ClickHouse/programs/diagnostics/internal/platform/database/native.go

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2022-04-27 12:22:20 +00:00
package database
import (
"database/sql"
"fmt"
"strings"
"github.com/ClickHouse/ClickHouse/programs/diagnostics/internal/platform/data"
2022-04-27 12:22:20 +00:00
_ "github.com/ClickHouse/clickhouse-go/v2"
"github.com/pkg/errors"
)
type ClickhouseNativeClient struct {
host string
connection *sql.DB
}
func NewNativeClient(host string, port uint16, username string, password string) (*ClickhouseNativeClient, error) {
// debug output ?debug=true
connection, err := sql.Open("clickhouse", fmt.Sprintf("clickhouse://%s:%s@%s:%d/", username, password, host, port))
if err != nil {
return &ClickhouseNativeClient{}, err
}
if err := connection.Ping(); err != nil {
return &ClickhouseNativeClient{}, err
}
return &ClickhouseNativeClient{
host: host,
connection: connection,
}, nil
}
func (c *ClickhouseNativeClient) Ping() error {
return c.connection.Ping()
}
func (c *ClickhouseNativeClient) ReadTable(databaseName string, tableName string, excludeColumns []string, orderBy data.OrderBy, limit int64) (data.Frame, error) {
exceptClause := ""
if len(excludeColumns) > 0 {
exceptClause = fmt.Sprintf("EXCEPT(%s) ", strings.Join(excludeColumns, ","))
}
limitClause := ""
if limit >= 0 {
limitClause = fmt.Sprintf(" LIMIT %d", limit)
}
rows, err := c.connection.Query(fmt.Sprintf("SELECT * %sFROM %s.%s%s%s", exceptClause, databaseName, tableName, orderBy.String(), limitClause))
if err != nil {
return data.DatabaseFrame{}, err
}
return data.NewDatabaseFrame(fmt.Sprintf("%s.%s", databaseName, tableName), rows)
}
func (c *ClickhouseNativeClient) ReadTableNamesForDatabase(databaseName string) ([]string, error) {
rows, err := c.connection.Query(fmt.Sprintf("SHOW TABLES FROM %s", databaseName))
if err != nil {
return nil, err
}
defer rows.Close()
var tableNames []string
var name string
for rows.Next() {
if err := rows.Scan(&name); err != nil {
return nil, err
}
tableNames = append(tableNames, name)
}
return tableNames, nil
}
func (c *ClickhouseNativeClient) ExecuteStatement(id string, statement string) (data.Frame, error) {
rows, err := c.connection.Query(statement)
if err != nil {
return data.DatabaseFrame{}, err
}
return data.NewDatabaseFrame(id, rows)
}
func (c *ClickhouseNativeClient) Version() (string, error) {
frame, err := c.ExecuteStatement("version", "SELECT version() as version")
if err != nil {
return "", err
}
values, ok, err := frame.Next()
if err != nil {
return "", err
}
if !ok {
return "", errors.New("unable to read ClickHouse version")
}
if len(values) != 1 {
return "", errors.New("unable to read ClickHouse version - no rows returned")
}
return values[0].(string), nil
}