2. improve vacuum for gist
- use FSM
- full vacuum:
- reforms parent tuple if it's needed
( tuples was deleted on child page or parent tuple remains invalid
after crash recovery )
- truncate index file if possible
3. fixes bugs and mistakes
scankeys arrays that it needs can never have more than INDEX_MAX_KEYS
entries, so it's reasonable to just allocate them as fixed-size local
arrays, and save the cost of palloc/pfree. Not a huge savings, but
a cycle saved is a cycle earned ...
includes error checking and an appropriate ereport(ERROR) message.
This gets rid of rather tedious and error-prone manipulation of errno,
as well as a Windows-specific bug workaround, at more than a dozen
call sites. After an idea in a recent patch by Heikki Linnakangas.
given reasonably short lifespans for prepared transactions, this should
mean that only a small minority of state files ever need to be fsynced
at all. Per discussion with Heikki Linnakangas.
not memcpy() to copy the offered key into the hash table during HASH_ENTER.
This avoids possible core dump if the passed key is located very near the
end of memory. Per report from Stefan Kaltenbrunner.
old suggestion by Oliver Jowett. Also, add a transaction column to the
pg_locks view to show the xid of each transaction holding or awaiting
locks; this allows prepared transactions to be properly associated with
the locks they own. There was already a column named 'transaction',
and I chose to rename it to 'transactionid' --- since this column is
new in the current devel cycle there should be no backwards compatibility
issue to worry about.
> * Auto-fill the free space map by scanning the buffer cache or by
> checking pages written by the background writer
< * Auto-fill the free space map by scanning the buffer cache or by
< checking pages written by the background writer
>
> * Create a bitmap of pages that need vacuuming
>
> Instead of sequentially scanning the entire table, have the background
> writer or some other process record pages that have expired rows, then
> VACUUM can look at just those pages rather than the entire table. In
> the event of a system crash, the bitmap would probably be invalidated.
work if either of the join relations are empty. The logic is:
(1) if the inner relation's startup cost is less than the outer
relation's startup cost and this is not an outer join, read
a single tuple from the inner relation via ExecHash()
- if NULL, we're done
(2) read a single tuple from the outer relation
- if NULL, we're done
(3) build the hash table on the inner relation
- if hash table is empty and this is not an outer join,
we're done
(4) otherwise, do hash join as usual
The implementation uses the new MultiExecProcNode API, per a
suggestion from Tom: invoking ExecHash() now produces the first
tuple from the Hash node's child node, whereas MultiExecHash()
builds the hash table.
I had to put in a bit of a kludge to get the row count returned
for EXPLAIN ANALYZE to be correct: since ExecHash() is invoked to
return a tuple, and then MultiExecHash() is invoked, we would
return one too many tuples to EXPLAIN ANALYZE. I hacked around
this by just manually detecting this situation and subtracting 1
from the EXPLAIN ANALYZE row count.
> against rc1. It simply checks with GetDatabaseEncoding() if the current
> database is in UTF-8, and if so, sets the UTF-8 flag on the arguments
> that are passed to perl. This means that it isn't necessary to
> utf8::upgrade() every string, as perl has no way of knowing offhand
> that a string is UTF-8 -- but postgres does, because the database
> encoding is specified, so it makes sense to turn the flag on. You
> should also be able to properly manipulate UTF-8 strings now from
> plperl as opposed to plperlu, because otherwise you'd have to use
> encoding 'utf8' which was not allowed. It could also eliminate some
> unexpected bugs if you assume that perl knows the string is unicode.
It
> is enabled only for perl 5.6 and higher, so earlier versions will not
> be affected.
>
> I have been assured by crab that the patch is quite harmless and will
> not break anything. It would be great to see it in 8 final! :-)
David Kamholz
"AT TIME ZONE", and not just the shorlist previously available. For
example:
SELECT CURRENT_TIMESTAMP AT TIME ZONE 'Europe/London';
works fine now. It will also obey whatever DST rules were in effect at
just that date, which the previous implementation did not.
It also supports the AT TIME ZONE on the timetz datatype. The whole
handling of DST is a bit bogus there, so I chose to make it use whatever
DST rules are in effect at the time of executig the query. not sure if
anybody is actuallyi *using* timetz though, it seems pretty
unpredictable just because of this...
Magnus Hagander
>> assuming this sideeffect is removed, though?
>
>I have no problem with the hashtable, only with preloading it with
>everything. What I'd like to see is that the table inherited at fork()
>contains just the data for the default timezone. (At least in the
>normal case where that setting hasn't been changed since postmaster
>start.)
Here's a patch doing this. Changes score_timezone not to use pg_tzset(),
and thus not loading all the zones in the cache. The actual timezone
being picked will be set using set_global_timezone() which in turn calls
pg_tzset() and loads it in the cache.
Magnus Hagander
