Kent Yao created SPARK-30203:
--------------------------------
Summary: store assignable if there exists an appropriate
user-defined cast function
Key: SPARK-30203
URL: https://issues.apache.org/jira/browse/SPARK-30203
Project: Spark
Issue Type: Sub-task
Components: SQL
Affects Versions: 3.0.0
Reporter: Kent Yao
h3. 9.2 Store assignment
h4. Syntax Rules
1) Let T be the TARGET and let V be the VALUE in an application of the Syntax
Rules of this Subclause.
2) Let TD and SD be the declared types of T and V, respectively.
3) If TD is character string, binary string, numeric, boolean, datetime,
interval, or a user-defined type, then
either SD shall be assignable to TD or there shall exist an appropriate
user-defined cast function UDCF
from SD to TD.
_NOTE 319 — “Appropriate user-defined cast function” is defined in Subclause
4.11, “Data conversions”_
h3. 4.11 Data conversions
Implicit type conversion can occur in expressions, fetch operations, single row
select operations, inserts, deletes,
and updates. Explicit type conversions can be specified by the use of the CAST
operator.
The current implementation for ANSI store assignment is totally out of context.
According to this rule, `there shall exist an appropriate user-defined cast
function UDCF`, the spark legacy store assignment is just fine because we do
have *a_ppropriate cast_* _*functions.*_
At least according to the ansi cast rule, the current ANSI assignment policy is
too strict to the ANSI cast rules
{code:java}
* (SD) --------------------- (TD) -------------------------
* | EN AN C D T TS YM DT BO UDT B RT CT RW
* EN | Y Y Y N N N M M N M N M N N
* AN | Y Y Y N N N N N N M N M N N
* C | Y Y Y Y Y Y Y Y Y M N M N N
* D | N N Y Y N Y N N N M N M N N
* T | N N Y N Y Y N N N M N M N N
* TS | N N Y Y Y Y N N N M N M N N
* YM | M N Y N N N Y N N M N M N N
* DT | M N Y N N N N Y N M N M N N
* BO | N N Y N N N N N Y M N M N N
* UDT | M M M M M M M M M M M M M N
* B | N N N N N N N N N M Y M N N
* RT | M M M M M M M M M M M M N N
* CT | N N N N N N N N N M N N M N
* RW | N N N N N N N N N N N N N M
*
* Where:
* EN = Exact Numeric
* AN = Approximate Numeric
* C = Character (Fixed- or Variable-Length, or Character Large Object)
* D = Date
* T = Time
* TS = Timestamp
* YM = Year-Month Interval
* DT = Day-Time Interval
* BO = Boolean
* UDT = User-Defined Type
* B = Binary (Fixed- or Variable-Length or Binary Large Object)
* RT = Reference type
* CT = Collection type
* RW = Row type
{code}
_cc [~cloud_fan] [~gengliang]_ [~maropu]
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscr...@spark.apache.org
For additional commands, e-mail: issues-h...@spark.apache.org
