[
https://issues.apache.org/jira/browse/CALCITE-4911?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17452968#comment-17452968
]
duan xiong commented on CALCITE-4911:
-------------------------------------
I have tried some unit tests in PostgreSQL:
{code:java}
CREATE TABLE decimalTable(value numeric(7,2));
INSERT INTO decimalTable(value) VALUES (12.34);
INSERT INTO decimalTable(value) VALUES (12.45);
INSERT INTO decimalTable(value) VALUES (12.55);
// test1
select value::decimal(5,1)::decimal(4,2) from decimalTable;
value
12.30
12.50
12.60
// test2
select value::decimal(2,1) from decimalTable;
ERROR: numeric field overflow
DETAIL: A field with precision 2, scale 1 must round to an absolute value less
than 10^1.
SQL state: 22003{code}
Yes, [~zabetak] you are right, This throws an exception or doesn't which is
decided by the true number, not the declared decimal type.
> CAST operation should throw an exception when cast DECIMAL type lose
> significant digits
> ---------------------------------------------------------------------------------------
>
> Key: CALCITE-4911
> URL: https://issues.apache.org/jira/browse/CALCITE-4911
> Project: Calcite
> Issue Type: Bug
> Affects Versions: 1.28.0
> Reporter: duan xiong
> Priority: Major
>
> In Calcite:
> {code:java}
> select avg(comm) as a from "scott".emp{code}
> This SQL physical plan is:
> {noformat}
> EnumerableCalc(expr#0..1=[{inputs}], expr#2=[0], expr#3=[=($t1, $t2)],
> expr#4=[null:DECIMAL(19, 2)], expr#5=[CASE($t3, $t4, $t0)],
> expr#6=[CAST($t5):DECIMAL(7, 2)], expr#7=[/($t6, $t1)],
> expr#8=[CAST($t7):DECIMAL(7, 2)], A=[$t8])
> EnumerableAggregate(group=[{}], agg#0=[$SUM0($6)], agg#1=[COUNT($6)])
> EnumerableTableScan(table=[[scott, EMP]]){noformat}
> As above:
> The Calcite tries to cast DECIMAL(19,2) to DECIMAL(7,2). Actually, this cast
> should throw an exception but not.[digits number from 17 to 5]
> According to SQL Standard's description about <CAST specification>:
> If TD is exact numeric, then
> Case:
> a) If SD is exact numeric or approximate numeric, then
> Case:
> i) If there is a representation of SV in the data type *TD that does not lose
> any leading significant digits* after rounding or truncating if necessary,
> then TV is that representation. The choice of whether to round or truncate is
> implementation-defined.
> ii) Otherwise, {*}an exception condition is raised{*}: data
> exception------numeric value out of range.
--
This message was sent by Atlassian Jira
(v8.20.1#820001)
