[ https://issues.apache.org/jira/browse/LUCENE-2373?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12885022#action_12885022 ]
Michael McCandless commented on LUCENE-2373: -------------------------------------------- bq. DefaultCodecProvider does exactly this. Or do you mean instead of using abstract methods in CodecProvider? Right, I meant move the default impls into CodecProvider, so an app with a custom CodecProvider need not implement the defaults. bq. The reading is already factored out, but the writing ... Well, it's just 8 bytes per segment ... the reason I didn't factor it out is that it would require additional before/after delegation, or a replication of larger sections of code... I hear you, but it looks sort of hackish to factor out one part (seeking to the dir) but not the other part (writing/reading the dirOffset); but I'm fine w/ committing it like this. Maybe just add a comment in AppendingTermsDictReader.seekDir that dirOffset, which the writer had written into header of file, is ignored? > Create a Codec to work with streaming and append-only filesystems > ----------------------------------------------------------------- > > Key: LUCENE-2373 > URL: https://issues.apache.org/jira/browse/LUCENE-2373 > Project: Lucene - Java > Issue Type: Improvement > Components: Index > Reporter: Andrzej Bialecki > Fix For: 4.0 > > Attachments: appending.patch > > > Since early 2.x times Lucene used a skip/seek/write trick to patch the length > of the terms dict into a place near the start of the output data file. This > however made it impossible to use Lucene with append-only filesystems such as > HDFS. > In the post-flex trunk the following code in StandardTermsDictWriter > initiates this: > {code} > // Count indexed fields up front > CodecUtil.writeHeader(out, CODEC_NAME, VERSION_CURRENT); > out.writeLong(0); // leave space for end > index pointer > {code} > and completes this in close(): > {code} > out.seek(CodecUtil.headerLength(CODEC_NAME)); > out.writeLong(dirStart); > {code} > I propose to change this layout so that this pointer is stored simply at the > end of the file. It's always 8 bytes long, and we known the final length of > the file from Directory, so it's a single additional seek(length - 8) to read > it, which is not much considering the benefits. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online. --------------------------------------------------------------------- To unsubscribe, e-mail: dev-unsubscr...@lucene.apache.org For additional commands, e-mail: dev-h...@lucene.apache.org