Fri Oct 26 00:37:08 PDT 2007
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On Thu, 2007-10-25 at 19:59 -0700, David Fetter wrote: > Does Slony-I 2-to-be use INSERT ... VALUES (...), ..., (...); to pass > INSERTs? It seems to me this would be quicker than a flock of > single-tuple INSERTs, and since we're having flag day with 8.3, we're > guaranteed the feature is there. :) It's not easily possible to do this because each invocation of the log trigger has a different set of values and they can't see each others values. It could be possible to do this on the apply side by saving up data from log table row to row until we can issue a single mega-INSERT. But if we were going to do that, why not initiate a COPY, which would handle the bulk cases even better? The difficulty would be in deciding what the logic should be to invoke the special case SQL construction. Another thought: I notice that Slony writes out all of the column names for each insert e.g. (col1, col2, col3) VALUES (x, y, x) It would be straightforward to remove the (col1, col2, col3) text from each INSERT statement since that is optional. That would reduce the overhead of each INSERT row and reduce the parsing time on the other side also. -- Simon Riggs 2ndQuadrant http://www.2ndQuadrant.com
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