mirror of
https://git.postgresql.org/git/postgresql.git
synced 2024-11-21 03:13:05 +08:00
Significantly improve ranking:
1) rank_cd now use weight of lexemes
2) rank_cd and rank can use any combination of normalization methods:
no normalization
normalization by log(length of document)
-----/------- by length of document
-----/------- by number of unique word in document
-----/------- by log(number of unique word in document)
-----/------- by number of covers (only rank_cd)
Improve cover's search.
TODO: changes in documentation
This commit is contained in:
Teodor Sigaev
parent
85fa9f516c
commit
38c4fe87ac
@ -2315,9 +2315,9 @@ An hour of storm to place
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The sculpture of these granite seams,
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Upon a woman s face. E. J. Pratt (1882 1964)
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'), to_tsquery('sea&thousand&years'));
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rank_cd
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---------
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1.2
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rank_cd
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-----------
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0.0555556
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(1 row)
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select rank_cd(to_tsvector('Erosion It took the sea a thousand years,
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@ -2329,9 +2329,9 @@ An hour of storm to place
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The sculpture of these granite seams,
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Upon a woman s face. E. J. Pratt (1882 1964)
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'), to_tsquery('granite&sea'));
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rank_cd
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----------
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0.880303
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rank_cd
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-----------
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0.0238095
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(1 row)
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select rank_cd(to_tsvector('Erosion It took the sea a thousand years,
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@ -2345,7 +2345,7 @@ Upon a woman s face. E. J. Pratt (1882 1964)
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'), to_tsquery('sea'));
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rank_cd
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---------
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2
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0.2
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(1 row)
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select get_covers(to_tsvector('Erosion It took the sea a thousand years,
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@ -41,7 +41,13 @@ static float weights[] = {0.1, 0.2, 0.4, 1.0};
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#define wpos(wep) ( w[ WEP_GETWEIGHT(wep) ] )
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#define DEF_NORM_METHOD 0
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#define RANK_NO_NORM 0x00
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#define RANK_NORM_LOGLENGTH 0x01
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#define RANK_NORM_LENGTH 0x02
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#define RANK_NORM_EXTDIST 0x04
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#define RANK_NORM_UNIQ 0x08
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#define RANK_NORM_LOGUNIQ 0x10
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#define DEF_NORM_METHOD RANK_NO_NORM
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static float calc_rank_or(float *w, tsvector * t, QUERYTYPE * q);
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static float calc_rank_and(float *w, tsvector * t, QUERYTYPE * q);
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@ -328,23 +334,21 @@ calc_rank(float *w, tsvector * t, QUERYTYPE * q, int4 method)
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if (res < 0)
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res = 1e-20;
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switch (method)
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{
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case 0:
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break;
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case 1:
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res /= log((float) (cnt_length(t) + 1)) / log(2.0);
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break;
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case 2:
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len = cnt_length(t);
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if (len > 0)
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res /= (float) len;
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break;
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default:
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/* internal error */
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elog(ERROR, "unrecognized normalization method: %d", method);
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if ( (method & RANK_NORM_LOGLENGTH) && t->size>0 )
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res /= log((double) (cnt_length(t) + 1)) / log(2.0);
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if ( method & RANK_NORM_LENGTH ) {
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len = cnt_length(t);
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if ( len>0 )
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res /= (float) len;
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}
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if ( (method & RANK_NORM_UNIQ) && t->size > 0 )
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res /= (float)( t->size );
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if ( (method & RANK_NORM_LOGUNIQ) && t->size > 0 )
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res /= log((double) (t->size + 1)) / log(2.0);
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return res;
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}
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@ -420,6 +424,7 @@ typedef struct
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ITEM **item;
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int16 nitem;
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bool needfree;
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uint8 wclass;
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int32 pos;
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} DocRepresentation;
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@ -452,19 +457,28 @@ reset_istrue_flag(QUERYTYPE * query)
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}
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}
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typedef struct {
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int pos;
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int p;
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int q;
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DocRepresentation *begin;
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DocRepresentation *end;
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} Extention;
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static bool
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Cover(DocRepresentation * doc, int len, QUERYTYPE * query, int *pos, int *p, int *q)
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Cover(DocRepresentation * doc, int len, QUERYTYPE * query, Extention *ext)
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{
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DocRepresentation *ptr;
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int lastpos = *pos;
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int lastpos = ext->pos;
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int i;
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bool found = false;
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reset_istrue_flag(query);
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*p = 0x7fffffff;
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*q = 0;
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ptr = doc + *pos;
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ext->p = 0x7fffffff;
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ext->q = 0;
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ptr = doc + ext->pos;
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/* find upper bound of cover from current position, move up */
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while (ptr - doc < len)
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@ -473,9 +487,10 @@ Cover(DocRepresentation * doc, int len, QUERYTYPE * query, int *pos, int *p, int
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ptr->item[i]->istrue = 1;
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if (TS_execute(GETQUERY(query), NULL, false, checkcondition_ITEM))
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{
