The docs showed that early-January dates can be considered part of the
previous year for week-counting purposes, but failed to say explicitly
that late-December dates can also be considered part of the next year.
Fix that, and add a cross-reference to the "isoyear" field. Per bug
#7967 from Pawel Kobylak.
Remove use of PageSetTLI() from all page manipulation functions
and adjust README to indicate change in the way we make changes
to pages. Repurpose those bytes into the pd_checksum field and
explain how that works in comments about page header.
Refactoring ahead of actual feature patch which would make use
of the checksum field, arriving later.
Jeff Davis, with comments and doc changes by Simon Riggs
Direction suggested by Robert Haas; many others providing
review comments.
This GUC allows limiting the time spent waiting to acquire any one
heavyweight lock.
In support of this, improve the recently-added timeout infrastructure
to permit efficiently enabling or disabling multiple timeouts at once.
That reduces the performance hit from turning on lock_timeout, though
it's still not zero.
Zoltán Böszörményi, reviewed by Tom Lane,
Stephen Frost, and Hari Babu
Clarify the docs explaining what commit_delay does, and add a
recommendation about a useful value for it, namely half of the single-page
fsync time reported by pg_test_fsync. This is informed by testing of
the new-in-9.3 implementation of commit_delay; in prior versions it
was far harder to arrive at a useful setting.
In passing, do some wordsmithing and markup-fixing in the same general
area.
Also, change pg_test_fsync's default time-per-test from 2 seconds to 5.
The old value was about the minimum at which the results could be taken
seriously at all, and so seems a tad optimistic as a default.
Peter Geoghegan, reviewed by Noah Misch; some additional editing by me
There's still some discussion about exactly how postgres_fdw ought to
handle this case, but there seems no debate that we want to allow defaults
to be used for inserts into foreign tables. So remove the core-code
restrictions that prevented it.
While at it, get rid of the special grammar productions for CREATE FOREIGN
TABLE, and instead add explicit FEATURE_NOT_SUPPORTED error checks for the
disallowed cases. This makes the grammar a shade smaller, and more
importantly results in much more intelligible error messages for
unsupported cases. It's also one less thing to fix if we ever start
supporting constraints on foreign tables.
Apparently I lost some of the edits I had done on this page for commit
0ac5ad5134.
Per note from Etsuro Fujita, although I didn't use his patch.
Make some of the wording in the affected section a bit more complete,
too.
This adds the following:
json_agg(anyrecord) -> json
to_json(any) -> json
hstore_to_json(hstore) -> json (also used as a cast)
hstore_to_json_loose(hstore) -> json
The last provides heuristic treatment of numbers and booleans.
Also, in json generation, if any non-builtin type has a cast to json,
that function is used instead of the type's output function.
Andrew Dunstan, reviewed by Steve Singer.
Catalog version bumped.
This patch adds the core-system infrastructure needed to support updates
on foreign tables, and extends contrib/postgres_fdw to allow updates
against remote Postgres servers. There's still a great deal of room for
improvement in optimization of remote updates, but at least there's basic
functionality there now.
KaiGai Kohei, reviewed by Alexander Korotkov and Laurenz Albe, and rather
heavily revised by Tom Lane.
A materialized view has a rule just like a view and a heap and
other physical properties like a table. The rule is only used to
populate the table, references in queries refer to the
materialized data.
This is a minimal implementation, but should still be useful in
many cases. Currently data is only populated "on demand" by the
CREATE MATERIALIZED VIEW and REFRESH MATERIALIZED VIEW statements.
It is expected that future releases will add incremental updates
with various timings, and that a more refined concept of defining
what is "fresh" data will be developed. At some point it may even
be possible to have queries use a materialized in place of
references to underlying tables, but that requires the other
above-mentioned features to be working first.
Much of the documentation work by Robert Haas.
Review by Noah Misch, Thom Brown, Robert Haas, Marko Tiikkaja
Security review by KaiGai Kohei, with a decision on how best to
implement sepgsql still pending.
