Category: DBMS

Database Management Systems

Using TRY_CAST() to Handle Errors When Converting Between Data Types in DuckDB

Posted on by Ian

Encountering errors while converting between data types can be frustrating when working with SQL databases like DuckDB. But it usually means that something’s wrong. In most cases these errors occur because we’re trying to perform an impossible conversion, like from a number to a date or something.

But sometimes errors can get in the way, especially when we’re trying to convert a bunch of values. Sometimes it would be better for the system to return NULL for such failed conversions than to return an error and mess up the whole operation. Fortunately, we can do this.

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A Quick Look at the LIST_AGGREGATE() Function in DuckDB

Posted on by Ian

DuckDB’s list_aggregate() function is a handy tool for performing grouped aggregations over lists. It allows us to apply any aggregate function (like sum, avg, min, max, count, etc.) to a list column as if each list item were a row.

The way it works is that we pass the list as the first argument, followed by the name of an aggregate function we want to apply to that list. The function will return its result as if it were the named aggregate function.

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Fix “No function matches the given name and argument types ‘list_concat…” When Using array_push_front() or array_push_back() in DuckDB

Posted on by Ian

If you’re getting a binder error that reads something like “No function matches the given name and argument types ‘list_concat(STRING_LITERAL, VARCHAR[][])’. You might need to add explicit type casts.” in DuckDB when using either the array_push_front() or array_push_back() functions, it could be due to a slight syntax error.

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An Overview of DuckDB’s EPOCH() Function

Posted on by Ian

DuckDB’s epoch() function is a useful time conversion tool that allows us to transform timestamp values into Unix epoch time – the number of seconds that have elapsed since January 1, 1970 (UTC).

The function is particularly useful when working with time-series data and when we need to perform mathematical operations on timestamp values. By converting timestamps to integer representations, we can easily calculate time differences, group time-based data, or integrate with systems that use epoch time.

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2 Ways to Check if a Table has any Partial Indexes in SQLite

Posted on by Ian

In SQLite, a partial index includes only the rows that meet a specified condition, set by a WHERE clause in the index definition. This is different from a regular, or “full,” index, which covers all rows in a table. Partial indexes are helpful when you frequently query specific subsets of data, as they can improve query performance and reduce storage.

If you ever need to check a table to see if it contains any partial indexes, you can use either of the following methods.

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