/ Check-in [b6b93a33]
Login

Many hyperlinks are disabled.
Use anonymous login to enable hyperlinks.

Overview
Comment:Write doclists using a segmented technique to amortize costs better. New items for a term are merged with the term's segment 0 doclist, until that doclist exceeds CHUNK_MAX. Then the segments are merged in exponential fashion, so that segment 1 contains approximately 2*CHUNK_MAX data, segment 2 4*CHUNK_MAX, and so on. (CVS 3398)
Downloads: Tarball | ZIP archive | SQL archive
Timelines: family | ancestors | descendants | both | trunk
Files: files | file ages | folders
SHA1:b6b93a3325d3e728ca36255c0ff6e1f63e03b0ac
User & Date: shess 2006-09-08 17:00:17
Context
2006-09-09
23:11
Add support for OR and NOT terms in fts1. (CVS 3399) check-in: ae502657 user: drh tags: trunk
2006-09-08
17:00
Write doclists using a segmented technique to amortize costs better. New items for a term are merged with the term's segment 0 doclist, until that doclist exceeds CHUNK_MAX. Then the segments are merged in exponential fashion, so that segment 1 contains approximately 2*CHUNK_MAX data, segment 2 4*CHUNK_MAX, and so on. (CVS 3398) check-in: b6b93a33 user: shess tags: trunk
12:49
Add HAVE_GMTIME_R and HAVE_LOCALTIME_R flags and use them if defined. Unable to modify the configure script to test for gmtime_r and localtime_r, however, because on my SuSE 10.2 system, autoconf generates a configure script that does not work. Bummer. Ticket #1906 (CVS 3397) check-in: 862302ea user: drh tags: trunk
Changes
Hide Diffs Unified Diffs Ignore Whitespace Patch

Changes to ext/fts1/fts1.c.

324
325
326
327
328
329
330
331
332
333
334
335
336
337
338

339
340
341
342
343
344
345
346
347
348
349


350
351
352
353
354



355
356





357
358
359
360


361
362
363
364
365
366
367
368
369

370

371
372
373
374
375
376
377
378
379



380
381
382

383
384
385

386
387











388











389
390
391
392
393
394
395
...
406
407
408
409
410
411
412





413
414
415
416
417
418
419
...
478
479
480
481
482
483
484




485

486
487
488
489




490
491
492
493

494
495
496
497
498
499
500
...
560
561
562
563
564
565
566











567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
...
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
...
754
755
756
757
758
759
760
761

762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829











830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
...
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976










977
978
979
980
981
982
983
984
985
986
987
988
....
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124

1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
....
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
....
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
....
1384
1385
1386
1387
1388
1389
1390

1391
1392
1393
1394
1395
1396

1397
1398
1399
1400
1401

1402
1403
1404

1405
1406
1407
1408




1409
1410
1411
1412




1413
1414
1415
1416
1417






1418
1419
1420
1421









1422
1423






1424
1425

1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
....
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498

1499
1500
1501
1502
1503
1504
1505
1506







1507
1508
1509
1510
1511
1512
1513
1514
1515

1516

1517
1518
1519
1520
1521
1522
1523

static sqlite_int64 firstDocid(DocList *d){
  DocListReader r;
  readerInit(&r, d);
  return readDocid(&r);
}

/* Doclist multi-tool.  Pass pUpdate==NULL to delete the indicated docid;
 * otherwise pUpdate, which must contain only the single docid [iDocid], is
 * inserted (if not present) or updated (if already present). */
static int docListUpdate(DocList *d, sqlite_int64 iDocid, DocList *pUpdate){
  int modified = 0;
  DocListReader reader;
  int found;
  char *p;


  if( pUpdate!=NULL ){
    assert( d->iType==pUpdate->iType);
    assert( iDocid==firstDocid(pUpdate) );
  }

  readerInit(&reader, d);
  found = skipToDocid(&reader, iDocid);

  p = reader.p;
  /* Delete if there is a matching element. */


  if( found ){
    skipDocument(&reader);
    memmove(p, reader.p, docListEnd(d) - reader.p);
    d->nData -= (reader.p - p);
    modified = 1;



  }






  /* Insert if indicated. */
  if( pUpdate!=NULL ){
    int iDoclist = p-d->pData;



    d->pData = realloc(d->pData, d->nData+pUpdate->nData);
    p = d->pData + iDoclist;

    memmove(p+pUpdate->nData, p, docListEnd(d) - p);
    memcpy(p, pUpdate->pData, pUpdate->nData);
    d->nData += pUpdate->nData;
    modified = 1;
  }


  return modified;

}

/* Split the second half of doclist d into a separate doclist d2.  Returns 1
 * if successful, or 0 if d contains a single document and hence can't be
 * split. */
static int docListSplit(DocList *d, DocList *d2){
  const char *pSplitPoint = d->pData + d->nData / 2;
  DocListReader reader;




  readerInit(&reader, d);
  while( reader.p<pSplitPoint ){
    skipDocument(&reader);

  }
  if( atEnd(&reader) ) return 0;
  docListInit(d2, d->iType, reader.p, docListEnd(d) - reader.p);

  d->nData = reader.p - d->pData;
  d->pData = realloc(d->pData, d->nData);











  return 1;











}

/* A DocListMerge computes the AND of an in-memory DocList [in] and a chunked
 * on-disk doclist, resulting in another in-memory DocList [out].  [in]
 * and [out] may or may not store position information according to the
 * caller's wishes.  The on-disk doclist always comes with positions.
 *
................................................................................
 * A merge is performed using an integer [iPhrasePos] provided by the caller.
 * [iPhrasePos] is subtracted from each position in the on-disk doclist for the
 * purpose of position comparison; this is helpful in implementing phrase
 * searches.
 *
 * A DocListMerge is not yet able to propagate offsets through query
 * processing; we should add that capability soon.