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if (ptr->pos > *q)
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if (ptr->pos > ext->q)
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{
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*q = ptr->pos;
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ext->q = ptr->pos;
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ext->end = ptr;
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lastpos = ptr - doc;
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found = true;
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}
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@ -498,25 +513,27 @@ Cover(DocRepresentation * doc, int len, QUERYTYPE * query, int *pos, int *p, int
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ptr->item[i]->istrue = 1;
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if (TS_execute(GETQUERY(query), NULL, true, checkcondition_ITEM))
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{
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if (ptr->pos < *p)
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*p = ptr->pos;
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if (ptr->pos < ext->p) {
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ext->begin = ptr;
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ext->p = ptr->pos;
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}
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break;
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}
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ptr--;
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}
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if (*p <= *q)
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if (ext->p <= ext->q)
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{
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/*
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* set position for next try to next lexeme after begining of founded
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* cover
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*/
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*pos = (ptr - doc) + 1;
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ext->pos = (ptr - doc) + 1;
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return true;
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}
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(*pos)++;
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return Cover(doc, len, query, pos, p, q);
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ext->pos++;
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return Cover(doc, len, query, ext);
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}
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static DocRepresentation *
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@ -593,6 +610,7 @@ get_docrep(tsvector * txt, QUERYTYPE * query, int *doclen)
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doc[cur].item = doc[cur - 1].item;
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}
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doc[cur].pos = WEP_GETPOS(post[j]);
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doc[cur].wclass = WEP_GETWEIGHT(post[j]);
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cur++;
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}
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}
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@ -610,61 +628,110 @@ get_docrep(tsvector * txt, QUERYTYPE * query, int *doclen)
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return NULL;
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}
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Datum
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rank_cd(PG_FUNCTION_ARGS)
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{
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int K = PG_GETARG_INT32(0);
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tsvector *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(1));
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QUERYTYPE *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(2));
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int method = DEF_NORM_METHOD;
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static float4
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calc_rank_cd(float4 *arrdata, tsvector *txt, QUERYTYPE *query, int method) {
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DocRepresentation *doc;
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float res = 0.0;
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int p = 0,
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q = 0,
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len,
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cur,
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int len,
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i,
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doclen = 0;
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Extention ext;
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double Wdoc = 0.0;
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double invws[lengthof(weights)];
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double SumDist=0.0, PrevExtPos=0.0, CurExtPos=0.0;
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int NExtent=0;
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for (i = 0; i < lengthof(weights); i++)
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{
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invws[i] = ((double)((arrdata[i] >= 0) ? arrdata[i] : weights[i]));
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if (invws[i] > 1.0)
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ereport(ERROR,
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(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
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errmsg("weight out of range")));
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invws[i] = 1.0/invws[i];
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}
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doc = get_docrep(txt, query, &doclen);
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if (!doc)
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{
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PG_FREE_IF_COPY(txt, 1);
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PG_FREE_IF_COPY(query, 2);
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PG_RETURN_FLOAT4(0.0);
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if (!doc)
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return 0.0;
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MemSet( &ext, 0, sizeof(Extention) );
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while (Cover(doc, doclen, query, &ext)) {
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double Cpos = 0.0;
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double InvSum = 0.0;
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DocRepresentation *ptr = ext.begin;
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while ( ptr<=ext.end ) {
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InvSum += invws[ ptr->wclass ];
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ptr++;
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}
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Cpos = ((double)( ext.end-ext.begin+1 )) / InvSum;
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Wdoc += Cpos / ( (double)(( 1 + (ext.q - ext.p) - (ext.end - ext.begin) )) );
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CurExtPos = ((double)(ext.q + ext.p))/2.0;
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if ( NExtent>0 && CurExtPos > PrevExtPos /* prevent devision by zero in a case of multiple lexize */ )
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SumDist += 1.0/( CurExtPos - PrevExtPos );
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PrevExtPos = CurExtPos;
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NExtent++;
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}
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cur = 0;
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if (K <= 0)
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K = 4;
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while (Cover(doc, doclen, query, &cur, &p, &q))
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res += (q - p + 1 > K) ? ((float) K) / ((float) (q - p + 1)) : 1.0;
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if ( (method & RANK_NORM_LOGLENGTH) && txt->size > 0 )
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Wdoc /= log((double) (cnt_length(txt) + 1));
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if (PG_NARGS() == 4)
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method = PG_GETARG_INT32(3);
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switch (method)
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{
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case 0:
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break;
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case 1:
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res /= log((float) (cnt_length(txt) + 1));
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break;
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case 2:
