| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
| Cc: | Robert Haas <robertmhaas(at)gmail(dot)com>, Dimitri Fontaine <dfontaine(at)hi-media(dot)com>, Emmanuel Cecchet <manu(at)asterdata(dot)com>, Emmanuel Cecchet <Emmanuel(dot)Cecchet(at)asterdata(dot)com>, PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: COPY enhancements |
| Date: | 2009-10-09 13:44:42 |
| Message-ID: | 6960.1255095882@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Simon Riggs <simon(at)2ndQuadrant(dot)com> writes:
> Another thing that has occurred to me is that RI checks are currently
> resolved at end of statement and could end up rejecting any/all rows
> loaded. If we break down the load into subtransaction pieces we would
> really want the RI checks on the rows to be performed during the
> subtransaction that makes them. The good thing about that is that it
> would lend itself to holding successful checks in a hash table to allow
> a fast path optimization of continual re-checks of same values.
If we did that it would guarantee that cases like self-referential RI
would fail. (Think parent-child links in a tree, for example.)
I see the point about wishing that such checks would be part of the
per-row error handling, but we can't just unconditionally do things
that way.
regards, tom lane
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