// Encodes datum at the end of key, using direction `dir` for the encoding.
// The key is a span end key, which is exclusive, but `val` needs to
// be inclusive. So if datum is the last end constraint, we transform it accordingly.
func encodeInclusiveEndValue(
key roachpb.Key, datum parser.Datum, dir encoding.Direction,
isLastEndConstraint bool) roachpb.Key {
// Since the end of a span is exclusive, if the last constraint is an
// inclusive one, we might need to make the key exclusive by applying a
// PrefixEnd(). We normally avoid doing this by transforming "a = x" to
// "a = x±1" for the last end constraint, depending on the encoding direction
// (since this keeps the key nice and pretty-printable).
// However, we might not be able to do the ±1.
needExclusiveKey := false
if isLastEndConstraint {
if dir == encoding.Ascending {
if datum.IsMax() {
needExclusiveKey = true
} else {
datum = datum.Next()
}
} else {
if datum.IsMin() || !datum.HasPrev() {
needExclusiveKey = true
} else {
datum = datum.Prev()
}
}
}
key, pErr := encodeTableKey(key, datum, dir)
if pErr != nil {
panic(pErr)
}
if needExclusiveKey {
key = key.PrefixEnd()
}
return key
}
// TODO(dt): Batch checks of many rows.
func (f baseFKHelper) check(values parser.DTuple) (parser.DTuple, error) {
var key roachpb.Key
if values != nil {
keyBytes, _, err := sqlbase.EncodeIndexKey(f.searchIdx, f.ids, values, f.searchPrefix)
if err != nil {
return nil, err
}
key = roachpb.Key(keyBytes)
} else {
key = roachpb.Key(f.searchPrefix)
}
spans := sqlbase.Spans{sqlbase.Span{Start: key, End: key.PrefixEnd()}}
if err := f.rf.StartScan(f.txn, spans, 1); err != nil {
return nil, err
}
return f.rf.NextRow()
}
func (sc *SchemaChanger) truncateAndBackfillColumnsChunk(
added []sqlbase.ColumnDescriptor,
dropped []sqlbase.ColumnDescriptor,
nonNullableColumn string,
defaultExprs []parser.TypedExpr,
evalCtx parser.EvalContext,
sp sqlbase.Span,
) (roachpb.Key, bool, error) {
var curSentinel roachpb.Key
done := false
err := sc.db.Txn(func(txn *client.Txn) error {
tableDesc, err := getTableDescFromID(txn, sc.tableID)
if err != nil {
return err
}
// Short circuit the backfill if the table has been deleted.
if tableDesc.Deleted {
done = true
return nil
}
// Run a scan across the table using the primary key. Running
// the scan and applying the changes in many transactions is
// fine because the schema change is in the correct state to
// handle intermediate OLTP commands which delete and add
// values during the scan.
b := &client.Batch{}
b.Scan(sp.Start, sp.End, ColumnTruncateAndBackfillChunkSize)
if err := txn.Run(b); err != nil {
return err
}
// Use a different batch to truncate/backfill columns.
writeBatch := &client.Batch{}
marshalled := make([]roachpb.Value, len(defaultExprs))
done = true
for _, result := range b.Results {
var sentinelKey roachpb.Key
for _, kv := range result.Rows {
// Still processing table.
done = false
if nonNullableColumn != "" {
return fmt.Errorf("column %s contains null values", nonNullableColumn)
}
if sentinelKey == nil || !bytes.HasPrefix(kv.Key, sentinelKey) {
// Sentinel keys have a 0 suffix indicating 0 bytes of
// column ID. Strip off that suffix to determine the
// prefix shared with the other keys for the row.
sentinelKey = sqlbase.StripColumnIDLength(kv.Key)
// Store away key for the next table row as the point from
// which to start from.
curSentinel = sentinelKey
// Delete the entire dropped columns. This used to use SQL
// UPDATE in the past to update the dropped column to
// NULL; but a column in the process of being dropped is
// placed in the table descriptor mutations, and a SQL
// UPDATE of a column in mutations will fail.
for _, columnDesc := range dropped {
// Delete the dropped column.
colKey := keys.MakeColumnKey(sentinelKey, uint32(columnDesc.ID))
if log.V(2) {
log.Infof("Del %s", colKey)
}
writeBatch.Del(colKey)
}
// Add the new columns and backfill the values.
for i, expr := range defaultExprs {
if expr == nil {
continue
}
col := added[i]
colKey := keys.MakeColumnKey(sentinelKey, uint32(col.ID))
d, err := expr.Eval(evalCtx)
if err != nil {
return err
}
marshalled[i], err = sqlbase.MarshalColumnValue(col, d)
if err != nil {
return err
}
if log.V(2) {
log.Infof("Put %s -> %v", colKey, d)
}
// Insert default value into the column. If this row
// was recently added the default value might have
// already been populated, because the
// ColumnDescriptor is in the WRITE_ONLY state.
