*/

#define FTS5_DEFAULT_PAGE_SIZE   1000

#define FTS5_WORK_UNIT      64    /* Number of leaf pages in unit of work */
#define FTS5_MIN_MERGE       4    /* Minimum number of segments to merge */



/*
** Details:
**
** The %_data table managed by this module,
**
**     CREATE TABLE %_data(id INTEGER PRIMARY KEY, block BLOB);
**
................................................................................
**     * either an 0x00 or 0x01 byte. If the value 0x01 is used, then there 
**       is an associated index-by-rowid record.
**     * the number of zero-term leaves as a varint.
**
** 5. Segment doclist indexes:
**
**   A list of varints - the first docid on each page (starting with the
**   second) of the doclist. First element in the list is a literal docid.
**   Each docid thereafter is a (negative) delta.


*/

/*
** Rowids for the averages and structure records in the %_data table.
*/
#define FTS5_AVERAGES_ROWID     1    /* Rowid used for the averages record */
#define FTS5_STRUCTURE_ROWID(iIdx) (10 + (iIdx))     /* For structure records */
................................................................................
#endif

/*
** The height of segment b-trees is actually limited to one less than 
** (1<<HEIGHT_BITS). This is because the rowid address space for nodes
** with such a height is used by doclist indexes.
*/
#define FTS5_SEGMENT_MAX_HEIGHT ((1 << FTS5_SEGMENT_HEIGHT_BITS)-1)

/*
** The rowid for the doclist index associated with leaf page pgno of segment
** segid in index idx.
*/
#define FTS5_DOCLIST_IDX_ROWID(idx, segid, pgno) \
        FTS5_SEGMENT_ROWID(idx, segid, FTS5_SEGMENT_MAX_HEIGHT, pgno)
................................................................................
** An object of type Fts5SegWriter is used to write to segments.
*/
struct Fts5PageWriter {
  int pgno;                       /* Page number for this page */
  Fts5Buffer buf;                 /* Buffer containing page data */
  Fts5Buffer term;                /* Buffer containing previous term on page */
};

struct Fts5SegWriter {
  int iIdx;                       /* Index to write to */
  int iSegid;                     /* Segid to write to */
  int nWriter;                    /* Number of entries in aWriter */
  Fts5PageWriter *aWriter;        /* Array of PageWriter objects */
  i64 iPrevRowid;                 /* Previous docid written to current leaf */
  u8 bFirstRowidInDoclist;        /* True if next rowid is first in doclist */
  u8 bFirstRowidInPage;           /* True if next rowid is first in page */
  int nLeafWritten;               /* Number of leaf pages written */
  int nEmpty;                     /* Number of contiguous term-less nodes */



};

/*
** Object for iterating through the merged results of one or more segments,
** visiting each term/docid pair in the merged data.
**
** nSeg is always a power of two greater than or equal to the number of
................................................................................
** An Fts5BtreeIter object is used to iterate through all entries in the
** b-tree hierarchy belonging to a single fts5 segment. In this case the
** "b-tree hierarchy" is all b-tree nodes except leaves. Each entry in the
** b-tree hierarchy consists of the following:
**
**   iLeaf:  The page number of the leaf page the entry points to.
**
**   term:   A split-key that all terms on leaf page $leaf must be greater
**           than or equal to. The "term" associated with the first b-tree
**           hierarchy entry (the one that points to leaf page 1) is always 
**           an empty string.
**
**   nEmpty: The number of empty (termless) leaf pages that immediately
**           following iLeaf.
**
................................................................................
*/
static void fts5SegIterInit(
  Fts5Index *p,          
  int iIdx,                       /* Config.aHash[] index of FTS index */
  Fts5StructureSegment *pSeg,     /* Description of segment */
  Fts5SegIter *pIter              /* Object to populate */
){










  if( p->rc==SQLITE_OK ){
    memset(pIter, 0, sizeof(*pIter));
    pIter->pSeg = pSeg;
    pIter->iIdx = iIdx;
    pIter->iLeafPgno = pSeg->pgnoFirst-1;
    fts5SegIterNextPage(p, pIter);
................................................................................
  int i;
  for(i=0; i<nNew && i<nOld; i++){
    if( pOld[i]!=pNew[i] ) break;
  }
  return i;
}





























