libpq single-row mode performance - Mailing list pgsql-interfaces

<div class="WordSection1"><p class="MsoNormal">Hi,<p class="MsoNormal"> <p class="MsoNormal">I’m writing an app on top
oflibpq. To avoid running out of memory I’m using the single-row mode, but am finding the overhead in using this quite
significant.<pclass="MsoNormal"> <p class="MsoNormal">What I see is that ~60% of my application’s run time when
retrievingdata is spent in calls to either PQgetResult() and PQclear(). I’ve added a switch in my app to turn off
single-rowmode and the performance roughly doubles.<p class="MsoNormal"> <p class="MsoNormal">Would it be possible to
optimizethe single-row mode? For example, add an API call PQnextRow(PGConn*), which is only usable in single-row mode
andwill just update the existing result with the contents of the next row? This would let us avoid to overhead of:<p
class="MsoListParagraph"style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">1.<span
style="font:7.0pt"Times New Roman"">       </span></span>Malloc’ing a PGResult and initializing its defaults.<p
class="MsoListParagraph"style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">2.<span
style="font:7.0pt"Times New Roman"">       </span></span>Copying the column metadata to the new results.<p
class="MsoListParagraph"style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">3.<span
style="font:7.0pt"Times New Roman"">       </span></span>Possibly we can avoid malloc’ing cell data if the next row has
cellsthe same size or smaller than a previous row, though I’m not sure of the internals here.<p
class="MsoListParagraph"style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><span style="mso-list:Ignore">4.<span
style="font:7.0pt"Times New Roman"">       </span></span>Release memory with PQclear().<p class="MsoNormal"> <p
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