This includes backend "COPY TO/FROM PROGRAM '...'" syntax, and corresponding
psql \copy syntax. Like with reading/writing files, the backend version is
superuser-only, and in the psql version, the program is run in the client.
In the passing, the psql \copy STDIN/STDOUT syntax is subtly changed: if you
the stdin/stdout is quoted, it's now interpreted as a filename. For example,
"\copy foo from 'stdin'" now reads from a file called 'stdin', not from
standard input. Before this, there was no way to specify a filename called
stdin, stdout, pstdin or pstdout.
This creates a new function in pgport, wait_result_to_str(), which can
be used to convert the exit status of a process, as returned by wait(3),
to a human-readable string.
Etsuro Fujita, reviewed by Amit Kapila.
Like with pg_basebackup and pg_receivexlog, it's a bit strange to call the
option -d/--dbname, when in fact you cannot pass a database name in it.
Original patch by Amit Kapila, heavily modified by me.
You could already pass a database name just by passing it as the last
option, without -d. This is an alias for that, like the -d/--dbname option
in psql and many other client applications. For consistency.
Without this, there's no way to pass arbitrary libpq connection parameters
to these applications. It's a bit strange that the option is called
-d/--dbname, when in fact you can *not* pass a database name in it, but it's
consistent with other client applications where a connection string is also
passed using -d.
Original patch by Amit Kapila, heavily modified by me.
This program relies on rm_desc backend routines and the xlogreader
infrastructure to emit human-readable rendering of WAL records.
Author: Andres Freund, with many reworks by Álvaro
Reviewed (in a much earlier version) by Peter Eisentraut
There's still a lot of room for improvement, but it basically works,
and we need this to be present before we can do anything much with the
writable-foreign-tables patch. So let's commit it and get on with testing.
Shigeru Hanada, reviewed by KaiGai Kohei and Tom Lane
This generalizes the existing ALTER ROLE ... SET and ALTER DATABASE
... SET functionality to allow creating settings that apply to all users
in all databases.
reviewed by Pavel Stehule
The reason this wasn't supported before was that GiST indexes need an
increasing sequence to detect concurrent page-splits. In a regular WAL-
logged GiST index, the LSN of the page-split record is used for that
purpose, and in a temporary index, we can get away with a backend-local
counter. Neither of those methods works for an unlogged relation.
To provide such an increasing sequence of numbers, create a "fake LSN"
counter that is saved and restored across shutdowns. On recovery, unlogged
relations are blown away, so the counter doesn't need to survive that
either.
Jeevan Chalke, based on discussions with Robert Haas, Tom Lane and me.
Improve description of the vacuum_freeze_table_age bug (it's much more
serious than we realized at the time the fix was committed), and correct
attribution of pg_upgrade -O/-o fix (Marti Raudsepp contributed that,
but Bruce forgot to credit him in the commit log).
No need to back-patch right now, it'll happen when the next set of
release notes are prepared.
Instead of hardcoding a specific link, give a general link to the
download section of the web site. This gives the user more download
options and the sysadmins more flexibility. Also, the previously
presented link didn't work for devel versions.
This function was misdeclared to take cstring when it should take internal.
This at least allows crashing the server, and in principle an attacker
might be able to use the function to examine the contents of server memory.
The correct fix is to adjust the system catalog contents (and fix the
regression tests that should have caught this but failed to). However,
asking users to correct the catalog contents in existing installations
is a pain, so as a band-aid fix for the back branches, install a check
in enum_recv() to make it throw error if called with a cstring argument.
We will later revert this in HEAD in favor of correcting the catalogs.
Our thanks to Sumit Soni (via Secunia SVCRP) for reporting this issue.
Security: CVE-2013-0255
This patch changes pg_get_viewdef() and allied functions so that
PRETTY_INDENT processing is always enabled. Per discussion, only the
PRETTY_PAREN processing (that is, stripping of "unnecessary" parentheses)
poses any real forward-compatibility risk, so we may as well make dump
output look as nice as we safely can.
