Oh right, I confused TermEnum.skipTo w/ TermDocs.seek. Thanks for reminding
me that.
BTW, the flex implementation looks really useful. I like it that I won't
need to compare the field anymore. Looking forward to it.
Thanks
Shai
On Sun, Jan 17, 2010 at 12:24 PM, Michael McCandless <
luc...@mikemccandless.com> wrote:
> On Sun, Jan 17, 2010 at 5:01 AM, Shai Erera <ser...@gmail.com> wrote:
>
> > I remember a while ago a discussion around the efficiency of
> TermDocs.seek
> > and how it is inefficient and it's better to call IndexReader.termDocs
> > instead (actually someone was proposing to remove seek entirely from the
> > interface because of that). I've looked at FieldCacheImpl's
> > ByteCache.createValue and noticed it calls termDocs.seek.
>
> Actually, I think the discussion was about TermEnum.skipTo, which is
> in fact now removed as of 3.0, not TermDocs.seek. I think
> TermDocs.seek is OK to call.
>
> > So is it 'safe' to call seek again? Has the implementation improved? I
> > checked SegmentTermDocs change history but didn't see anything related,
> nor
> > in FieldCacheImpl. I'm iterating a TermEnum and need to get the documents
> > associated with each term. Basically, more or so what FieldCacheImpl
> does.
> > So I thought to use the same methodology (I used to call reader.termDocs
> on
> > every term before I saw FieldCacheImpl's implementation). Since TermEnum
> > moves forward, I hope that termDocs.seek will move forward as well, and I
> > only do it within the same field.
>
> I think TermDocs.seek has no forward only "constraint", meaning,
> whatever term you give it (whether it's before or after where it
> currently is), it will go to.
>
> > BTW, if there is a better way to do what I'm trying to (such as a better
> > API), I'd appreciate if you can give me a hint.
>
> Just to give a preview of the current flex API... you'd do it roughly
> like this (this is what FieldCacheImpl on flex branch does):
>
> // represents all terms in the field
> Terms terms = reader.fields().terms(field);
>
> // assuming you want to skip the deleted docs...
> Bits skipDocs = reader.getDeletedDocs();
>
> if (terms != null) {
> // field exists
> TermsEnum termsEnum = terms.iterator();
> while(true) {
> final BytesRef term = termsEnum.next();
> if (term == null) {
> break;
> }
> DocsEnum docs = termsEnum.docs(skipDocs);
> while(true) {
> final int docID = docs.nextDoc();
> if (docID == DocsEnum.NO_MORE_DOCS) {
> break;
> }
> // do something with docID
> }
> }
> }
>
> Mike
>
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