Commit Graph

3 Commits

Author SHA1 Message Date
Bruce Momjian 7559d8ebfa Update copyrights for 2020
Backpatch-through: update all files in master, backpatch legal files through 9.4
2020-01-01 12:21:45 -05:00
Tom Lane 9e58705a7f Make our perfect hash functions be valid C++.
While C is happy to cast "const void *" to "const unsigned char *"
silently, C++ insists on an explicit cast.  Since we put these
functions into header files, cpluspluscheck whines about that.
Add the cast to pacify it.

Discussion: https://postgr.es/m/b517ec3918d645eb950505eac8dd434e@gaz-is.ru
2019-05-31 10:40:00 -04:00
Tom Lane c64d0cd5ce Use perfect hashing, instead of binary search, for keyword lookup.
We've been speculating for a long time that hash-based keyword lookup
ought to be faster than binary search, but up to now we hadn't found
a suitable tool for generating the hash function.  Joerg Sonnenberger
provided the inspiration, and sample code, to show us that rolling our
own generator wasn't a ridiculous idea.  Hence, do that.

The method used here requires a lookup table of approximately 4 bytes
per keyword, but that's less than what we saved in the predecessor commit
afb0d0712, so it's not a big problem.  The time savings is indeed
significant: preliminary testing suggests that the total time for raw
parsing (flex + bison phases) drops by ~20%.

Patch by me, but it owes its existence to Joerg Sonnenberger;
thanks also to John Naylor for review.

Discussion: https://postgr.es/m/20190103163340.GA15803@britannica.bec.de
2019-01-09 19:47:46 -05:00