Also, set the default wrap length to zero (i.e, wrap after each SELECT
or FROM list item), since there's no very principled argument for the
former default of 80-column wrapping, and most people seem to agree this
way looks better.
Marko Tiikkaja, reviewed by Jeevan Chalke, further hacking by Tom Lane
In the previous coding, psql's state variable saying that output should
go to a file was only reset after successful completion of a query
returning tuples. Thus for example,
regression=# select 1/0
regression-# \g somefile
ERROR: division by zero
regression=# select 1/2;
regression=#
... huh, I wonder where that output went. Even more oddly, the state
was not reset even if it's the file that's causing the failure:
regression=# select 1/2 \g /foo
/foo: Permission denied
regression=# select 1/2;
/foo: Permission denied
regression=# select 1/2;
/foo: Permission denied
This seems to me not to satisfy the principle of least surprise.
\g is certainly not documented in a way that suggests its effects are
at all persistent.
To fix, adjust the code so that the flag is reset at exit from SendQuery
no matter what happened.
Noted while reviewing the \gset patch, which had comparable issues.
Arguably this is a bug fix, but I'll refrain from back-patching for now.
This is specified in the SQL standard. The CREATE RECURSIVE VIEW
specification is transformed into a normal CREATE VIEW statement with a
WITH RECURSIVE clause.
reviewed by Abhijit Menon-Sen and Stephen Frost
The new option specifies length of aggregation interval (in
seconds). May be used only together with -l. With this option, the log
contains per-interval summary (number of transactions, min/max latency
and two additional fields useful for variance estimation).
Patch contributed by Tomas Vondra, reviewed by Pavel Stehule. Slight
change by Tatsuo Ishii, suggested by Robert Hass to emit an error
message indicating that the option is not currently supported on
Windows.
This patch addresses the problem that applications currently have to
extract object names from possibly-localized textual error messages,
if they want to know for example which index caused a UNIQUE_VIOLATION
failure. It adds new error message fields to the wire protocol, which
can carry the name of a table, table column, data type, or constraint
associated with the error. (Since the protocol spec has always instructed
clients to ignore unrecognized field types, this should not create any
compatibility problem.)
Support for providing these new fields has been added to just a limited set
of error reports (mainly, those in the "integrity constraint violation"
SQLSTATE class), but we will doubtless add them to more calls in future.
Pavel Stehule, reviewed and extensively revised by Peter Geoghegan, with
additional hacking by Tom Lane.
Beyond 21474, the number of accounts exceed the range for int4. Change the
initialization code to use bigint for account id columns when scale is large
enough, and switch to using int64s for the variables in pgbench code. The
threshold where we switch to bigints is set at 20000, because that's easier
to remember and document than 21474, and ensures that there is some headroom
when int4s are used.
Greg Smith, with various changes by Euler Taveira de Oliveira, Gurjeet
Singh and Satoshi Nagayasu.
Give away ownership of shared objects (databases, tablespaces) along
with local objects, per original code intention. Try to make the
documentation clearer, too.
Per discussion about DROP OWNED's brokenness, in bug #7748.
This is not backpatched because it'd require some refactoring of the
ALTER/SET OWNER code for databases and tablespaces.
My "fix" for bugs #7578 and #6116 on DROP OWNED at fe3b5eb08a not only
misstated that it applied to REASSIGN OWNED (which it did not affect),
but it also failed to fix the problems fully, because I didn't test the
case of owned shared objects. Thus I created a new bug, reported by
Thomas Kellerer as #7748, which would cause DROP OWNED to fail with a
not-for-user-consumption error message. The code would attempt to drop
the database, which not only fails to work because the underlying code
does not support that, but is a pretty dangerous and undesirable thing
to be doing as well.
This patch fixes that bug by having DROP OWNED only attempt to process
shared objects when grants on them are found, ignoring ownership.
Backpatch to 8.3, which is as far as the previous bug was backpatched.
The SQL standard does not have general functions-in-FROM, but it does
allow UNNEST() there (see the <collection derived table> production),
and the semantics of that are defined to include lateral references.
