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Overview
| Comment: | Improvements to the LogEst command-line tool used to convert between ordinary numbers and the LogEst representation. |
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| Downloads: | Tarball | ZIP archive | SQL archive |
| Timelines: | family | ancestors | descendants | both | row-size-est |
| Files: | files | file ages | folders |
| SHA1: |
5252aeb61988e511dcf8d527fa81e51a |
| User & Date: | drh 2013-10-05 18:32:30 |
Context
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2013-10-05
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| 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
Changes to tool/logest.c.
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while( x<8 ){ y -= 10; x <<= 1; }
}else{
while( x>255 ){ y += 40; x >>= 4; }
while( x>15 ){ y += 10; x >>= 1; }
}
return a[x&7] + y - 10;
}
static unsigned long int logEstToInt(LogEst x){
unsigned long int n;
if( x<10 ) return 1;
n = x%10;
x /= 10;
if( n>=5 ) n -= 2;
else if( n>=1 ) n -= 1;
if( x>=3 ) return (n+8)<<(x-3);
return (n+8)>>(3-x);
}
static LogEst logEstFromDouble(double x){
sqlite3_uint64 a;
LogEst e;
assert( sizeof(x)==8 && sizeof(a)==8 );
if( x<=0 ) return -32768;
if( x<1 ) return -logEstFromDouble(1/x);
if( x<=2000000000 ) return logEstFromInteger((sqlite3_uint64)x);
memcpy(&a, &x, 8);
e = (a>>52) - 1022;
return e*10;
}
int isFloat(const char *z){
while( z[0] ){
................................................................................
a[n++] = logEstFromInteger(atoi(z));
}
}
for(i=n-1; i>=0; i--){
if( a[i]<0 ){
printf("%d (%f)\n", a[i], 1.0/(double)logEstToInt(-a[i]));
}else{
printf("%d (%lu)\n", a[i], logEstToInt(a[i]));
}
}
return 0;
}
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while( x<8 ){ y -= 10; x <<= 1; }
}else{
while( x>255 ){ y += 40; x >>= 4; }
while( x>15 ){ y += 10; x >>= 1; }
}
return a[x&7] + y - 10;
}
static sqlite3_uint64 logEstToInt(LogEst x){
sqlite3_uint64 n;
if( x<10 ) return 1;
n = x%10;
x /= 10;
if( n>=5 ) n -= 2;
else if( n>=1 ) n -= 1;
if( x>=3 ) return (n+8)<<(x-3);
return (n+8)>>(3-x);
}
static LogEst logEstFromDouble(double x){
sqlite3_uint64 a;
LogEst e;
assert( sizeof(x)==8 && sizeof(a)==8 );
if( x<=0.0 ) return -32768;
if( x<1.0 ) return -logEstFromDouble(1/x);
if( x<1024.0 ) return logEstFromInteger((sqlite3_uint64)(1024.0*x)) - 100;
if( x<=2000000000.0 ) return logEstFromInteger((sqlite3_uint64)x);
memcpy(&a, &x, 8);
e = (a>>52) - 1022;
return e*10;
}
int isFloat(const char *z){
while( z[0] ){
................................................................................
a[n++] = logEstFromInteger(atoi(z));
}
}
for(i=n-1; i>=0; i--){
if( a[i]<0 ){
printf("%d (%f)\n", a[i], 1.0/(double)logEstToInt(-a[i]));
}else{
sqlite3_uint64 x = logEstToInt(a[i]+100)*100/1024;
printf("%d (%lld.%02lld)\n", a[i], x/100, x%100);
}
}
return 0;
}
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