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Overview
Comment:Avoid loading doclists for infrequent terms that are part of phrases twice.
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SHA1: 8f939723f742329cedba8930f71dff42004f3d0d
User & Date: dan 2011-06-17 17:37:31
Context
2011-06-17
18:52
Fix a header dependency in nmake Makefile. check-in: 54492212 user: shaneh tags: trunk
17:37
Avoid loading doclists for infrequent terms that are part of phrases twice. check-in: 8f939723 user: dan tags: trunk
16:04
Add a missing declaration to fts3Int.h. check-in: 3bfd4466 user: dan tags: trunk
Changes
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Changes to ext/fts3/fts3.c.

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            pToken->z, pToken->n, pToken->isPrefix, &pToken->pSegcsr
        );
        if( rc!=SQLITE_OK ){
          *pRc = rc;
          return;
        }
      }


    }else{
      *pnOr += (pExpr->eType==FTSQUERY_OR);
      fts3EvalAllocateReaders(pCsr, pExpr->pLeft, pnToken, pnOr, pRc);
      fts3EvalAllocateReaders(pCsr, pExpr->pRight, pnToken, pnOr, pRc);
    }
  }
}























































static int fts3EvalPhraseLoad(
  Fts3Cursor *pCsr, 
  Fts3Phrase *p
){
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  int iToken;
  int rc = SQLITE_OK;

  char *aDoclist = 0;
  int nDoclist = 0;
  int iPrev = -1;

  for(iToken=0; rc==SQLITE_OK && iToken<p->nToken; iToken++){
    Fts3PhraseToken *pToken = &p->aToken[iToken];
    assert( pToken->pSegcsr || pToken->pDeferred );


    if( pToken->pDeferred==0 ){
      int nThis = 0;
      char *pThis = 0;
      rc = fts3TermSelect(pTab, pToken, p->iColumn, 1, &nThis, &pThis);
      if( rc==SQLITE_OK ){
        if( pThis==0 ){
          sqlite3_free(aDoclist);
          aDoclist = 0;
          nDoclist = 0;
          break;
        }else if( aDoclist==0 ){
          aDoclist = pThis;
          nDoclist = nThis;
        }else{
          assert( iPrev>=0 );
          fts3DoclistPhraseMerge(pTab->bDescIdx,
              iToken-iPrev, aDoclist, nDoclist, pThis, &nThis
          );
          sqlite3_free(aDoclist);
          aDoclist = pThis;
          nDoclist = nThis;
        }
        iPrev = iToken;
      }

    }
  }

  if( rc==SQLITE_OK ){
    p->doclist.aAll = aDoclist;
    p->doclist.nAll = nDoclist;
  }else{
    sqlite3_free(aDoclist);
  }
  return rc;
}

static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
  int iToken;
  int rc = SQLITE_OK;

  int nMaxUndeferred = -1;
  char *aPoslist = 0;
  int nPoslist = 0;
  int iPrev = -1;

  assert( pPhrase->doclist.bFreeList==0 );

  for(iToken=0; rc==SQLITE_OK && iToken<pPhrase->nToken; iToken++){
................................................................................
          sqlite3_free(aPoslist);
          pPhrase->doclist.pList = 0;
          pPhrase->doclist.nList = 0;
          return SQLITE_OK;
        }
      }
      iPrev = iToken;
    }else{
      nMaxUndeferred = iToken;
    }
  }

  if( iPrev>=0 ){
    if( nMaxUndeferred<0 ){
      pPhrase->doclist.pList = aPoslist;
      pPhrase->doclist.nList = nPoslist;
................................................................................
** used with fts3EvalPhraseNext() to iterate through the matching docids.
*/
static int fts3EvalPhraseStart(Fts3Cursor *pCsr, int bOptOk, Fts3Phrase *p){
  int rc;
  Fts3PhraseToken *pFirst = &p->aToken[0];
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;

  assert( p->doclist.aAll==0 );
  if( pCsr->bDesc==pTab->bDescIdx && bOptOk==1 && p->nToken==1 