So spec compliance requires allowing lateral references within UNNEST()
even without an explicit LATERAL keyword. Rather than making UNNEST()
a special case, it seems best to extend this flexibility to any
function-in-FROM. We'll still allow LATERAL to be written explicitly
for clarity's sake, but it's now a noise word in this context.
In theory this change could result in a change in behavior of existing
queries, by allowing what had been an outer reference in a function-in-FROM
to be captured by an earlier FROM-item at the same level. However, all
pre-9.3 PG releases have a bug that causes them to match variable
references to earlier FROM-items in preference to outer references (and
then throw an error). So no previously-working query could contain the
type of ambiguity that would risk a change of behavior.
Per a suggestion from Andrew Gierth, though I didn't use his patch.
Previously non-honored FREEZE mode was ignored. This also issues an
appropriate error message based on the cause of the failure, per
suggestion from Tom. Additional regression test case added.
In the initial implementation of plan caching, we saved the active
search_path when a plan was first cached, then reinstalled that path
anytime we needed to reparse or replan. The idea of that was to try to
reselect the same referenced objects, in somewhat the same way that views
continue to refer to the same objects in the face of schema or name
changes. Of course, that analogy doesn't bear close inspection, since
holding the search_path fixed doesn't cope with object drops or renames.
Moreover sticking with the old path seems to create more surprises than
it avoids. So instead of doing that, consider that the cached plan depends
on search_path, and force reparse/replan if the active search_path is
different than it was when we last saved the plan.
This gets us fairly close to having "transparency" of plan caching, in the
sense that the cached statement acts the same as if you'd just resubmitted
the original query text for another execution. There are still some corner
cases where this fails though: a new object added in the search path
schema(s) might capture a reference in the query text, but we'd not realize
that and force a reparse. We might try to fix that in the future, but for
the moment it looks too expensive and complicated.
Previously, the VARIADIC labeling was effectively ignored, but now these
functions act as though the array elements had all been given as separate
arguments.
Pavel Stehule
Since 9.0, the count parameter has only limited the number of tuples
actually returned by the executor. It doesn't affect the behavior of
INSERT/UPDATE/DELETE unless RETURNING is specified, because without
RETURNING, the ModifyTable plan node doesn't return control to execMain.c
for each tuple. And we only check the limit at the top level.
While this behavioral change was unintentional at the time, discussion of
bug #6572 led us to the conclusion that we prefer the new behavior anyway,
and so we should just adjust the docs to match rather than change the code.
Accordingly, do that. Back-patch as far as 9.0 so that the docs match the
code in each branch.
This patch introduces two additional lock modes for tuples: "SELECT FOR
KEY SHARE" and "SELECT FOR NO KEY UPDATE". These don't block each
other, in contrast with already existing "SELECT FOR SHARE" and "SELECT
FOR UPDATE". UPDATE commands that do not modify the values stored in
the columns that are part of the key of the tuple now grab a SELECT FOR
NO KEY UPDATE lock on the tuple, allowing them to proceed concurrently
with tuple locks of the FOR KEY SHARE variety.
Foreign key triggers now use FOR KEY SHARE instead of FOR SHARE; this
means the concurrency improvement applies to them, which is the whole
point of this patch.
The added tuple lock semantics require some rejiggering of the multixact
module, so that the locking level that each transaction is holding can
be stored alongside its Xid. Also, multixacts now need to persist
across server restarts and crashes, because they can now represent not
only tuple locks, but also tuple updates. This means we need more
careful tracking of lifetime of pg_multixact SLRU files; since they now
persist longer, we require more infrastructure to figure out when they
can be removed. pg_upgrade also needs to be careful to copy
pg_multixact files over from the old server to the new, or at least part
of multixact.c state, depending on the versions of the old and new
servers.
Tuple time qualification rules (HeapTupleSatisfies routines) need to be
careful not to consider tuples with the "is multi" infomask bit set as
being only locked; they might need to look up MultiXact values (i.e.
possibly do pg_multixact I/O) to find out the Xid that updated a tuple,
whereas they previously were assured to only use information readily
available from the tuple header. This is considered acceptable, because
the extra I/O would involve cases that would previously cause some
commands to block waiting for concurrent transactions to finish.
