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Overview
Comment:Experimental change to ANALYZE so that when computing values for sqlite_stat1, it uses the maximum number for the number of rows having equivalent values, rather than the average.
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SHA3-256:085f17e124d183d1da371250f24988aed5697924e7950162bb6f0bb514298e2a
User & Date: drh 2018-07-20 18:01:21
Context
2018-07-20
18:01
Experimental change to ANALYZE so that when computing values for sqlite_stat1, it uses the maximum number for the number of rows having equivalent values, rather than the average. Leaf check-in: 085f17e1 user: drh tags: stat1-max
15:44
New checks in PRAGMA integrity_check to validate the autovacuum settings in the header. check-in: a4663f09 user: drh tags: trunk
Changes
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Changes to src/analyze.c.

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** information.
*/
typedef struct Stat4Accum Stat4Accum;
typedef struct Stat4Sample Stat4Sample;
struct Stat4Sample {
  tRowcnt *anEq;                  /* sqlite_stat4.nEq */
  tRowcnt *anDLt;                 /* sqlite_stat4.nDLt */

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  tRowcnt *anLt;                  /* sqlite_stat4.nLt */
  union {
    i64 iRowid;                     /* Rowid in main table of the key */
    u8 *aRowid;                     /* Key for WITHOUT ROWID tables */
  } u;
  u32 nRowid;                     /* Sizeof aRowid[] */
................................................................................
  assert( nKeyCol<=nCol );
  assert( nKeyCol>0 );

  /* Allocate the space required for the Stat4Accum object */
  n = sizeof(*p) 
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anEq */
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anDLt */

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anLt */
    + sizeof(Stat4Sample)*(nCol+mxSample)     /* Stat4Accum.aBest[], a[] */
    + sizeof(tRowcnt)*3*nColUp*(nCol+mxSample)
#endif
  ;
  db = sqlite3_context_db_handle(context);
................................................................................
  }

  p->db = db;
  p->nRow = 0;
  p->nCol = nCol;
  p->nKeyCol = nKeyCol;
  p->current.anDLt = (tRowcnt*)&p[1];
  p->current.anEq = &p->current.anDLt[nColUp];


#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  {
    u8 *pSpace;                     /* Allocated space not yet assigned */
    int i;                          /* Used to iterate through p->aSample[] */

    p->iGet = -1;
................................................................................
  UNUSED_PARAMETER( argc );
  UNUSED_PARAMETER( context );
  assert( p->nCol>0 );
  assert( iChng<p->nCol );

  if( p->nRow==0 ){
    /* This is the first call to this function. Do initialization. */
    for(i=0; i<p->nCol; i++) p->current.anEq[i] = 1;



  }else{
    /* Second and subsequent calls get processed here */
    samplePushPrevious(p, iChng);

    /* Update anDLt[], anLt[] and anEq[] to reflect the values that apply
    ** to the current row of the index. */
    for(i=0; i<iChng; i++){
................................................................................
      p->current.anEq[i]++;
    }
    for(i=iChng; i<p->nCol; i++){
      p->current.anDLt[i]++;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
      p->current.anLt[i] += p->current.anEq[i];
#endif



      p->current.anEq[i] = 1;
    }
  }
  p->nRow++;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  if( sqlite3_value_type(argv[2])==SQLITE_INTEGER ){
    sampleSetRowidInt64(p->db, &p->current, sqlite3_value_int64(argv[2]));
................................................................................
      sqlite3_result_error_nomem(context);
      return;
    }

    sqlite3_snprintf(24, zRet, "%llu", (u64)p->nRow);
    z = zRet + sqlite3Strlen30(zRet);
    for(i=0; i<p->nKeyCol; i++){

      u64 nDistinct = p->current.anDLt[i] + 1;
      u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
      sqlite3_snprintf(24, z, " %llu", iVal);
      z += sqlite3Strlen30(z);
      assert( p->current.anEq[i] );






    }
    assert( z[0]=='\0' && z>zRet );

    sqlite3_result_text(context, zRet, -1, sqlite3_free);
  }
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  else if( eCall==STAT_GET_ROWID ){







