gustavodemorais commented on code in PR #27603:
URL: https://github.com/apache/flink/pull/27603#discussion_r2816044573
##########
flink-table/flink-table-common/src/main/java/org/apache/flink/table/types/logical/utils/LogicalTypeCasts.java:
##########
@@ -110,124 +110,186 @@ public final class LogicalTypeCasts {
private static final Map<LogicalTypeRoot, Set<LogicalTypeRoot>>
explicitCastingRules;
+ private static final Map<LogicalTypeRoot, Set<LogicalTypeRoot>>
injectiveCastingRules;
+
+ // Types with deterministic, unique string representations (for injective
casts to STRING)
+ private static final LogicalTypeRoot[] STRING_INJECTIVE_SOURCES = {
+ TINYINT,
+ SMALLINT,
+ INTEGER,
+ BIGINT,
+ FLOAT,
+ DOUBLE,
+ BOOLEAN,
+ DATE,
+ TIMESTAMP_WITHOUT_TIME_ZONE,
+ TIMESTAMP_WITH_TIME_ZONE,
+ TIMESTAMP_WITH_LOCAL_TIME_ZONE
+ };
+
static {
implicitCastingRules = new HashMap<>();
explicitCastingRules = new HashMap<>();
+ injectiveCastingRules = new HashMap<>();
- // identity casts
-
+ // Identity casts: all types can be cast to themselves, and identity
is always injective
for (LogicalTypeRoot typeRoot : allTypes()) {
- castTo(typeRoot).implicitFrom(typeRoot).build();
+
castTo(typeRoot).implicitFrom(typeRoot).injectiveFrom(typeRoot).build();
}
- // cast specification
+ //
-----------------------------------------------------------------------------------------
+ // Character string types
+ //
-----------------------------------------------------------------------------------------
castTo(CHAR)
.implicitFrom(CHAR)
.explicitFromFamily(PREDEFINED, CONSTRUCTED)
.explicitFrom(RAW, NULL, STRUCTURED_TYPE)
+ .injectiveFrom(CHAR)
+ .injectiveFrom(STRING_INJECTIVE_SOURCES)
.build();
castTo(VARCHAR)
.implicitFromFamily(CHARACTER_STRING)
.explicitFromFamily(PREDEFINED, CONSTRUCTED)
.explicitFrom(RAW, NULL, STRUCTURED_TYPE)
+ .injectiveFrom(CHAR, VARCHAR)
+ .injectiveFrom(STRING_INJECTIVE_SOURCES)
.build();
- castTo(BOOLEAN)
- .implicitFrom(BOOLEAN)
- .explicitFromFamily(CHARACTER_STRING, INTEGER_NUMERIC)
- .build();
+ //
-----------------------------------------------------------------------------------------
+ // Binary string types
+ //
-----------------------------------------------------------------------------------------
castTo(BINARY)
.implicitFrom(BINARY)
.explicitFromFamily(CHARACTER_STRING)
- .explicitFrom(VARBINARY)
- .explicitFrom(RAW)
+ .explicitFrom(VARBINARY, RAW)
+ .injectiveFrom(BINARY)
.build();
castTo(VARBINARY)
.implicitFromFamily(BINARY_STRING)
.explicitFromFamily(CHARACTER_STRING)
- .explicitFrom(BINARY)
- .explicitFrom(RAW)
+ .explicitFrom(BINARY, RAW)
+ .injectiveFrom(BINARY, VARBINARY)
.build();
- castTo(DECIMAL)
- .implicitFromFamily(NUMERIC)
- .explicitFromFamily(CHARACTER_STRING, INTERVAL)
- .explicitFrom(BOOLEAN, TIMESTAMP_WITHOUT_TIME_ZONE,
TIMESTAMP_WITH_LOCAL_TIME_ZONE)
- .build();
+ //
-----------------------------------------------------------------------------------------
+ // Exact numeric types
+ //
-----------------------------------------------------------------------------------------
castTo(TINYINT)
.implicitFrom(TINYINT)
.explicitFromFamily(NUMERIC, CHARACTER_STRING, INTERVAL)
.explicitFrom(BOOLEAN, TIMESTAMP_WITHOUT_TIME_ZONE,
TIMESTAMP_WITH_LOCAL_TIME_ZONE)
+ .injectiveFrom(TINYINT)
.build();
castTo(SMALLINT)
.implicitFrom(TINYINT, SMALLINT)
.explicitFromFamily(NUMERIC, CHARACTER_STRING, INTERVAL)
.explicitFrom(BOOLEAN, TIMESTAMP_WITHOUT_TIME_ZONE,
TIMESTAMP_WITH_LOCAL_TIME_ZONE)
+ .injectiveFrom(TINYINT, SMALLINT)
.build();
castTo(INTEGER)
.implicitFrom(TINYINT, SMALLINT, INTEGER)
.explicitFromFamily(NUMERIC, CHARACTER_STRING, INTERVAL)
.explicitFrom(BOOLEAN, TIMESTAMP_WITHOUT_TIME_ZONE,
TIMESTAMP_WITH_LOCAL_TIME_ZONE)
+ .injectiveFrom(TINYINT, SMALLINT, INTEGER)
.build();
castTo(BIGINT)
.implicitFrom(TINYINT, SMALLINT, INTEGER, BIGINT)
.explicitFromFamily(NUMERIC, CHARACTER_STRING, INTERVAL)
.explicitFrom(BOOLEAN, TIMESTAMP_WITHOUT_TIME_ZONE,
TIMESTAMP_WITH_LOCAL_TIME_ZONE)
+ .injectiveFrom(TINYINT, SMALLINT, INTEGER, BIGINT)
+ .build();
+
+ castTo(DECIMAL)
+ .implicitFromFamily(NUMERIC)
+ .explicitFromFamily(CHARACTER_STRING, INTERVAL)
+ .explicitFrom(BOOLEAN, TIMESTAMP_WITHOUT_TIME_ZONE,
TIMESTAMP_WITH_LOCAL_TIME_ZONE)
+ .injectiveFrom(TINYINT, SMALLINT, INTEGER, BIGINT, DECIMAL)
Review Comment:
Hmmmm, that's a good point since we can pick the precision and I think it
aligns with not supporting float/double. Removing it.
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