Another important change is the fact that locking tuples that have
previously been updated causes the future versions to be marked as
locked, too; this is essential for correctness of foreign key checks.
This causes additional WAL-logging, also (there was previously a single
WAL record for a locked tuple; now there are as many as updated copies
of the tuple there exist.)
With all this in place, contention related to tuples being checked by
foreign key rules should be much reduced.
As a bonus, the old behavior that a subtransaction grabbing a stronger
tuple lock than the parent (sub)transaction held on a given tuple and
later aborting caused the weaker lock to be lost, has been fixed.
Many new spec files were added for isolation tester framework, to ensure
overall behavior is sane. There's probably room for several more tests.
There were several reviewers of this patch; in particular, Noah Misch
and Andres Freund spent considerable time in it. Original idea for the
patch came from Simon Riggs, after a problem report by Joel Jacobson.
Most code is from me, with contributions from Marti Raudsepp, Alexander
Shulgin, Noah Misch and Andres Freund.
This patch was discussed in several pgsql-hackers threads; the most
important start at the following message-ids:
AANLkTimo9XVcEzfiBR-ut3KVNDkjm2Vxh+t8kAmWjPuv@mail.gmail.com1290721684-sup-3951@alvh.no-ip.org1294953201-sup-2099@alvh.no-ip.org1320343602-sup-2290@alvh.no-ip.org1339690386-sup-8927@alvh.no-ip.org4FE5FF020200002500048A3D@gw.wicourts.gov4FEAB90A0200002500048B7D@gw.wicourts.gov
Remove extra line at bottom of table for new 'latex' mode border=3.
Also update 'latex'-longtable 'tableattr' docs to say
'whitespace-separated' instead of 'space'.
This mirrors the changes done earlier to the server in standby mode. When
receivelog reaches the end of a timeline, as reported by the server, it
fetches the timeline history file of the next timeline, and restarts
streaming from the new timeline by issuing a new START_STREAMING command.
When pg_receivexlog crosses a timeline, it leaves the .partial suffix on the
last segment on the old timeline. This helps you to tell apart a partial
segment left in the directory because of a timeline switch, and a completed
segment. If you just follow a single server, it won't make a difference, but
it can be significant in more complicated scenarios where new WAL is still
generated on the old timeline.
This includes two small changes to the streaming replication protocol:
First, when you reach the end of timeline while streaming, the server now
sends the TLI of the next timeline in the server's history to the client.
pg_receivexlog uses that as the next timeline, so that it doesn't need to
parse the timeline history file like a standby server does. Second, when
BASE_BACKUP command sends the begin and end WAL positions, it now also sends
the timeline IDs corresponding the positions.
On top of the previous support in pg_dump, add support to specify
multiple tables (by using the -t option multiple times) to
pg_restore, clsuterdb, reindexdb and vacuumdb.
Josh Kupershmidt, reviewed by Karl O. Pinc
(-i), producing only one progress message per 5 seconds along with
elapsed time and estimated remaining time. Also add elapsed time and
estimated remaining time to the default logging(prints one message
each 100000 rows).
Patch contributed by Tomas Vondra, reviewed by Jeevan Chalke and
Tatsuo Ishii.
Adds commandline option -R to pg_basebackup that creates a recovery.conf which
enables standby mode using the same parameters that pg_basebackup used to
connect to the master, and writes it into the output directory (or injects it
in the tar file when tar format is used).
Zoltan Boszormenyi, modified by Magnus Hagander, reviewed by Amit Kapila & Fujii Masao
SPI_execute() and related functions create a CachedPlan, execute it once,
and immediately discard it, so that the functionality offered by
plancache.c is of no value in this code path. And performance measurements
show that the extra data copying and invalidation checking done by
plancache.c slows down simple queries by 10% or more compared to 9.1.
However, enough of the SPI code is shared with functions that do need plan
caching that it seems impractical to bypass plancache.c altogether.
