ch: implement GetTableSchemaConnector

flow/connectors/clickhouse/clickhouse.go

@@ -23,6 +23,7 @@ import (
 	metadataStore "github.com/PeerDB-io/peer-flow/connectors/external_metadata"
 	"github.com/PeerDB-io/peer-flow/connectors/utils"
 	"github.com/PeerDB-io/peer-flow/generated/protos"
+	"github.com/PeerDB-io/peer-flow/model/qvalue"
 	"github.com/PeerDB-io/peer-flow/peerdbenv"
 	"github.com/PeerDB-io/peer-flow/shared"
 )
@@ -542,3 +543,71 @@ func (c *ClickHouseConnector) GetVersion(ctx context.Context) (string, error) {
 	c.logger.Info("[clickhouse] version", slog.Any("version", clickhouseVersion.DisplayName))
 	return clickhouseVersion.Version.String(), nil
 }
+
+func GetTableSchemaForTable(tableName string, columns []driver.ColumnType) (*protos.TableSchema, error) {
+	colFields := make([]*protos.FieldDescription, 0, len(columns))
+	for _, column := range columns {
+		var qkind qvalue.QValueKind
+		switch column.DatabaseTypeName() {
+		case "String", "Nullable(String)":
+			qkind = qvalue.QValueKindString
+		case "Bool", "Nullable(Bool)":
+			qkind = qvalue.QValueKindBoolean
+		case "Int16", "Nullable(Int16)":
+			qkind = qvalue.QValueKindInt16
+		case "Int32", "Nullable(Int32)":
+			qkind = qvalue.QValueKindInt32
+		case "Int64", "Nullable(Int64)":
+			qkind = qvalue.QValueKindInt64
+		case "UUID", "Nullable(UUID)":
+			qkind = qvalue.QValueKindUUID
+		case "DateTime64(6)", "Nullable(DateTime64(6))":
+			qkind = qvalue.QValueKindTimestamp
+		case "Date32", "Nullable(Date32)":
+			qkind = qvalue.QValueKindDate
+		default:
+			if strings.Contains(column.DatabaseTypeName(), "Decimal") {
+				qkind = qvalue.QValueKindNumeric
+			} else {
+				return nil, fmt.Errorf("failed to resolve QValueKind for %s", column.DatabaseTypeName())
+			}
+		}
+
+		colFields = append(colFields, &protos.FieldDescription{
+			Name:         column.Name(),
+			Type:         string(qkind),
+			TypeModifier: -1,
+			Nullable:     column.Nullable(),
+		})
+	}
+
+	return &protos.TableSchema{
+		TableIdentifier: tableName,
+		Columns:         colFields,
+		System:          protos.TypeSystem_Q,
+	}, nil
+}
+
+func (c *ClickHouseConnector) GetTableSchema(
+	ctx context.Context,
+	_env map[string]string,
+	_system protos.TypeSystem,
+	tableIdentifiers []string,
+) (map[string]*protos.TableSchema, error) {
+	res := make(map[string]*protos.TableSchema, len(tableIdentifiers))
+	for _, tableName := range tableIdentifiers {
+		rows, err := c.database.Query(ctx, fmt.Sprintf("select * from %s limit 0", tableName))
+		if err != nil {
+			return nil, err
+		}
+
+		tableSchema, err := GetTableSchemaForTable(tableName, rows.ColumnTypes())
+		rows.Close()
+		if err != nil {
+			return nil, err
+		}
+		res[tableName] = tableSchema
+	}
+
+	return res, nil
+}

flow/connectors/core.go

@@ -470,6 +470,7 @@ var (
 
 	_ GetTableSchemaConnector = &connpostgres.PostgresConnector{}
 	_ GetTableSchemaConnector = &connsnowflake.SnowflakeConnector{}
+	_ GetTableSchemaConnector = &connclickhouse.ClickHouseConnector{}
 
 	_ NormalizedTablesConnector = &connpostgres.PostgresConnector{}
 	_ NormalizedTablesConnector = &connbigquery.BigQueryConnector{}

flow/e2e/clickhouse/clickhouse.go

@@ -96,6 +96,7 @@ func (s ClickHouseSuite) GetRows(table string, cols string) (*model.QRecordBatch
 	if err != nil {
 		return nil, err
 	}
+	defer ch.Close()
 
 	rows, err := ch.Query(
 		context.Background(),
@@ -104,36 +105,25 @@ func (s ClickHouseSuite) GetRows(table string, cols string) (*model.QRecordBatch
 	if err != nil {
 		return nil, err
 	}
+	defer rows.Close()
 
 	batch := &model.QRecordBatch{}
 	types := rows.ColumnTypes()
 	row := make([]interface{}, 0, len(types))
-	for _, ty := range types {
-		nullable := ty.Nullable()
+	tableSchema, err := connclickhouse.GetTableSchemaForTable(table, types)
+	if err != nil {
+		return nil, err
+	}
+
+	for idx, ty := range types {
+		fieldDesc := tableSchema.Columns[idx]
 		row = append(row, reflect.New(ty.ScanType()).Interface())
-		var qkind qvalue.QValueKind
-		switch ty.DatabaseTypeName() {
-		case "String", "Nullable(String)":
-			qkind = qvalue.QValueKindString
-		case "Int32", "Nullable(Int32)":
-			qkind = qvalue.QValueKindInt32
-		case "DateTime64(6)", "Nullable(DateTime64(6))":
-			qkind = qvalue.QValueKindTimestamp
-		case "Date32", "Nullable(Date32)":
-			qkind = qvalue.QValueKindDate
-		default:
-			if strings.Contains(ty.DatabaseTypeName(), "Decimal") {
-				qkind = qvalue.QValueKindNumeric
-			} else {
-				return nil, fmt.Errorf("failed to resolve QValueKind for %s", ty.DatabaseTypeName())
-			}
-		}
 		batch.Schema.Fields = append(batch.Schema.Fields, qvalue.QField{
 			Name:      ty.Name(),
-			Type:      qkind,
+			Type:      qvalue.QValueKind(fieldDesc.Type),
 			Precision: 0,
 			Scale:     0,
-			Nullable:  nullable,
+			Nullable:  fieldDesc.Nullable,
 		})
 	}