Increasing Aggregate Field Length¶
By default, Aggregate's datastore layer limits text values to 255 characters or less. If a submission includes a value longer than 255 characters, those additional characters are not saved in the database and no warning is shown. That means there is a risk of data loss when using question types that save long text values such as geotrace, geoshape or select multiple. This limitation exists for performance reasons, particularly for older versions of MySQL.
It is possible to set the desired database field length for a particular question. This value can go up to about 16000 UTF-8 characters but the datastore storage efficiency may get worse as the value increases.
In an XLSForm, the database field length is set from the bind::odk:length column. On form upload, Aggregate will adjust the database field length of questions that have a whole number in that column. Other questions will get a default length of 255.
XLSForm
| type | name | label | bind::odk:length |
|---|---|---|---|
| select_multiple opt_abc | multi | Select multi | 500 |
| geoshape | shape | Select an area | 1000 |
| list_name | name | label |
|---|---|---|
| opt_abc | a | A |
| opt_abc | b | B |
| opt_abc | c | C |