Implement INSENSITIVE property for PSQL explicit cursors
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Key: CORE-5781
URL: http://tracker.firebirdsql.org/browse/CORE-5781
Project: Firebird Core
Issue Type: New Feature
Components: Engine
Reporter: Vlad Khorsun
The SQL Standard say:
--- begin quote ---
The following paragraphs define several terms used to discuss issues relating
to a cursor's operational sensitivity
property:
A change to SQL-data is said to be independent of a cursor CR if and only if it
is not made by an <update
statement: positioned> or a <delete statement: positioned> that is positioned
on CR.
A change to SQL-data is said to be significant to CR if and only if it is
independent of CR, and, had it been
committed before CR was opened, would have caused the sequence of rows in the
result set descriptor of CR
to be different in any respect.
A change to SQL-data is said to be visible to CR if and only if it has an
effect on the sequence of rows SR of
the result set descriptor of CR by inserting a row in SR, deleting a row from
SR, changing the value of a column
of a row of SR, or reordering the rows of SR.
If a cursor is open, and the SQL-transaction in which the cursor was opened
makes a significant change to
SQL-data, then whether that change is visible through that cursor before it is
closed is determined as follows:
— If the cursor is insensitive, then significant changes are not visible.
— If the cursor is sensitive, then significant changes are visible.
— If the cursor is asensitive, then the visibility of significant changes is
implementation-dependent.
--- end quote ---
This ticket offers to implement INSENSITIVE PSQL explicit cursors.
Current implementation is ASENSITIVE - ability of cursor to see significant
changes is dependent on execution plan.
Implementation of SENSITIVE cursors is out of scope of this ticket.
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