Instead, let's invent a variant version of cached plans that preserves
99% of the API but doesn't offer any of the actual functionality, nor the
overhead. This puts SPI_execute() performance back on par, or maybe even
slightly better, than it was before. This change should resolve recent
complaints of performance degradation from Dong Ye, Pavel Stehule, and
others.
By avoiding data copying, this change also reduces the amount of memory
needed to execute many-statement SPI_execute() strings, as for instance in
a recent complaint from Tomas Vondra.
An additional benefit of this change is that multi-statement SPI_execute()
query strings are now processed fully serially, that is we complete
execution of earlier statements before running parse analysis and planning
on following ones. This eliminates a long-standing POLA violation, in that
DDL that affects the behavior of a later statement will now behave as
expected.
Back-patch to 9.2, since this was a performance regression compared to 9.1.
(In 9.2, place the added struct fields so as to avoid changing the offsets
of existing fields.)
Heikki Linnakangas and Tom Lane
Code review for commit 2f582f76b1: don't use
a static variable for what ought to be a deparse_context field, fix
non-multibyte-safe test for spaces, avoid useless and potentially O(N^2)
(though admittedly with a very small constant) calculations of wrap
positions when we aren't going to wrap.
If pg_extension_config_dump() is executed again for a table already listed
in the extension's extconfig, the code was blindly making a new array entry.
This does not seem useful. Fix it to replace the existing array entry
instead, so that it's possible for extension update scripts to alter the
filter conditions for configuration tables.
In addition, teach ALTER EXTENSION DROP TABLE to check for an extconfig
entry for the target table, and remove it if present. This is not a 100%
solution because it's allowed for an extension update script to just
summarily DROP a member table, and that code path doesn't go through
ExecAlterExtensionContentsStmt. We could probably make that case clean
things up if we had to, but it would involve sticking a very ugly wart
somewhere in the guts of dependency.c. Since on the whole it seems quite
unlikely that extension updates would want to remove pre-existing
configuration tables, making the case possible with an explicit command
seems sufficient.
Per bug #7756 from Regina Obe. Back-patch to 9.1 where extensions were
introduced.
Before this patch, streaming replication would refuse to start replicating
if the timeline in the primary doesn't exactly match the standby. The
situation where it doesn't match is when you have a master, and two
standbys, and you promote one of the standbys to become new master.
Promoting bumps up the timeline ID, and after that bump, the other standby
would refuse to continue.
There's significantly more timeline related logic in streaming replication
now. First of all, when a standby connects to primary, it will ask the
primary for any timeline history files that are missing from the standby.
The missing files are sent using a new replication command TIMELINE_HISTORY,
and stored in standby's pg_xlog directory. Using the timeline history files,
the standby can follow the latest timeline present in the primary
(recovery_target_timeline='latest'), just as it can follow new timelines
appearing in an archive directory.
START_REPLICATION now takes a TIMELINE parameter, to specify exactly which
timeline to stream WAL from. This allows the standby to request the primary
to send over WAL that precedes the promotion. The replication protocol is
changed slightly (in a backwards-compatible way although there's little hope
of streaming replication working across major versions anyway), to allow
replication to stop when the end of timeline reached, putting the walsender
back into accepting a replication command.
Many thanks to Amit Kapila for testing and reviewing various versions of
this patch.
Commit 729205571e added privileges on data
types, but there were a number of oversights. The implementation of
default privileges for types missed a few places, and pg_dump was
utterly innocent of the whole concept. Per bug #7741 from Nathan Alden,
and subsequent wider investigation.
This patch makes "simple" views automatically updatable, without the need
to create either INSTEAD OF triggers or INSTEAD rules. "Simple" views
are those classified as updatable according to SQL-92 rules. The rewriter
transforms INSERT/UPDATE/DELETE commands on such views directly into an
equivalent command on the underlying table, which will generally have
noticeably better performance than is possible with either triggers or
user-written rules. A view that has INSTEAD OF triggers or INSTEAD rules
continues to operate the same as before.
