NAME

Xapian::Search::WritableDatabase - writable database object

DESCRIPTION

This class represents a Xapian database for indexing. It's a subclass of Xapian::Database, which is used for searching.

METHODS

new <database> <options>

Class constructor. Can either take a path to an existing database or another database class as the first parameter. the options can be DB_OPEN,DB_CREATE,DB_CREATE_OR_OPEN or DB_CREATE_OR_OVERWRITE. these are exported by Search::Xapian with the 'db' option.

clone

Return a clone of this class.

flush

Flush to disk any modifications made to the database.

For efficiency reasons, when performing multiple updates to a database it is best (indeed, almost essential) to make as many modifications as memory will permit in a single pass through the database. To ensure this, Xapian batches up modifications.

Flush may be called at any time to ensure that the modifications which have been made are written to disk: if the flush succeeds, all the preceding modifications will have been written to disk.

If any of the modifications fail, an exception will be thrown and the database will be left in a state in which each separate addition, replacement or deletion operation has either been fully performed or not performed at all: it is then up to the application to work out which operations need to be repeated.

If called within a transaction, this will flush database modifications made before the transaction was begun, but will not flush modifications made since begin_transaction() was called.

Beware of calling flush too frequently: this will have a severe performance cost.

Note that flush need not be called explicitly: it will be called automatically when the database is closed, or when a sufficient number of modifications have been made.

begin_transaction

Begin a transaction.

For the purposes of Xapian, a transaction is a group of modifications to the database which are grouped together such that either all or none of them will succeed. Even in the case of a power failure, this characteristic should be preserved (as long as the filesystem isn't corrupted, etc).

Transactions are only available with certain access methods, and as you might expect will generally have a fairly high performance cost.

commit_transaction

End the transaction currently in progress, committing the modifications made to the database.

If this completes successfully, all the database modifications made during the transaction will have been committed to the database.

If an error occurs, an exception will be thrown, and none of the modifications made to the database during the transaction will have been applied to the database.

Whatever occurs, after this method the transaction will no longer be in progress.

cancel_transaction

End the transaction currently in progress, cancelling the potential modifications made to the database.

If an error occurs in this method, an exception will be thrown, but the transaction will be cancelled anyway.

add_document <document>

dd a new document to the database.

This method adds the specified document to the database, returning a newly allocated document ID.

Note that this does not mean the document will immediately appear in the database; see flush() for more details.

As with all database modification operations, the effect is atomic: the document will either be fully added, or the document fails to be added and an exception is thrown (possibly at a later time when flush is called or the database is closed).

delete_document <doc_id>

Delete a document from the database. This method removes the document with the specified document ID from the database.

Note that this does not mean the document will immediately disappear from the database; see flush() for more details.

As with all database modification operations, the effect is atomic: the document will either be fully removed, or the document fails to be removed and an exception is thrown (possibly at a later time when flush is called or the database is closed).

delete_document_by_term <term>

Delete any documents indexed by a term from the database. This method removes any documents indexed by the specified term from the database.

The intended use is to allow UIDs from another system to easily be mapped to terms in Xapian, although this method probably has other uses.

replace_document <doc_id> <document>

eplace a given document in the database.

This method replaces the document with the specified document ID. Note that this does not mean the document will immediately change in the database; see flush() for more details.

As with all database modification operations, the effect is atomic: the document will either be fully replaced, or the document fails to be replaced and an exception is thrown (possibly at a later time when flush is called or the database is closed).

replace_document_by_term <unique_term> <document>

Replace any documents matching an unique term.

This method replaces any documents indexed by the specified term with the specified document. If any documents are indexed by the term, the lowest document ID will be used for the document, otherwise a new document ID will be generated as for add_document.

The intended use is to allow UIDs from another system to easily be mapped to terms in Xapian, although this method probably has other uses.

Note that this does not mean the document(s) will immediately change in the database; see flush() for more details.

As with all database modification operations, the effect is atomic: the document(s) will either be fully replaced, or the document(s) fail to be replaced and an exception is thrown (possibly at a later time when flush is called or the database is closed).

reopen

Re-open the database. makes sure you have a fresh db handle.

SEE ALSO

Search::Xapian,Search::Xapian::Enquire,Search::Xapian::Database