in be/src/exec/parquet/parquet-common.h [203:246]
static int DecimalSize(const ColumnType& t) {
DCHECK(t.type == TYPE_DECIMAL);
// Numbers in the comment is the max positive value that can be represented
// with those number of bits (max negative is -(X + 1)).
// TODO: use closed form for this?
switch (t.precision) {
case 1: case 2:
return 1; // 127
case 3: case 4:
return 2; // 32,767
case 5: case 6:
return 3; // 8,388,607
case 7: case 8: case 9:
return 4; // 2,147,483,427
case 10: case 11:
return 5; // 549,755,813,887
case 12: case 13: case 14:
return 6; // 140,737,488,355,327
case 15: case 16:
return 7; // 36,028,797,018,963,967
case 17: case 18:
return 8; // 9,223,372,036,854,775,807
case 19: case 20: case 21:
return 9; // 2,361,183,241,434,822,606,847
case 22: case 23:
return 10; // 604,462,909,807,314,587,353,087
case 24: case 25: case 26:
return 11; // 154,742,504,910,672,534,362,390,527
case 27: case 28:
return 12; // 39,614,081,257,132,168,796,771,975,167
case 29: case 30: case 31:
return 13; // 10,141,204,801,825,835,211,973,625,643,007
case 32: case 33:
return 14; // 2,596,148,429,267,413,814,265,248,164,610,047
case 34: case 35:
return 15; // 664,613,997,892,457,936,451,903,530,140,172,287
case 36: case 37: case 38:
return 16; // 170,141,183,460,469,231,731,687,303,715,884,105,727
default:
DCHECK(false);
break;
}
return -1;
}