cloud-fan commented on code in PR #58080:
URL: https://github.com/apache/spark/pull/58080#discussion_r3819861773
##########
sql/catalyst/src/main/java/org/apache/spark/sql/catalyst/util/CharVarcharCodegenUtils.java:
##########
@@ -54,6 +54,24 @@ public static UTF8String
varcharTypeWriteSideCheck(UTF8String inputStr, int limi
}
}
+ /**
+ * Applies the SQL explicit-cast rules for a character string source and
CHAR target.
+ *
+ * Unlike store assignment, an explicit character-to-character cast
truncates non-space
+ * characters instead of raising a right-truncation exception.
+ */
+ public static UTF8String charTypeCast(UTF8String inputStr, int limit) {
+ UTF8String truncated = varcharTypeCast(inputStr, limit);
+ return truncated.numChars() < limit ? truncated.rpad(limit, SPACE) :
truncated;
Review Comment:
**Non-blocking:**
Compute `inputStr.numChars()` once and branch directly to pad, return, or
truncate. The current path scans over-limit strings once in `varcharTypeCast`
and again here.
##########
sql/core/src/test/resources/sql-tests/inputs/charvarchar-standard-semantics.sql:
##########
@@ -66,22 +79,108 @@ SELECT typeof(reverse(array(1, 2)));
SELECT typeof(str_to_map(cast('a:1,b:2' AS CHAR(7))));
SELECT typeof(c0) FROM (SELECT json_tuple(cast('{"a":"1"}' AS CHAR(9)), 'a')
AS c0);
--- R2 with collation. A declared collation survives the CAST and an LCT over
equally constrained
--- operands. The mixed-length case (CHAR(2) with CHAR(4), same collation) is
deliberately not
--- covered here: CollationTypeCoercion reads the differing lengths as a
collation mismatch and
--- yields an indeterminate collation. That predates this change (it reproduces
under
--- spark.sql.preserveCharVarcharTypeInfo) and is tracked separately, so
goldening it would
--- normalize the bug.
+-- Collation survives CAST and LCT. Mixed lengths with the same collation
widen to max(n, m);
+-- they must not collapse to an indeterminate collation.
SELECT typeof(cast('a' AS CHAR(2) COLLATE UTF8_LCASE));
SELECT typeof(coalesce(
cast('a' AS CHAR(2) COLLATE UTF8_LCASE), cast('bb' AS CHAR(2) COLLATE
UTF8_LCASE)));
+SELECT typeof(coalesce(
+ cast('a' AS CHAR(2) COLLATE UTF8_LCASE), cast('bb' AS CHAR(4) COLLATE
UTF8_LCASE)));
+SELECT hex(coalesce(
+ cast('a' AS CHAR(2) COLLATE UTF8_LCASE), cast('bb' AS CHAR(4) COLLATE
UTF8_LCASE)));
+SELECT typeof(coalesce(
+ cast('a' AS CHAR(2) COLLATE UTF8_LCASE), cast('bb' AS VARCHAR(4) COLLATE
UTF8_LCASE)));
+-- Mixed strength, same collation: Implicit string CAST CHAR(2) vs Default
+-- non-string CAST CHAR(4). Length still widens to max(n, m); the COLLATE
+-- operator itself is STRING, so it is not used here.
+SELECT typeof(coalesce(
+ cast('a' AS CHAR(2) COLLATE UTF8_LCASE),
+ cast(1 AS CHAR(4) COLLATE UTF8_LCASE)));
+SELECT hex(coalesce(
+ cast('a' AS CHAR(2) COLLATE UTF8_LCASE),
+ cast(1 AS CHAR(4) COLLATE UTF8_LCASE)));
--- UNION LCT
+-- Set operations and multi-row VALUES share the same LCT as COALESCE.
SELECT typeof(c) FROM (
SELECT cast('a' AS VARCHAR(3)) AS c
UNION ALL
SELECT cast('abcd' AS VARCHAR(8)) AS c
) t LIMIT 1;
+SELECT typeof(c) FROM (
+ SELECT cast('a' AS CHAR(2)) AS c
+ UNION ALL
+ SELECT cast('bb' AS CHAR(4)) AS c
+) t LIMIT 1;
+SELECT concat('<', c, '>') FROM (
+ SELECT cast('a' AS CHAR(2)) AS c
+ UNION ALL
+ SELECT cast('bb' AS CHAR(4)) AS c
+) t;
+SELECT typeof(c) FROM (
+ SELECT cast('a' AS CHAR(2)) AS c
+ UNION
+ SELECT cast('a' AS CHAR(4)) AS c
+) t;
+SELECT concat('<', c, '>') FROM (
+ SELECT cast('a' AS CHAR(2)) AS c
+ UNION
+ SELECT cast('a' AS CHAR(4)) AS c
+) t;
+SELECT typeof(c) FROM (
+ SELECT cast('ab' AS CHAR(2)) AS c
+ INTERSECT
+ SELECT cast('ab' AS CHAR(4)) AS c
+) t;
+SELECT concat('<', c, '>') FROM (
+ SELECT cast('ab' AS CHAR(2)) AS c
+ INTERSECT
+ SELECT cast('ab' AS CHAR(4)) AS c
+) t;
+-- Non-empty EXCEPT: after widening, 'ab ' is not 'xy '.
+SELECT typeof(c) FROM (
+ SELECT cast('ab' AS CHAR(2)) AS c
+ EXCEPT
+ SELECT cast('xy' AS CHAR(4)) AS c
+) t;
+SELECT concat('<', c, '>') FROM (
+ SELECT cast('ab' AS CHAR(2)) AS c
+ EXCEPT
+ SELECT cast('xy' AS CHAR(4)) AS c
+) t;
+SELECT typeof(c) FROM (VALUES
+ (cast('a' AS CHAR(2))),
+ (cast('bb' AS CHAR(4)))
+) t(c);
+SELECT concat('<', c, '>') FROM (VALUES
+ (cast('a' AS CHAR(2))),
+ (cast('bb' AS CHAR(4)))
+) t(c);
+
+-- Comparison and IN: both sides (including the IN left-hand side) are cast to
the LCT of all
+-- participants. Casting to CHAR pads, so CHAR vs CHAR of different lengths
compares equal after
+-- widen; casting to VARCHAR/STRING keeps the CHAR pad, so CHAR 'a' (stored as
'a ') is not equal
Review Comment:
**Nit:**
```suggestion
-- widening; casting to VARCHAR/STRING keeps the CHAR pad, so CHAR 'a'
(stored as 'a ') is not equal
```
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