fix(bigquery-jdbc): fallback to standard precision and scale for numeric, integer, and temporal types

Author: Neenu1995

java-bigquery-jdbc/src/main/java/com/google/cloud/bigquery/jdbc/BigQueryResultSetMetadata.java

@@ -133,12 +133,53 @@ public String getColumnName(int column) {
 
   @Override
   public int getPrecision(int column) {
-    return (int) (getField(column).getPrecision() != null ? getField(column).getPrecision() : 0);
+    Long precision = getField(column).getPrecision();
+    if (precision != null) {
+      return precision.intValue();
+    }
+    StandardSQLTypeName type = getStandardSQLTypeName(column);
+    switch (type) {
+      case BOOL:
+        return 1; // 1 digit
+      case INT64:
+        return 19; // Maximum digits for a signed 64-bit integer
+      case FLOAT64:
+        return 15; // Approximate decimal precision of a double-precision float
+      case NUMERIC:
+        return 38; // Standard BigQuery NUMERIC precision
+      case BIGNUMERIC:
+        return 77; // Standard BigQuery BIGNUMERIC precision
+      case DATE:
+        return 10; // Character length of "YYYY-MM-DD"
+      case TIME:
+        return 15; // Character length of "HH:MM:SS.ffffff" (microsecond resolution)
+      case TIMESTAMP:
+      case DATETIME:
+        return 26; // Character length of "YYYY-MM-DD HH:MM:SS.ffffff" (microsecond resolution)
+      default:
+        return 0;
+    }
   }
 
   @Override
   public int getScale(int column) {
-    return (int) (getField(column).getScale() != null ? getField(column).getScale() : 0);
+    Long scale = getField(column).getScale();
+    if (scale != null) {
+      return scale.intValue();
+    }
+    StandardSQLTypeName type = getStandardSQLTypeName(column);
+    switch (type) {
+      case NUMERIC:
+        return 9; // Standard BigQuery NUMERIC scale
+      case BIGNUMERIC:
+        return 38; // Standard BigQuery BIGNUMERIC scale
+      case TIME:
+      case TIMESTAMP:
+      case DATETIME:
+        return 6; // Microsecond resolution
+      default:
+        return 0;
+    }
   }
 
   @Override

java-bigquery-jdbc/src/test/java/com/google/cloud/bigquery/jdbc/BigQueryResultSetMetadataTest.java

@@ -181,9 +181,19 @@ public void testResultSetMetadataProperties() throws SQLException {
 
   @Test
   public void testPrecision() throws SQLException {
-    assertThat(resultSetMetaData.getPrecision(10)).isEqualTo(12L);
-    assertThat(resultSetMetaData.getPrecision(1))
-        .isEqualTo(0); // schema doesn't have this info, should be defaulted to 0
+    assertThat(resultSetMetaData.getPrecision(1)).isEqualTo(1);
+    assertThat(resultSetMetaData.getPrecision(2)).isEqualTo(19);
+    assertThat(resultSetMetaData.getPrecision(3)).isEqualTo(15);
+    assertThat(resultSetMetaData.getPrecision(4)).isEqualTo(0);
+    assertThat(resultSetMetaData.getPrecision(5)).isEqualTo(26);
+    assertThat(resultSetMetaData.getPrecision(6)).isEqualTo(0);
+    assertThat(resultSetMetaData.getPrecision(7)).isEqualTo(0);
+    assertThat(resultSetMetaData.getPrecision(8)).isEqualTo(0);
+    assertThat(resultSetMetaData.getPrecision(9)).isEqualTo(0);
+    assertThat(resultSetMetaData.getPrecision(10)).isEqualTo(12);
+    assertThat(resultSetMetaData.getPrecision(11)).isEqualTo(77);
+    assertThat(resultSetMetaData.getPrecision(12)).isEqualTo(15);
+    assertThat(resultSetMetaData.getPrecision(13)).isEqualTo(10);
   }
 
   @Test
@@ -209,8 +219,19 @@ public void testCheckCaseSensitive() throws SQLException {
 
   @Test
   public void testScale() throws SQLException {
-    assertThat(resultSetMetaData.getScale(10)).isEqualTo(9L);
-    assertThat(resultSetMetaData.getScale(4)).isEqualTo(0L);
+    assertThat(resultSetMetaData.getScale(1)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(2)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(3)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(4)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(5)).isEqualTo(6);
+    assertThat(resultSetMetaData.getScale(6)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(7)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(8)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(9)).isEqualTo(0);
+    assertThat(resultSetMetaData.getScale(10)).isEqualTo(9);
+    assertThat(resultSetMetaData.getScale(11)).isEqualTo(38);
+    assertThat(resultSetMetaData.getScale(12)).isEqualTo(6);
+    assertThat(resultSetMetaData.getScale(13)).isEqualTo(0);
   }
 
   @Test