available output buffer when presented with corrupt input. Some testing
suggests that this slows the decompression loop about 1%, which seems an
acceptable price to pay for more robustness. (Curiously, the penalty
seems to be *less* on not-very-compressible data, which I didn't expect
since the overhead per output byte ought to be more in the literal-bytes
path.)
Patch from Zdenek Kotala. I fixed a corner case and did some renaming
of variables to make the routine more readable.
were discussed last year, but we felt it was too late in the 8.3 cycle to
change the code immediately. Specifically, the patch:
* Reduces the minimum datum size to be considered for compression from
256 to 32 bytes, as suggested by Greg Stark.
* Increases the required compression rate for compressed storage from
20% to 25%, again per Greg's suggestion.
* Replaces force_input_size (size above which compression is forced)
with a maximum size to be considered for compression. It was agreed
that allowing large inputs to escape the minimum-compression-rate
requirement was not bright, and that indeed we'd rather have a knob
that acted in the other direction. I set this value to 1MB for the
moment, but it could use some performance studies to tune it.
* Adds an early-failure path to the compressor as suggested by Jan:
if it's been unable to find even one compressible substring in the
first 1KB (parameterizable), assume we're looking at incompressible
input and give up. (Possibly this logic can be improved, but I'll
commit it as-is for now.)
* Improves the toasting heuristics so that when we have very large
fields with attstorage 'x' or 'e', we will push those out to toast
storage before considering inline compression of shorter fields.
This also responds to a suggestion of Greg's, though my original
proposal for a solution was a bit off base because it didn't fix
the problem for large 'e' fields.
There was some discussion in the earlier threads of exposing some
of the compression knobs to users, perhaps even on a per-column
basis. I have not done anything about that here. It seems to me
that if we are changing around the parameters, we'd better get some
experience and be sure we are happy with the design before we set
things in stone by providing user-visible knobs.
TopMemoryContext, rather than scattered through executor per-query contexts.
This poses no danger of memory leak since the ResourceOwner mechanism
guarantees release of no-longer-needed items. It is needed because the
per-query context might already be released by the time we try to clean up
the hash scan list. Report by ykhuang, diagnosis by Heikki.
Back-patch to 8.0, where the ResourceOwner-based cleanup was introduced.
The given test case does not fail before 8.2, probably because we rearranged
transaction abort processing somehow; but this coding is undoubtedly risky
so I'll patch 8.0 and 8.1 anyway.
>
> * Add comments on system tables/columns using the information in
> catalogs.sgml
>
> Ideally the information would be pulled from the SGML file
> automatically.
>
a unused memory holes in tsquery.
Per report by Richard Huxton <dev@archonet.com>.
It was working well because in fact tsquery->size is not used for any
kind of operation except comparing tsqueries. So, in HEAD it's enough to
fix to_tsquery function, but for previous version it's needed to
remove optimization in CompareTSQ to prevent requirement of renew all
stored tsquery.
>
> * Allow client certificate names to be checked against the client
> hostname
>
> This is already implemented in
> libpq/fe-secure.c::verify_peer_name_matches_certificate() but the code
> is commented out.
> * Prevent malicious functions from being executed with the permissions
> of unsuspecting users
>
> Index functions are safe, so VACUUM and ANALYZE are safe too.
> Triggers, CHECK and DEFAULT expressions, and rules are still vulnerable.
> http://archives.postgresql.org/pgsql-hackers/2008-01/msg00268.php
>
> o Have CONSTRAINT cname NOT NULL preserve the contraint name
>
> Right now pg_attribute.attnotnull records the NOT NULL status
> of the column, but does not record the contraint name
>
caches that we don't actually need to touch. This saves some trivial
number of cycles and avoids certain cases of deadlock when doing concurrent
VACUUM FULL on system catalogs. Per report from Gavin Roy.
Backpatch to 8.2. In earlier versions, CatalogCacheInitializeCache didn't
lock the relation so there's no deadlock risk (though that certainly had
plenty of risks of its own).
temporary table; we can't support that because there's no way to clean up the
source backend's internal state if the eventual COMMIT PREPARED is done by
another backend. This was checked correctly in 8.1 but I broke it in 8.2 :-(.
Patch by Heikki Linnakangas, original trouble report by John Smith.
<
< o To better utilize resources, restore data, primary keys, and
< indexes for a single table before restoring the next table
<
< Hopefully this will allow the CPU-I/O load to be more uniform
< for simultaneous restores. The idea is to start data restores
< for several objects, and once the first object is done, to move
< on to its primary keys and indexes. Over time, simultaneous
< data loads and index builds will be running.
< * pg_dump
> * pg_dump / pg_restore
> o Allow pg_dump to utilize multiple CPUs and I/O channels by dumping
> multiple objects simultaneously
>
> The difficulty with this is getting multiple dump processes to
> produce a single dump output file.
> http://archives.postgresql.org/pgsql-hackers/2008-02/msg00205.php
>
> o Allow pg_restore to utilize multiple CPUs and I/O channels by
> restoring multiple objects simultaneously
>
> This might require a pg_restore flag to indicate how many
> simultaneous operations should be performed. Only pg_dump's
> -Fc format has the necessary dependency information.
>
> o To better utilize resources, restore data, primary keys, and
> indexes for a single table before restoring the next table
>
> Hopefully this will allow the CPU-I/O load to be more uniform
> for simultaneous restores. The idea is to start data restores
> for several objects, and once the first object is done, to move
> on to its primary keys and indexes. Over time, simultaneous
> data loads and index builds will be running.
>
> o To better utilize resources, allow pg_restore to check foreign
> keys simultaneously, where possible
> o Allow pg_restore to create all indexes of a table
> concurrently, via a single heap scan
>
> This requires a pg_dump -Fc file because that format contains
> the required dependency information.
> http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
>
> o Allow pg_restore to load different parts of the COPY data
> simultaneously
< single heap scan, and have a restore of a pg_dump somehow use it
> single heap scan, and have pg_restore use it
< http://archives.postgresql.org/pgsql-general/2007-05/msg01274.php
Tom Lane
Bruce Momjian
Teodor Sigaev
Alvaro Herrera
Magnus Hagander