Basic Data Types
Data types are configured within the datatype
object using the object type
.
"settings": {
"output_columns": [
{
"name": "a_string_column",
"datatype": {
"type": "string",
.........
Basic Types
The following are supported.
Type | Indexed | Nullable | Description | Stored as |
---|---|---|---|---|
boolean | Yes (Default) | Yes | Converted to a uint8 prior to storage. The case-insensitive strings "false" or "0" get converted to 0 . Any other non-0 value gets converted to 1 . | uint8 |
double | No (can not be indexed). | Yes | A 64-bit floating-point number. | float64 |
int8 | Yes (Default) | Yes | A signed 8-bit integer (-128 : 127 ). | int8 |
int32 | Yes (Default) | Yes | A signed 32-bit integer (-2147483648 : 2147483647 ). | int32 |
int64 | Yes (Default) | Yes | A signed 64-bit integer (-9223372036854775808 : 9223372036854775807 ). | int64 |
string | Yes (Default) | Yes | A variable-length string. Equivalent to VARCHAR or CLOB in other data systems. | string |
uint8 | Yes (Default) | Yes | An unsigned 8-bit integer (0 : 255 ). | uint8 |
uint32 | Yes (Default) | Yes | An unsigned 32-bit integer (0 : 4294967295 ). | uint32 |
uint64 | Yes (Default) | Yes | An unsigned 64-bit integer (0 : 18446744073709551615 ). | uint64 |
Nullables
Nullables in Hydrolix are not directly defined in the type and instead are defined by the default
setting within the datatype
object. By default all columns (except primary columns) are nullable, to make a field non-nullable a default
is set forcing a value if one is not provided.
It should be noted that the default
setting should be appropriate to the type, e.g. setting ""
(empty string) for the type uint64 will cause unexpected and likely unwanted behaviours.
Performance, Nulls and Strings
Hydrolix has seen performance improvements in query times if nulls are not required. For example setting a string
default
set as""
(empty string).
"settings": {
"output_columns": [
{
"name": "nullable_string",
"datatype": {
"type": "string",
"default": null
}
},
{
"name": "non_nullable_string",
"datatype": {
"type": "string",
"default": ""
}
},
{
"name": "nullable_uint64",
"datatype": {
"type": "uint64",
"default": null
}
},
{
"name": "non_nullable_string",
"datatype": {
"type": "uint64",
"default": 0
}
},
..................
Indexing
Hydrolix has been specifically designed to index by default, without the traditional penalties found in older data platforms. It is therefore strongly suggested that the user should only turn off indexing of a column when absolutely necessary. By default Hydrolix indexes all data types except doubles.
Indexing is turned (on and) off within the data type descriptor in Output Columns.
"settings": {
"output_columns": [
{
"name": "indexed_string_column",
"datatype": {
"type": "string",
"index": true
}
},
{
"name": "not_indexed_string_column",
"datatype": {
"type": "string",
"index": false
}
}
]
}
Updated 10 months ago