   && pFirst->pSegcsr && pFirst->pSegcsr->bLookup 
  ){
    /* Use the incremental approach. */
    int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
    rc = sqlite3Fts3MsrIncrStart(
        pTab, pFirst->pSegcsr, iCol, pFirst->z, pFirst->n);
    p->bIncr = 1;

................................................................................
      fts3EvalStartReaders(pCsr, pExpr->pLeft, bOptOk, pRc);
      fts3EvalStartReaders(pCsr, pExpr->pRight, bOptOk, pRc);
      pExpr->bDeferred = (pExpr->pLeft->bDeferred && pExpr->pRight->bDeferred);
    }
  }
}


typedef struct Fts3TokenAndCost Fts3TokenAndCost;
struct Fts3TokenAndCost {


  Fts3PhraseToken *pToken;
  Fts3Expr *pRoot;
  int nOvfl;
  int iCol;

};

static void fts3EvalTokenCosts(
  Fts3Cursor *pCsr, 
  Fts3Expr *pRoot, 
  Fts3Expr *pExpr, 
  Fts3TokenAndCost **ppTC,
................................................................................
){
  if( *pRc==SQLITE_OK && pExpr ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      for(i=0; *pRc==SQLITE_OK && i<pPhrase->nToken; i++){
        Fts3TokenAndCost *pTC = (*ppTC)++;


        pTC->pRoot = pRoot;
        pTC->pToken = &pPhrase->aToken[i];
        pTC->iCol = pPhrase->iColumn;
        *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
      }
    }else if( pExpr->eType!=FTSQUERY_NOT ){
      if( pExpr->eType==FTSQUERY_OR ){
................................................................................
    assert( pTC );

    /* At this point pTC points to the cheapest remaining token. */
    if( ii==0 ){
      if( pTC->nOvfl ){
        nDocEst = (pTC->nOvfl * pTab->nPgsz + pTab->nPgsz) / 10;
      }else{
        /* TODO: Fix this so that the doclist need not be read twice. */
        Fts3PhraseToken *pToken = pTC->pToken;
        int nList = 0;
        char *pList = 0;
        rc = fts3TermSelect(pTab, pToken, pTC->iCol, 1, &nList, &pList);
        if( rc==SQLITE_OK ){
          nDocEst = fts3DoclistCountDocids(1, pList, nList);
        }
        sqlite3_free(pList);
        if( rc==SQLITE_OK ){
          rc = sqlite3Fts3TermSegReaderCursor(pCsr, 
              pToken->z, pToken->n, pToken->isPrefix, &pToken->pSegcsr
          );


        }
      }
    }else{
      if( pTC->nOvfl>=(nDocEst*nDocSize) ){
        Fts3PhraseToken *pToken = pTC->pToken;
        rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
        fts3SegReaderCursorFree(pToken->pSegcsr);







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            pToken->z, pToken->n, pToken->isPrefix, &pToken->pSegcsr
        );
        if( rc!=SQLITE_OK ){
          *pRc = rc;
          return;
        }
      }
      assert( pExpr->pPhrase->iDoclistToken==0 );
      pExpr->pPhrase->iDoclistToken = -1;
    }else{
      *pnOr += (pExpr->eType==FTSQUERY_OR);
      fts3EvalAllocateReaders(pCsr, pExpr->pLeft, pnToken, pnOr, pRc);
      fts3EvalAllocateReaders(pCsr, pExpr->pRight, pnToken, pnOr, pRc);
    }
  }
}

static void fts3EvalPhraseMergeToken(
  Fts3Table *pTab,
  Fts3Phrase *p,
  int iToken,
  char *pList,
  int nList
){
  assert( iToken!=p->iDoclistToken );

  if( pList==0 ){
    sqlite3_free(p->doclist.aAll);
    p->doclist.aAll = 0;
    p->doclist.nAll = 0;
  }

  else if( p->iDoclistToken<0 ){
    p->doclist.aAll = pList;
    p->doclist.nAll = nList;
  }

  else if( p->doclist.aAll==0 ){
    sqlite3_free(pList);
  }

  else {
    char *pLeft;
    char *pRight;
    int nLeft;
    int nRight;
    int nDiff;

