Re: Patch: show relation and tuple infos of a lock to acquire

On Mon, Feb 24, 2014 at 10:13 AM, Christian Kruse
<christian(at)2ndquadrant(dot)com> wrote:
> To be honest, I don't like the idea of setting up this error context
> only for log_lock_wait messages. This sounds unnecessary complex to me
> and I think that in the few cases where this message doesn't add a
> value (and thus is useless) don't justify such complexity.

Reading this over, I'm not sure I understand why this is a CONTEXT at
all and not just a DETAIL for the particular error message that it's
supposed to be decorating. Generally CONTEXT should be used for
information that will be relevant to all errors in a given code path,
and DETAIL for extra information specific to a particular error.

If we're going to stick with CONTEXT, we could rephrase it like this:

CONTEXT: while attempting to lock tuple (1,2) in relation with OID 3456

or when the relation name is known:

CONTEXT: while attempting to lock tuple (1,2) in relation "public"."foo"

>> Displaying whole tuple doesn't seem to be the most right way
>> to get debug information and especially in this case we are
>> already displaying tuple offset(ctid) which is unique identity
>> to identify a tuple. It seems to me that it is sufficient to display
>> unique value of tuple if present.
>> I understand that there is no clear issue here, so may be if others also
>> share their opinion then it will be quite easy to take a call.

I wouldn't be inclined to dump the whole tuple under any
circumstances. That could be a lot more data than what you want
dumped in your log. The PK could already be somewhat unreasonably
large, but the whole tuple could be a lot more unreasonably large.

--
Robert Haas
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