SQL: Fix type and value in SYS TYPES (elastic/x-pack-elasticsearch#3979)

The type of BUFFER_LENGTH needs to be an integer (not NULL) and unsigned
indicate the opposite of signed.
Change isSigned from Object to primitive
Since all the consumer of isSigned expect a primitive, an Object is just causing troubles by being null.
Update description table

Original commit: elastic/x-pack-elasticsearch@8e1960bdb5

plugin/sql/sql-proto/src/main/java/org/elasticsearch/xpack/sql/type/DataType.java

@@ -128,11 +128,11 @@ public enum DataType {
     }
 
     /**
-     * Returns true if value is signed, false if it is unsigned or null if the type doesn't represent a number
+     * Returns true if value is signed, false otherwise (including if the type is not numeric)
      */
-    public Boolean isSigned() {
+    public boolean isSigned() {
         // For now all numeric values that es supports are signed
-        return isNumeric() ? true : null;
+        return isNumeric();
     }
 
     public boolean isString() {

plugin/sql/src/main/java/org/elasticsearch/xpack/sql/plan/logical/command/sys/SysColumns.java

@@ -63,7 +63,7 @@ public class SysColumns extends Command {
                       field("DATA_TYPE", INTEGER),
                       keyword("TYPE_NAME"),
                       field("COLUMN_SIZE", INTEGER),
-                      field("BUFFER_LENGTH", NULL),
+                      field("BUFFER_LENGTH", INTEGER),
                       field("DECIMAL_DIGITS", INTEGER),
                       field("NUM_PREC_RADIX", INTEGER),
                       field("NULLABLE", INTEGER),

plugin/sql/src/main/java/org/elasticsearch/xpack/sql/plan/logical/command/sys/SysTypes.java

@@ -81,7 +81,7 @@ public class SysTypes extends Command {
                         // everything is searchable,
                         DatabaseMetaData.typeSearchable,
                         // only numerics are signed
-                        t.isSigned(),
+                        !t.isSigned(),
                         //no fixed precision scale SQL_FALSE
                         0,
                         null,

plugin/sql/src/test/java/org/elasticsearch/xpack/sql/plan/logical/command/sys/SysParserTests.java

@@ -16,6 +16,7 @@ import org.elasticsearch.xpack.sql.expression.function.FunctionRegistry;
 import org.elasticsearch.xpack.sql.parser.SqlParser;
 import org.elasticsearch.xpack.sql.plan.logical.command.Command;
 import org.elasticsearch.xpack.sql.session.SqlSession;
+import org.elasticsearch.xpack.sql.type.DataType;
 import org.elasticsearch.xpack.sql.type.EsField;
 import org.elasticsearch.xpack.sql.type.TypesTests;
 import org.joda.time.DateTimeZone;
@@ -62,7 +63,10 @@ public class SysParserTests extends ESTestCase {
         cmd.execute(null, ActionListener.wrap(r -> {
             assertEquals(19, r.columnCount());
             assertEquals(17, r.size());
-
+            assertFalse(r.schema().types().contains(DataType.NULL));
+            // test numeric as signed
+            assertFalse(r.column(9, Boolean.class));
+            
             for (int i = 0; i < r.size(); i++) {
                 assertEquals(names.get(i), r.column(0));
                 r.advanceRow();

qa/sql/src/main/resources/setup_mock_metadata_get_columns.sql

@@ -5,7 +5,7 @@ CREATE TABLE mock (
   DATA_TYPE INTEGER,
   TYPE_NAME VARCHAR,
   COLUMN_SIZE INTEGER,
-  BUFFER_LENGTH NULL,
+  BUFFER_LENGTH INTEGER,
   DECIMAL_DIGITS INTEGER,
   NUM_PREC_RADIX INTEGER,
   NULLABLE INTEGER,
@@ -23,27 +23,27 @@ CREATE TABLE mock (
   IS_AUTOINCREMENT VARCHAR,
   IS_GENERATEDCOLUMN VARCHAR
 ) AS
-SELECT null, 'test1', 'name', 12, 'TEXT', 0, null, null, null,
+SELECT null, 'test1', 'name', 12, 'TEXT', 0, 2147483647, null, null,
   1, -- columnNullable
   null, null, 12, null, 2147483647, 1, 'YES', null, null, null, null, 'NO', 'NO'
 FROM DUAL
 UNION ALL
-SELECT null, 'test1', 'name.keyword', 12, 'KEYWORD', 0, null, null, null,
+SELECT null, 'test1', 'name.keyword', 12, 'KEYWORD', 0, 2147483647, null, null,
   1, -- columnNullable
   null, null, 12, null, 2147483647, 1, 'YES', null, null, null, null, 'NO', 'NO'
 FROM DUAL
 UNION ALL
-SELECT null, 'test2', 'date', 93, 'DATE', 20, null, null, null,
+SELECT null, 'test2', 'date', 93, 'DATE', 20, 8, null, null,
   1, -- columnNullable
   null, null, 93, null, null, 1, 'YES', null, null, null, null, 'NO', 'NO'
 FROM DUAL
 UNION ALL
-SELECT null, 'test2', 'float', 7, 'FLOAT', 15, null, null, 2,
+SELECT null, 'test2', 'float', 7, 'FLOAT', 15, 4, null, 2,
   1, -- columnNullable
   null, null, 7, null, null, 2, 'YES', null, null, null, null, 'NO', 'NO'
 FROM DUAL
 UNION ALL
-SELECT null, 'test2', 'number', -5, 'LONG', 20, null, null, 10,
+SELECT null, 'test2', 'number', -5, 'LONG', 20, 8, null, 10,
   1, -- columnNullable
   null, null, -5, null, null, 3, 'YES', null, null, null, null, 'NO', 'NO'
 FROM DUAL