*/
typedef struct DocListMerge {
  DocListReader in;
  DocList *pOut;
  int iPhrasePos;
} DocListMerge;

................................................................................
static void mergeBlock(DocListMerge *m, DocList *pBlock){
  DocListReader blockReader;
  assert( pBlock->iType>=DL_POSITIONS );
  readerInit(&blockReader, pBlock);
  while( !atEnd(&blockReader) ){
    sqlite_int64 iDocid = readDocid(&blockReader);
    if( m->in.pDoclist==NULL ){




      copyDocument(m->pOut, iDocid, &blockReader);

      continue;
    }
    if( skipToDocid(&m->in, iDocid) ){  /* we have a docid match */
      readDocid(&m->in);




      if( m->in.pDoclist->iType>=DL_POSITIONS ){
        mergePosList(m, iDocid, &blockReader);
      } else {
        copyDocument(m->pOut, iDocid, &blockReader);

      }
    } else if( !atEnd(&m->in) ){
      skipPositionList(&blockReader);  /* skip this docid in the block */
    } else return;  /* nothing more to merge */
  }
}

................................................................................
}

/* end utility functions */

#define QUERY_GENERIC 0
#define QUERY_FULLTEXT 1












#define CHUNK_MAX 1024

typedef enum fulltext_statement {
  CONTENT_INSERT_STMT,
  CONTENT_SELECT_STMT,
  CONTENT_DELETE_STMT,

  TERM_SELECT_STMT,
  TERM_CHUNK_SELECT_STMT,
  TERM_INSERT_STMT,
  TERM_UPDATE_STMT,
  TERM_DELETE_STMT,

  MAX_STMT                     /* Always at end! */
} fulltext_statement;

................................................................................
*/
static const char *const fulltext_zStatement[MAX_STMT] = {
  /* CONTENT_INSERT */ "insert into %_content (rowid, content) values (?, ?)",
  /* CONTENT_SELECT */ "select content from %_content where rowid = ?",
  /* CONTENT_DELETE */ "delete from %_content where rowid = ?",

  /* TERM_SELECT */
  "select rowid, doclist from %_term where term = ? and first = ?",
  /* TERM_CHUNK_SELECT */
  "select max(first) from %_term where term = ? and first <= ?",
  /* TERM_INSERT */
  "insert into %_term (term, first, doclist) values (?, ?, ?)",
  /* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
  /* TERM_DELETE */ "delete from %_term where rowid = ?",
};

typedef struct fulltext_vtab {
  sqlite3_vtab base;
  sqlite3 *db;
................................................................................

  rc = sqlite3_bind_int64(s, 1, iRow);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, CONTENT_DELETE_STMT, &s);
}

/* select rowid, doclist from %_term where term = [pTerm] and first = [iFirst]

 * If found, returns SQLITE_OK; the caller must free the returned doclist.
 * If no rows found, returns SQLITE_ERROR. */
static int term_select(fulltext_vtab *v, const char *pTerm, int nTerm,
                       sqlite_int64 iFirst,
                       sqlite_int64 *rowid,
                       DocList *out){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_SELECT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 2, iFirst);
  if( rc!=SQLITE_OK ) return rc;

  rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
  if( rc!=SQLITE_ROW ) return rc==SQLITE_DONE ? SQLITE_ERROR : rc;

  *rowid = sqlite3_column_int64(s, 0);
  docListInit(out, DL_POSITIONS_OFFSETS,
              sqlite3_column_blob(s, 1), sqlite3_column_bytes(s, 1));

  /* We expect only one row.  We must execute another sqlite3_step()
   * to complete the iteration; otherwise the table will remain locked. */
  rc = sqlite3_step(s);
  return rc==SQLITE_DONE ? SQLITE_OK : rc;
}

/* select max(first) from %_term where term = [pTerm] and first <= [iFirst]
 * If found, returns SQLITE_ROW and result in *piResult; if the query returns
 * NULL (meaning no row found) returns SQLITE_DONE.
 */
static int term_chunk_select(fulltext_vtab *v, const char *pTerm, int nTerm,
                           sqlite_int64 iFirst, sqlite_int64 *piResult){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_CHUNK_SELECT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 2, iFirst);
  if( rc!=SQLITE_OK ) return rc;

  rc = sql_step_statement(v, TERM_CHUNK_SELECT_STMT, &s);
  if( rc!=SQLITE_ROW ) return rc==SQLITE_DONE ? SQLITE_ERROR : rc;

  switch( sqlite3_column_type(s, 0) ){
    case SQLITE_NULL:
      rc = SQLITE_DONE;
      break;
    case SQLITE_INTEGER:
     *piResult = sqlite3_column_int64(s, 0);
     break;
    default:
      return SQLITE_ERROR;
  }
  /* We expect only one row.  We must execute another sqlite3_step()
   * to complete the iteration; otherwise the table will remain locked. */
  if( sqlite3_step(s) != SQLITE_DONE ) return SQLITE_ERROR;
  return rc;
}

