MigsLab Amazon DynamoDB
Supported data types
What each .NET type is stored as in Amazon DynamoDB, and what each Amazon DynamoDB type reads back as.
Writing: .NET to the database
The values Create and Update accept, and what each column stores.
| .NET value | Stored as |
|---|---|
string |
S (string); an empty key value is ARX1001 |
char |
S |
a plain enum |
refused (ARX1007): write (int)value or value.ToString(), or use a selection set |
int, long, short, byte and the unsigned types |
N (number) |
decimal |
N, exact up to 38 digits (more is ARX4001) |
double, float |
N; NaN and infinity are ARX4001 |
bool |
BOOL |
Guid |
S, D format (5f0c…-…) |
byte[], ArxBytea |
B (binary) |
ArxJsonB |
M (map) or L (list), its JSON parsed |
| an array or a list | L, a list of the values above |
ArxSelectionSetValue |
its code, checked against the catalog |
ArxEntityReference |
the referenced id, checked against the catalog (ARX1005) |
null |
NULL |
Dates and times
DynamoDB has no date type: ARX stores dates as sortable text, so a sort key or a condition on a date compares in time order.
| .NET value | Stored as |
|---|---|
DateTime (UTC) |
S, 2026-11-09T10:30:00.0000000Z (every tick kept) |
DateTime (Local) |
converted to UTC |
DateTime (Unspecified) |
taken as UTC |
DateTimeOffset |
its UTC instant (the offset isn't kept) |
DateOnly |
S, 2026-11-09 |
TimeOnly, TimeSpan |
S (09:30:00.0000000, 1.02:03:04) |
default(DateTime), default(DateTimeOffset), default(DateOnly) |
refused (ARX1013): they mean "not set" |
Reading: the database to .NET
What Retrieve and RetrieveMultiple give back for each column.
| Stored as | Read back as |
|---|---|
| S (string) | string, or the preloaded type (Guid, DateTime, DateOnly, …) |
| N (number) | decimal (a double past decimal's range), or the preloaded type |
| BOOL | bool |
| B (binary) | byte[] |
| M (map) | ArxJsonB |
| L (list) | string[] or decimal[] when every element is that kind; otherwise ArxJsonB |
| SS, NS, BS (sets) | string[], a number array, byte[][] |
| NULL, or no attribute | null |
| a declared lookup | ArxEntityReference |