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At least on Linux and macOS, fread() turns out to have far higher per-call overhead than one could wish. Reading 64KB of data at a time and then parceling it out with our own memcpy logic makes binary COPY from a file significantly faster --- around 30% in simple testing for cases with narrow text columns (on Linux ... even more on macOS). In binary COPY from frontend, there's no per-call fread(), and this patch introduces an extra layer of memcpy'ing, but it still manages to eke out a small win. Apparently, the control-logic overhead in CopyGetData() is enough to be worth avoiding for small fetches. Bharath Rupireddy and Amit Langote, reviewed by Vignesh C, cosmetic tweaks by me Discussion: https://postgr.es/m/CALj2ACU5Bz06HWLwqSzNMN=Gupoj6Rcn_QVC+k070V4em9wu=A@mail.gmail.com
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.
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