Compilation errors and warning are fixed.
The design of create_immv is also chaned as similar to PG17, that is,
firstly a relation is created without data then it is populated
by using the refresh logic.
This commit contains the following changes:
- Change functions to use a safe search_path during maintenance operations
when used with PostgreSQL 17
This prevents maintenance operations (automatic maintenance of IMMVs and
refresh_immv) from performing unsafe access. Functions used by IMMVs that
need to reference non-default schemas must specify a search path during
function creation.
- refresh_immv can be executed by users with the MAINTAIN privilege
when used with PostgreSQL 17
Issue #90
Build errors/warnings against PostgreSQL 16 are fixed.
Also, adapted to the change of codes, including:
- Get rid of the "new" and "old" entries in a view's rangetable.
(Although, removed codes were dead codes because pg_ivm doesn't
have any rules in pg_rewrite.)
- Rework query relation permission checking
- Require empty Bitmapsets to be represented as NULL
- Fix some compiler warnings
Currently, types that does not have an equality operator cannot
be used in the target list of the view definition, because all
of target list entries are used for comparison to identify rows
to be updated or deleted in the view. Previously, an error is
raised at the time such view is incrementally maintained, this
is fixed to check that at the view creation time.
This restriction may be relaxed in future after we can use an
index to identify rows in the view.
Issue #61
Add EXISTS clause support in IVM
Correlated subqueries using EXISTS in WHERE clause are supported.
An EXISTS subquery in WHERE clause is rewritten to LATERAL subquery
in FROM clause, and IVM' process can handle this like as a normal join.
Also, hidden columns "ivm_exists_count_X__" are added to check if
EXISTS condition is satisfied. This column stores the count of how many
rows in the subquery are correlated to (joined to) each row of the main
query. When a base table contained in EXISTS clause is modified, this
count value in IMMV is updated, and a row whose count becomes zero
is deleted.
restrictions :
- EXISTS subqueries are allowed only in WHERE clause.
- aggregate functions are not supported together with EXISTS.
- EXISTS subqueries in a subquery are not supported.
- EXISTS condition can use only with AND Expr
Simple CTEs which does not contain aggregates or DISTINCT are
now supported similarly to simple sub-queries.
Before a view is maintained, all CTEs are converted to corresponding
subqueries to enable to treat CTEs as same as subqueries. For this
end, codes of the static function inline_cte in the core
(optimizer/plan/subselect.c) was imported.
Prohibit Unreferenced CTE is prohibited.
When a table in a unreferenced CTE is TRUNCATEd, the contents
of the IMMV is not affected so it must not be truncated. For
confirming it at the maintenance time, we have to check if the
modified table used in a CTE is actually referenced. Although
it would possible, we just disallow to create such IMMVs for now
since such unreferenced CTE is useless unless it doesn't contain
modifying commands, that is already prohibited.
When using DELETE or UPDATE, we must use exclusive lock for now
because apply_old_delta(_with_count) could result in wrong results
with concurrent transactions. We would like to improve it in future,
but we prevent it by using the lock for now.
- Allow to use qualified name
- Confirm if executed by the owner of the IMMV
- Improve the message when specified relation is not an IMMV
- Create a unique index at refresh with no dat if possible
This is actually required, but we want it behave as same
as the pgsql-ivm version for now.