    if( p->iDoclistToken<iToken ){
      pLeft = p->doclist.aAll;
      nLeft = p->doclist.nAll;
      pRight = pList;
      nRight = nList;
      nDiff = iToken - p->iDoclistToken;
    }else{
      pRight = p->doclist.aAll;
      nRight = p->doclist.nAll;
      pLeft = pList;
      nLeft = nList;
      nDiff = p->iDoclistToken - iToken;
    }

    fts3DoclistPhraseMerge(pTab->bDescIdx, nDiff, pLeft, nLeft, pRight,&nRight);
    sqlite3_free(pLeft);
    p->doclist.aAll = pRight;
    p->doclist.nAll = nRight;
  }

  if( iToken>p->iDoclistToken ) p->iDoclistToken = iToken;
}

static int fts3EvalPhraseLoad(
  Fts3Cursor *pCsr, 
  Fts3Phrase *p
){
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;
  int iToken;
  int rc = SQLITE_OK;





  for(iToken=0; rc==SQLITE_OK && iToken<p->nToken; iToken++){
    Fts3PhraseToken *pToken = &p->aToken[iToken];

    assert( pToken->pDeferred==0 || pToken->pSegcsr==0 );

    if( pToken->pSegcsr ){
      int nThis = 0;
      char *pThis = 0;
      rc = fts3TermSelect(pTab, pToken, p->iColumn, 1, &nThis, &pThis);
      if( rc==SQLITE_OK ){
        fts3EvalPhraseMergeToken(pTab, p, iToken, pThis, nThis);















      }

    }
    assert( pToken->pSegcsr==0 );
  }








  return rc;
}

static int fts3EvalDeferredPhrase(Fts3Cursor *pCsr, Fts3Phrase *pPhrase){
  int iToken;
  int rc = SQLITE_OK;

  int nMaxUndeferred = pPhrase->iDoclistToken;
  char *aPoslist = 0;
  int nPoslist = 0;
  int iPrev = -1;

  assert( pPhrase->doclist.bFreeList==0 );

  for(iToken=0; rc==SQLITE_OK && iToken<pPhrase->nToken; iToken++){
................................................................................
          sqlite3_free(aPoslist);
          pPhrase->doclist.pList = 0;
          pPhrase->doclist.nList = 0;
          return SQLITE_OK;
        }
      }
      iPrev = iToken;


    }
  }

  if( iPrev>=0 ){
    if( nMaxUndeferred<0 ){
      pPhrase->doclist.pList = aPoslist;
      pPhrase->doclist.nList = nPoslist;
................................................................................
** used with fts3EvalPhraseNext() to iterate through the matching docids.
*/
static int fts3EvalPhraseStart(Fts3Cursor *pCsr, int bOptOk, Fts3Phrase *p){
  int rc;
  Fts3PhraseToken *pFirst = &p->aToken[0];
  Fts3Table *pTab = (Fts3Table *)pCsr->base.pVtab;


  if( pCsr->bDesc==pTab->bDescIdx 
   && bOptOk==1 
   && p->nToken==1 
   && pFirst->pSegcsr 
   && pFirst->pSegcsr->bLookup 
  ){
    /* Use the incremental approach. */
    int iCol = (p->iColumn >= pTab->nColumn ? -1 : p->iColumn);
    rc = sqlite3Fts3MsrIncrStart(
        pTab, pFirst->pSegcsr, iCol, pFirst->z, pFirst->n);
    p->bIncr = 1;

................................................................................
      fts3EvalStartReaders(pCsr, pExpr->pLeft, bOptOk, pRc);
      fts3EvalStartReaders(pCsr, pExpr->pRight, bOptOk, pRc);
      pExpr->bDeferred = (pExpr->pLeft->bDeferred && pExpr->pRight->bDeferred);
    }
  }
}


typedef struct Fts3TokenAndCost Fts3TokenAndCost;
struct Fts3TokenAndCost {
  Fts3Phrase *pPhrase;            /* The phrase the token belongs to */
  int iToken;                     /* Position of token in phrase */
  Fts3PhraseToken *pToken;        /* The token itself */
  Fts3Expr *pRoot; 
  int nOvfl;