/*
** This is called once for each leaf page except the first that contains
** at least one term. Argument (nTerm/pTerm) is the split-key - a term that
** is larger than all terms written to earlier leaves, and equal to or
** smaller than the first term on the new leaf.
**
................................................................................
      fts5BufferAppendVarint(&p->rc, &pNew->buf, 1);

      pWriter->nWriter++;
      pWriter->aWriter = aNew;
    }
    pPage = &pWriter->aWriter[iHeight];

    if( pWriter->nEmpty ){
      assert( iHeight==1 );
      fts5BufferAppendVarint(&p->rc, &pPage->buf, 0);
      fts5BufferAppendVarint(&p->rc, &pPage->buf, pWriter->nEmpty);
      pWriter->nEmpty = 0;
    }

    if( pPage->buf.n>=p->pgsz ){
      /* pPage will be written to disk. The term will be written into the
      ** parent of pPage.  */
      i64 iRowid = FTS5_SEGMENT_ROWID(
          pWriter->iIdx, pWriter->iSegid, iHeight, pPage->pgno
      );
................................................................................
  }
}

static void fts5WriteBtreeNoTerm(
  Fts5Index *p,                   /* FTS5 backend object */
  Fts5SegWriter *pWriter          /* Writer object */
){





  pWriter->nEmpty++;
}





















static void fts5WriteFlushLeaf(Fts5Index *p, Fts5SegWriter *pWriter){
  static const u8 zero[] = { 0x00, 0x00, 0x00, 0x00 };
  Fts5PageWriter *pPage = &pWriter->aWriter[0];
  i64 iRowid;

  if( pPage->term.n==0 ){
................................................................................
  Fts5Index *p, 
  Fts5SegWriter *pWriter,
  i64 iRowid
){
  Fts5PageWriter *pPage = &pWriter->aWriter[0];

  /* If this is to be the first docid written to the page, set the 
  ** docid-pointer in the page-header.  */


  if( pWriter->bFirstRowidInPage ) fts5PutU16(pPage->buf.p, pPage->buf.n);



  /* Write the docid. */
  if( pWriter->bFirstRowidInDoclist || pWriter->bFirstRowidInPage ){
    fts5BufferAppendVarint(&p->rc, &pPage->buf, iRowid);
  }else{
    assert( iRowid<pWriter->iPrevRowid );
    fts5BufferAppendVarint(&p->rc, &pPage->buf, pWriter->iPrevRowid - iRowid);
................................................................................
    }
  }

  /* Write the doclist terminator */
  fts5WriteAppendZerobyte(p, pWriter);
}





static void fts5WriteFinish(
  Fts5Index *p, 
  Fts5SegWriter *pWriter, 
  int *pnHeight,
  int *pnLeaf

){
  int i;
  *pnLeaf = pWriter->aWriter[0].pgno;
  *pnHeight = pWriter->nWriter;
  fts5WriteFlushLeaf(p, pWriter);
  if( pWriter->nWriter>1 && pWriter->nEmpty ){
    Fts5PageWriter *pPg = &pWriter->aWriter[1];
    fts5BufferAppendVarint(&p->rc, &pPg->buf, 0);
    fts5BufferAppendVarint(&p->rc, &pPg->buf, pWriter->nEmpty);
  }
  for(i=1; i<pWriter->nWriter; i++){
    Fts5PageWriter *pPg = &pWriter->aWriter[i];
    i64 iRow = FTS5_SEGMENT_ROWID(pWriter->iIdx, pWriter->iSegid, i, pPg->pgno);
    fts5DataWrite(p, iRow, pPg->buf.p, pPg->buf.n);
  }
  for(i=0; i<pWriter->nWriter; i++){
    Fts5PageWriter *pPg = &pWriter->aWriter[i];
    fts5BufferFree(&pPg->term);
    fts5BufferFree(&pPg->buf);
  }
  sqlite3_free(pWriter->aWriter);

