// Creates a new table.
func (db *Database) Create(name string) (*table.Table, int) {
var newTable *table.Table
_, exists := db.Tables[name]
if exists {
return nil, st.TableAlreadyExists
}
if len(name) > constant.MaxTableNameLength {
return nil, st.TableNameTooLong
}
// Create table files and directories.
tablefilemanager.Create(db.Path, name)
// Open the table
var status int
newTable, status = table.Open(db.Path, name)
if status == st.OK {
// Add default columns
for columnName, length := range constant.DatabaseColumns() {
status = newTable.Add(columnName, length)
if status != st.OK {
return nil, status
}
}
db.Tables[name] = newTable
}
return newTable, st.OK
}
// Rebuild data file, get rid off removed rows, optionally leaves space for a new column.
func (table *Table) RebuildDataFile(name string, length int) int {
// Create a temporary table named by an accurate timestamp.
tempName := strconv.Itoa(time.Now().Nanosecond())
// tempName := strconv.Itoa(time.Nanosecond)
tablefilemanager.Create(table.Path, tempName)
var tempTable *Table
tempTable, status := Open(table.Path, tempName)
if status != st.OK {
return status
}
// Put all columns of this table to the temporary table.
for _, column := range table.ColumnsInOrder {
tempTable.Add(column.Name, column.Length)
}
// Add the new column into the table as well.
if name != "" {
tempTable.Add(name, length)
}
var numberOfRows int
numberOfRows, status = table.NumberOfRows()
if status != st.OK {
return status
}
var everFailed bool
if name == "" {
// If no new column, simply copy rows from this table to the temp table.
for i := 0; i < numberOfRows; i++ {
row, ret := table.Read(i)
if ret != st.OK {
everFailed = true
}
if row["~del"] != "y" {
tempTable.Insert(row)
}
}
} else {
// If adding new column, not only copy rows from this table to the temporary one.
// Also leave space for the new column's values.
for i := 0; i < numberOfRows; i++ {
row, ret := table.Read(i)
if ret != st.OK {
everFailed = true
}
if row["~del"] != "y" {
row[name] = ""
tempTable.Insert(row)
}
}
}
// Flush all the changes made to temporary table.
status = tempTable.Flush()
if everFailed || status != st.OK {
return st.FailedToCopyCertainRows
}
// Delete the old table (one that is rebuilt), and rename the temporary
// table to the name of the rebuilt table.
status = tablefilemanager.Delete(table.Path, table.Name)
if status == st.OK {
status = tablefilemanager.Rename(table.Path, tempName, table.Name)
if status == st.OK {
// Files have been changed, thus re-open file handles.
return table.OpenFiles()
}
}
return st.OK
}