/* insert into %_term (term, first, doclist)
               values ([pTerm], [iFirst], [doclist]) */
static int term_insert(fulltext_vtab *v, const char *pTerm, int nTerm,
                       sqlite_int64 iFirst, DocList *doclist){











  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int64(s, 2, iFirst);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_blob(s, 3, doclist->pData, doclist->nData, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, TERM_INSERT_STMT, &s);
}
................................................................................
  ** the rowid used as the docid.
  **
  ** The %_term table maps each term to a document list blob
  ** containing elements sorted by ascending docid, each element
  ** encoded as:
  **
  **   docid varint-encoded
  **   token count varint-encoded
  **   "count" token elements (poslist):
  **     position varint-encoded as delta from previous position
  **     start offset varint-encoded as delta from previous start offset
  **     end offset varint-encoded as delta from start offset
  **
  ** Additionally, doclist blobs can be chunked into multiple rows,
  ** using "first" to order the blobs.  "first" is simply the first
  ** docid in the blob.
  */
  /*
  ** NOTE(shess) That last sentence is incorrect in the face of
  ** deletion, which can leave a doclist that doesn't contain the
  ** first from that row.  I _believe_ this does not matter to the
  ** operation of the system, but it might be reasonable to update
  ** appropriately in case this assumption becomes more important.










  */
  rc = sql_exec(db, argv[2],
    "create table %_content(content text);"
    "create table %_term(term text, first integer, doclist blob);"
    "create index %_index on %_term(term, first)");
  if( rc!=SQLITE_OK ) return rc;

  return fulltextConnect(db, pAux, argc, argv, ppVTab);
}

/* Decide how to handle an SQL query.
 * At the moment, MATCH queries can include implicit boolean ANDs; we
................................................................................
      return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
    default:
      assert( 0 );
      return SQLITE_ERROR;  /* not reached */
  }
}

static int term_select_doclist(fulltext_vtab *v, const char *pTerm, int nTerm,
                               sqlite3_stmt **ppStmt){
  int rc;
  if( *ppStmt ){
    rc = sqlite3_reset(*ppStmt);
  } else {
    rc = sql_prepare(v->db, v->zName, ppStmt,
      "select doclist from %_term where term = ? order by first");
  }
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(*ppStmt, 1, pTerm, nTerm, SQLITE_TRANSIENT);
  if( rc!=SQLITE_OK ) return rc;

  return sqlite3_step(*ppStmt);   /* TODO(adamd): handle schema error */
}

/* Read the posting list for [pTerm]; AND it with the doclist [pIn] to
 * produce the doclist [out], using the given phrase position [iPhrasePos].
 * (*pSelect) is used to hold an SQLite statement used inside this function;
 * the caller should initialize *pSelect to NULL before the first call.
 */
static int mergeQuery(fulltext_vtab *v, sqlite3_stmt **pSelect,
                       const char *pTerm, int nTerm,
                       DocList *pIn, int iPhrasePos, DocList *out){
  int rc;
  DocListMerge merge;


  /* If [pIn] is already empty, there's no point in reading the
   * posting list to AND it in; return immediately. */
  if( pIn!=NULL && !pIn->nData ) return SQLITE_OK;

  rc = term_select_doclist(v, pTerm, nTerm, pSelect);
  if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ) return rc;

  mergeInit(&merge, pIn, iPhrasePos, out);
  while( rc==SQLITE_ROW ){
    DocList block;
    docListInit(&block, DL_POSITIONS_OFFSETS,
                sqlite3_column_blob(*pSelect, 0),
                sqlite3_column_bytes(*pSelect, 0));
    mergeBlock(&merge, &block);
    docListDestroy(&block);

    rc = sqlite3_step(*pSelect);
    if( rc!=SQLITE_ROW && rc!=SQLITE_DONE ) return rc;
  }
  
  return SQLITE_OK;
}

typedef struct QueryTerm {
  int isPhrase;    /* true if this term begins a new phrase */
  char *pTerm;
  int nTerm;
................................................................................

/* Perform a full-text query; return a list of documents in [pResult]. */
static int fulltextQuery(fulltext_vtab *v, const char *pInput, int nInput,
                          DocList **pResult){
  Query q;
  int phrase_start = -1;
  int i;
  sqlite3_stmt *pSelect = NULL;
  DocList *d = NULL;

  int rc = parseQuery(v, pInput, nInput, &q);
  if( rc!=SQLITE_OK ) return rc;

  /* Merge terms. */
  for(i = 0 ; i < q.nTerms ; ++i){
................................................................................
    /* In each merge step, we need to generate positions whenever we're
     * processing a phrase which hasn't ended yet. */
    int needPositions = i<q.nTerms-1 && !q.pTerms[i+1].isPhrase;
    DocList *next = docListNew(needPositions ? DL_POSITIONS : DL_DOCIDS);
    if( q.pTerms[i].isPhrase ){
      phrase_start = i;
    }
    rc = mergeQuery(v, &pSelect, q.pTerms[i].pTerm, q.pTerms[i].nTerm,
                     d, i-phrase_start, next);
    if( rc!=SQLITE_OK ) break;
    if( d!=NULL ){
      docListDelete(d);
    }
    d = next;
  }

  sqlite3_finalize(pSelect);
  queryDestroy(&q);
  *pResult = d;
  return rc;
}

static int fulltextFilter(sqlite3_vtab_cursor *pCursor,
                          int idxNum, const char *idxStr,
................................................................................
  ** this point?  Actually, same question about sqlite3_finalize(),
  ** though one could argue that failure there means that the data is
  ** not durable.  *ponder*
  */
  pTokenizer->pModule->xClose(pCursor);
  return rc;
}