  int iCol;                       /* The column the token must match */
};

static void fts3EvalTokenCosts(
  Fts3Cursor *pCsr, 
  Fts3Expr *pRoot, 
  Fts3Expr *pExpr, 
  Fts3TokenAndCost **ppTC,
................................................................................
){
  if( *pRc==SQLITE_OK && pExpr ){
    if( pExpr->eType==FTSQUERY_PHRASE ){
      Fts3Phrase *pPhrase = pExpr->pPhrase;
      int i;
      for(i=0; *pRc==SQLITE_OK && i<pPhrase->nToken; i++){
        Fts3TokenAndCost *pTC = (*ppTC)++;
        pTC->pPhrase = pPhrase;
        pTC->iToken = i;
        pTC->pRoot = pRoot;
        pTC->pToken = &pPhrase->aToken[i];
        pTC->iCol = pPhrase->iColumn;
        *pRc = sqlite3Fts3MsrOvfl(pCsr, pTC->pToken->pSegcsr, &pTC->nOvfl);
      }
    }else if( pExpr->eType!=FTSQUERY_NOT ){
      if( pExpr->eType==FTSQUERY_OR ){
................................................................................
    assert( pTC );

    /* At this point pTC points to the cheapest remaining token. */
    if( ii==0 ){
      if( pTC->nOvfl ){
        nDocEst = (pTC->nOvfl * pTab->nPgsz + pTab->nPgsz) / 10;
      }else{

        Fts3PhraseToken *pToken = pTC->pToken;
        int nList = 0;
        char *pList = 0;
        rc = fts3TermSelect(pTab, pToken, pTC->iCol, 1, &nList, &pList);
        assert( rc==SQLITE_OK || pList==0 );



        if( rc==SQLITE_OK ){



          nDocEst = fts3DoclistCountDocids(1, pList, nList);
          fts3EvalPhraseMergeToken(pTab, pTC->pPhrase, pTC->iToken,pList,nList);
        }
      }
    }else{
      if( pTC->nOvfl>=(nDocEst*nDocSize) ){
        Fts3PhraseToken *pToken = pTC->pToken;
        rc = sqlite3Fts3DeferToken(pCsr, pToken, pTC->iCol);
        fts3SegReaderCursorFree(pToken->pSegcsr);

Changes to ext/fts3/fts3Int.h.

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  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */

  /* Variables above this point are populated when the expression is
  ** parsed (by code in fts3_expr.c). Below this point the variables are
  ** used when evaluating the expression. */
  int bFulltext;                  /* True if full-text index was used */
  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
  Fts3MultiSegReader *pSegcsr;    /* Segment-reader for this token */
};

struct Fts3Phrase {
  /* Cache of doclist for this phrase. */
  Fts3Doclist doclist;
  int bIncr;                 /* True if doclist is loaded incrementally */


  /* Variables below this point are populated by fts3_expr.c when parsing 
  ** a MATCH expression. Everything above is part of the evaluation phase. 
  */
  int nToken;                /* Number of tokens in the phrase */
  int iColumn;               /* Index of column this phrase must match */
  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */







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  char *z;                        /* Text of the token */
  int n;                          /* Number of bytes in buffer z */
  int isPrefix;                   /* True if token ends with a "*" character */

  /* Variables above this point are populated when the expression is
  ** parsed (by code in fts3_expr.c). Below this point the variables are
  ** used when evaluating the expression. */

  Fts3DeferredToken *pDeferred;   /* Deferred token object for this token */
  Fts3MultiSegReader *pSegcsr;    /* Segment-reader for this token */
};

struct Fts3Phrase {
  /* Cache of doclist for this phrase. */
  Fts3Doclist doclist;
  int bIncr;                 /* True if doclist is loaded incrementally */
  int iDoclistToken;

  /* Variables below this point are populated by fts3_expr.c when parsing 
  ** a MATCH expression. Everything above is part of the evaluation phase. 
  */
  int nToken;                /* Number of tokens in the phrase */
  int iColumn;               /* Index of column this phrase must match */
  Fts3PhraseToken aToken[1]; /* One entry for each token in the phrase */