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Issues with updating many rows oracle

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You can also set constraints to VALIDATE or NOVALIDATE, in any combination with ENABLE or DISABLE, where: ENABLE ensures that all incoming data conforms to the constraint DISABLE allows incoming data, regardless of whether it conforms to the constraint VALIDATE ensures that existing data conforms to the constraint NOVALIDATE means that some existing data may not conform to the constraint In addition: - ENABLE VALIDATE is the same as ENABLE.The constraint is checked and is guaranteed to hold for all rows.In an ALTER TABLE statement, ENABLE NOVALIDATE resumes constraint checking on disabled constraints without first validating all data in the table. The constraint is not checked and is not necessarily true.DISABLE VALIDATE disables the constraint, drops the index on the constraint, and disallows any modification of the constrained columns.As you know (or may not know) there are two engines running in the Oracle database.The PL/SQL engine for executing all your PL/SQL code and the SQL engine for executing all you SQL statements.I have tried to keep this guide straight-forward and practical.

issues with updating many rows oracle-40

This guide tackles a small set of the problems which I have encountered, but is in no way an extensive guide.

This means that every time your PL/SQL code needs data from the database, or writes to it control is passed from the PL/SQL runtime engine to the SQL. Not too much time individually, which is why you don’t see any slowdown of the program when you run a SQL statement that returns a single row, but when you run SQL statements in a loop then you actually perform a lot of SQL statements, which involves a lot of context switching.

This process involves a lot of work which has to be done by the two engines, like writing the SQL statement in an area the SQL engine can access and having the SQL engine write the result in an area the PL/SQL engine can access. You actually want to reduce these context switches to a single one and bring back the entire resultset in one pass.

A RIGHT OUTER JOIN contains all records in the "right" table even if it has no matches in the "left" table.

A FULL OUTER JOIN contains all records of both the left and right tables.