/* Update the %_terms table to map the term [zTerm] to the given rowid. */
static int index_insert_term(fulltext_vtab *v, const char *pTerm, int nTerm,
                             sqlite_int64 iDocid, DocList *p){
  sqlite_int64 iFirst;
  sqlite_int64 iIndexRow;
  DocList doclist;


  int rc = term_chunk_select(v, pTerm, nTerm, iDocid, &iFirst);
  if( rc==SQLITE_DONE ){
    docListInit(&doclist, DL_POSITIONS_OFFSETS, 0, 0);
    if( docListUpdate(&doclist, iDocid, p) ){

      rc = term_insert(v, pTerm, nTerm, iDocid, &doclist);
      docListDestroy(&doclist);
      return rc;

    }
    return SQLITE_OK;
  }
  if( rc!=SQLITE_ROW ) return SQLITE_ERROR;





  /* This word is in the index; add this document ID to its blob. */

  rc = term_select(v, pTerm, nTerm, iFirst, &iIndexRow, &doclist);




  if( rc!=SQLITE_OK ) return rc;

  if( docListUpdate(&doclist, iDocid, p) ){
    /* If the blob is too big, split it in half. */
    if( doclist.nData>CHUNK_MAX ){






      DocList half;
      if( docListSplit(&doclist, &half) ){
        rc = term_insert(v, pTerm, nTerm, firstDocid(&half), &half);
        docListDestroy(&half);









        if( rc!=SQLITE_OK ) goto err;
      }






    }
    rc = term_update(v, iIndexRow, &doclist);

  }

err:
  docListDestroy(&doclist);
  return rc;
}

/* Insert a row into the full-text index; set *piRowid to be the ID of the
 * new row. */
static int index_insert(fulltext_vtab *v, sqlite3_value *pRequestRowid,
................................................................................
  if( !pText || !nText ) return SQLITE_OK;   /* nothing to index */

  rc = buildTerms(&terms, v->pTokenizer, pText, nText, *piRowid);
  if( rc!=SQLITE_OK ) return rc;

  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    rc = index_insert_term(v, fts1HashKey(e), fts1HashKeysize(e), *piRowid, p);
    if( rc!=SQLITE_OK ) break;
  }

  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    docListDelete(p);
  }
  fts1HashClear(&terms);
  return rc;
}

static int index_delete_term(fulltext_vtab *v, const char *pTerm, int nTerm,
                             sqlite_int64 iDocid){
  sqlite_int64 iFirst;
  sqlite_int64 iIndexRow;
  DocList doclist;
  int rc;

  assert( nTerm>=0 );

  rc = term_chunk_select(v, pTerm, nTerm, iDocid, &iFirst);
  if( rc!=SQLITE_ROW ) return SQLITE_ERROR;

  rc = term_select(v, pTerm, nTerm, iFirst, &iIndexRow, &doclist);
  if( rc!=SQLITE_OK ) return rc;

  if( docListUpdate(&doclist, iDocid, NULL) ){
    if( doclist.nData>0 ){
      rc = term_update(v, iIndexRow, &doclist);
    } else {  /* empty posting list */
      rc = term_delete(v, iIndexRow);
    }
  }
  docListDestroy(&doclist);
  return rc;
}

/* Delete a row from the full-text index. */
static int index_delete(fulltext_vtab *v, sqlite_int64 iRow){
  char *pText;
  int nText;
  fts1Hash terms;
  fts1HashElem *e;


  int rc = content_select(v, iRow, &pText, &nText);
  if( rc!=SQLITE_OK ) return rc;

  rc = buildTerms(&terms, v->pTokenizer, pText, nText, iRow);
  free(pText);
  if( rc!=SQLITE_OK ) return rc;








  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    rc = index_delete_term(v, fts1HashKey(e), fts1HashKeysize(e), iRow);
    if( rc!=SQLITE_OK ) break;
  }
  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    docListDelete(p);
  }
  fts1HashClear(&terms);



  return content_delete(v, iRow);
}

static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
                   sqlite_int64 *pRowid){
  fulltext_vtab *v = (fulltext_vtab *) pVtab;








|
|
|
|
|
|
|
|
>

<
<
<
<
<
<
|

<
<
>
>

|
<
<
<
>
>
>


>
>
>
>
>
|
|
<
|
>
>
|
|
|
<
|
|
<


>
|
>


<
|
<
|
<


>
>
>

<
|
>
|
<
<
>
|
|
>
>
>
>
>
>
>
>
>
>
>
|
>
>
>
>
>
>
>
>
>
>
>







 







>
>
>
>
>







 







>
>
>
>
|
>




>
>
>
>
|
|
|
|
>







 







>
>
>
>
>
>
>
>
>
>
>
|







|







 







|
|
|

|







 







|
>
|
|

<
|
|







|



|








|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
>
>
>
>
>
>
>
>
>
>
>







|







 







|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
>
>
>
>
>
>
>
>
>
>



|
|







 







