rename table model fields (#114)

diff --git a/client/tablet.go b/client/tablet.go
index 7d8e253..6bbc779 100644
--- a/client/tablet.go
+++ b/client/tablet.go
@@ -36,8 +36,8 @@
 type ColumnCategory int8
 
 const (
-	ID = iota
-	MEASUREMENT
+	TAG = iota
+	FIELD
 	ATTRIBUTE
 )
 
diff --git a/example/session_pool/table/table_session_pool_example.go b/example/session_pool/table/table_session_pool_example.go
index 950a11b..b9106c5 100644
--- a/example/session_pool/table/table_session_pool_example.go
+++ b/example/session_pool/table/table_session_pool_example.go
@@ -68,7 +68,7 @@
 			}()
 			checkError(session.ExecuteNonQueryStatement("create database " + dbName))
 			checkError(session.ExecuteNonQueryStatement("use " + dbName))
-			checkError(session.ExecuteNonQueryStatement("create table table_of_" + dbName + " (id1 string id, id2 string id, s1 text measurement, s2 text measurement)"))
+			checkError(session.ExecuteNonQueryStatement("create table table_of_" + dbName + " (tag1 string tag, tag2 string tag, s1 text field, s2 text field)"))
 		}()
 	}
 	wg.Wait()
@@ -126,7 +126,7 @@
 				return
 			}
 			defer session.Close()
-			checkError(session.ExecuteNonQueryStatement("create table " + tableName + " (id1 string id, id2 string id, s1 text measurement, s2 text measurement)"))
+			checkError(session.ExecuteNonQueryStatement("create table " + tableName + " (tag1 string tag, tag2 string tag, s1 text field, s2 text field)"))
 		}()
 	}
 	wg.Wait()
@@ -156,7 +156,7 @@
 			defer session.Close()
 			checkError(session.ExecuteNonQueryStatement("create database " + dbName))
 			checkError(session.ExecuteNonQueryStatement("use " + dbName))
-			checkError(session.ExecuteNonQueryStatement("create table t1 (id1 string id, id2 string id, s1 text measurement, s2 text measurement)"))
+			checkError(session.ExecuteNonQueryStatement("create table t1 (tag1 string tag, tag2 string tag, s1 text field, s2 text field)"))
 		}()
 	}
 	wg.Wait()
diff --git a/example/table/table_session_example.go b/example/table/table_session_example.go
index c2eb2f5..24eab7f 100644
--- a/example/table/table_session_example.go
+++ b/example/table/table_session_example.go
@@ -46,7 +46,7 @@
 
 	checkError(session.ExecuteNonQueryStatement("create database test_db"))
 	checkError(session.ExecuteNonQueryStatement("use test_db"))
-	checkError(session.ExecuteNonQueryStatement("create table t1 (id1 string id, id2 string id, s1 text measurement, s2 text measurement)"))
+	checkError(session.ExecuteNonQueryStatement("create table t1 (tag1 string tag, tag2 string tag, s1 text field, s2 text field)"))
 	insertRelationalTablet(session)
 	showTables(session)
 	query(session)
@@ -63,11 +63,11 @@
 func insertRelationalTablet(session client.ITableSession) {
 	tablet, err := client.NewRelationalTablet("t1", []*client.MeasurementSchema{
 		{
-			Measurement: "id1",
+			Measurement: "tag1",
 			DataType:    client.STRING,
 		},
 		{
-			Measurement: "id2",
+			Measurement: "tag2",
 			DataType:    client.STRING,
 		},
 		{
@@ -78,7 +78,7 @@
 			Measurement: "s2",
 			DataType:    client.TEXT,
 		},
-	}, []client.ColumnCategory{client.ID, client.ID, client.MEASUREMENT, client.MEASUREMENT}, 1024)
+	}, []client.ColumnCategory{client.TAG, client.TAG, client.FIELD, client.FIELD}, 1024)
 	if err != nil {
 		log.Fatal("Failed to create relational tablet {}", err)
 	}
@@ -86,8 +86,8 @@
 	for row := 0; row < 16; row++ {
 		ts++
 		tablet.SetTimestamp(ts, row)
-		tablet.SetValueAt("id1_field_"+strconv.Itoa(row), 0, row)
-		tablet.SetValueAt("id2_field_"+strconv.Itoa(row), 1, row)
+		tablet.SetValueAt("tag1_value_"+strconv.Itoa(row), 0, row)
+		tablet.SetValueAt("tag2_value_"+strconv.Itoa(row), 1, row)
 		tablet.SetValueAt("s1_value_"+strconv.Itoa(row), 2, row)
 		tablet.SetValueAt("s2_value_"+strconv.Itoa(row), 3, row)
 		tablet.RowSize++
@@ -99,8 +99,8 @@
 	for row := 0; row < 16; row++ {
 		ts++
 		tablet.SetTimestamp(ts, row)
-		tablet.SetValueAt("id1_field_1", 0, row)
-		tablet.SetValueAt("id2_field_1", 1, row)
+		tablet.SetValueAt("tag1_value_1", 0, row)
+		tablet.SetValueAt("tag2_value_1", 1, row)
 		tablet.SetValueAt("s1_value_"+strconv.Itoa(row), 2, row)
 		tablet.SetValueAt("s2_value_"+strconv.Itoa(row), 3, row)
 
