[Pypgsql-users] Patch for PGunescapeBytea

[Ben L. <be...@zu...>]

Hi,

I found the libpq function PGunescapeBytea a little slow. It was taking a 
minute and a half to decode a 500Kb on a fairly fast machine. I think the 
culprit is sscanf.

I attach a patch that replaces the function with one used to perform the same 
task in pyPgSQL (a Python interface to PostgreSQL). This code was written by 
Billy Allie, author of pyPgSQL. I've changed a few variable names to match 
those in the original code and removed a bit of Pythonness.

I've checked with the author, the code is licensed under a BSD license.

I've performed limited testing of the function by putting JPEGs into 
PostgreSQL, extracting them using them using the new function and diffing 
against the original files.

The new function is significantly faster on my machine with the JPEGs being 
decoded in less than a second. I attach a modified libpq example program that 
I used for my testing.

Regards,

Ben Lamb.

The patch modifies fe-exec.c in /src/interfaces/libpq from PostgreSQL 7.3.2.