For the moment, security_barrier views are not considered simple.
Also, we do not support WITH CHECK OPTION. These features may be
added in future.
Dean Rasheed, reviewed by Amit Kapila
For some reason lost in the mists of prehistory, RETURN was only coded to
allow a simple reference to a composite variable when the function's return
type is composite. Allow an expression instead, while preserving the
efficiency of the original code path in the case where the expression is
indeed just a composite variable's name. Likewise for RETURN NEXT.
As is true in various other places, the supplied expression must yield
exactly the number and data types of the required columns. There was some
discussion of relaxing that for pl/pgsql, but no consensus yet, so this
patch doesn't address that.
Asif Rehman, reviewed by Pavel Stehule
Background workers are postmaster subprocesses that run arbitrary
user-specified code. They can request shared memory access as well as
backend database connections; or they can just use plain libpq frontend
database connections.
Modules listed in shared_preload_libraries can register background
workers in their _PG_init() function; this is early enough that it's not
necessary to provide an extra GUC option, because the necessary extra
resources can be allocated early on. Modules can install more than one
bgworker, if necessary.
Care is taken that these extra processes do not interfere with other
postmaster tasks: only one such process is started on each ServerLoop
iteration. This means a large number of them could be waiting to be
started up and postmaster is still able to quickly service external
connection requests. Also, shutdown sequence should not be impacted by
a worker process that's reasonably well behaved (i.e. promptly responds
to termination signals.)
The current implementation lets worker processes specify their start
time, i.e. at what point in the server startup process they are to be
started: right after postmaster start (in which case they mustn't ask
for shared memory access), when consistent state has been reached
(useful during recovery in a HOT standby server), or when recovery has
terminated (i.e. when normal backends are allowed).
In case of a bgworker crash, actions to take depend on registration
data: if shared memory was requested, then all other connections are
taken down (as well as other bgworkers), just like it were a regular
backend crashing. The bgworker itself is restarted, too, within a
configurable timeframe (which can be configured to be never).
More features to add to this framework can be imagined without much
effort, and have been discussed, but this seems good enough as a useful
unit already.
An elementary sample module is supplied.
Author: Álvaro Herrera
This patch is loosely based on prior patches submitted by KaiGai Kohei,
and unsubmitted code by Simon Riggs.
Reviewed by: KaiGai Kohei, Markus Wanner, Andres Freund,
Heikki Linnakangas, Simon Riggs, Amit Kapila
storage.
Have pg_upgrade use it, and enable server options fsync=off and
full_page_writes=off.
Document that users turning fsync from off to on should run initdb
--sync-only.
[ Previous commit was incorrectly applied as a git merge. ]
We've generally recommended use of INSTEAD triggers over rules since that
feature was added; but this old text in the CREATE VIEW reference page
didn't get the memo. Noted by Thomas Kellerer.
When a relfilenode is created in this subtransaction or
a committed child transaction and it cannot otherwise
be seen by our own process, mark tuples committed ahead
of transaction commit for all COPY commands in same
transaction. If FREEZE specified on COPY
and pre-conditions met then rows will also be frozen.
Both options designed to avoid revisiting rows after commit,
increasing performance of subsequent commands after
data load and upgrade. pg_restore changes later.
Simon Riggs, review comments from Heikki Linnakangas, Noah Misch and design
input from Tom Lane, Robert Haas and Kevin Grittner
This allows a caller to get back the exact conninfo array that was
used to create a connection, including parameters read from the
environment.
In doing this, restructure how options are copied from the conninfo
to the actual connection.
Zoltan Boszormenyi and Magnus Hagander
Commit 8cb53654db, which introduced DROP
INDEX CONCURRENTLY, managed to break CREATE INDEX CONCURRENTLY via a poor
choice of catalog state representation. The pg_index state for an index
that's reached the final pre-drop stage was the same as the state for an
index just created by CREATE INDEX CONCURRENTLY. This meant that the
(necessary) change to make RelationGetIndexList ignore about-to-die indexes
also made it ignore freshly-created indexes; which is catastrophic because
the latter do need to be considered in HOT-safety decisions. Failure to
do so leads to incorrect index entries and subsequently wrong results from
queries depending on the concurrently-created index.
