As an example, consider following index on integer attributes.
SQL>create index X on T (A, B, C) nologging;
Single range scan means that bounds are set on
an initial sequence of index keys, and all but last is an equality.
For example following scans are supported (the last 2 not via NDB ODBC).
SQL>select * from T where A = 1;
SQL>select * from T where A = 1 and B = 10 and C = 20;
SQL>select * from T where A < 10;
SQL>select * from T where A = 1 and 10 < B and B < 20;
Following scans are NOT supported:
SQL>select * from T where B = 1;
SQL>select * from T where A < 10 and B < 20;
| Feature | Now | Jan 30 | Mar 01 | Never |
|---|---|---|---|---|
| Index maintenance | X | - | - | - |
| Basic scan | X 1) | - | - | - |
| Scan bounds on nullable attributes | - | X | - | - |
| Scan with locking | - | X | - | - |
| NDB ODBC equality bounds | - | X | - | - |
| MySQL integration | - | X | - | - |
| Index build | 2) | X | - | - |
| Unlimited number of scans | 3) | - | X | - |
| Total ordering | - | - | X | - |
| Multiple range scan | - | - | X | - |
| NDB ODBC range bounds | - | - | - | X |
| Logging | - | - | - | X |
1) No locking and bounds must be on non-nullable key attributes.
2) Currently table must be empty when index is created.
3) Currently limited to 11 simultaneous per fragment.