server.
  • Managed code
    The Recital Universal .NET Data Adaptor written in C# is 100% .NET Framework managed code.
  • Runs on Windows Mobile
    The Recital Universal .NET Data Adaptor runs under the .NET Compact Framework on Windows Mobile.
Recital Universal JDBC Driver

The JDBC API is the industry standard for database-independent connectivity between the Java programming language and a wide range of databases. The JDBC API provides a call-level API for SQL-based database access. JDBC technology allows you to use the Java programming language to exploit "Write Once, Run Anywhere" capabilities for applications that require access to enterprise data.

Key features of the Recital Universal JDBC Driver:

  • Fully Internet enabled
    The Recital Universal JDBC driver works across the internet providing access to a wide range of data sources located on remote servers running Windows, Linux, Unix and OpenVMS.
  • JDBC 3.0 API
    The Recital Universal JDBC driver supports the JDBC 3.0 API.
  • Pure Java Type 3 Driver
    The Recital Universal JDBC driver is a 100% pure Java Type 3 driver.
  • Full Access to Metadata
    The JDBC API provides metadata access that enables the development of sophisticated applications that need to understand the underlying facilities and capabilities of a specific database connection.
  • Cross-platform Data Integration
    Using the Recital Universal JDBC driver, you can connect to remote Windows, Linux, Unix or OpenVMS servers and access any data source supported by the Recital Database Server.
  • No Installation
    A pure JDBC technology-based driver does not require special installation; it is automatically downloaded as part of the applet that makes the JDBC calls. The Recital Universal JDBC Driver is 100% java.
Recital Universal ODBC Driver

Connect to remote data from Microsoft Office or other applications that support ODBC data access. The Recital Universal ODBC Driver is also available for Linux and Unix.

Key features of the Recital Universal ODBC Driver:

  • Fully Internet enabled
    The Recital Universal ODBC driver works across the internet providing access to a wide range of data sources located on remote servers running Windows, Linux, Unix and OpenVMS.
  • Works with Crystal Reports
    The Recital Universal ODBC driver supports the SQL syntax generated by Crystal Reports.
  • Works with Microsoft Office
    The Recital Universal ODBC driver works with Microsoft Office products.
  • Works with PHP on Linux
    The Recital Universal ODBC driver is available for Linux and works with PHP.
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In an interesting article at Linux Magazine, Sam Ockman discusses the origin of the term "Open Source". Check it out here.
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Recital 10 introduced the ECHO command. This command operates in the same way as the PHP ECHO command. It does not append a newline to the output but rather operates in the same way as the existing ?? command in Recital. The string being output can contain C-style string escapes \n \t or \r (newline, tab and carriage return respectively) e.g.
echo "Hello world\n"
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Recital 10 enhances the APPEND FROM command. The enhancement was added to the following syntax ;
APPEND FROM  <table-name> 
Before when appending into a shared Recital table each new row was locked along with the table header, then unlocked after it was inserted. This operation has now been enhanced to lock the table once, complete inserting all the rows from the table and then unlock the table. The performance of this operation has been increased by using this method. All the database and table constraints are still enforced.
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This website runs in a  virtual machine under vmware server. It is clustered between two servers using heartbeat and DRBD.
 
When VMware server starts up a virtual machine it generates a uuid (unique id) based on the machine it is running on and stores this in the .vmx file.
 
When heartbeat switches from slave to master, it will start VMware server (which is setup as a resource in the haresources file).
 
Virtual machines that you want started automatically when you start VMware server will not start because the uuid changes between the master and backup systems. To get around this problem always do the following:
  • edit the .vmx file and add the following line

    uuid.action = "keep"
If this is not done then everytime you try to run the virtual machine on the backup system in your cluster, VMware server will complain that the virtual machine has been copied or moved and it will not start it.
  • set the virtual machine to power off when vmware is stopped. Do not set this to "suspend" or it will not restart on the backup machine.
This will allow the virtual machine to start properly on the backup machine.
 
 
 
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Occasionally subversion can get itself confused about what is and what is not in a working copy. This usually occurs if you have replaced the contents of a directory such as when you upgrade a component in Joomla!

You receive a message such containing this:

"working copy admin area is missing"

How to resolve this: 

Step 1 -- Rename the directory that is causing the error from a shell prompt and prefix it with __ 

mv com_docman __com_docman

Step 2 -- Using your subversion client refresh your working copy, then "update" the directory that is causing the problem e.g. update com_docman.

Step 3 -- Now you can commit the __com_docman directory.

After you have done this follow these steps, using your subversion client:

Step 4 -- delete the com_docman directory from your working copy
Step 5 -- rename __com_docman back to com_docman

Now "commit all" and both your working copy and repository will be in sync.
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If you are running your Redhat/Centos or Fedora machine in an enterprise environment you may be sitting behind a network proxy server like squid.

If you try and update or install software it will fail with timeouts or errors contacting the repository mirrors.

To configure YUM to work with your proxy server you need to add the following line to your /etc/yum.conf file.

Anonymous proxy configuration:
proxy=http://yourproxyip:port/

If your proxy server requires authentication add the following lines to your /etc/yum.conf file instead.

proxy=http://yourproxyip:port/
proxy_username=youruser
proxy_password=yourpassword

 You will be able to update and install software now, give it a go!

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The PHP ODBC functions can be used to access Recital data via the Recital Universal ODBC Driver.

The following example connects to a Recital ODBC datasource, executes a query then outputs all the results from the resultset.

<?php
$sql = "select country from customers limit 10";
$conn = odbc_connect('Recital ODBC test', '?', '?');
$rs = odbc_exec($conn, $sql);
odbc_result_all($rs);
odbc_close($conn);
?>

Output:

<table><tr><th>Country</th></tr>
<tr><td>Germany        </td></tr>
<tr><td>Mexico         </td></tr>
<tr><td>Mexico         </td></tr>
<tr><td>UK             </td></tr>
<tr><td>Sweden         </td></tr>
<tr><td>Germany        </td></tr>
<tr><td>France         </td></tr>
<tr><td>Spain          </td></tr>
<tr><td>France         </td></tr>
<tr><td>Canada         </td></tr>
</table>

For information on installing and configuring the Recital Universal ODBC Driver and creating and modifying datasources, please see the Documentation section of this web site.

Note: Use of ? for the username and password on the local server is dependent on DB_LOCAL_LOGIN being enabled.



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