The improvements from using a transaction are familiar to me and make intuitive sense. But can someone explain why using a prepared statement results in a roughly 5x improvement? Parsing the very simple SQL doesn't seem like it would account for much time, so is the extra time spent redoing query planning or something else?
>Parsing the very simple SQL doesn't seem like it would account for much time, so is the extra time spent redoing query planning or something else?
If you're inserting one million rows, even 5 microseconds of parse and planning time per query is five extra seconds on a job that could be done in half a second.
Depends on the complexity of the planning, but... typically planning (in mssql, am not familiar with sqlite).
Parsing is linear, planning gets exponential very quickly. It's got to consider data distribution, presence or not of indexes, output ordering, presence of foreign keys, uniqueness, and lots more I can't think of right now.
So, planning is much heavier than parsing (for any non-trivial query).
A very simple statement may not be as simple as it looks to execute.
The table here is unconstrained (from the article "CREATE TABLE integers (value INTEGER);") but suppose that table had a primary key and a foreign key – a simple insertion of a single value into such a table would look trivial but consider what the query plan would look like as it verifies the PK and FK aren't violated. And maybe there are a couple of indexes to be updated as well. And a check constraint or three. Suddenly a simple INSERT of a literal value becomes quite involved under the skin.
(edit: and you can add possible triggers on the table)
