The old algorithm was found to not be the usual CRC-32 algorithm, used by
Ethernet et al. We were using a non-reflected lookup table with code meant
for a reflected lookup table. That's a strange combination that AFAICS does
not correspond to any bit-wise CRC calculation, which makes it difficult to
reason about its properties. Although it has worked well in practice, seems
safer to use a well-known algorithm.
Since we're changing the algorithm anyway, we might as well choose a
different polynomial. The Castagnoli polynomial has better error-correcting
properties than the traditional CRC-32 polynomial, even if we had
implemented it correctly. Another reason for picking that is that some new
CPUs have hardware support for calculating CRC-32C, but not CRC-32, let
alone our strange variant of it. This patch doesn't add any support for such
hardware, but a future patch could now do that.
The old algorithm is kept around for tsquery and pg_trgm, which use the
values in indexes that need to remain compatible so that pg_upgrade works.
While we're at it, share the old lookup table for CRC-32 calculation
between hstore, ltree and core. They all use the same table, so might as
well.
return true for exactly the characters treated as whitespace by their flex
scanners. Per report from Victor Snezhko and subsequent investigation.
Also fix a passel of unsafe usages of <ctype.h> functions, that is, ye olde
char-vs-unsigned-char issue. I won't miss <ctype.h> when we are finally
able to stop using it.
Christopher Kings-Lynne wrote:
> I'm still getting ltree failures on 64bit freebsd:
>
> sed 's,MODULE_PATHNAME,$libdir/ltree,g' ltree.sql.in >ltree.sql
> gcc -pipe -O -g -Wall -Wmissing-prototypes -Wmissing-declarations -fpic -DPI
> C -DLOWER_NODE -I. -I../../src/include -c -o ltree_io.o ltree_io.c -MMD
> ltree_io.c: In function `ltree_in':
> ltree_io.c:57: warning: int format, different type arg (arg 3)
> ltree_io.c:63: warning: int format, different type arg (arg 4)
> ltree_io.c:68: warning: int format, different type arg (arg 3)
Teodor Sigaev
Heikki Linnakangas
Bruce Momjian
Magnus Hagander
Tom Lane