// Reinserting the default value is not a big deal.
//
// Note: a column in the WRITE_ONLY state cannot be
// populated directly through SQL. A SQL INSERT cannot
// directly reference the column, and the INSERT
// populates the column with the default value.
writeBatch.Put(colKey, &marshalled[i])
}
}
}
}
if err := txn.Run(writeBatch); err != nil {
for _, r := range writeBatch.Results {
if r.PErr != nil {
return convertBackfillError(tableDesc, writeBatch, r.PErr)
}
}
return err
}
return nil
})
return curSentinel.PrefixEnd(), done, err
}
func (sc *SchemaChanger) truncateAndBackfillColumnsChunk(
added []sqlbase.ColumnDescriptor,
dropped []sqlbase.ColumnDescriptor,
defaultExprs []parser.TypedExpr,
evalCtx *parser.EvalContext,
sp sqlbase.Span,
) (roachpb.Key, bool, error) {
var curIndexKey roachpb.Key
done := false
err := sc.db.Txn(func(txn *client.Txn) error {
tableDesc, err := getTableDescFromID(txn, sc.tableID)
if err != nil {
return err
}
// Short circuit the backfill if the table has been deleted.
if tableDesc.Deleted() {
done = true
return nil
}
updateCols := append(added, dropped...)
fkTables := TablesNeededForFKs(*tableDesc, CheckUpdates)
for k := range fkTables {
if fkTables[k], err = getTableDescFromID(txn, k); err != nil {
return err
}
}
// TODO(dan): Tighten up the bound on the requestedCols parameter to
// makeRowUpdater.
requestedCols := make([]sqlbase.ColumnDescriptor, 0, len(tableDesc.Columns)+len(added))
requestedCols = append(requestedCols, tableDesc.Columns...)
requestedCols = append(requestedCols, added...)
ru, err := makeRowUpdater(
txn, tableDesc, fkTables, updateCols, requestedCols, rowUpdaterOnlyColumns,
)
if err != nil {
return err
}
// TODO(dan): This check is an unfortunate bleeding of the internals of
// rowUpdater. Extract the sql row to k/v mapping logic out into something
// usable here.
if !ru.isColumnOnlyUpdate() {
panic("only column data should be modified, but the rowUpdater is configured otherwise")
}
// Run a scan across the table using the primary key. Running
// the scan and applying the changes in many transactions is
// fine because the schema change is in the correct state to
// handle intermediate OLTP commands which delete and add
// values during the scan.
var rf sqlbase.RowFetcher
colIDtoRowIndex := colIDtoRowIndexFromCols(tableDesc.Columns)
valNeededForCol := make([]bool, len(tableDesc.Columns))
for i := range valNeededForCol {
_, valNeededForCol[i] = ru.fetchColIDtoRowIndex[tableDesc.Columns[i].ID]
}
err = rf.Init(tableDesc, colIDtoRowIndex, &tableDesc.PrimaryIndex, false, false,
tableDesc.Columns, valNeededForCol)
if err != nil {
return err
}
// StartScan uses 0 as a sentinal for the default limit of entries scanned.
if err := rf.StartScan(txn, sqlbase.Spans{sp}, 0); err != nil {
return err
}
indexKeyPrefix := sqlbase.MakeIndexKeyPrefix(tableDesc, tableDesc.PrimaryIndex.ID)
oldValues := make(parser.DTuple, len(ru.fetchCols))
updateValues := make(parser.DTuple, len(updateCols))
writeBatch := &client.Batch{}
var i int
for ; i < ColumnTruncateAndBackfillChunkSize; i++ {
row, err := rf.NextRow()
if err != nil {
return err
}
if row == nil {
break // Done
}
curIndexKey, _, err = sqlbase.EncodeIndexKey(
tableDesc, &tableDesc.PrimaryIndex, colIDtoRowIndex, row, indexKeyPrefix)
for j, col := range added {
if defaultExprs == nil || defaultExprs[j] == nil {
updateValues[j] = parser.DNull
} else {
updateValues[j], err = defaultExprs[j].Eval(evalCtx)
if err != nil {
return err
}
}
if !col.Nullable && updateValues[j].Compare(parser.DNull) == 0 {
return sqlbase.NewNonNullViolationError(col.Name)
}
}
for j := range dropped {
updateValues[j+len(added)] = parser.DNull
}
copy(oldValues, row)
for j := len(row); j < len(oldValues); j++ {
oldValues[j] = parser.DNull
}
if _, err := ru.updateRow(writeBatch, oldValues, updateValues); err != nil {
return err
}
}
if i < ColumnTruncateAndBackfillChunkSize {
done = true
}
if err := txn.Run(writeBatch); err != nil {
return convertBackfillError(tableDesc, writeBatch)
}
return nil
})
return curIndexKey.PrefixEnd(), done, err
}