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Unverified Commit afeeab14 authored by Alex Yarosh's avatar Alex Yarosh Committed by GitHub
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update custom expressions limitations (#49447)

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docs/questions/query-builder/expressions-list.md
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......@@ -147,7 +147,7 @@ Syntax: `Median(column)`.
Example: `Median([Age])` would find the midpoint age where half of the ages are older, and half of the ages are younger.
Databases that don't support `median`: MariaDB, MySQL, SQLite, Vertica, and SQL Server. Presto only provides approximate results.
Databases that don't support `median`: Druid, MariaDB, MongoDB, MySQL, SQLite, Vertica, and SQL Server. Presto only provides approximate results.
Related: [Min](#min), [Max](#max), [Average](#average).
......@@ -169,7 +169,7 @@ Syntax: `Percentile(column, percentile-value)`
Example: `Percentile([Score], 0.9)` would return the value at the 90th percentile for all values in that column.
Databases that don't support `percentile`: H2, MariaDB, MySQL, SQL Server, SQLite, Vertica. Presto only provides approximate results.
Databases that don't support `percentile`: Druid, H2, MariaDB, MySQL, MongoDB, SQL Server, SQLite, Vertica. Presto only provides approximate results.
### Share
......@@ -187,6 +187,8 @@ Syntax: `StandardDeviation(column)`
Example: `StandardDeviation([Population])` would return the SD for the values in the `Population` column.
Databases that don't support `StandardDeviation`: Druid, SQLite.
### Sum
Adds up all the values of the column.
......@@ -213,6 +215,8 @@ Example: `Variance([Temperature])` will return a measure of the dispersion from
Related: [StandardDeviation](#standarddeviation), [Average](#average).
Databases that don't support `Variance`: Druid, SQLite.
## Functions
Function expressions apply to each individual value. They can be used to alter or filter values in a column, or create new, custom columns.
......@@ -567,6 +571,8 @@ Syntax: `datetimeDiff(datetime1, datetime2, unit)`.
Example: `datetimeDiff("2022-02-01", "2022-03-01", "month")` would return `1`.
See the [database limitations](./expressions/datetimediff.md#limitations) for `datetimediff`.
### [datetimeSubtract](./expressions/datetimesubtract.md)
Subtracts some unit of time from a date or timestamp value.
......@@ -744,7 +750,7 @@ Related: [Sum](#sum) and [SumIf](#sumif).
### Offset
> ⚠️ The `Offset` function is currently unavailable for MySQL/MariaDB.
> ⚠️ The `Offset` function is currently unavailable for MySQL/MariaDB, MongoDB, and Druid.
For more info, check out our page on [Offset](./expressions/offset.md).
......@@ -773,25 +779,31 @@ Example: `Offset(Sum([Total]), -1)` would get the `Sum([Total])` value from the
Limitations are noted for each aggregation and function above, and here there are in summary:
**H2** (including Metabase Sample Database): `Median`, `Percentile`, `convertTimezone` and `regexextract`
**H2** (including Metabase Sample Database): `Median`, `Percentile`, `convertTimezone` and `regexextract`.
**Druid**: `regexextract` is only available for the Druid-JDBC driver.
**Athena**: `convertTimezone`.
**MongoDB**: `regexextract`
**Databricks**: `convertTimezone`.
**Druid**: `Median`, `Percentile`, `StandardDeviation`, `power`, `log`, `exp`, `sqrt`, `Offset`. Function `regexextract` is only available for the Druid-JDBC driver.
**MongoDB**: `Median`, `Percentile`, `power`, `log`, `exp`, `sqrt`, `Offset`, `regexextract`
**MariaDB**: `Median`, `Percentile`, `Offset`.
**MySQL**: `Median`, `Percentile`, `Offset`.
**Presto**: Only provides _approximate_ results for `Median` and `Percentile`.
**Presto**: `convertTimezone`. Only provides _approximate_ results for `Median` and `Percentile`.
**Redshift**: `Average` will return [integer results for integer columns](https://docs.aws.amazon.com/redshift/latest/dg/r_AVG.html#r_AVG-data-types).
**SQL Server**: `Median`, `Percentile` and `regexextract`
**SparkSQL**: `convertTimezone`.
**SQL Server**: `Median`, `Percentile` and `regexextract`.
**SQLite**: `log`, `Median`, `Percentile`, `power`, `regexextract`, `StandardDeviation`, `sqrt` and `Variance`
**SQLite**: `exp`, `log`, `Median`, `Percentile`, `power`, `regexextract`, `StandardDeviation`, `sqrt` and `Variance`.
**Vertica**: `Median` and `Percentile`
**Vertica**: `Median` and `Percentile`.
If you're using or maintaining a third-party database driver, please [refer to the wiki](https://github.com/metabase/metabase/wiki/What's-new-in-0.35.0-for-Metabase-driver-authors) to see how your driver might be impacted.
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docs/questions/query-builder/expressions/converttimezone.md
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......@@ -87,12 +87,12 @@ For more gory details, see [Limitations](#limitations).
## Accepted data types
| [Data type](https://www.metabase.com/learn/grow-your-data-skills/data-fundamentals/data-types-overview#examples-of-data-types) | Works with `convertTimezone` |
| ------------------------------------------------------------------------------------------------ | ---------------------------- |
| String | ❌ |
| Number | ❌ |
| Timestamp | ✅ |
| Boolean | ❌ |
| JSON | ❌ |
| ------------------------------------------------------------------------------------------------------------------------------ | ---------------------------- |
| String | ❌ |
| Number | ❌ |
| Timestamp | ✅ |
| Boolean | ❌ |
| JSON | ❌ |
We use "timestamp" and "datetime" to talk about any temporal data type that's supported by Metabase.
......@@ -115,6 +115,7 @@ Note that the first part of the timestamp is in UTC (same thing as GMT). The tim
`convertTimezone` is currently unavailable for the following databases:
- Amazon Athena
- Databricks
- Druid
- MongoDB
- Presto
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docs/questions/query-builder/expressions/offset.md
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......@@ -4,7 +4,7 @@ title: Offset
# Offset
> ⚠️ The `Offset` function is currently unavailable for MySQL/MariaDB.
> ⚠️ The `Offset` function is currently unavailable for MySQL/MariaDB, MongoDB, and Druid.
The `Offset` function returns the value of an expression in a different row. `Offset` can only be used in the query builder's Summarize step (you cannot use `Offset` to create a custom column).
......@@ -25,12 +25,12 @@ Because `Offset` refers to other rows, the order of the breakouts matters (the b
The `Offset` function returns whatever value is in the offset row.
| [Data type](https://www.metabase.com/learn/grow-your-data-skills/data-fundamentals/data-types-overview#examples-of-data-types) | Returned by `Offset` |
| ------------------------------------------------------------------------------------------------ | -------------------- |
| String | ✅ |
| Number | ✅ |
| Timestamp | ✅ |
| Boolean | ✅ |
| JSON | ✅ |
| ------------------------------------------------------------------------------------------------------------------------------ | -------------------- |
| String | ✅ |
| Number | ✅ |
| Timestamp | ✅ |
| Boolean | ✅ |
| JSON | ✅ |
## Example year-over-year (YoY) time series comparison using `Offset`
......@@ -86,7 +86,6 @@ The `Offset` function compares with SQL's `LAG` and `LEAD` window functions.
For example, if you're trying to create a line chart with two series to compare a) this month's order counts with b) the previous month's order counts, you'd `count` the orders for this month, then use an `offset` expression to count the previous month's orders, like so:
```
Offset(count, -1)
```
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