Here's a small patch which greatly increases the speed of pg_dump --column-inserts.
Previous to this patch a string was being build for the names of the columns for each row in the table... I've now changed this to only do this once for the table.
I also did some clean ups to remove calling the va_args function to write to the backup file when it was not needed, it instead now uses the puts type function which should be faster.
Here are some benchmark results on how it performs:
*** patched ***
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 5850 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 5790 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 5700 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 5760 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 5730 ms
*** unpatched ***
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 9580 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 9330 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 9250 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 9230 ms
D:\9.4\bin>timer pg_dump --column-inserts -f d:\postgres_backup.sql postgres
Ran for 9240 ms
The database contained a single 1 million record table with 6 columns.
Regards
David Rowley