SQLite

** This function advances the iterator so that it points to the last 
** relevant rowid on the page and, if necessary, initializes the 
** aRowidOffset[] and iRowidOffset variables. At this point the iterator
** is in its regular state - Fts5SegIter.iLeafOffset points to the first
** byte of the position list content associated with said rowid.
*/
static void fts5SegIterReverseInitPage(Fts5Index *p, Fts5SegIter *pIter){
  int eDetail = p->pConfig->eDetail;
  int n = pIter->pLeaf->szLeaf;
  int i = pIter->iLeafOffset;
  u8 *a = pIter->pLeaf->p;
  int iRowidOffset = 0;

  if( n>pIter->iEndofDoclist ){
    n = pIter->iEndofDoclist;
  }

  ASSERT_SZLEAF_OK(pIter->pLeaf);
  while( 1 ){
    i64 iDelta = 0;
    int nPos;
    int bDummy;

    if( eDetail==FTS5_DETAIL_NONE ){
      /* todo */

    }else{
      i += fts5GetPoslistSize(&a[i], &nPos, &bDummy);
      i += nPos;
    }
    if( i>=n ) break;
    i += fts5GetVarint(&a[i], (u64*)&iDelta);
    pIter->iRowid += iDelta;

    /* If necessary, grow the pIter->aRowidOffset[] array. */
    if( iRowidOffset>=pIter->nRowidOffset ){
      int nNew = pIter->nRowidOffset + 8;
      int *aNew = (int*)sqlite3_realloc(pIter->aRowidOffset, nNew*sizeof(int));
      if( aNew==0 ){
        p->rc = SQLITE_NOMEM;
        break;
      }

        int iOff;
        int nPos;
        int bDummy;
        i64 iDelta;

        pIter->iRowidOffset--;
        pIter->iLeafOffset = iOff = pIter->aRowidOffset[pIter->iRowidOffset];
        if( p->pConfig->eDetail!=FTS5_DETAIL_NONE ){
          iOff += fts5GetPoslistSize(&a[iOff], &nPos, &bDummy);
          iOff += nPos;
        }
        fts5GetVarint(&a[iOff], (u64*)&iDelta);
        pIter->iRowid -= iDelta;
        fts5SegIterLoadNPos(p, pIter);
      }else{
        fts5SegIterReverseNewPage(p, pIter);
      }
    }else{

/*
** Iterator pIter currently points to the first rowid in a doclist. This
** function sets the iterator up so that iterates in reverse order through
** the doclist.
*/
static void fts5SegIterReverse(Fts5Index *p, Fts5SegIter *pIter){
  int eDetail = p->pConfig->eDetail;
  Fts5DlidxIter *pDlidx = pIter->pDlidx;
  Fts5Data *pLast = 0;
  int pgnoLast = 0;

  if( pDlidx ){
    int iSegid = pIter->pSeg->iSegid;
    pgnoLast = fts5DlidxIterPgno(pDlidx);
    pLast = fts5DataRead(p, FTS5_SEGMENT_ROWID(iSegid, pgnoLast));
  }else{
    Fts5Data *pLeaf = pIter->pLeaf;         /* Current leaf data */

    /* Currently, Fts5SegIter.iLeafOffset points to the first byte of
    ** position-list content for the current rowid. Back it up so that it
    ** points to the start of the position-list size field. */
    if( eDetail!=FTS5_DETAIL_NONE ){
      pIter->iLeafOffset -= sqlite3Fts5GetVarintLen(pIter->nPos*2+pIter->bDel);
    }

    /* If this condition is true then the largest rowid for the current
    ** term may not be stored on the current page. So search forward to
    ** see where said rowid really is.  */
    if( pIter->iEndofDoclist>=pLeaf->szLeaf ){
      int pgno;
      Fts5StructureSegment *pSeg = pIter->pSeg;

  int nRem = pSeg->nPos;          /* Number of bytes still to come */
  Fts5Data *pData = 0;
  u8 *pChunk = &pSeg->pLeaf->p[pSeg->iLeafOffset];
  int nChunk = MIN(nRem, pSeg->pLeaf->szLeaf - pSeg->iLeafOffset);
  int pgno = pSeg->iLeafPgno;
  int pgnoSave = 0;