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len = cnt_length(txt);
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if (len > 0)
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res /= (float) len;
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break;
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default:
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/* internal error */
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elog(ERROR, "unrecognized normalization method: %d", method);
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if ( method & RANK_NORM_LENGTH ) {
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len = cnt_length(txt);
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if ( len>0 )
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Wdoc /= (double) len;
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}
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if ( (method & RANK_NORM_EXTDIST) && SumDist > 0 )
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Wdoc /= ((double)NExtent) / SumDist;
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if ( (method & RANK_NORM_UNIQ) && txt->size > 0 )
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Wdoc /= (double)( txt->size );
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if ( (method & RANK_NORM_LOGUNIQ) && txt->size > 0 )
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Wdoc /= log((double) (txt->size + 1)) / log(2.0);
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for (i = 0; i < doclen; i++)
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if (doc[i].needfree)
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pfree(doc[i].item);
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pfree(doc);
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return (float4)Wdoc;
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}
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Datum
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rank_cd(PG_FUNCTION_ARGS)
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{
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ArrayType *win = (ArrayType *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
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tsvector *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(1));
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QUERYTYPE *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(2));
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int method = DEF_NORM_METHOD;
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float4 res;
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if (ARR_NDIM(win) != 1)
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ereport(ERROR,
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(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
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errmsg("array of weight must be one-dimensional")));
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if (ARRNELEMS(win) < lengthof(weights))
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ereport(ERROR,
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(errcode(ERRCODE_ARRAY_SUBSCRIPT_ERROR),
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errmsg("array of weight is too short")));
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if (ARR_HASNULL(win))
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ereport(ERROR,
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(errcode(ERRCODE_NULL_VALUE_NOT_ALLOWED),
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errmsg("array of weight must not contain nulls")));
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if (PG_NARGS() == 4)
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method = PG_GETARG_INT32(3);
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res = calc_rank_cd( (float4 *) ARR_DATA_PTR(win), txt, query, method);
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PG_FREE_IF_COPY(win, 0);
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PG_FREE_IF_COPY(txt, 1);
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PG_FREE_IF_COPY(query, 2);
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@ -675,13 +742,16 @@ rank_cd(PG_FUNCTION_ARGS)
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Datum
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rank_cd_def(PG_FUNCTION_ARGS)
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{
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PG_RETURN_DATUM(DirectFunctionCall4(
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rank_cd,
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Int32GetDatum(-1),
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PG_GETARG_DATUM(0),
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PG_GETARG_DATUM(1),
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(PG_NARGS() == 3) ? PG_GETARG_DATUM(2) : Int32GetDatum(DEF_NORM_METHOD)
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));
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tsvector *txt = (tsvector *) PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
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QUERYTYPE *query = (QUERYTYPE *) PG_DETOAST_DATUM_COPY(PG_GETARG_DATUM(1));
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float4 res;
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res = calc_rank_cd( weights, txt, query, (PG_NARGS() == 3) ? PG_GETARG_DATUM(2) : DEF_NORM_METHOD);
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PG_FREE_IF_COPY(txt, 1);
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PG_FREE_IF_COPY(query, 2);
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PG_RETURN_FLOAT4(res);
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}
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/**************debug*************/
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@ -721,11 +791,9 @@ get_covers(PG_FUNCTION_ARGS)
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text *out;
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char *cptr;
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DocRepresentation *doc;
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int pos = 0,
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p,
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q,
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olddwpos = 0;
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int olddwpos = 0;
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int ncover = 1;
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Extention ext;
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doc = get_docrep(txt, query, &rlen);
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@ -765,14 +833,15 @@ get_covers(PG_FUNCTION_ARGS)
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}
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qsort((void *) dw, dlen, sizeof(DocWord), compareDocWord);
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while (Cover(doc, rlen, query, &pos, &p, &q))
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MemSet( &ext, 0, sizeof(Extention) );
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while (Cover(doc, rlen, query, &ext))
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{
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dwptr = dw + olddwpos;
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while (dwptr->pos < p && dwptr - dw < dlen)
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while (dwptr->pos < ext.p && dwptr - dw < dlen)
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dwptr++;
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olddwpos = dwptr - dw;
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dwptr->start = ncover;
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while (dwptr->pos < q + 1 && dwptr - dw < dlen)
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while (dwptr->pos < ext.q + 1 && dwptr - dw < dlen)
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dwptr++;
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(dwptr - 1)->finish = ncover;
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len += 4 /* {}+two spaces */ + 2 * 16 /* numbers */ ;
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@ -534,12 +534,12 @@ RETURNS float4
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AS 'MODULE_PATHNAME', 'rank_def'
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LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;
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CREATE FUNCTION rank_cd(int4, tsvector, tsquery)
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CREATE FUNCTION rank_cd(float4[], tsvector, tsquery)
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RETURNS float4
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AS 'MODULE_PATHNAME'
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LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;
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CREATE FUNCTION rank_cd(int4, tsvector, tsquery, int4)
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CREATE FUNCTION rank_cd(float4[], tsvector, tsquery, int4)
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RETURNS float4
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AS 'MODULE_PATHNAME'
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LANGUAGE C RETURNS NULL ON NULL INPUT IMMUTABLE;
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