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** information.
*/
typedef struct Stat4Accum Stat4Accum;
typedef struct Stat4Sample Stat4Sample;
struct Stat4Sample {
  tRowcnt *anEq;                  /* sqlite_stat4.nEq */
  tRowcnt *anDLt;                 /* sqlite_stat4.nDLt */
  tRowcnt *amxEq;                 /* Maximum vlaues for anEq[] */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  tRowcnt *anLt;                  /* sqlite_stat4.nLt */
  union {
    i64 iRowid;                     /* Rowid in main table of the key */
    u8 *aRowid;                     /* Key for WITHOUT ROWID tables */
  } u;
  u32 nRowid;                     /* Sizeof aRowid[] */
................................................................................
  assert( nKeyCol<=nCol );
  assert( nKeyCol>0 );

  /* Allocate the space required for the Stat4Accum object */
  n = sizeof(*p) 
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anEq */
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anDLt */
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.amxEq */
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
    + sizeof(tRowcnt)*nColUp                  /* Stat4Accum.anLt */
    + sizeof(Stat4Sample)*(nCol+mxSample)     /* Stat4Accum.aBest[], a[] */
    + sizeof(tRowcnt)*3*nColUp*(nCol+mxSample)
#endif
  ;
  db = sqlite3_context_db_handle(context);
................................................................................
  }

  p->db = db;
  p->nRow = 0;
  p->nCol = nCol;
  p->nKeyCol = nKeyCol;
  p->current.anDLt = (tRowcnt*)&p[1];
  p->current.amxEq = &p->current.anDLt[nColUp];
  p->current.anEq = &p->current.amxEq[nColUp];

#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  {
    u8 *pSpace;                     /* Allocated space not yet assigned */
    int i;                          /* Used to iterate through p->aSample[] */

    p->iGet = -1;
................................................................................
  UNUSED_PARAMETER( argc );
  UNUSED_PARAMETER( context );
  assert( p->nCol>0 );
  assert( iChng<p->nCol );

  if( p->nRow==0 ){
    /* This is the first call to this function. Do initialization. */
    for(i=0; i<p->nCol; i++){
      p->current.anEq[i] = 1;
      p->current.amxEq[i] = 1;
    }
  }else{
    /* Second and subsequent calls get processed here */
    samplePushPrevious(p, iChng);

    /* Update anDLt[], anLt[] and anEq[] to reflect the values that apply
    ** to the current row of the index. */
    for(i=0; i<iChng; i++){
................................................................................
      p->current.anEq[i]++;
    }
    for(i=iChng; i<p->nCol; i++){
      p->current.anDLt[i]++;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
      p->current.anLt[i] += p->current.anEq[i];
#endif
      if( p->current.amxEq[i]<p->current.anEq[i] ){
        p->current.amxEq[i] = p->current.anEq[i];
      }
      p->current.anEq[i] = 1;
    }
  }
  p->nRow++;
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  if( sqlite3_value_type(argv[2])==SQLITE_INTEGER ){
    sampleSetRowidInt64(p->db, &p->current, sqlite3_value_int64(argv[2]));
................................................................................
      sqlite3_result_error_nomem(context);
      return;
    }

    sqlite3_snprintf(24, zRet, "%llu", (u64)p->nRow);
    z = zRet + sqlite3Strlen30(zRet);
    for(i=0; i<p->nKeyCol; i++){
#if 0
      u64 nDistinct = p->current.anDLt[i] + 1;
      u64 iVal = (p->nRow + nDistinct - 1) / nDistinct;
      sqlite3_snprintf(24, z, " %llu", iVal);
      z += sqlite3Strlen30(z);
      assert( p->current.anEq[i] );
#else
      u64 iVal = p->current.amxEq[i];
      if( iVal<p->current.anEq[i] ) iVal = p->current.anEq[i];
      sqlite3_snprintf(24, z, " %llu", iVal);
      z += sqlite3Strlen30(z);
#endif
    }
    assert( z[0]=='\0' && z>zRet );

    sqlite3_result_text(context, zRet, -1, sqlite3_free);
  }
#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
  else if( eCall==STAT_GET_ROWID ){