SQLite: Check-in [5252aeb6]

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Overview

Comment:	Improvements to the LogEst command-line tool used to convert between ordinary numbers and the LogEst representation.
Downloads:	Tarball \| ZIP archive \| SQL archive
Timelines:	family \| ancestors \| descendants \| both \| row-size-est
Files:	files \| file ages \| folders
SHA1:	5252aeb61988e511dcf8d527fa81e51a5c9385f9
User & Date:	drh 2013-10-05 18:32:30

Context

2013-10-05
19:18		Completely remove the iScanRatio field. The PRAGMA index_list(TABLE) command shows the estimated row size in the forth column. It also generates a row for the table with an index name of NULL. The query planner still does not take row size estimates into account - that is the next step. check-in: 8b4aa0c7 user: drh tags: row-size-est
18:32		Improvements to the LogEst command-line tool used to convert between ordinary numbers and the LogEst representation. check-in: 5252aeb6 user: drh tags: row-size-est
18:16		Begin an experimental refactoring to estimate the average number of bytes in table and index rows and to use that information in query planner. Begin by renaming WhereCost to LogEst and making that type and its conversion routines available outside of where.c. check-in: 66c4a251 user: drh tags: row-size-est

Changes

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Changes to tool/logest.c.

    70     70       while( x<8 ){  y -= 10; x <<= 1; }
    71     71     }else{
    72     72       while( x>255 ){ y += 40; x >>= 4; }
    73     73       while( x>15 ){  y += 10; x >>= 1; }
    74     74     }
    75     75     return a[x&7] + y - 10;
    76     76   }
    77         -static unsigned long int logEstToInt(LogEst x){
    78         -  unsigned long int n;
           77  +static sqlite3_uint64 logEstToInt(LogEst x){
           78  +  sqlite3_uint64 n;
    79     79     if( x<10 ) return 1;
    80     80     n = x%10;
    81     81     x /= 10;
    82     82     if( n>=5 ) n -= 2;
    83     83     else if( n>=1 ) n -= 1;
    84     84     if( x>=3 ) return (n+8)<<(x-3);
    85     85     return (n+8)>>(3-x);
    86     86   }
    87     87   static LogEst logEstFromDouble(double x){
    88     88     sqlite3_uint64 a;
    89     89     LogEst e;
    90     90     assert( sizeof(x)==8 && sizeof(a)==8 );
    91         -  if( x<=0 ) return -32768;
    92         -  if( x<1 ) return -logEstFromDouble(1/x);
    93         -  if( x<=2000000000 ) return logEstFromInteger((sqlite3_uint64)x);
           91  +  if( x<=0.0 ) return -32768;
           92  +  if( x<1.0 ) return -logEstFromDouble(1/x);
           93  +  if( x<1024.0 ) return logEstFromInteger((sqlite3_uint64)(1024.0*x)) - 100;
           94  +  if( x<=2000000000.0 ) return logEstFromInteger((sqlite3_uint64)x);
    94     95     memcpy(&a, &x, 8);
    95     96     e = (a>>52) - 1022;
    96     97     return e*10;
    97     98   }
    98     99   
    99    100   int isFloat(const char *z){
   100    101     while( z[0] ){
................................................................................
   128    129         a[n++] = logEstFromInteger(atoi(z));
   129    130       }
   130    131     }
   131    132     for(i=n-1; i>=0; i--){
   132    133       if( a[i]<0 ){
   133    134         printf("%d (%f)\n", a[i], 1.0/(double)logEstToInt(-a[i]));
   134    135       }else{
   135         -      printf("%d (%lu)\n", a[i], logEstToInt(a[i]));
          136  +      sqlite3_uint64 x = logEstToInt(a[i]+100)*100/1024;
          137  +      printf("%d (%lld.%02lld)\n", a[i], x/100, x%100);
   136    138       }
   137    139     }
   138    140     return 0;
   139    141   }