}

static void fts5WriteInit(
  Fts5Index *p, 
  Fts5SegWriter *pWriter, 
  int iIdx, int iSegid
){
................................................................................
  assert( nArg==2 );
  memset(&s, 0, sizeof(Fts5Buffer));
  iRowid = sqlite3_value_int64(apVal[0]);
  n = sqlite3_value_bytes(apVal[1]);
  a = sqlite3_value_blob(apVal[1]);
  fts5DecodeRowid(iRowid, &iIdx, &iSegid, &iHeight, &iPgno);























  if( iSegid==0 ){
    if( iRowid==FTS5_AVERAGES_ROWID ){
      sqlite3Fts5BufferAppendPrintf(&rc, &s, "{averages} ");
    }else{
      sqlite3Fts5BufferAppendPrintf(&rc, &s, 
          "{structure idx=%d}", (int)(iRowid-10)
      );

*/

#define FTS5_DEFAULT_PAGE_SIZE   1000

#define FTS5_WORK_UNIT      64    /* Number of leaf pages in unit of work */
#define FTS5_MIN_MERGE       4    /* Minimum number of segments to merge */

#define FTS5_MIN_DLIDX_SIZE  4    /* Add dlidx if this many empty pages */

/*
** Details:
**
** The %_data table managed by this module,
**
**     CREATE TABLE %_data(id INTEGER PRIMARY KEY, block BLOB);
**
................................................................................
**     * either an 0x00 or 0x01 byte. If the value 0x01 is used, then there 
**       is an associated index-by-rowid record.
**     * the number of zero-term leaves as a varint.
**
** 5. Segment doclist indexes:
**
**   A list of varints - the first docid on each page (starting with the
**   first termless page) of the doclist. First element in the list is a
**   literal docid. Each docid thereafter is a (negative) delta. If there
**   are no docids at all on a page, a 0x00 byte takes the place of the
**   delta value.
*/

/*
** Rowids for the averages and structure records in the %_data table.
*/
#define FTS5_AVERAGES_ROWID     1    /* Rowid used for the averages record */
#define FTS5_STRUCTURE_ROWID(iIdx) (10 + (iIdx))     /* For structure records */
................................................................................
#endif

/*
** The height of segment b-trees is actually limited to one less than 
** (1<<HEIGHT_BITS). This is because the rowid address space for nodes
** with such a height is used by doclist indexes.
*/
#define FTS5_SEGMENT_MAX_HEIGHT ((1 << FTS5_DATA_HEIGHT_B)-1)

/*
** The rowid for the doclist index associated with leaf page pgno of segment
** segid in index idx.
*/
#define FTS5_DOCLIST_IDX_ROWID(idx, segid, pgno) \
        FTS5_SEGMENT_ROWID(idx, segid, FTS5_SEGMENT_MAX_HEIGHT, pgno)
................................................................................
** An object of type Fts5SegWriter is used to write to segments.
*/
struct Fts5PageWriter {
  int pgno;                       /* Page number for this page */
  Fts5Buffer buf;                 /* Buffer containing page data */
  Fts5Buffer term;                /* Buffer containing previous term on page */
};

struct Fts5SegWriter {
  int iIdx;                       /* Index to write to */
  int iSegid;                     /* Segid to write to */
  int nWriter;                    /* Number of entries in aWriter */
  Fts5PageWriter *aWriter;        /* Array of PageWriter objects */
  i64 iPrevRowid;                 /* Previous docid written to current leaf */
  u8 bFirstRowidInDoclist;        /* True if next rowid is first in doclist */
  u8 bFirstRowidInPage;           /* True if next rowid is first in page */
  int nLeafWritten;               /* Number of leaf pages written */
  int nEmpty;                     /* Number of contiguous term-less nodes */
  Fts5Buffer dlidx;               /* Doclist index */
  i64 iDlidxPrev;                 /* Previous rowid appended to dlidx */
  int bDlidxPrevValid;            /* True if iDlidxPrev is valid */
};

