DbDirectory (Lucene 2.9.4 API)

java.lang.Object
- org.apache.lucene.store.Directory
- - org.apache.lucene.store.db.DbDirectory

```
public class DbDirectory
extends Directory
```
A DbDirectory is a Berkeley DB 4.3 based implementation of Directory. It uses two Db database handles, one for storing file records and another for storing file data blocks.

Field Summary

Fields
Modifier and Type Field and Description

protected Db blocks

protected Db files

protected int flags

protected java.util.Set openFiles

protected DbTxn txn
- Fields inherited from class org.apache.lucene.store.Directory
  isOpen, lockFactory

Fields
Modifier and Type	Field and Description
`protected Db`	`blocks`
`protected Db`	`files`
`protected int`	`flags`
`protected java.util.Set`	`openFiles`
`protected DbTxn`	`txn`

Constructor Summary

Constructors
Constructor and Description
`DbDirectory(DbTxn txn, Db files, Db blocks, int flags)` Instantiate a DbDirectory.
`DbDirectory(Transaction txn, Database files, Database blocks)`
`DbDirectory(Transaction txn, Database files, Database blocks, int flags)`

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`close()` Closes the store.
`IndexOutput`	`createOutput(java.lang.String name)` Creates a new, empty file in the directory with the given name.
`void`	`deleteFile(java.lang.String name)` Removes an existing file in the directory.
`boolean`	`fileExists(java.lang.String name)` Returns true iff a file with the given name exists.
`long`	`fileLength(java.lang.String name)` Returns the length of a file in the directory.
`long`	`fileModified(java.lang.String name)` Returns the time the named file was last modified.
`void`	`flush()` Flush the currently open files.
`java.lang.String[]`	`list()` List the files in the directory.
`Lock`	`makeLock(java.lang.String name)` Construct a `Lock`.
`IndexInput`	`openInput(java.lang.String name)` Returns a stream reading an existing file.
`void`	`renameFile(java.lang.String from, java.lang.String to)` Renames an existing file in the directory.
`void`	`setTransaction(DbTxn txn)` Once a transaction handle was committed it is no longer valid.
`void`	`setTransaction(Transaction txn)` Once a transaction handle was committed it is no longer valid.
`void`	`touchFile(java.lang.String name)` Set the modified time of an existing file to now.

Methods inherited from class org.apache.lucene.store.Directory
clearLock, copy, ensureOpen, getLockFactory, getLockID, listAll, openInput, setLockFactory, sync, toString

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - openFiles
```
protected java.util.Set openFiles
```
  - files
```
protected Db files
```
  - blocks
```
protected Db blocks
```
  - txn
```
protected DbTxn txn
```
  - flags
```
protected int flags
```
- Constructor Detail
  - DbDirectory
```
public DbDirectory(DbTxn txn,
                   Db files,
                   Db blocks,
                   int flags)
```
    Instantiate a DbDirectory. The same threading rules that apply to Berkeley DB handles apply to instances of DbDirectory.
    
    Parameters:
    
    txn - a transaction handle that is going to be used for all db operations done by this instance. This parameter may be null.
    
    files - a db handle to store file records.
    
    blocks - a db handle to store file data blocks.
    
    flags - flags used for db read operations.
  - DbDirectory
```
public DbDirectory(Transaction txn,
                   Database files,
                   Database blocks,
                   int flags)
```
  - DbDirectory
```
public DbDirectory(Transaction txn,
                   Database files,
                   Database blocks)
```
- Method Detail
  - close
```
public void close()
           throws java.io.IOException
```
    Description copied from class: Directory
    
    Closes the store.
    
    Specified by:
    
    close in class Directory
    
    Throws:
    
    java.io.IOException
  - flush
```
public void flush()
           throws java.io.IOException
```
    Flush the currently open files. After they have been flushed it is safe to commit the transaction without closing this DbDirectory instance first.
    
