mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-10-19 23:10:50 +00:00
0a4a5b36cc
* Additional .gitignore entries * Merge a bunch of small articles about system tables into single one * Merge a bunch of small articles about formats into single one * Adapt table with formats to English docs too * Add SPb meetup link to main page * Move Utilities out of top level of docs (the location is probably not yet final) + translate couple articles * Merge MacOS.md into build_osx.md * Move Data types higher in ToC * Publish changelog on website alongside documentation * Few fixes for en/table_engines/file.md * Use smaller header sizes in changelogs * Group up table engines inside ToC * Move table engines out of top level too * Specificy in ToC that query language is SQL based. Thats a bit excessive, but catches eye. * Move stuff that is part of query language into respective folder * Move table functions lower in ToC * Lost redirects.txt update * Do not rely on comments in yaml + fix few ru titles * Extract major parts of queries.md into separate articles * queries.md has been supposed to be removed * Fix weird translation * Fix a bunch of links * There is only table of contents left * "Query language" is actually part of SQL abbreviation * Change filename in README.md too * fix mistype
71 lines
1.8 KiB
Markdown
71 lines
1.8 KiB
Markdown
# Float32, Float64
|
||
|
||
[Floating point numbers](https://en.wikipedia.org/wiki/IEEE_754).
|
||
|
||
Types are equivalent to types of C:
|
||
|
||
- `Float32` - `float`
|
||
- `Float64` - `double`
|
||
|
||
We recommend that you store data in integer form whenever possible. For example, convert fixed precision numbers to integer values, such as monetary amounts or page load times in milliseconds.
|
||
|
||
## Using floating-point numbers
|
||
|
||
- Computations with floating-point numbers might produce a rounding error.
|
||
|
||
```sql
|
||
SELECT 1 - 0.9
|
||
```
|
||
```
|
||
┌───────minus(1, 0.9)─┐
|
||
│ 0.09999999999999998 │
|
||
└─────────────────────┘
|
||
```
|
||
|
||
- The result of the calculation depends on the calculation method (the processor type and architecture of the computer system).
|
||
- Floating-point calculations might result in numbers such as infinity (`Inf`) and "not-a-number" (`NaN`). This should be taken into account when processing the results of calculations.
|
||
- When reading floating point numbers from rows, the result might not be the nearest machine-representable number.
|
||
|
||
## NaN and Inf
|
||
|
||
In contrast to standard SQL, ClickHouse supports the following categories of floating-point numbers:
|
||
|
||
- `Inf` – Infinity.
|
||
|
||
```sql
|
||
SELECT 0.5 / 0
|
||
```
|
||
|
||
```
|
||
┌─divide(0.5, 0)─┐
|
||
│ inf │
|
||
└────────────────┘
|
||
```
|
||
|
||
- `-Inf` – Negative infinity.
|
||
|
||
```sql
|
||
SELECT -0.5 / 0
|
||
```
|
||
|
||
```
|
||
┌─divide(-0.5, 0)─┐
|
||
│ -inf │
|
||
└─────────────────┘
|
||
```
|
||
|
||
- `NaN` – Not a number.
|
||
|
||
```
|
||
SELECT 0 / 0
|
||
```
|
||
|
||
```
|
||
┌─divide(0, 0)─┐
|
||
│ nan │
|
||
└──────────────┘
|
||
```
|
||
|
||
See the rules for ` NaN` sorting in the section [ORDER BY clause](../query_language/select.md#query_language-queries-order_by).
|
||
|