Table of Contents
Once a database handle has been created using db_create(), there are several standard access method operations. Each of these operations is performed using a method referred to by the returned handle. Generally, the database will be opened using DB->open(). If the database is from an old release of Berkeley DB, it may need to be upgraded to the current release before it is opened using DB->upgrade().
Once a database has been opened, records may be retrieved (DB->get()), stored (DB->put()), and deleted (DB->del()).
Additional operations supported by the database handle include statistics (DB->stat()), truncation (DB->truncate()), version upgrade (DB->upgrade()), verification and salvage (DB->verify()), flushing to a backing file (DB->sync()), and association of secondary indices (DB->associate()). Database handles are eventually closed using DB->close().
| Database Operations | Description |
|---|---|
| db_create() | Create a database handle |
| DB->associate() | Associate a secondary index |
| DB->associate_foreign() | Associate a foreign index |
| DB->close() | Close a database |
| DB->compact() | Compact a database |
| DB->cursor() | Create a cursor |
| DB->del() | Delete items from a database |
| DB->err() | Error message |
| DB->existis() | Return if an item appears in a database |
| DB->fd() | Return a file descriptor from a database |
| DB->get() | Get items from a database |
| DB->get_byteswapped() | Return if the underlying database is in host order |
| DB->get_type() | Return the database type |
| DB->join() | Perform a database join on cursors |
| DB->key_range() | Return estimate of key location |
| DB->open() | Open a database |
| DB->put() | Store items into a database |
| DB->remove() | Remove a database |
| DB->rename() | Rename a database |
| DB->set_priority() | Set cache page priority |
| DB->stat() | Database statistics |
| DB->sync() | Flush a database to stable storage |
| DB->truncate() | Empty a database |
| DB->upgrade() | Upgrade a database |
| DB->verify() | Verify/salvage a database |
| Database Configuration | |
| DB->set_alloc() | Set local space allocation functions |
| DB->set_cachesize() | Set the database cache size |
| DB->set_dup_compare() | Set a duplicate comparison function |
| DB->set_encrypt() | Set the database cryptographic key |
| DB->set_errcall() | Set error and informational message callback |
| DB->set_errfile() | Set error and informational message FILE |
| DB->set_errpfx() | Set error message prefix |
| DB->set_feedback() | Set feedback callback |
| DB->set_flags() | General database configuration |
| DB->set_lorder() | Set the database byte order |
| DB->set_pagesize() | Set the underlying database page size |
| Btree/Recno Configuration | |
| DB->set_append_recno() | Set record append callback |
| DB->set_bt_compare() | Set a Btree comparison function |
| DB->set_bt_minkey() | Set the minimum number of keys per Btree page |
| DB->set_bt_prefix() | Set a Btree prefix comparison function |
| DB->set_re_delim() | Set the variable-length record delimiter |
| DB->set_re_len() | Set the fixed-length record length |
| DB->set_re_pad() | Set the fixed-length record pad byte |
| DB->set_re_source() | Set the backing Recno text file |
| Hash Configuration | |
| DB->set_h_compare() | Set a Hash comparison function |
| DB->set_h_ffactor() | Set the Hash table density |
| DB->set_h_hash() | Set a hashing function |
| DB->set_h_nelem() | Set the Hash table size |
| Queue Configuration | |
| DB->set_q_extentsize() | Set Queue database extent size |
The DB->open() method opens a database, and takes five arguments:
There are a few flags that you can set to customize open: