Thread: Remove unneeded left joins from psql
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 In response to Bruce's recent question, and remembering the recent scolding received about removing a "LEFT" from an unrelated patch :), here's a patch that does that and nothing more: removes all unnecessary left joins from psql. Done in the theory that we often point people to psql -E, so our queries there should be as correct as possible: if the joining column is not null, then we don't need a left join. - -- Greg Sabino Mullane greg@turnstep.com PGP Key: 0x14964AC8 200504112254 http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 -----BEGIN PGP SIGNATURE----- iD8DBQFCWzjVvJuQZxSWSsgRAkwLAKDRMAV3GK/mYEMYEkP4SGC6CWqGNgCg1yIf oQf+YvYkHJRK1WDz11Hw1Oc= =oZDp -----END PGP SIGNATURE-----
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Greg Sabino Mullane <greg@turnstep.com> writes:
> here's a patch that does that and nothing more: removes all
> unnecessary left joins from psql. Done in the theory that we often
> point people to psql -E, so our queries there should be as correct
> as possible: if the joining column is not null, then we don't need
> a left join.
I'm still not happy about this. "Joining column is not null" has
nothing to do with it --- what is at issue is whether there is certain
to be a match. Since we do not have foreign-key enforcement on the
system catalog interrelationships, it is possible for system bugs or
manual intervention to create non-matching situations.
We have seen enough failures associated with "can't happen" missing
links that I think it's just folly to remove error tolerance like this.
I mean, there are *many* thousands of lines of code that we can remove
if the only criterion is readability and robustness means nothing...
who needs WAL for example?
regards, tom lane
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 > I'm still not happy about this. "Joining column is not null" has > nothing to do with it --- what is at issue is whether there is certain > to be a match. Since we do not have foreign-key enforcement on the > system catalog interrelationships, it is possible for system bugs or > manual intervention to create non-matching situations. Yes, you are right about this: we should fail in a way that puts a null schema rather than not matching at all. Must get more sleep before blindly patching next time. :) - -- Greg Sabino Mullane greg@turnstep.com PGP Key: 0x14964AC8 200504122121 http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8 -----BEGIN PGP SIGNATURE----- iD8DBQFCXHRhvJuQZxSWSsgRAv8yAJ97xvvNVJ5Tvcwlr7f5mIDqtXBqpACgkvro pvWsWqanqcTnfO9thU8n0j4= =aYbU -----END PGP SIGNATURE-----