<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<





|
<



>





|
|


<
<
<
<
<
|
|

<
<
<
<







 







<







 







|








<







 







>
|

|
<


>

|


|
>
|
<
<
>
|
|
|
<
>
>
>
>
|
<

<
>
>
>
>
|

<
<
<
>
>
>
>
>
>
|
<
<
<
>
>
>
>
>
>
>
>
>
|
|
>
>
>
>
>
>
|
<
>


|







 







|











<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<


|
|


>








>
>
>
>
>
>
>

|







>

>







324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340






341
342


343
344
345
346



347
348
349
350
351
352
353
354
355
356
357
358

359
360
361
362
363
364

365
366

367
368
369
370
371
372
373

374

375

376
377
378
379
380
381

382
383
384


385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
...
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
...
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
...
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
...
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
...
802
803
804
805
806
807
808
809
810
811
812
813

814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
....
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
....
1160
1161
1162
1163
1164
1165
1166

















1167
1168
1169
1170
1171
1172

1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185





1186
1187
1188




1189
1190
1191
1192
1193
1194
1195
....
1290
1291
1292
1293
1294
1295
1296

1297
1298
1299
1300
1301
1302
1303
....
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319

1320
1321
1322
1323
1324
1325
1326
....
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435

1436
1437
1438
1439
1440
1441
1442
1443
1444
1445


1446
1447
1448
1449

1450
1451
1452
1453
1454

1455

1456
1457
1458
1459
1460
1461



1462
1463
1464
1465
1466
1467
1468



1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486

1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
....
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528


























1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569

static sqlite_int64 firstDocid(DocList *d){
  DocListReader r;
  readerInit(&r, d);
  return readDocid(&r);
}

/* Helper function for docListUpdate() and docListAccumulate().
** Splices a doclist element into the doclist represented by r,
** leaving r pointing after the newly spliced element.
*/
static void docListSpliceElement(DocListReader *r, sqlite_int64 iDocid,
                                 const char *pSource, int nSource){
  DocList *d = r->pDoclist;
  char *pTarget;
  int nTarget, found;







  found = skipToDocid(r, iDocid);



  /* Describe slice in d to place pSource/nSource. */
  pTarget = r->p;
  if( found ){
    skipDocument(r);



    nTarget = r->p-pTarget;
  }else{
    nTarget = 0;
  }

  /* The sense of the following is that there are three possibilities.
  ** If nTarget==nSource, we should not move any memory nor realloc.
  ** If nTarget>nSource, trim target and realloc.
  ** If nTarget<nSource, realloc then expand target.
  */
  if( nTarget>nSource ){
    memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));

  }
  if( nTarget!=nSource ){
    int iDoclist = pTarget-d->pData;
    d->pData = realloc(d->pData, d->nData+nSource-nTarget);
    pTarget = d->pData+iDoclist;
  }

  if( nTarget<nSource ){
    memmove(pTarget+nSource, pTarget+nTarget, docListEnd(d)-(pTarget+nTarget));

  }

  memcpy(pTarget, pSource, nSource);
  d->nData += nSource-nTarget;
  r->p = pTarget+nSource;
}


/* Insert/update pUpdate into the doclist. */

static void docListUpdate(DocList *d, DocList *pUpdate){

  DocListReader reader;

  assert( d!=NULL && pUpdate!=NULL );
  assert( d->iType==pUpdate->iType);

  readerInit(&reader, d);

  docListSpliceElement(&reader, firstDocid(pUpdate),
                       pUpdate->pData, pUpdate->nData);
}



/* Propagate elements from pUpdate to pAcc, overwriting elements with
** matching docids.
*/
static void docListAccumulate(DocList *pAcc, DocList *pUpdate){
  DocListReader accReader, updateReader;

  /* Handle edge cases where one doclist is empty. */
  assert( pAcc!=NULL );
  if( pUpdate==NULL || pUpdate->nData==0 ) return;
  if( pAcc->nData==0 ){
    pAcc->pData = malloc(pUpdate->nData);
    memcpy(pAcc->pData, pUpdate->pData, pUpdate->nData);
    pAcc->nData = pUpdate->nData;
    return;
  }

  readerInit(&accReader, pAcc);
  readerInit(&updateReader, pUpdate);

  while( !atEnd(&updateReader) ){
    char *pSource = updateReader.p;
    sqlite_int64 iDocid = readDocid(&updateReader);
    skipPositionList(&updateReader);
    docListSpliceElement(&accReader, iDocid, pSource, updateReader.p-pSource);
  }
}

/* A DocListMerge computes the AND of an in-memory DocList [in] and a chunked
 * on-disk doclist, resulting in another in-memory DocList [out].  [in]
 * and [out] may or may not store position information according to the
 * caller's wishes.  The on-disk doclist always comes with positions.
 *
................................................................................
 * A merge is performed using an integer [iPhrasePos] provided by the caller.
 * [iPhrasePos] is subtracted from each position in the on-disk doclist for the
 * purpose of position comparison; this is helpful in implementing phrase
 * searches.
 *
 * A DocListMerge is not yet able to propagate offsets through query
 * processing; we should add that capability soon.
*/
/* TODO(shess) Adam indicates that since we no longer can stream
** ordered doclist chunks, DocListMerge is no longer as useful and
** should be removed.  Not removing at this time so that the removal
** doesn't obscure the exponential-chunking change.
*/
typedef struct DocListMerge {
  DocListReader in;
  DocList *pOut;
  int iPhrasePos;
} DocListMerge;