    Throws:
    
    java.io.IOException
    
    See Also:
    
    setTransaction(Transaction)
  - createOutput
```
public IndexOutput createOutput(java.lang.String name)
                         throws java.io.IOException
```
    Description copied from class: Directory
    
    Creates a new, empty file in the directory with the given name. Returns a stream writing this file.
    
    Specified by:
    
    createOutput in class Directory
    
    Throws:
    
    java.io.IOException
  - deleteFile
```
public void deleteFile(java.lang.String name)
                throws java.io.IOException
```
    Description copied from class: Directory
    
    Removes an existing file in the directory.
    
    Specified by:
    
    deleteFile in class Directory
    
    Throws:
    
    java.io.IOException
  - fileExists
```
public boolean fileExists(java.lang.String name)
                   throws java.io.IOException
```
    Description copied from class: Directory
    
    Returns true iff a file with the given name exists.
    
    Specified by:
    
    fileExists in class Directory
    
    Throws:
    
    java.io.IOException
  - fileLength
```
public long fileLength(java.lang.String name)
                throws java.io.IOException
```
    Description copied from class: Directory
    
    Returns the length of a file in the directory.
    
    Specified by:
    
    fileLength in class Directory
    
    Throws:
    
    java.io.IOException
  - fileModified
```
public long fileModified(java.lang.String name)
                  throws java.io.IOException
```
    Description copied from class: Directory
    
    Returns the time the named file was last modified.
    
    Specified by:
    
    fileModified in class Directory
    
    Throws:
    
    java.io.IOException
  - list
```
public java.lang.String[] list()
                        throws java.io.IOException
```
    Description copied from class: Directory
    
    List the files in the directory.
    
    Specified by:
    
    list in class Directory
    
    Throws:
    
    java.io.IOException
  - openInput
```
public IndexInput openInput(java.lang.String name)
                     throws java.io.IOException
```
    Description copied from class: Directory
    
    Returns a stream reading an existing file.
    
    Specified by:
    
    openInput in class Directory
    
    Throws:
    
    java.io.IOException
  - makeLock
```
public Lock makeLock(java.lang.String name)
```
    Description copied from class: Directory
    
    Construct a Lock.
    
    Overrides:
    
    makeLock in class Directory
    
    Parameters:
    
    name - the name of the lock file
  - renameFile
```
public void renameFile(java.lang.String from,
                       java.lang.String to)
                throws java.io.IOException
```
    Description copied from class: Directory
    
    Renames an existing file in the directory. If a file already exists with the new name, then it is replaced. This replacement is not guaranteed to be atomic.
    
    Specified by:
    
    renameFile in class Directory
    
    Throws:
    
    java.io.IOException
  - touchFile
```
public void touchFile(java.lang.String name)
               throws java.io.IOException
```
    Description copied from class: Directory
    
    Set the modified time of an existing file to now.
    
    Specified by:
    
    touchFile in class Directory
    
    Throws:
    
    java.io.IOException
  - setTransaction
```
public void setTransaction(Transaction txn)
```
    Once a transaction handle was committed it is no longer valid. In order to continue using this DbDirectory instance after a commit, the transaction handle has to be replaced.
    
    Parameters:
    
    txn - the new transaction handle to use
  - setTransaction
```
public void setTransaction(DbTxn txn)
```
    Once a transaction handle was committed it is no longer valid. In order to continue using this DbDirectory instance after a commit, the transaction handle has to be replaced.
    
    Parameters:
    
    txn - the new transaction handle to use

Class DbDirectory

Field Summary

Fields inherited from class org.apache.lucene.store.Directory

Constructor Summary

Method Summary

Methods inherited from class org.apache.lucene.store.Directory

Methods inherited from class java.lang.Object

Field Detail

openFiles

files

blocks

txn

flags

Constructor Detail

DbDirectory

DbDirectory

DbDirectory

Method Detail

close

flush

createOutput

deleteFile

fileExists

fileLength

fileModified

list

openInput

makeLock

renameFile

touchFile

setTransaction

setTransaction