JDBC Type 4 Driver 1.1 Programmer's Reference

Reserving Data Locators
A data locator is the reference pointer value (SQL LARGEINT data type) that is substituted for
the BLOB or CLOB column in the base table definition. Each object stored into the LOB table is
assigned a unique data locator value. Because the LOB table is a shared resource among all
accessors that use the particular LOB table, reserving data locators reduces contention for
getting the next value. The default setting is 100 reserved data locators; therefore, each JVM
instance can insert 100 large objects (not chunks) before needing a new allocation.
Specify the number of data locators (n) to reserve for your application by using the Type 4
driver property t4sqlmx.reserveDataLocators. For information about specifying this
property, see reserveDataLocators Property.
Storing CLOB Data
Inserting CLOB Columns by Using the Clob Interface
Writing ASCII or MBCS Data to a CLOB Column
Inserting CLOB Data by Using the PreparedStatement Interface
Inserting a Clob Object by Using the setClob Method
Inserting CLOB Columns by Using the Clob Interface
When you insert a row containing a CLOB data type, and before the column can be updated with
real CLOB data, you can insert a row that has an empty CLOB value. To insert an empty CLOB
value in a NonStop SQL/MX database, specify the EMPTY_CLOB() function for the CLOB
column in the insert statement.
Note:
The EMPTY_CLOB() function is an HP NonStop specific function and might
not work on other databases.
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Do not use the EMPTY_CLOB() function when using the
PreparedStatement interface.
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The Type 4 driver scans the SQL string for the EMPTY_CLOB() function and substitutes the
next-available data locator.
Then, obtain the handle to the empty CLOB column by selecting the CLOB column for update.
The following code illustrates how to obtain the handle to an empty CLOB column:
Clob myClob = null;
Statement s = conn.createStatement();
ResultSet rs = s.executeQuery("Select myClobColumn