Appending values to lists is a common task when working with DuckDB and other DBMSs (not to mention programming languages in general). Usually we’ll get a function that’s purpose built for the task. As it turns out, DuckDB provides us with at least three functions to do this task.
arrays
3 DuckDB Functions that Prepend a Value to a List
DuckDB provides us with a few functions that prepend a value to a list. Actually, these functions are synonymous, so they all do the same thing, with the same/similar basic syntax.
Fix “Macro function generate_subscripts(arr, dim) requires 2 positional arguments” in DuckDB
If you’re getting an error that reads something like “Macro function generate_subscripts(arr, dim) requires 2 positional arguments” in DuckDB, it appears that you’re calling the generate_subscripts() function with the wrong number of arguments.
Understanding DuckDB’s LIST_GRADE_UP() Function
Among DuckDB’s many tools for handling list data is the list_grade_up() function. This function works similarly to a sort operation, but instead of returning the sorted values themselves, it returns the indexes that represent the positions of those values in the original list.
Let’s take a quick look.
Fix “No function matches the given name and argument types” When Using GENERATE_SUBSCRIPTS() in DuckDB
If you’re getting an error that reads something like “No function matches the given name and argument types” when using the generate_subscripts() function in DuckDB, it could be that your first argument is not an array. Or it could be that your second argument is not compatible with the INT64 type.
Fix “Out of Range Error” When Using GENERATE_SUBSCRIPTS() in DuckDB
If you’re getting an “Out of Range Error” when using the generate_subscripts() function in DuckDB, it could be that you’re specifying a non-existent dimension for the array.
DuckDB’s generate_subscripts() function accepts the array as the first argument, and the dimension as the second argument. The second argument must correspond to an actual dimension present in the array.
To fix this issue, be sure to specify a dimension that actually exists in the array.
Fix ‘Binder Error: Could not find key “…” in struct’ When Using DuckDB’s ARRAY_EXTRACT() Function
If you’re getting an error that reads something like “Binder Error: Could not find key “…” in struct” when using the array_extract() function in DuckDB, it could be that you’re specifying a non-existent key.
When using DuckDB’s array_extract() function to extract a value from a struct, we must provide a key that actually exists in the struct. Otherwise we’ll end up with an error like the above one.
To fix this issue, be sure to specify a key that actually exists in the struct.
Fix “Could not convert string ‘…’ to INT64” When Using the GENERATE_SUBSCRIPTS() Function in DuckDB
If you’re getting an error that reads something like “Could not convert string ‘…’ to INT64” when using the generate_subscripts() function in DuckDB, it appears that your second argument is a string, when it should be an integer.
DuckDB’s generate_subscripts() function accepts two arguments; the array as the first argument, and the dimension as the second argument. The second argument must be INT64 (or be able to be implicitly converted to that type). Passing the wrong data type as the second argument can cause the above error to occur.
To fix this issue, make sure that the second argument is compatible with INT64.
Looking at the GENERATE_SUBSCRIPTS() Function in DuckDB
The generate_subscripts() function in DuckDB creates a series of index values for accessing elements in an array. It can help us iterate through array indices when we need to work with array elements.
Here’s a quick look at DuckDB’s generate_subscripts() function, along with examples.
Exploring ARRAY_AGG() in DuckDB
array_agg() is an aggregate function in DuckDB that allows you to combine values from multiple rows into a list. This article explores how array_agg() works, along with some examples that demonstrate its usage.
