feat: add description for Client interface

opengemini/client.go

@@ -44,8 +44,14 @@ type Client interface {
 	ShowRetentionPolicies(database string) ([]RetentionPolicy, error)
 	DropRetentionPolicy(database, retentionPolicy string) error
 
+	// ShowTagKeys get key field names from a database, return []{"Measurement":"XXX","Values":[]string{"TAG1"}}
+	// command such as: show tag keys | show tag keys from MEASUREMENT_NAME | show tag keys from MEASUREMENT_NAME limit N offset M
 	ShowTagKeys(database, command string) ([]ValuesResult, error)
+	// ShowTagValues get key field values from a measurement, return []{"Measurement":"XXX","Values":[]string{"tagName", "tagValue"}}
+	// command such as: show tag values from MEASUREMENT_NAME with key = "TAG_NAME"
 	ShowTagValues(database, command string) ([]ValuesResult, error)
+	// ShowFieldKeys get field key names from a database, return []{"Measurement":"XXX","Values":[]string{"fieldName", "fieldType"}}
+	// command such as: show field keys | show field keys from MEASUREMENT_NAME
 	ShowFieldKeys(database, command string) ([]ValuesResult, error)
 	// ShowSeries returns the series of specified databases
 	// return [measurement1,tag1=value1 measurement2,tag2=value2]

opengemini/measurement.go

@@ -52,7 +52,6 @@ func (c *client) ShowFieldKeys(database, command string) ([]ValuesResult, error)
 }
 
 func (c *client) ShowSeries(database, command string) ([]string, error) {
-	var series = make([]string, 0)
 	if len(database) == 0 {
 		return nil, errors.New("empty database name")
 	}
@@ -63,6 +62,7 @@ func (c *client) ShowSeries(database, command string) ([]string, error) {
 	if len(seriesResult) == 0 {
 		return []string{}, nil
 	}
+	var series = make([]string, 0, len(seriesResult[0].Values))
 	for _, v := range seriesResult[0].Values {
 		strV, ok := v.(string)
 		if !ok {

opengemini/query.go

@@ -91,28 +91,27 @@ func (c *client) queryPost(q Query) (*QueryResult, error) {
 }
 
 func (c *client) showTagSeriesQuery(database, command string) ([]ValuesResult, error) {
-	tagSeries := make([]ValuesResult, 0)
 	tagSeriesResult, err := c.Query(Query{Database: database, Command: command})
 	if err != nil {
-		return tagSeries, err
+		return nil, err
 	}
-
 	err = tagSeriesResult.hasError()
 	if err != nil {
-		return tagSeries, fmt.Errorf("get tagSeriesResult failed, error: %s", err)
+		return nil, fmt.Errorf("get tagSeriesResult failed, error: %s", err)
 	}
 	if len(tagSeriesResult.Results) == 0 {
-		return tagSeries, nil
+		return []ValuesResult{}, nil
 	}
 
+	tagSeries := make([]ValuesResult, 0, len(tagSeriesResult.Results[0].Series))
 	for _, res := range tagSeriesResult.Results[0].Series {
 		tagSeriesRes := new(ValuesResult)
 		tagSeriesRes.Measurement = res.Name
 		for _, valRes := range res.Values {
 			for _, value := range valRes {
 				strVal, ok := value.(string)
 				if !ok {
-					return tagSeries, nil
+					return []ValuesResult{}, errors.New("value is not string")
 				}
 				tagSeriesRes.Values = append(tagSeriesRes.Values, strVal)
 			}
@@ -142,7 +141,7 @@ func (c *client) showTagFieldQuery(database, command string) ([]ValuesResult, er
 		for _, valRes := range res.Values {
 			tagValue := new(keyValue)
 			if len(valRes) < 2 {
-				return tagValueResult, nil
+				return nil, errors.New("invalid tag value format")
 			}
 			if strVal, ok := valRes[0].(string); ok {
 				tagValue.Name = strVal