// getSharedColumns returns the intersection of two lists of columns in same order as the first list
func (this *Inspector) getSharedColumns(originalColumns, ghostColumns *sql.ColumnList, columnRenameMap map[string]string) (*sql.ColumnList, *sql.ColumnList) {
columnsInGhost := make(map[string]bool)
for _, ghostColumn := range ghostColumns.Names {
columnsInGhost[ghostColumn] = true
}
sharedColumnNames := []string{}
for _, originalColumn := range originalColumns.Names {
if columnsInGhost[originalColumn] || columnsInGhost[columnRenameMap[originalColumn]] {
sharedColumnNames = append(sharedColumnNames, originalColumn)
}
}
mappedSharedColumnNames := []string{}
for _, columnName := range sharedColumnNames {
if mapped, ok := columnRenameMap[columnName]; ok {
mappedSharedColumnNames = append(mappedSharedColumnNames, mapped)
} else {
mappedSharedColumnNames = append(mappedSharedColumnNames, columnName)
}
}
return sql.NewColumnList(sharedColumnNames), sql.NewColumnList(mappedSharedColumnNames)
}
// getTableColumns reads column list from given table
func (this *Inspector) getTableColumns(databaseName, tableName string) (*sql.ColumnList, error) {
query := fmt.Sprintf(`
show columns from %s.%s
`,
sql.EscapeName(databaseName),
sql.EscapeName(tableName),
)
columnNames := []string{}
err := sqlutils.QueryRowsMap(this.db, query, func(rowMap sqlutils.RowMap) error {
columnNames = append(columnNames, rowMap.GetString("Field"))
return nil
})
if err != nil {
return nil, err
}
if len(columnNames) == 0 {
return nil, log.Errorf("Found 0 columns on %s.%s. Bailing out",
sql.EscapeName(databaseName),
sql.EscapeName(tableName),
)
}
return sql.NewColumnList(columnNames), nil
}