DuckDB reports DECIMAL(17,14) as column type, but mosaic expects DECIMAL => Unsupported type error

[Robert-M-Muench]

When trying to plot my data I get the following error:

Uncaught (in promise) Error: Unsupported type: DECIMAL(17,14)
y                   	js-type.js:34
(anonymous function)	Catalog.js:75
Async call from await
(anonymous function)	plot.js:7
Zt                  	plot.js:7
(anonymous function)	my.js:46

Using DuckDB's shell I recreated the table and get this:

duckdb> describe mytable;
┌─────────────────────────────────┬────────────────┬──────┬─────┬─────────┬───────┐
│ column_name                     ┆ column_type    ┆ null ┆ key ┆ default ┆ extra │
╞═════════════════════════════════╪════════════════╪══════╪═════╪═════════╪═══════╡
│ MyData                          ┆ DECIMAL(17,14) ┆ YES  ┆     ┆         ┆       │
└─────────────────────────────────┴────────────────┴──────┴─────┴─────────┴───────┘

And this is the code giving the error:

export function jsType(type) {
  switch (type) {
    case 'BIGINT':
    case 'HUGEINT':
    case 'INTEGER':
    case 'SMALLINT':
    case 'TINYINT':
    case 'UBIGINT':
    case 'UINTEGER':
    case 'USMALLINT':
    case 'UTINYINT': // integers
    case 'DOUBLE':
    case 'FLOAT':
    case 'REAL':
    case 'DECIMAL':
      return 'number';
    case 'DATE':
    case 'TIMESTAMP':
    case 'TIMESTAMPTZ':
    case 'TIME':
      return 'date';
    case 'BOOLEAN':
      return 'boolean';
    case 'VARCHAR':
    case 'UUID':
      return 'string';
    case 'LIST':
      return 'array';
    case 'BLOB':
    case 'STRUCT':
    case 'MAP':
      return 'object';
    default:
      throw new Error(`Unsupported type: ${type}`);
  }
}

So, there are several angles:

1. Why does DuckDB use a type of DECIMAL(17,14) and not only DECIMAL?
2. Why does mosaic doesn't handle the DECIMAL type check more flexible supporting the digits stored (17) and after decimal point (14) specification?

How can I solve this problem?

[Robert-M-Muench]

Some more information:

This is the data in DuckDB:

duckdb> select "ID", "MyData" from products;
┌────┬────────────────────┐
│ ID ┆ MyData             │
╞════╪════════════════════╡
│  1 ┆  58.00876801310440 │
│  4 ┆   9.81974174441254 │
│  5 ┆  21.78496638801490 │
│  6 ┆   9.61899355201230 │
│  7 ┆  14.70704004506260 │
│  8 ┆  23.05684167612960 │
│  9 ┆   8.32657889567500 │
│ 12 ┆  13.53855450029060 │
│ 15 ┆  10.98496131109280 │
│ 17 ┆  30.43534065099590 │
│ 18 ┆   9.22529067035384 │
│ 22 ┆   7.64181831981637 │
│ 24 ┆   8.94462646935125 │
│ 25 ┆ 497.52951502941700 │
│ 26 ┆   7.64181831981637 │
│ 27 ┆   5.32343979510389 │
│ 28 ┆   4.97782292683956 │
└────┴────────────────────┘

I loaded the data via loadObjects(...) from a JSON array. The typeof() that field is number on the JS side.

[jheer]

Previously Mosaic was unable to handle Decimal type values, largely because of incomplete decoding support within the Apache Arrow JS lib.

But Mosaic / vgplot v0.7.0 now supports decoding Decimal values to JS numbers! Though potentially lossy with high digit counts (JS numbers may have floating point discretization error), this allows decimal values to be processed and visualized.