................................................................................
static void mergeBlock(DocListMerge *m, DocList *pBlock){
  DocListReader blockReader;
  assert( pBlock->iType>=DL_POSITIONS );
  readerInit(&blockReader, pBlock);
  while( !atEnd(&blockReader) ){
    sqlite_int64 iDocid = readDocid(&blockReader);
    if( m->in.pDoclist==NULL ){
      /* Skip document delete crumbs */
      if( *blockReader.p=='\0' ){
        skipPositionList(&blockReader);
      } else {
        copyDocument(m->pOut, iDocid, &blockReader);
      }
      continue;
    }
    if( skipToDocid(&m->in, iDocid) ){  /* we have a docid match */
      readDocid(&m->in);
      /* Skip document delete crumbs */
      if( *blockReader.p=='\0' ){
        skipPositionList(&blockReader);
      }else{
        if( m->in.pDoclist->iType>=DL_POSITIONS ){
          mergePosList(m, iDocid, &blockReader);
        } else {
          copyDocument(m->pOut, iDocid, &blockReader);
        }
      }
    } else if( !atEnd(&m->in) ){
      skipPositionList(&blockReader);  /* skip this docid in the block */
    } else return;  /* nothing more to merge */
  }
}

................................................................................
}

/* end utility functions */

#define QUERY_GENERIC 0
#define QUERY_FULLTEXT 1

/* TODO(shess) CHUNK_MAX controls how much data we allow in segment 0
** before we start aggregating into larger segments.  Lower CHUNK_MAX
** means that for a given input we have more individual segments per
** term, which means more rows in the table and a bigger index (due to
** both more rows and bigger rowids).  But it also reduces the average
** cost of adding new elements to the segment 0 doclist, and it seems
** to reduce the number of pages read and written during inserts.  256
** was chosen by measuring insertion times for a certain input (first
** 10k documents of Enron corpus), though including query performance
** in the decision may argue for a larger value.
*/
#define CHUNK_MAX 256

typedef enum fulltext_statement {
  CONTENT_INSERT_STMT,
  CONTENT_SELECT_STMT,
  CONTENT_DELETE_STMT,

  TERM_SELECT_STMT,
  TERM_SELECT_ALL_STMT,
  TERM_INSERT_STMT,
  TERM_UPDATE_STMT,
  TERM_DELETE_STMT,

  MAX_STMT                     /* Always at end! */
} fulltext_statement;

................................................................................
*/
static const char *const fulltext_zStatement[MAX_STMT] = {
  /* CONTENT_INSERT */ "insert into %_content (rowid, content) values (?, ?)",
  /* CONTENT_SELECT */ "select content from %_content where rowid = ?",
  /* CONTENT_DELETE */ "delete from %_content where rowid = ?",

  /* TERM_SELECT */
  "select rowid, doclist from %_term where term = ? and segment = ?",
  /* TERM_SELECT_ALL */
  "select doclist from %_term where term = ? order by segment",
  /* TERM_INSERT */
  "insert into %_term (term, segment, doclist) values (?, ?, ?)",
  /* TERM_UPDATE */ "update %_term set doclist = ? where rowid = ?",
  /* TERM_DELETE */ "delete from %_term where rowid = ?",
};

typedef struct fulltext_vtab {
  sqlite3_vtab base;
  sqlite3 *db;
................................................................................

  rc = sqlite3_bind_int64(s, 1, iRow);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, CONTENT_DELETE_STMT, &s);
}

/* select rowid, doclist from %_term
 *  where term = [pTerm] and segment = [iSegment]
 * If found, returns SQLITE_ROW; the caller must free the
 * returned doclist.  If no rows found, returns SQLITE_DONE. */
static int term_select(fulltext_vtab *v, const char *pTerm, int nTerm,

                       int iSegment,
                       sqlite_int64 *rowid, DocList *out){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_SELECT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int(s, 2, iSegment);
  if( rc!=SQLITE_OK ) return rc;

  rc = sql_step_statement(v, TERM_SELECT_STMT, &s);
  if( rc!=SQLITE_ROW ) return rc;

  *rowid = sqlite3_column_int64(s, 0);
  docListInit(out, DL_POSITIONS_OFFSETS,
              sqlite3_column_blob(s, 1), sqlite3_column_bytes(s, 1));

  /* We expect only one row.  We must execute another sqlite3_step()
   * to complete the iteration; otherwise the table will remain locked. */
  rc = sqlite3_step(s);
  return rc==SQLITE_DONE ? SQLITE_ROW : rc;
}

/* Load the segment doclists for term pTerm and merge them in
** appropriate order into out.  Returns SQLITE_OK if successful.  If
** there are no segments for pTerm, successfully returns an empty
** doclist in out.
*/
static int term_select_all(fulltext_vtab *v, const char *pTerm, int nTerm,
                           DocList *out){
  DocList doclist;
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_SELECT_ALL_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  docListInit(&doclist, DL_POSITIONS_OFFSETS, 0, 0);

  /* TODO(shess) Handle schema and busy errors. */
  while( (rc=sql_step_statement(v, TERM_SELECT_ALL_STMT, &s))==SQLITE_ROW ){
    DocList old;

