From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
---|---|
To: | Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com> |
Cc: | Surafel Temesgen <surafel3000(at)gmail(dot)com>, Adam Berlin <berlin(dot)ab(at)gmail(dot)com>, pgsql-hackers(at)lists(dot)postgresql(dot)org |
Subject: | Re: COPY FROM WHEN condition |
Date: | 2018-12-04 09:44:18 |
Message-ID: | 20181204094418.wpr6mxrtsuxb5mlq@alvherre.pgsql |
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Lists: | pgsql-hackers |
After reading this thread, I think I like WHERE better than FILTER.
Tally:
WHERE: Adam Berlin, Lim Myungkyu, Dean Rasheed, yours truly
FILTER: Tomas Vondra, Surafel Temesgen
Couldn't find others expressing an opinion in this regard.
On 2018-Nov-30, Tomas Vondra wrote:
> I think it should be enough just to switch to CIM_SINGLE and increment the
> command counter after each inserted row.
Do we apply command counter increment per row with some other COPY
option? Per-row CCI makes me a bit uncomfortable because with you'd get
in trouble with a large copy. I think it's particularly nasty here,
precisely because you may want to filter out some rows of a very large
file, and the CCI may prevent that from working.
I'm not convinced by the example case of reading how many tuples you've
imported so far in the WHERE/WHEN/FILTER clause each time (that'd become
incrementally slower as it progresses).
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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