Vladislav Pyatkov created IGNITE-28690:
------------------------------------------
Summary: SQL node rewrite extension cannot safely transform
expressions with dynamic parameters
Key: IGNITE-28690
URL: https://issues.apache.org/jira/browse/IGNITE-28690
Project: Ignite
Issue Type: Improvement
Reporter: Vladislav Pyatkov
Some Ignite SQL extensions need to transform SQL expressions during the
`SqlNode` rewrite phase (IGNITE-27940).
This works well for purely structural rewrites or expressions that contain only
literals. However, it becomes problematic when the expression contains dynamic
parameters.
For example, an extension may need to transform an expression like:
{code:sql}
some_special_expression <= NVL(?, 100000)
{code}
into a different SQL shape where the parameter has to be moved to another part
of the query tree, or where the expression has to be replaced with a value
computed from the parameter.
Currently this is not safe or not possible:
* Replacing a parameter-dependent expression with a concrete value would be
incorrect because the prepared plan may be reused with different parameter
values.
* Moving an existing dynamic parameter to another place in the query tree may
fail validation/planning, depending on where the parameter is moved.
* The rewrite extension cannot introduce additional bind parameters together
with their runtime values.
--
This message was sent by Atlassian Jira
(v8.20.10#820010)
