Re: Query > 1000× slowdown after adding datetime comparison

And another thing which comes out as a little surprising to me - if I replace
the *date_last_updated* condition with another one, say *doc.documenttype =
4*, the query finishes immediately. *documenttype* is an unindexed integer
column.

Here's the query plan:

<http://postgresql.nabble.com/file/n5864080/qp3.png>

What's so special about that *date_last_updated* condition that makes it so
slow to use? Is it because it involves the *date()* function call that it
makes it difficult for the planner to guess the data distribution in the
DOCUMENT table?

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