Excel Format Plugin
Introduced in release: 1.17.
This plugin enables Drill to read Microsoft Excel files. This format is best used with Excel files that do not have extensive formatting, however it will work with formatted files, by allowing you to define a region within the file which contains the data to be read by Drill.
The plugin will automatically evaluate cells which contain formulae.
Configuring the Excel Format Plugin
This plugin has several configuration variables which must be set in order to read Excel files effectively. Since Excel files often contain other elements besides data, you can use the configuration variables to define a region within your spreadsheet in which Drill should extract data. This is potentially useful if your spreadsheet contains a lot of formatting or other complications.
Configuration Options
The most basic configuration is simply to add the following to a file based storage plugin.
"excel": {
"type": "excel"
}
Additional configuration options are tabled below.
| Option | Default | Description |
|---|---|---|
| headerRow | 0 | Set to -1 if there are no column headers. If the data does not have a header row, Drill will assign column names of field_n for each column. |
| lastRow | 1048576 | This defines the last row of data. It is only necessary to set this if you want Drill to stop reading at a specific location. |
| sheetName | (first sheet) | This is the name of the sheet which Drill will query. Drill will throw an exception if the sheet is not found. |
| firstColumn | (none) | In order to define a region within a spreadsheet, this is the left-most column index. This is indexed from one. If set to 0, Drill will start at the left most column. |
| lastColumn | (none) | To define a region within a spreadsheet, this is the right-most column index. This is indexed from one. If set to 0 Drill will read all available columns. This is not right-inclusive, so if you ask for columns 2-5 you will get columns 2, 3 and 4. |
| allTextMode | false | When set to true, Drill will not attempt to infer column data types and will read everything as VARCHAR. |
Usage Notes
You can specify the configuration at runtime via the table() function or in the storage plugin configuration. For instance, if you just want to query an Excel file, you could
execute the query as follows:
SELECT <fields>
FROM dfs.`somefile.xlsx`
To query a different sheet other than the default, use the table() function as shown below:
SELECT <fields>
FROM table( dfs.`test_data.xlsx` (type => 'excel', sheetName => 'secondSheet'))
To join data together from different sheets in one file, use the query below:
SELECT <fields>
FROM table( dfs.`test_data.xlsx` (type => 'excel', sheetName => 'secondSheet')) AS t1
INNER JOIN table( dfs.`test_data.xlsx` (type => 'excel', sheetName => 'thirdSheet')) AS t2
ON t1.id = t2.id
Implicit Columns
Drill includes several columns of file metadata in the query results. These fields are not included in star queries and thus must be explicitly listed in a query.
The fields are:
_category
_content_status
_content_type;
_creator
_description
_identifier
_keywords
_last_modified_by_user
_revision
_subject
_title
_created
_last_printed
_modified
Known Limitations
At present, Drill requires that all columns be of the same data type. If they are not, Drill will throw an exception upon trying to read a column of mixed data type. If you are trying to query data with heterogenoeus columns, it will be necessary to set allTextMode to true.
An additional limitation is that Drill infers the column data type from the first row of data. If a column is null in the first row, Drill will default to a datatype of VARCHAR. However if in fact the column is NUMERIC this will cause errors.
Drill ignores blank rows.