  /* This function does notmwork with detail=none databases. */
  assert( p->pConfig->eDetail!=FTS5_DETAIL_NONE );

  if( (pSeg->flags & FTS5_SEGITER_REVERSE)==0 ){
    pgnoSave = pgno+1;
  }

  while( 1 ){
    xChunk(p, pCtx, pChunk, nChunk);
    nRem -= nChunk;

/*
** Append a rowid and position-list size field to the writers output. 
*/
static void fts5WriteAppendRowid(
  Fts5Index *p, 
  Fts5SegWriter *pWriter,
  i64 iRowid

){
  if( p->rc==SQLITE_OK ){
    Fts5PageWriter *pPage = &pWriter->writer;

    if( (pPage->buf.n + pPage->pgidx.n)>=p->pConfig->pgsz ){
      fts5WriteFlushLeaf(p, pWriter);
    }

    }else{
      assert( p->rc || iRowid>pWriter->iPrevRowid );
      fts5BufferAppendVarint(&p->rc, &pPage->buf, iRowid - pWriter->iPrevRowid);
    }
    pWriter->iPrevRowid = iRowid;
    pWriter->bFirstRowidInDoclist = 0;
    pWriter->bFirstRowidInPage = 0;


  }
}

static void fts5WriteAppendPoslistData(
  Fts5Index *p, 
  Fts5SegWriter *pWriter, 
  const u8 *aData, 

  Fts5IndexIter *pIter = 0;       /* Iterator to read input data */
  int nRem = pnRem ? *pnRem : 0;  /* Output leaf pages left to write */
  int nInput;                     /* Number of input segments */
  Fts5SegWriter writer;           /* Writer object */
  Fts5StructureSegment *pSeg;     /* Output segment */
  Fts5Buffer term;
  int bOldest;                    /* True if the output segment is the oldest */
  int eDetail = p->pConfig->eDetail;

  assert( iLvl<pStruct->nLevel );
  assert( pLvl->nMerge<=pLvl->nSeg );

  memset(&writer, 0, sizeof(Fts5SegWriter));
  memset(&term, 0, sizeof(Fts5Buffer));
  if( pLvl->nMerge ){

      /* This is a new term. Append a term to the output segment. */
      fts5WriteAppendTerm(p, &writer, nTerm, pTerm);
      fts5BufferSet(&p->rc, &term, nTerm, pTerm);
    }

    /* Append the rowid to the output */
    /* WRITEPOSLISTSIZE */

    fts5WriteAppendRowid(p, &writer, fts5MultiIterRowid(pIter));

    if( eDetail==FTS5_DETAIL_NONE ){
      if( pSegIter->bDel ){
        fts5BufferAppendVarint(&p->rc, &writer.writer.buf, 0);
        if( pSegIter->nPos>0 ){
          fts5BufferAppendVarint(&p->rc, &writer.writer.buf, 0);
        }
      }
    }else{
      /* Append the position-list data to the output */
      nPos = pSegIter->nPos*2 + pSegIter->bDel;
      fts5BufferAppendVarint(&p->rc, &writer.writer.buf, nPos);
      fts5ChunkIterate(p, pSegIter, (void*)&writer, fts5MergeChunkCallback);
    }
  }

  /* Flush the last leaf page to disk. Set the output segment b-tree height
  ** and last leaf page number at the same time.  */
  fts5WriteFinish(p, &writer, &pSeg->pgnoLast);

  if( fts5MultiIterEof(p, pIter) ){

  Fts5Buffer out;
  memset(&out, 0, sizeof(out));
  sqlite3Fts5BufferSize(&p->rc, &out, p1->n + p2->n);
  if( p->rc ) return;

  fts5NextRowid(p1, &i1, &iRowid1);
  fts5NextRowid(p2, &i2, &iRowid2);
  while( i1>=0 || i2>=0 ){
    if( i1>=0 && (i2<0 || iRowid1<iRowid2) ){
      fts5BufferSafeAppendVarint(&out, iRowid1 - iOut);
      iOut = iRowid1;
      fts5NextRowid(p1, &i1, &iRowid1);
    }else{
      fts5BufferSafeAppendVarint(&out, iRowid2 - iOut);