    /* TODO(shess) If we processed doclists from oldest to newest, we
    ** could skip the malloc() involved with the following call.  For
    ** now, I'd rather keep this logic similar to index_insert_term().
    ** We could additionally drop elements when we see deletes, but
    ** that would require a distinct version of docListAccumulate().
    */
    docListInit(&old, doclist.iType,
                sqlite3_column_blob(s, 0), sqlite3_column_bytes(s, 0));

    /* doclist contains the newer data, so write it over old.  Then
    ** steal accumulated result for doclist.
    */
    docListAccumulate(&old, &doclist);
    docListDestroy(&doclist);
    doclist = old;
  }
  if( rc!=SQLITE_DONE ){
    docListDestroy(&doclist);
    return rc;
  }

  *out = doclist;
  return SQLITE_OK;
}

/* insert into %_term (term, segment, doclist)
               values ([pTerm], [iSegment], [doclist]) */
static int term_insert(fulltext_vtab *v, const char *pTerm, int nTerm,
                       int iSegment, DocList *doclist){
  sqlite3_stmt *s;
  int rc = sql_get_statement(v, TERM_INSERT_STMT, &s);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_text(s, 1, pTerm, nTerm, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_int(s, 2, iSegment);
  if( rc!=SQLITE_OK ) return rc;

  rc = sqlite3_bind_blob(s, 3, doclist->pData, doclist->nData, SQLITE_STATIC);
  if( rc!=SQLITE_OK ) return rc;

  return sql_single_step_statement(v, TERM_INSERT_STMT, &s);
}
................................................................................
  ** the rowid used as the docid.
  **
  ** The %_term table maps each term to a document list blob
  ** containing elements sorted by ascending docid, each element
  ** encoded as:
  **
  **   docid varint-encoded
  **   token elements:
  **     position+1 varint-encoded as delta from previous position
  **     start offset varint-encoded as delta from previous start offset
  **     end offset varint-encoded as delta from start offset
  **
  ** The sentinel position of 0 indicates the end of the token list.
  **
  ** Additionally, doclist blobs are chunked into multiple segments,
  ** using segment to order the segments.  New elements are added to
  ** the segment at segment 0, until it exceeds CHUNK_MAX.  Then
  ** segment 0 is deleted, and the doclist is inserted at segment 1.
  ** If there is already a doclist at segment 1, the segment 0 doclist
  ** is merged with it, the segment 1 doclist is deleted, and the
  ** merged doclist is inserted at segment 2, repeating those
  ** operations until an insert succeeds.
  **
  ** Since this structure doesn't allow us to update elements in place
  ** in case of deletion or update, these are simply written to
  ** segment 0 (with an empty token list in case of deletion), with
  ** docListAccumulate() taking care to retain lower-segment
  ** information in preference to higher-segment information.
  */
  /* TODO(shess) Provide a VACUUM type operation which both removes
  ** deleted elements which are no longer necessary, and duplicated
  ** elements.  I suspect this will probably not be necessary in
  ** practice, though.
  */
  rc = sql_exec(db, argv[2],
    "create table %_content(content text);"
    "create table %_term(term text, segment integer, doclist blob, "
                        "primary key(term, segment));");
  if( rc!=SQLITE_OK ) return rc;

  return fulltextConnect(db, pAux, argc, argv, ppVTab);
}

/* Decide how to handle an SQL query.
 * At the moment, MATCH queries can include implicit boolean ANDs; we
................................................................................
      return rc==SQLITE_DONE ? SQLITE_ERROR : rc;
    default:
      assert( 0 );
      return SQLITE_ERROR;  /* not reached */
  }
}


















/* Read the posting list for [pTerm]; AND it with the doclist [pIn] to
 * produce the doclist [out], using the given phrase position [iPhrasePos].
 * (*pSelect) is used to hold an SQLite statement used inside this function;
 * the caller should initialize *pSelect to NULL before the first call.
 */
static int mergeQuery(fulltext_vtab *v, const char *pTerm, int nTerm,

                       DocList *pIn, int iPhrasePos, DocList *out){
  int rc;
  DocListMerge merge;
  DocList doclist;

  /* If [pIn] is already empty, there's no point in reading the
   * posting list to AND it in; return immediately. */
  if( pIn!=NULL && !pIn->nData ) return SQLITE_OK;

  rc = term_select_all(v, pTerm, nTerm, &doclist);
  if( rc!=SQLITE_OK ) return rc;

  mergeInit(&merge, pIn, iPhrasePos, out);





  mergeBlock(&merge, &doclist);
  docListDestroy(&doclist);





  return SQLITE_OK;
}

typedef struct QueryTerm {
  int isPhrase;    /* true if this term begins a new phrase */
  char *pTerm;
  int nTerm;
................................................................................

