SODA Guidelines

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Guidelines that apply across SODA implementations are described.

• AL32UTF8 database character set — Oracle recommends¹ that you use AL32UTF8 (Unicode) for your database character set. Otherwise:

  • Data can be altered by SODA when documents are written to a collection, because of lossy conversion to the database character set. (This affects only collections stored as VARCHAR2 and CLOB data; collections stored as BLOB data do not depend on the database character set.

  • Query-by-example (QBE) can return unpredictable results.

• Re-creating a collection² — Do notdrop a collection and then re-create it with different metadataif there is any application running that uses the collection in any way. Shut down any such applications before re-creating the collection, so that all live SODA objects are released.

  There is no problem just dropping a collection. Any read or write operation on a dropped collection raises an error. And there is no problem dropping a collection and then re-creating it with the same metadata. But if you re-create a collection with different metadata, and if there are any live applications using SODA objects, then there is a risk that a stale collection is accessed, and no error is raised in this case.

  Note: In SODA implementations that allow collection metadata caching, such as SODA for Java, this risk is increased if such caching is enabled. In that case, a cache can return an entry for a stale collection object even if the collection has been dropped.

See Also:

• Key Column Type for information about the importance of using AL32UTF8 with client-assigned document keys

• Oracle Database SODA for Java Developer's Guide for information about collection metadata caching

1. SODA for C requires that you use AL32UTF8 as the database character set. ↩

2. Day-to-day use of a typical application that makes use of SODA does not require that you drop and re-create collections. But if you need to do that for any reason then this guideline applies. ↩