c4ab7da606
Until now, when calling pq_putmessage to write new data to a libpq socket, all writes are copied into a buffer and that buffer gets flushed when full to avoid having to perform small writes to the socket. There are cases where we must write large amounts of data to the socket, sometimes larger than the size of the buffer. In this case, it's wasteful to memcpy this data into the buffer and flush it out, instead, we can send it directly from the memory location that the data is already stored in. Here we adjust internal_putbytes() so that after having just flushed the buffer to the socket, if the remaining bytes to send is as big or bigger than the buffer size, we just send directly rather than needlessly copying into the PqSendBuffer buffer first. Examples of operations that write large amounts of data in one message are; outputting large tuples with SELECT or COPY TO STDOUT and pg_basebackup. Author: Melih Mutlu Reviewed-by: Heikki Linnakangas Reviewed-by: Jelte Fennema-Nio Reviewed-by: David Rowley Reviewed-by: Ranier Vilela Reviewed-by: Andres Freund Discussion: https://postgr.es/m/CAGPVpCR15nosj0f6xe-c2h477zFR88q12e6WjEoEZc8ZYkTh3Q@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.
Copyright and license information can be found in the file COPYRIGHT.
General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/devel/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/devel/installation.html.
The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.