=?utf-8?Q?Micha=C5=82_K=C5=82eczek?= <michal(at)kleczek(dot)org> writes:
> Does that mean that *any* expression containing text constants is not going to be pushed down??
> That would be a really serious issues I’d say.
If it contains text constants and not text variables, possibly so.
Keep in mind though that this rule is applied after constant-folding,
so that what we're left with is normally going to contain variables
at every level. extract() is problematic because it combines a
text constant with a datetime (collation-less) variable.
regards, tom lane