  CREATE VIRTUAL TABLE t1 USING fts5(a, detail=none);
  BEGIN;
    INSERT INTO t1 VALUES('a1 b1 c1');
    INSERT INTO t1 VALUES('a2 b2 c2');
    INSERT INTO t1 VALUES('a3 b3 c3');
  COMMIT;
}

do_execsql_test 4.1 {
  SELECT rowid FROM t1('b*');
} {1 2 3}


#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 5.0 {
  CREATE VIRTUAL TABLE t1 USING fts5(a, detail=none);
  BEGIN;
  INSERT INTO t1 VALUES('a1 b1 c1');
  INSERT INTO t1 VALUES('a2 b2 c2');
  INSERT INTO t1 VALUES('a1 b1 c1');
  COMMIT;
}
do_execsql_test 5.1 { SELECT rowid FROM t1('b*') } {1 2 3}

#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 6.0 {
  CREATE VIRTUAL TABLE t1 USING fts5(a, detail=full);
  BEGIN;
  INSERT INTO t1 VALUES('a1 b1 c1');
  INSERT INTO t1 VALUES('a1 b1 c1');
  INSERT INTO t1 VALUES('a1 b1 c1');
  COMMIT;
}

do_execsql_test 6.1 { SELECT rowid FROM t1('a1') ORDER BY rowid DESC } {3 2 1}
do_execsql_test 6.2 { SELECT rowid FROM t1('b1') ORDER BY rowid DESC } {3 2 1}
do_execsql_test 6.3 { SELECT rowid FROM t1('c1') ORDER BY rowid DESC } {3 2 1}

#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 7.0 {
  CREATE VIRTUAL TABLE t1 USING fts5(a, detail=none);
  BEGIN;
  INSERT INTO t1 VALUES('a1 b1');
  INSERT INTO t1 VALUES('a1 b2');
  COMMIT;
}
do_execsql_test 7.0.4 { SELECT rowid FROM t1('b*') ORDER BY rowid DESC } {2 1}
do_execsql_test 7.0.5 { SELECT rowid FROM t1('a1') ORDER BY rowid DESC } {2 1}

#-------------------------------------------------------------------------
#
reset_db
do_execsql_test 7.0 {
  CREATE VIRTUAL TABLE t1 USING fts5(a, detail=none);
  INSERT INTO t1 VALUES('a1 b1 c1');
  INSERT INTO t1 VALUES('a2 b2 c2');
  INSERT INTO t1 VALUES('a1 b1 c1');
}
do_execsql_test 7.0.1 { SELECT rowid FROM t1('b*') } {1 2 3}
do_execsql_test 7.0.2 { SELECT rowid FROM t1('a1') } {1 3}
do_execsql_test 7.0.3 { SELECT rowid FROM t1('c2') } {2}

do_execsql_test 7.0.4 { SELECT rowid FROM t1('b*') ORDER BY rowid DESC } {3 2 1}
do_execsql_test 7.0.5 { SELECT rowid FROM t1('a1') ORDER BY rowid DESC } {3 1}
do_execsql_test 7.0.7 { SELECT rowid FROM t1('c2') ORDER BY rowid DESC } {2}

do_execsql_test 7.1.0 { INSERT INTO t1(t1) VALUES('optimize') }

do_execsql_test 7.1.1 { SELECT rowid FROM t1('b*') } {1 2 3}
do_execsql_test 7.1.2 { SELECT rowid FROM t1('a1') } {1 3}
do_execsql_test 7.1.3 { SELECT rowid FROM t1('c2') } {2}

do_execsql_test 7.2.1 { SELECT rowid FROM t1('b*') ORDER BY rowid DESC} {3 2 1}
do_execsql_test 7.2.2 { SELECT rowid FROM t1('a1') ORDER BY rowid DESC} {3 1}
do_execsql_test 7.2.3 { SELECT rowid FROM t1('c2') ORDER BY rowid DESC} {2}

finish_test