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by hot_gril 996 days ago
I'm curious which takes longer, parsing or planning.
1 comments

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).

That's what I expect, but for these very simple batch insert queries, it's hard to guess which takes longer.
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)

Right, but in this particular example, the table is just

  CREATE TABLE integers (value INTEGER);
I said exactly that.
My bad, missed the first part.