/*
** Object for iterating through the merged results of one or more segments,
** visiting each term/docid pair in the merged data.
**
** nSeg is always a power of two greater than or equal to the number of
................................................................................
** An Fts5BtreeIter object is used to iterate through all entries in the
** b-tree hierarchy belonging to a single fts5 segment. In this case the
** "b-tree hierarchy" is all b-tree nodes except leaves. Each entry in the
** b-tree hierarchy consists of the following:
**
**   iLeaf:  The page number of the leaf page the entry points to.
**
**   term:   A split-key that all terms on leaf page $iLeaf must be greater
**           than or equal to. The "term" associated with the first b-tree
**           hierarchy entry (the one that points to leaf page 1) is always 
**           an empty string.
**
**   nEmpty: The number of empty (termless) leaf pages that immediately
**           following iLeaf.
**
................................................................................
*/
static void fts5SegIterInit(
  Fts5Index *p,          
  int iIdx,                       /* Config.aHash[] index of FTS index */
  Fts5StructureSegment *pSeg,     /* Description of segment */
  Fts5SegIter *pIter              /* Object to populate */
){
  if( pSeg->pgnoFirst==0 ){
    /* This happens if the segment is being used as an input to an incremental
    ** merge and all data has already been "trimmed". See function
    ** fts5TrimSegments() for details. In this case leave the iterator empty.
    ** The caller will see the (pIter->pLeaf==0) and assume the iterator is
    ** at EOF already. */
    assert( pIter->pLeaf==0 );
    return;
  }

  if( p->rc==SQLITE_OK ){
    memset(pIter, 0, sizeof(*pIter));
    pIter->pSeg = pSeg;
    pIter->iIdx = iIdx;
    pIter->iLeafPgno = pSeg->pgnoFirst-1;
    fts5SegIterNextPage(p, pIter);
................................................................................
  int i;
  for(i=0; i<nNew && i<nOld; i++){
    if( pOld[i]!=pNew[i] ) break;
  }
  return i;
}

/*
** If an "nEmpty" record must be written to the b-tree before the next
** term, write it now.
*/
static void fts5WriteBtreeNEmpty(Fts5Index *p, Fts5SegWriter *pWriter){
  if( pWriter->nEmpty ){
    Fts5PageWriter *pPg = &pWriter->aWriter[1];
    int bFlag = 0;
    if( pWriter->nEmpty>=FTS5_MIN_DLIDX_SIZE ){
      i64 iKey = FTS5_DOCLIST_IDX_ROWID(
          pWriter->iIdx, pWriter->iSegid, 
          pWriter->aWriter[0].pgno - 1 - pWriter->nEmpty
      );
      fts5DataWrite(p, iKey, pWriter->dlidx.p, pWriter->dlidx.n);
      bFlag = 1;
    }
    fts5BufferAppendVarint(&p->rc, &pPg->buf, bFlag);
    fts5BufferAppendVarint(&p->rc, &pPg->buf, pWriter->nEmpty);
    pWriter->nEmpty = 0;
  }

  /* Whether or not it was written to disk, zero the doclist index at this
  ** point */
  sqlite3Fts5BufferZero(&pWriter->dlidx);
  pWriter->bDlidxPrevValid = 0;
}


