I talked with the Hibernate people about using streams and was told that it is
not supported by all
databases.
As an alternative to the proposal below I would like to propose a filesystem
based storage mechanism.
The main advantage of using the database to store everything is that
administrators need only use
mysql_dump and they have their entire wiki backed up.
If we are to abandon that requirement, we can have much faster attachment
storage by using the
filesystem. For this, I propose BinaryStore interface remains the same but
com.xpn.xwiki.doc.BinaryObject would contain:
void addContent(InputStream content)
OutputStream addContent()
void clear()
InputStream getContent()
void getContent(OutputStream writeTo)
clear() would clear the underlying file whereas addContent would always append
to it.
The added column would look like this:
<class name="com.xpn.xwiki.store.doc.FilesystemBinaryObject"
table="filesystembinaryobject">
<id name="id" column="id">
<generator class="native" />
</id>
<property name="fileURI" type="string">
<column name="fileuri" length="255" not-null="true"/>
</property>
</class>
This would as with the original proposal be useful for not only storing
attachments but attachment
history, deleted attachments and even document history or deleted documents.
WDYT?
Caleb
On 10/15/2010 04:21 PM, Caleb James DeLisle wrote:
> Because the storage of large attachments is limited by database constraints
> and the fact that the
> JDBC does not allow us to stream content out of the database, I propose we
> add a new database table
> binarychunk.
>
> The mapping will read as follows:
>
> <class name="com.xpn.xwiki.store.hibernate.HibernateBinaryStore$BinaryChunk"
> table="binarychunk">
> <composite-id unsaved-value="undefined">
> <key-property name="id" column="id" type="integer" />
> <key-property name="chunkNumber" column="chunknumber" type="integer"
> />
> </composite-id>
>
> <property name="content" type="binary">
> <column name="content" length="983040" not-null="true"/>
> </property>
> </class>
>
> Notice the maximum length (983040 bytes) is a number which is divisible by
> many common buffer sizes
> and is slightly less than the default max_packet_size in mysql which means
> that using the
> xwikibinary table, we could store attachments of arbitrary size without
> hitting mysql default limits.
>
>
> com.xpn.xwiki.store.BinaryStore will contain:
>
> @param toLoad a binary object with an id number set, will be loaded.
> void loadObject(BinaryObject toLoad)
>
> @param toStore a binary object, if no id is present then it will be given one
> upon successful
> store, if id is present then that id number will be used.
> void storeObject(BinaryObject toStore)
>
> This will be implemented by:
> com.xpn.xwiki.store.hibernate.HibernateBinaryStore
>
>
> com.xpn.xwiki.doc.BinaryObject will contain:
>
> void setContent(InputStream content)
>
> OutputStream setContent()
>
> InputStream getContent()
>
> void getContent(OutputStream writeTo)
>
> Note: The get function and set functions will be duplicated with input or
> output streams to maximize
> ease of use.
>
> This will be implemented by com.xpn.xwiki.doc.TempFileBinaryObject which will
> store the binary
> content in a temporary FileItem (see Apache commons fileupload).
>
>
>
> + This will be able to provide a back end for not only attachment content,
> but for attachment
> archive and document archive if it is so desired.
> + I have no intent of exposing it as public API at the moment.
>
>
> WDYT?
>
> Caleb
>
> _______________________________________________
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> [email protected]
> http://lists.xwiki.org/mailman/listinfo/devs
>
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