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Overview
Comment:Increase the estimated full-scan cost for an FTS3 table.
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Timelines: family | ancestors | descendants | both | nextgen-query-plan-exp
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SHA1: 8d9f29f847f38612447c79a5fb366a9143ef6205
User & Date: drh 2013-06-04 13:07:44.387
Context
2013-06-04
13:37
Better determination of when an index is UNIQUE. (check-in: 63fd025ad9 user: drh tags: nextgen-query-plan-exp)
13:07
Increase the estimated full-scan cost for an FTS3 table. (check-in: 8d9f29f847 user: drh tags: nextgen-query-plan-exp)
12:58
Fix a display issue with EXPLAIN QUERY PLAN. (check-in: ff2fa40755 user: drh tags: nextgen-query-plan-exp)
Changes
Unified Diff Ignore Whitespace Patch
Changes to ext/fts3/fts3.c.
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  int iLangidCons = -1;           /* Index of langid=x constraint, if present */

  /* By default use a full table scan. This is an expensive option,
  ** so search through the constraints to see if a more efficient 
  ** strategy is possible.
  */
  pInfo->idxNum = FTS3_FULLSCAN_SEARCH;
  pInfo->estimatedCost = 500000;
  for(i=0; i<pInfo->nConstraint; i++){
    struct sqlite3_index_constraint *pCons = &pInfo->aConstraint[i];
    if( pCons->usable==0 ) continue;

    /* A direct lookup on the rowid or docid column. Assign a cost of 1.0. */
    if( iCons<0 
     && pCons->op==SQLITE_INDEX_CONSTRAINT_EQ 








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1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433

  int iLangidCons = -1;           /* Index of langid=x constraint, if present */

  /* By default use a full table scan. This is an expensive option,
  ** so search through the constraints to see if a more efficient 
  ** strategy is possible.
  */
  pInfo->idxNum = FTS3_FULLSCAN_SEARCH;
  pInfo->estimatedCost = 5000000;
  for(i=0; i<pInfo->nConstraint; i++){
    struct sqlite3_index_constraint *pCons = &pInfo->aConstraint[i];
    if( pCons->usable==0 ) continue;

    /* A direct lookup on the rowid or docid column. Assign a cost of 1.0. */
    if( iCons<0 
     && pCons->op==SQLITE_INDEX_CONSTRAINT_EQ
︙︙