/* Perform a full-text query; return a list of documents in [pResult]. */
static int fulltextQuery(fulltext_vtab *v, const char *pInput, int nInput,
                          DocList **pResult){
  Query q;
  int phrase_start = -1;
  int i;

  DocList *d = NULL;

  int rc = parseQuery(v, pInput, nInput, &q);
  if( rc!=SQLITE_OK ) return rc;

  /* Merge terms. */
  for(i = 0 ; i < q.nTerms ; ++i){
................................................................................
    /* In each merge step, we need to generate positions whenever we're
     * processing a phrase which hasn't ended yet. */
    int needPositions = i<q.nTerms-1 && !q.pTerms[i+1].isPhrase;
    DocList *next = docListNew(needPositions ? DL_POSITIONS : DL_DOCIDS);
    if( q.pTerms[i].isPhrase ){
      phrase_start = i;
    }
    rc = mergeQuery(v, q.pTerms[i].pTerm, q.pTerms[i].nTerm,
                     d, i-phrase_start, next);
    if( rc!=SQLITE_OK ) break;
    if( d!=NULL ){
      docListDelete(d);
    }
    d = next;
  }


  queryDestroy(&q);
  *pResult = d;
  return rc;
}

static int fulltextFilter(sqlite3_vtab_cursor *pCursor,
                          int idxNum, const char *idxStr,
................................................................................
  ** this point?  Actually, same question about sqlite3_finalize(),
  ** though one could argue that failure there means that the data is
  ** not durable.  *ponder*
  */
  pTokenizer->pModule->xClose(pCursor);
  return rc;
}

/* Update the %_terms table to map the term [pTerm] to the given rowid. */
static int index_insert_term(fulltext_vtab *v, const char *pTerm, int nTerm,
                             DocList *d){

  sqlite_int64 iIndexRow;
  DocList doclist;
  int iSegment = 0, rc;

  rc = term_select(v, pTerm, nTerm, iSegment, &iIndexRow, &doclist);
  if( rc==SQLITE_DONE ){
    docListInit(&doclist, DL_POSITIONS_OFFSETS, 0, 0);
    docListUpdate(&doclist, d);
    /* TODO(shess) Consider length(doclist)>CHUNK_MAX? */
    rc = term_insert(v, pTerm, nTerm, iSegment, &doclist);


    goto err;
  }
  if( rc!=SQLITE_ROW ) return SQLITE_ERROR;


  docListUpdate(&doclist, d);
  if( doclist.nData<=CHUNK_MAX ){
    rc = term_update(v, iIndexRow, &doclist);
    goto err;
  }



  /* Doclist doesn't fit, delete what's there, and accumulate
  ** forward.
  */
  rc = term_delete(v, iIndexRow);
  if( rc!=SQLITE_OK ) goto err;




  /* Try to insert the doclist into a higher segment bucket.  On
  ** failure, accumulate existing doclist with the doclist from that
  ** bucket, and put results in the next bucket.
  */
  iSegment++;
  while( (rc=term_insert(v, pTerm, nTerm, iSegment, &doclist))!=SQLITE_OK ){
    DocList old;



    int rc2;

    /* Retain old error in case the term_insert() error was really an
    ** error rather than a bounced insert.
    */
    rc2 = term_select(v, pTerm, nTerm, iSegment, &iIndexRow, &old);
    if( rc2!=SQLITE_ROW ) goto err;

    rc = term_delete(v, iIndexRow);
    if( rc!=SQLITE_OK ) goto err;

    /* doclist contains the newer data, so accumulate it over old.
    ** Then steal accumulated data for doclist.
    */
    docListAccumulate(&old, &doclist);
    docListDestroy(&doclist);
    doclist = old;


    iSegment++;
  }

 err:
  docListDestroy(&doclist);
  return rc;
}

/* Insert a row into the full-text index; set *piRowid to be the ID of the
 * new row. */
static int index_insert(fulltext_vtab *v, sqlite3_value *pRequestRowid,
................................................................................
  if( !pText || !nText ) return SQLITE_OK;   /* nothing to index */

  rc = buildTerms(&terms, v->pTokenizer, pText, nText, *piRowid);
  if( rc!=SQLITE_OK ) return rc;

  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    rc = index_insert_term(v, fts1HashKey(e), fts1HashKeysize(e), p);
    if( rc!=SQLITE_OK ) break;
  }

  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    docListDelete(p);
  }
  fts1HashClear(&terms);
  return rc;
}



























/* Delete a row from the full-text index. */
static int index_delete(fulltext_vtab *v, sqlite_int64 iRow){
  char *pText = 0;
  int nText = 0;
  fts1Hash terms;
  fts1HashElem *e;
  DocList doclist;

  int rc = content_select(v, iRow, &pText, &nText);
  if( rc!=SQLITE_OK ) return rc;

  rc = buildTerms(&terms, v->pTokenizer, pText, nText, iRow);
  free(pText);
  if( rc!=SQLITE_OK ) return rc;

  /* Delete by inserting a doclist with no positions.  This will
  ** overwrite existing data as it is merged forward by
  ** index_insert_term().
  */
  docListInit(&doclist, DL_POSITIONS_OFFSETS, 0, 0);
  docListAddDocid(&doclist, iRow);

  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    rc = index_insert_term(v, fts1HashKey(e), fts1HashKeysize(e), &doclist);
    if( rc!=SQLITE_OK ) break;
  }
  for(e=fts1HashFirst(&terms); e; e=fts1HashNext(e)){
    DocList *p = fts1HashData(e);
    docListDelete(p);
  }
  fts1HashClear(&terms);
  docListDestroy(&doclist);

  if( rc!=SQLITE_OK ) return rc;
  return content_delete(v, iRow);
}

static int fulltextUpdate(sqlite3_vtab *pVtab, int nArg, sqlite3_value **ppArg,
                   sqlite_int64 *pRowid){
  fulltext_vtab *v = (fulltext_vtab *) pVtab;