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Overview
Comment:Enhance the generate_series() table-valued function to support negative step values.
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SHA3-256: 9b60fc48706bb77b2d4fe27a7b5834a6dc229b4051a9285032da578e4f2849e6
User & Date: drh 2020-12-03 14:21:26
Context
2020-12-03
19:25
Do not simulate OOM faults on the SQLITE_FCNTL_CKPT_START and SQLITE_FCNTL_CKPT_DONE file-controls, as those are write-only and the return value is always ignored. (check-in: 62a2d394 user: drh tags: trunk)
14:21
Enhance the generate_series() table-valued function to support negative step values. (check-in: 9b60fc48 user: drh tags: trunk)
2020-12-02
20:07
Prevent potential segfault in the sqlite-expert idxPopulateStat1 context cleanup code. (check-in: c24f1344 user: mistachkin tags: trunk)
Changes
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Changes to ext/misc/series.c.

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** is a bitmask showing which constraints are available:
**
**    1:    start=VALUE
**    2:    stop=VALUE
**    4:    step=VALUE
**
** Also, if bit 8 is set, that means that the series should be output
** in descending order rather than in ascending order.

**
** This routine should initialize the cursor and position it so that it
** is pointing at the first row, or pointing off the end of the table
** (so that seriesEof() will return true) if the table is empty.
*/
static int seriesFilter(
  sqlite3_vtab_cursor *pVtabCursor, 








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** is a bitmask showing which constraints are available:
**
**    1:    start=VALUE
**    2:    stop=VALUE
**    4:    step=VALUE
**
** Also, if bit 8 is set, that means that the series should be output
** in descending order rather than in ascending order.  If bit 16 is
** set, then output must appear in ascending order.
**
** This routine should initialize the cursor and position it so that it
** is pointing at the first row, or pointing off the end of the table
** (so that seriesEof() will return true) if the table is empty.
*/
static int seriesFilter(
  sqlite3_vtab_cursor *pVtabCursor,
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  if( idxNum & 2 ){
    pCur->mxValue = sqlite3_value_int64(argv[i++]);
  }else{
    pCur->mxValue = 0xffffffff;
  }
  if( idxNum & 4 ){
    pCur->iStep = sqlite3_value_int64(argv[i++]);
    if( pCur->iStep<1 ) pCur->iStep = 1;





  }else{
    pCur->iStep = 1;
  }
  for(i=0; i<argc; i++){
    if( sqlite3_value_type(argv[i])==SQLITE_NULL ){
      /* If any of the constraints have a NULL value, then return no rows.
      ** See ticket https://www.sqlite.org/src/info/fac496b61722daf2 */








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  if( idxNum & 2 ){
    pCur->mxValue = sqlite3_value_int64(argv[i++]);
  }else{
    pCur->mxValue = 0xffffffff;
  }
  if( idxNum & 4 ){
    pCur->iStep = sqlite3_value_int64(argv[i++]);
    if( pCur->iStep==0 ){
      pCur->iStep = 1;
    }else if( pCur->iStep<0 ){
      pCur->iStep = -pCur->iStep;
      if( (idxNum & 16)==0 ) idxNum |= 8;
    }
  }else{
    pCur->iStep = 1;
  }
  for(i=0; i<argc; i++){
    if( sqlite3_value_type(argv[i])==SQLITE_NULL ){
      /* If any of the constraints have a NULL value, then return no rows.
      ** See ticket https://www.sqlite.org/src/info/fac496b61722daf2 */
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  }
  if( (idxNum & 3)==3 ){
    /* Both start= and stop= boundaries are available.  This is the 
    ** the preferred case */
    pIdxInfo->estimatedCost = (double)(2 - ((idxNum&4)!=0));
    pIdxInfo->estimatedRows = 1000;
    if( pIdxInfo->nOrderBy==1 ){
      if( pIdxInfo->aOrderBy[0].desc ) idxNum |= 8;




      pIdxInfo->orderByConsumed = 1;
    }
  }else{
    /* If either boundary is missing, we have to generate a huge span
    ** of numbers.  Make this case very expensive so that the query
    ** planner will work hard to avoid it. */
    pIdxInfo->estimatedRows = 2147483647;








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  }
  if( (idxNum & 3)==3 ){
    /* Both start= and stop= boundaries are available.  This is the 
    ** the preferred case */
    pIdxInfo->estimatedCost = (double)(2 - ((idxNum&4)!=0));
    pIdxInfo->estimatedRows = 1000;
    if( pIdxInfo->nOrderBy==1 ){
      if( pIdxInfo->aOrderBy[0].desc ){
        idxNum |= 8;
      }else{
        idxNum |= 16;
      }
      pIdxInfo->orderByConsumed = 1;
    }
  }else{
    /* If either boundary is missing, we have to generate a huge span
    ** of numbers.  Make this case very expensive so that the query
    ** planner will work hard to avoid it. */
    pIdxInfo->estimatedRows = 2147483647;
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