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https://issues.apache.org/jira/browse/LUCENE-1458?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Michael McCandless updated LUCENE-1458:
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Attachment: LUCENE-1458.tar.bz2
LUCENE-1458-back-compat.patch
Attached current patch. All tests pass:
* Cutover merging to flex API.
* Cutover FieldCache to flex API. This got tricky, because terms
are now UTF8 byte[]. First, we have a back-compat issue (I
changed FieldCache's parsers to take TermRef not String). Second,
parsing float/double from byte[] is tricky. I just punted and
made a new String(), and then called parseDouble/parseFloat, which
is slow (but, NumericFields don't do this -- they are easy to
parse straight from byte[], I think). Net/net this should be
faster loading the FieldCache now. Also, later we can make a
String/StringIndex FieldCache variant that keeps things as byte[].
* Cutover CheckIndex to flex API.
* Removed the codec-owned extensions from IndexFileNames; added
methods to quey a Codec for all file extensions it may write. As
part of this there is a minor (I think) runtime change whereby
Directory.copy or new RamDirectory(Directory) will now copy all
files not just index-related files.
I'm now working towards getting this committable. While PforDelta
works, I think we should move its codec over to LUCENE-1410 and get it
working well, separately, after this is committed.
Still need to cutover more stuff (queries, AllTermDocs, etc.) to flex
API, get the ThreadLocal cache carried over, fix a bunch of nocommits,
remove debugging, do perf testing & fix issues, add some more tests,
etc.
> Further steps towards flexible indexing
> ---------------------------------------
>
> Key: LUCENE-1458
> URL: https://issues.apache.org/jira/browse/LUCENE-1458
> Project: Lucene - Java
> Issue Type: New Feature
> Components: Index
> Affects Versions: 2.9
> Reporter: Michael McCandless
> Assignee: Michael McCandless
> Priority: Minor
> Attachments: LUCENE-1458-back-compat.patch,
> LUCENE-1458-back-compat.patch, LUCENE-1458-back-compat.patch,
> LUCENE-1458-back-compat.patch, LUCENE-1458-back-compat.patch,
> LUCENE-1458.patch, LUCENE-1458.patch, LUCENE-1458.patch, LUCENE-1458.patch,
> LUCENE-1458.patch, LUCENE-1458.patch, LUCENE-1458.tar.bz2,
> LUCENE-1458.tar.bz2, LUCENE-1458.tar.bz2, LUCENE-1458.tar.bz2,
> LUCENE-1458.tar.bz2, LUCENE-1458.tar.bz2
>
>
> I attached a very rough checkpoint of my current patch, to get early
> feedback. All tests pass, though back compat tests don't pass due to
> changes to package-private APIs plus certain bugs in tests that
> happened to work (eg call TermPostions.nextPosition() too many times,
> which the new API asserts against).
> [Aside: I think, when we commit changes to package-private APIs such
> that back-compat tests don't pass, we could go back, make a branch on
> the back-compat tag, commit changes to the tests to use the new
> package private APIs on that branch, then fix nightly build to use the
> tip of that branch?o]
> There's still plenty to do before this is committable! This is a
> rather large change:
> * Switches to a new more efficient terms dict format. This still
> uses tii/tis files, but the tii only stores term & long offset
> (not a TermInfo). At seek points, tis encodes term & freq/prox
> offsets absolutely instead of with deltas delta. Also, tis/tii
> are structured by field, so we don't have to record field number
> in every term.
> .
> On first 1 M docs of Wikipedia, tii file is 36% smaller (0.99 MB
> -> 0.64 MB) and tis file is 9% smaller (75.5 MB -> 68.5 MB).
> .
> RAM usage when loading terms dict index is significantly less
> since we only load an array of offsets and an array of String (no
> more TermInfo array). It should be faster to init too.
> .
> This part is basically done.
> * Introduces modular reader codec that strongly decouples terms dict
> from docs/positions readers. EG there is no more TermInfo used
> when reading the new format.
> .
> There's nice symmetry now between reading & writing in the codec
> chain -- the current docs/prox format is captured in:
> {code}
> FormatPostingsTermsDictWriter/Reader
> FormatPostingsDocsWriter/Reader (.frq file) and
> FormatPostingsPositionsWriter/Reader (.prx file).
> {code}
> This part is basically done.
> * Introduces a new "flex" API for iterating through the fields,
> terms, docs and positions:
> {code}
> FieldProducer -> TermsEnum -> DocsEnum -> PostingsEnum
> {code}
> This replaces TermEnum/Docs/Positions. SegmentReader emulates the
> old API on top of the new API to keep back-compat.
>
> Next steps:
> * Plug in new codecs (pulsing, pfor) to exercise the modularity /
> fix any hidden assumptions.
> * Expose new API out of IndexReader, deprecate old API but emulate
> old API on top of new one, switch all core/contrib users to the
> new API.
> * Maybe switch to AttributeSources as the base class for TermsEnum,
> DocsEnum, PostingsEnum -- this would give readers API flexibility
> (not just index-file-format flexibility). EG if someone wanted
> to store payload at the term-doc level instead of
> term-doc-position level, you could just add a new attribute.
> * Test performance & iterate.
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