This allows users to scale and service more users than there are connections available. Sessions and transactions can be migrated between connections to the same server. ODBC affects server scalability. Using ODBC and having n number of concurrent users forces the server to have n number of processes service the clients if Oracle8i is operating in dedicated server mode. Your operating system may or may not support so many connections and processes. By Rampradeep Pakalapati at February 01, Newsletter Topics Select minimum 1 topic.
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Vlamis Posted April 5, 0 Comments. Missing keywords are read from the Administrator entry for the data source. Values specified in the connection string override those contained in the Administrator entry.
Sets the token size to the nearest multiple of 1 KB bytes beginning at 4 KB bytes. If the following keyword is specified in the connection string, the Oracle ODBC Driver does not read values defined from the Administrator:. The Oracle server waits indefinitely for lock conflicts between transactions to be resolved. Refer to Reducing Lock Timeout for more information on specifying a value in the oraodbc.
For Windows platforms, when you link your program, you must link it with the import library odbc However, the rowid value must be presented in a parameter marker. Oracle reference cursors Result Sets allow an application to retrieve data using stored procedures and stored functions. The ODBC syntax for calling stored procedures must be used. The following identifies how to call the procedure or function without a package and within a package.
The package name in this case is RSET. For example, assume procedure Example2 is defined to have four parameters. Parameters 1 and 3 are reference cursor parameters and parameters 2 and 4 are character strings. The call is specified as:. Migrated procedures are often reorganized and created in schemas in one of these ways:.
All procedures defined in one SQL Server database are migrated to the schema named with that database name. To support these three ways of organizing migrated procedures, you can specify one of these schema name options for translating procedure names. Object names in the translated Oracle procedure call are not case-sensitive. The symbols for the new attributes are defined in the file sqora. This attribute is necessary for the ODBC application to determine which connection the failure event is taking place on.
Null is returned if the attribute has not been set. The failure events map directly to the events defined in the OCI programming interface.
The list of possible events is:. Use this option when you migrate any third party ODBC application to Oracle Database and you want to use implicit results functionality as supported by the previous vendor. Data loss is possible when the Driver Manager is converting from Unicode to the local code page.
An ODBC application developer need not explicitly call entry points with the suffix. String arguments are converted from Unicode to the local code page. The text of the SQL statement parameter is converted from Unicode to the local code page.
Convert return parameters that are character data from the local code page to Unicode. In this case, the Oracle ODBC Driver uses the knowledge it has about the data type of the column as defined in the database to determine how to best default to fetching the column through OCI. The driver could default to receiving the column as Unicode, however, this may result in as many as two unnecessary conversions.
The default encoding of the Oracle client is used when fetching data. The following example retrieves the employee names and the job titles from the EMP table. This example shows how to update data. This example may be the most complicated case to update and retrieve data for long data, like CLOB , in Oracle. This section describes some general programming tips to improve the performance of an ODBC application.
Enable connection pooling if the application will frequently connect and disconnect from a data source. Reusing pooled connections is extremely efficient compared to reestablishing a connection. Minimize the number of times a statement must be prepared. Where possible, use bind parameters to make a statement reusable for different parameter values. Preparing a statement once and executing it several times is much more efficient than preparing the statement for every SQLExecute.
This topic discusses performance implications of the following ODBC data source configuration options:. This option enables the support of returning result sets for example, RefCursor from procedure calls. The default is enabling the returning of result sets. The ODBC Driver must query the database server to determine the set of parameters for a procedure and their data types to determine if there are any RefCursor parameters.
This query incurs an additional network round trip the first time any procedure is prepared and executed. The application can reopen the cursor by executing the statement again without doing a SQLPrepare again.
A typical scenario for this is an application that is idle for a while but reuses the same SQL statement. While the application is idle, it might free up associated server resources. The cursor and associated resources remain open on the database server. Enabling this option causes the associated cursor to be closed on the database server.
However, this results in the parse context of the SQL statement being lost. Enabling this option severely impacts performance of applications that prepare a statement once and execute it repeatedly. If an application is single-threaded, this option can be disabled. By default, the ODBC Driver ensures that access to all internal structures environment, connection, statement are thread-safe. Did I understand right? DaeYoung: correct.
I'd appreciate your reply and answer. Have a blessed day! Show 1 more comment. Applications but also libraries written in C, which notably enables interaction with OCI from software written in other languages, even interpreted languages such as PHP, Ruby and Python.
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