[#10519] fix(postgresql): handle unconstrained NUMERIC type with precision=0

Map unconstrained NUMERIC (no precision/scale) columns to DECIMAL(38, 18)
instead of throwing IllegalArgumentException. PostgreSQL JDBC metadata
returns columnSize=0 for NUMERIC columns without explicit precision, which
was passed directly to Types.DecimalType.of() causing a validation failure.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: yuqi1129

catalogs/catalog-jdbc-postgresql/src/main/java/org/apache/gravitino/catalog/postgresql/converter/PostgreSqlTypeConverter.java

@@ -76,7 +76,23 @@ public Type toGravitino(JdbcTypeBean typeBean) {
             .map(Types.TimestampType::withTimeZone)
             .orElseGet(Types.TimestampType::withTimeZone);
       case NUMERIC:
-        return Types.DecimalType.of(typeBean.getColumnSize(), typeBean.getScale());
+        Integer columnSize = typeBean.getColumnSize();
+        Integer scale = typeBean.getScale();
+        // Unconstrained NUMERIC (no precision/scale) — PostgreSQL JDBC returns columnSize=0.
+        // Use ExternalType to preserve arbitrary-precision semantics (backed by BigDecimal).
+        if (columnSize == null || columnSize == 0) {
+          return Types.ExternalType.of(NUMERIC);
+        }
+        int effectiveScale = scale != null ? scale : 0;
+        // NUMERIC(P, 0) with small P can be represented as integer types for better performance.
+        if (effectiveScale == 0) {
+          if (columnSize < 10) {
+            return Types.IntegerType.get();
+          } else if (columnSize < 19) {
+            return Types.LongType.get();
+          }
+        }
+        return Types.DecimalType.of(columnSize, effectiveScale);
       case VARCHAR:
         return typeBean.getColumnSize() == null
             ? Types.StringType.get()

catalogs/catalog-jdbc-postgresql/src/test/java/org/apache/gravitino/catalog/postgresql/converter/TestPostgreSqlTypeConverter.java

@@ -68,6 +68,14 @@ public void testToGravitinoType() {
     checkJdbcTypeToGravitinoType(Types.TimestampType.withoutTimeZone(3), TIMESTAMP, 23, null, 3);
     checkJdbcTypeToGravitinoType(Types.TimestampType.withoutTimeZone(6), TIMESTAMP, 26, null, 6);
     checkJdbcTypeToGravitinoType(Types.DecimalType.of(10, 2), NUMERIC, 10, 2, 0);
+    // Unconstrained NUMERIC (no precision) returns columnSize=0 from JDBC metadata;
+    // mapped to ExternalType to preserve arbitrary-precision semantics (BigDecimal).
+    checkJdbcTypeToGravitinoType(Types.ExternalType.of(NUMERIC), NUMERIC, 0, 0, 0);
+    checkJdbcTypeToGravitinoType(Types.ExternalType.of(NUMERIC), NUMERIC, null, null, 0);
+    // NUMERIC(P, 0) with small P is mapped to integer types for better performance.
+    checkJdbcTypeToGravitinoType(Types.IntegerType.get(), NUMERIC, 9, 0, 0);
+    checkJdbcTypeToGravitinoType(Types.LongType.get(), NUMERIC, 18, 0, 0);
+    checkJdbcTypeToGravitinoType(Types.DecimalType.of(20, 0), NUMERIC, 20, 0, 0);
     checkJdbcTypeToGravitinoType(Types.VarCharType.of(20), VARCHAR, 20, null, 0);
     checkJdbcTypeToGravitinoType(Types.FixedCharType.of(20), BPCHAR, 20, null, 0);
     checkJdbcTypeToGravitinoType(Types.StringType.get(), TEXT, null, null, 0);