@@ -143,7 +143,7 @@
 		if !hasNext {
 			break
 		}
-		log.Printf("%v %v %v %v", getTextValueFromDataSet(dataSet, "id1"), getTextValueFromDataSet(dataSet, "id2"), getTextValueFromDataSet(dataSet, "s1"), getTextValueFromDataSet(dataSet, "s2"))
+		log.Printf("%v %v %v %v", getTextValueFromDataSet(dataSet, "tag1"), getTextValueFromDataSet(dataSet, "tag2"), getTextValueFromDataSet(dataSet, "s1"), getTextValueFromDataSet(dataSet, "s2"))
 	}
 }
 
diff --git a/test/e2e/e2e_table_test.go b/test/e2e/e2e_table_test.go
index 3df5b6e..de930d3 100644
--- a/test/e2e/e2e_table_test.go
+++ b/test/e2e/e2e_table_test.go
@@ -183,7 +183,7 @@
 
 	session1, err := sessionPool.GetSession()
 	assert.NoError(err)
-	s.checkError(session1.ExecuteNonQueryStatement("create table table_in_" + database + " (id1 string id, id2 string id, s1 text measurement, s2 text measurement)"))
+	s.checkError(session1.ExecuteNonQueryStatement("create table table_in_" + database + " (tag1 string tag, tag2 string tag, s1 text field, s2 text field)"))
 	session1.Close()
 
 	var wg sync.WaitGroup
@@ -239,7 +239,7 @@
 
 func (s *e2eTableTestSuite) Test_InsertTabletAndQuery() {
 	assert := s.Require()
-	s.checkError(s.session.ExecuteNonQueryStatement("create table t1 (id1 string id, id2 string id, s1 text measurement, s2 text measurement)"))
+	s.checkError(s.session.ExecuteNonQueryStatement("create table t1 (tag1 string tag, tag2 string tag, s1 text field, s2 text field)"))
 
 	timeoutInMs := int64(10000)
 
@@ -255,11 +255,11 @@
 	// insert relational tablet
 	tablet, err := client.NewRelationalTablet("t1", []*client.MeasurementSchema{
 		{
-			Measurement: "id1",
+			Measurement: "tag1",
 			DataType:    client.STRING,
 		},
 		{
-			Measurement: "id2",
+			Measurement: "tag2",
 			DataType:    client.STRING,
 		},
 		{
@@ -270,18 +270,18 @@
 			Measurement: "s2",
 			DataType:    client.TEXT,
 		},
-	}, []client.ColumnCategory{client.ID, client.ID, client.MEASUREMENT, client.MEASUREMENT}, 1024)
+	}, []client.ColumnCategory{client.TAG, client.TAG, client.FIELD, client.FIELD}, 1024)
 	assert.NoError(err)
 
 	values := [][]interface{}{
-		{"id1_field_1", "id2_field_1", "s1_value_1", "s2_value_1"},
-		{"id1_field_1", "id2_field_1", "s1_value_2", "s2_value_2"},
-		{"id1_field_1", "id2_field_1", nil, "s2_value_2"},
-		{"id1_field_2", "id2_field_2", "s1_value_1", "s2_value_1"},
-		{"id1_field_2", "id2_field_2", "s1_value_1", "s2_value_1"},
-		{"id1_field_3", "id2_field_3", "s1_value_1", "s2_value_1"},
-		{"id1_field_3", "id2_field_3", "s1_value_2", nil},
-		{"id1_field_3", "id2_field_3", "s1_value_3", "s2_value_3"},
+		{"tag1_value_1", "tag2_value_1", "s1_value_1", "s2_value_1"},
+		{"tag1_value_1", "tag2_value_1", "s1_value_2", "s2_value_2"},
+		{"tag1_value_1", "tag2_value_1", nil, "s2_value_2"},
+		{"tag1_value_2", "tag2_value_2", "s1_value_1", "s2_value_1"},
+		{"tag1_value_2", "tag2_value_2", "s1_value_1", "s2_value_1"},
+		{"tag1_value_3", "tag2_value_3", "s1_value_1", "s2_value_1"},
+		{"tag1_value_3", "tag2_value_3", "s1_value_2", nil},
+		{"tag1_value_3", "tag2_value_3", "s1_value_3", "s2_value_3"},
 	}
 
 	ts := int64(0)
@@ -308,8 +308,8 @@
 			break
 		}
 		assert.Equal(count, dataSet.GetInt64("time"))
-		assert.Equal(values[count][0], getValueFromDataSet(dataSet, "id1"))
-		assert.Equal(values[count][1], getValueFromDataSet(dataSet, "id2"))
+		assert.Equal(values[count][0], getValueFromDataSet(dataSet, "tag1"))
+		assert.Equal(values[count][1], getValueFromDataSet(dataSet, "tag2"))
 		assert.Equal(values[count][2], getValueFromDataSet(dataSet, "s1"))
 		assert.Equal(values[count][3], getValueFromDataSet(dataSet, "s2"))
 		count++