/*
** This is called once for each leaf page except the first that contains
** at least one term. Argument (nTerm/pTerm) is the split-key - a term that
** is larger than all terms written to earlier leaves, and equal to or
** smaller than the first term on the new leaf.
**
................................................................................
      fts5BufferAppendVarint(&p->rc, &pNew->buf, 1);

      pWriter->nWriter++;
      pWriter->aWriter = aNew;
    }
    pPage = &pWriter->aWriter[iHeight];

    fts5WriteBtreeNEmpty(p, pWriter);






    if( pPage->buf.n>=p->pgsz ){
      /* pPage will be written to disk. The term will be written into the
      ** parent of pPage.  */
      i64 iRowid = FTS5_SEGMENT_ROWID(
          pWriter->iIdx, pWriter->iSegid, iHeight, pPage->pgno
      );
................................................................................
  }
}

static void fts5WriteBtreeNoTerm(
  Fts5Index *p,                   /* FTS5 backend object */
  Fts5SegWriter *pWriter          /* Writer object */
){
  if( pWriter->bFirstRowidInPage ){
    /* No rowids on this page. Append an 0x00 byte to the current 
    ** doclist-index */
    sqlite3Fts5BufferAppendVarint(&p->rc, &pWriter->dlidx, 0);
  }
  pWriter->nEmpty++;
}

/*
** Rowid iRowid has just been appended to the current leaf page. As it is
** the first on its page, append an entry to the current doclist-index.
*/
static void fts5WriteDlidxAppend(
  Fts5Index *p, 
  Fts5SegWriter *pWriter, 
  i64 iRowid
){
  i64 iVal;
  if( pWriter->bDlidxPrevValid ){
    iVal = pWriter->iDlidxPrev - iRowid;
  }else{
    iVal = iRowid;
  }
  sqlite3Fts5BufferAppendVarint(&p->rc, &pWriter->dlidx, iVal);
  pWriter->bDlidxPrevValid = 1;
  pWriter->iDlidxPrev = iRowid;
}

static void fts5WriteFlushLeaf(Fts5Index *p, Fts5SegWriter *pWriter){
  static const u8 zero[] = { 0x00, 0x00, 0x00, 0x00 };
  Fts5PageWriter *pPage = &pWriter->aWriter[0];
  i64 iRowid;

  if( pPage->term.n==0 ){
................................................................................
  Fts5Index *p, 
  Fts5SegWriter *pWriter,
  i64 iRowid
){
  Fts5PageWriter *pPage = &pWriter->aWriter[0];

  /* If this is to be the first docid written to the page, set the 
  ** docid-pointer in the page-header. Also append a value to the dlidx
  ** buffer, in case a doclist-index is required.  */
  if( pWriter->bFirstRowidInPage ){
    fts5PutU16(pPage->buf.p, pPage->buf.n);
    fts5WriteDlidxAppend(p, pWriter, iRowid);
  }

  /* Write the docid. */
  if( pWriter->bFirstRowidInDoclist || pWriter->bFirstRowidInPage ){
    fts5BufferAppendVarint(&p->rc, &pPage->buf, iRowid);
  }else{
    assert( iRowid<pWriter->iPrevRowid );
    fts5BufferAppendVarint(&p->rc, &pPage->buf, pWriter->iPrevRowid - iRowid);
................................................................................
    }
  }

  /* Write the doclist terminator */
  fts5WriteAppendZerobyte(p, pWriter);
}

/*
** Flush any data cached by the writer object to the database. Free any
** allocations associated with the writer.
*/
static void fts5WriteFinish(
  Fts5Index *p, 
  Fts5SegWriter *pWriter,         /* Writer object */
  int *pnHeight,                  /* OUT: Height of the b-tree */

  int *pnLeaf                     /* OUT: Number of leaf pages in b-tree */
){
  int i;
  *pnLeaf = pWriter->aWriter[0].pgno;
  *pnHeight = pWriter->nWriter;
  fts5WriteFlushLeaf(p, pWriter);
  if( pWriter->nWriter>1 ){
    fts5WriteBtreeNEmpty(p, pWriter);


