Re: [PATCHES] hash index improving v3

2008-09-05 Thread Alex Hunsaker
On Thu, Sep 4, 2008 at 9:48 PM, Alex Hunsaker <[EMAIL PROTECTED]> wrote: > (obviously on a 64 bit machine) > int main(void) > { >unsigned long y = 0; >unsigned cnt = 0; > >printf("insert into test_hash (num) values "); > >//while(cnt != LONG_MAX/UINT_MAX) >wh

Re: [PATCHES] [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)

2008-09-05 Thread David Rowley
Heikki Linnakangas wrote: > After reading the wikipedia article on Boyer-Moore search algorithm, it > looks to me like this patch actually implements the simpler > Boyer-Moore-Horspool algorithm that only uses one lookup table. That's > probably fine, as it ought to be faster on small needles an

Re: [PATCHES] [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)

2008-09-05 Thread Tom Lane
"David Rowley" <[EMAIL PROTECTED]> writes: > Tom Lane wrote: >> Hmm. B-M-H has worst case search speed O(M*N) (where M = length of >> pattern, N = length of search string); whereas full B-M is O(N). Maybe we >> should build the second table when M is large? > I'll look into this. If it pays off

Re: [PATCHES] [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)

2008-09-05 Thread Heikki Linnakangas
Tom Lane wrote: "David Rowley" <[EMAIL PROTECTED]> writes: Tom Lane wrote: Hmm. B-M-H has worst case search speed O(M*N) (where M = length of pattern, N = length of search string); whereas full B-M is O(N). Maybe we should build the second table when M is large? I'll look into this. If it

Re: [PATCHES] [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)

2008-09-05 Thread Tom Lane
Heikki Linnakangas <[EMAIL PROTECTED]> writes: > Also, it would be nice to use B-M(-H) for LIKE as well. Right offhand, that seems impossible, at least in patterns with %. Or were you thinking of trying to separate out the fixed substrings of a pattern and search for them with BMH? Anyway, it's n

Re: [PATCHES] libpq events patch (with sgml docs)

2008-09-05 Thread Alvaro Herrera
Andrew Chernow escribió: > ! > printfPQExpBuffer(&conn->errorMessage, > ! > libpq_gettext("PGEventProc \"%s\" failed during PGEVT_CONNRESET event\n"), > !

Re: [PATCHES] [HACKERS] TODO item: Implement Boyer-Moore searching (First time hacker)

2008-09-05 Thread David Rowley
Heikki Linnakangas wrote: > The skip table really should be constructed only once in > text_position_start and stored in TextPositionState. That would make a > big difference to the performance of those functions that call > text_position_next repeatedly: replace_text, split_text and text_to_arr

Re: [PATCHES] hash index improving v3

2008-09-05 Thread Alex Hunsaker
Ok now that I made it so it actually *test* collisions, with the patch it always returns all rows that matched the hashed "key". For example (non lobotomized inthash8, I just brute forced some collisions for 0 so that anyone can try this) create table test_hash (num int8); insert into test_hash (

Re: [PATCHES] libpq events patch (with sgml docs)

2008-09-05 Thread David Rowley
Alvaro Herrera wrote: >Oh, BTW: don't post to pgsql-patches. It's deprecated. Use > pgsql-hackers instead. I thought this too until I read http://wiki.postgresql.org/wiki/Submitting_a_Patch Which is correct? David. -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To m

Re: [PATCHES] libpq events patch (with sgml docs)

2008-09-05 Thread Alvaro Herrera
David Rowley escribió: > Alvaro Herrera wrote: > >Oh, BTW: don't post to pgsql-patches. It's deprecated. Use > > pgsql-hackers instead. > > I thought this too until I read > http://wiki.postgresql.org/wiki/Submitting_a_Patch > > Which is correct? I just updated that page and the developer's FA

Re: [PATCHES] hash index improving v3

2008-09-05 Thread Alex Hunsaker
] On Fri, Sep 5, 2008 at 2:21 PM, Alex Hunsaker <[EMAIL PROTECTED]> wrote: > Ok now that I made it so it actually *test* collisions, with the patch > it always returns all rows that matched the hashed "key". And here is the fix, we just forget to set the recheck flag for bitmap scans. *** a/src/