Home
SQL programmingYou can use the HCL OneDB™ implementation of the SQL language to develop applications for HCL OneDB™ database servers.
Guide to SQL: SyntaxThe HCL OneDB™ Guide to SQL: Syntax describes the syntax of the statements, data types, expressions, operators, and built-in functions of the HCL OneDB™ dialect of the SQL language.
SQL statementsThis chapter describes the syntax and semantics of SQL statements that are recognized by HCL OneDB™.
ALTER FRAGMENT statementUse the ALTER FRAGMENT statement to change the distribution strategy or the storage location of an existing table or index. This statement is an extension to the ANSI/ISO standard for the SQL language.
INIT ClauseThe INIT clause of the ALTER FRAGMENT statement can define or modify the fragmentation strategy or the storage location of an existing table or an existing index.
WITH ROWIDS OptionNonfragmented tables contain a hidden column called rowid. Its integer value defines the physical location of a row. To include a rowid column in a fragmented table, you must explicitly request it by using the WITH ROWIDS clause in CREATE TABLE (or ADD ROWIDS in ALTER TABLE, or WITH ROWIDS in ALTER FRAGMENT INIT).

WITH ROWIDS Option

Nonfragmented tables contain a hidden column called rowid. Its integer value defines the physical location of a row. To include a rowid column in a fragmented table, you must explicitly request it by using the WITH ROWIDS clause in CREATE TABLE (or ADD ROWIDS in ALTER TABLE, or WITH ROWIDS in ALTER FRAGMENT INIT).

The rowid in a row of a fragmented table does not identify a physical location for the row in the same way that a rowid in a non-fragmented table does.

When you use the WITH ROWIDS option to add a new rowid column to a fragmented table, the database server assigns a unique rowid number to each row and creates an index that it can use to find the physical location of the row. Performance using this access method is comparable to using a SERIAL, BIGSERIAL, or SERIAL8 column. The rowid value of a row cannot be updated, but remains stable during the existence of the row. Each row requires an additional four bytes to store the rowid column after you specify the WITH ROWIDS option.

Recommendation: When creating new applications, use primary keys as a method of row identification instead of using rowid values.