  }
  for(i=1; i<pWriter->nWriter; i++){
    Fts5PageWriter *pPg = &pWriter->aWriter[i];
    i64 iRow = FTS5_SEGMENT_ROWID(pWriter->iIdx, pWriter->iSegid, i, pPg->pgno);
    fts5DataWrite(p, iRow, pPg->buf.p, pPg->buf.n);
  }
  for(i=0; i<pWriter->nWriter; i++){
    Fts5PageWriter *pPg = &pWriter->aWriter[i];
    fts5BufferFree(&pPg->term);
    fts5BufferFree(&pPg->buf);
  }
  sqlite3_free(pWriter->aWriter);
  sqlite3Fts5BufferFree(&pWriter->dlidx);
}

static void fts5WriteInit(
  Fts5Index *p, 
  Fts5SegWriter *pWriter, 
  int iIdx, int iSegid
){
................................................................................
  assert( nArg==2 );
  memset(&s, 0, sizeof(Fts5Buffer));
  iRowid = sqlite3_value_int64(apVal[0]);
  n = sqlite3_value_bytes(apVal[1]);
  a = sqlite3_value_blob(apVal[1]);
  fts5DecodeRowid(iRowid, &iIdx, &iSegid, &iHeight, &iPgno);

  if( iHeight==FTS5_SEGMENT_MAX_HEIGHT ){
    int i = 0;
    i64 iPrev;
    sqlite3Fts5BufferAppendPrintf(&rc, &s, "(dlidx idx=%d segid=%d pgno=%d)",
        iIdx, iSegid, iHeight, iPgno
    );
    if( n>0 ){
      i = getVarint(&a[i], (u64*)&iPrev);
      sqlite3Fts5BufferAppendPrintf(&rc, &s, " %lld", iPrev);
    }
    while( i<n ){
      i64 iVal;
      i += getVarint(&a[i], (u64*)&iVal);
      if( iVal==0 ){
        sqlite3Fts5BufferAppendPrintf(&rc, &s, " x");
      }else{
        iPrev = iPrev - iVal;
        sqlite3Fts5BufferAppendPrintf(&rc, &s, " %lld", iPrev);
      }
    }

  }else
  if( iSegid==0 ){
    if( iRowid==FTS5_AVERAGES_ROWID ){
      sqlite3Fts5BufferAppendPrintf(&rc, &s, "{averages} ");
    }else{
      sqlite3Fts5BufferAppendPrintf(&rc, &s, 
          "{structure idx=%d}", (int)(iRowid-10)
      );

# 2014 June 17
#
# The author disclaims copyright to this source code.  In place of
# a legal notice, here is a blessing:
#
#    May you do good and not evil.
#    May you find forgiveness for yourself and forgive others.
#    May you share freely, never taking more than you give.
#
#*************************************************************************
# This file implements regression tests for SQLite library.  The
# focus of this script is testing the FTS5 module.
#

set testdir [file dirname $argv0]
source $testdir/tester.tcl
set testprefix fts5ah

# If SQLITE_ENABLE_FTS3 is defined, omit this file.
ifcapable !fts3 {
  finish_test
  return
}

#-------------------------------------------------------------------------
# This file contains tests for very large doclists.
#

do_test 1.0 {
  execsql { CREATE VIRTUAL TABLE t1 USING fts5(a) }
  execsql { INSERT INTO t1(t1) VALUES('pgsz=128') }
  for {set i 1} {$i <= 10000} {incr i} {
    set v {x x x x x x x x x x x x x x x x x x x x}
    if {($i % 2139)==0} {lset v 3 Y ; lappend Y $i}
    if {($i % 1577)==0} {lset v 5 W ; lappend W $i}
    execsql { INSERT INTO t1 VALUES($v) }
  }
} {}

do_execsql_test 1.1 {
  SELECT rowid FROM t1 WHERE t1 MATCH 'x AND w'
} [lsort -integer -decr $W]

do_execsql_test 1.2 {
  SELECT rowid FROM t1 WHERE t1 MATCH 'y AND x'
} [lsort -integer -decr $Y]

do_execsql_test 1.3 {
  INSERT INTO t1(t1) VALUES('integrity-check');
}

do_execsql_test 1.4 {
  SELECT count(*) FROM t1_data
}


finish_test