To fix, add an additional boolean column "indislive" to pg_index, so that
the freshly-created and about-to-die states can be distinguished. (This
change obviously is only possible in HEAD. This patch will need to be
back-patched, but in 9.2 we'll use a kluge consisting of overloading the
formerly-impossible state of indisvalid = true and indisready = false.)
In addition, change CREATE/DROP INDEX CONCURRENTLY so that the pg_index
flag changes they make without exclusive lock on the index are made via
heap_inplace_update() rather than a normal transactional update. The
latter is not very safe because moving the pg_index tuple could result in
concurrent SnapshotNow scans finding it twice or not at all, thus possibly
resulting in index corruption. This is a pre-existing bug in CREATE INDEX
CONCURRENTLY, which was copied into the DROP code.
In addition, fix various places in the code that ought to check to make
sure that the indexes they are manipulating are valid and/or ready as
appropriate. These represent bugs that have existed since 8.2, since
a failed CREATE INDEX CONCURRENTLY could leave a corrupt or invalid
index behind, and we ought not try to do anything that might fail with
such an index.
Also fix RelationReloadIndexInfo to ensure it copies all the pg_index
columns that are allowed to change after initial creation. Previously we
could have been left with stale values of some fields in an index relcache
entry. It's not clear whether this actually had any user-visible
consequences, but it's at least a bug waiting to happen.
In addition, do some code and docs review for DROP INDEX CONCURRENTLY;
some cosmetic code cleanup but mostly addition and revision of comments.
This will need to be back-patched, but in a noticeably different form,
so I'm committing it to HEAD before working on the back-patch.
Problem reported by Amit Kapila, diagnosis by Pavan Deolassee,
fix by Tom Lane and Andres Freund.
This reverts commit d573e239f0, "Take fewer
snapshots". While that seemed like a good idea at the time, it caused
execution to use a snapshot that had been acquired before locking any of
the tables mentioned in the query. This created user-visible anomalies
that were not present in any prior release of Postgres, as reported by
Tomas Vondra. While this whole area could do with a redesign (since there
are related cases that have anomalies anyway), it doesn't seem likely that
any future patch would be reasonably back-patchable; and we don't want 9.2
to exhibit a behavior that's subtly unlike either past or future releases.
Hence, revert to prior code while we rethink the problem.
This way it works more like the DSSSL build, and dependencies are
tracked better by make.
Also copy the CSS stylesheet to the html directory. This was forgotten
when the output directory was changed.
Some versions of the XSLT stylesheets don't handle the missing slash
correctly (they concatenate directory and file name without the slash).
This might never have worked correctly.
Without this, the connection will be killed after timeout if
wal_sender_timeout is set in the server.
Original patch by Amit Kapila, modified by me to fit recent changes in the
code.
We used to send structs wrapped in CopyData messages, which works as long as
the client and server agree on things like endianess, timestamp format and
alignment. That's good enough for running a standby server, which has to run
on the same platform anyway, but it's useful for tools like pg_receivexlog
to work across platforms.
This breaks protocol compatibility of streaming replication, but we never
promised that to be compatible across versions, anyway.
Represent a sequence's current value as a separate TableDataInfo dumpable
object, so that it can be dumped within the data section of the archive
rather than in pre-data. This fixes an undesirable inconsistency between
the meanings of "--data-only" and "--section=data", and also fixes dumping
of sequences that are marked as extension configuration tables, as per a
report from Marko Kreen back in July. The main cost is that we do one more
SQL query per sequence, but that's probably not very meaningful in most
databases.
Back-patch to 9.1, since it has the extension configuration issue even
though not the --section switch.
... and have sepgsql use it to determine whether to check permissions
during certain operations. Indexes that are being created as a result
of REINDEX, for instance, do not need to have their permissions checked;
they were already checked when the index was created.
Author: KaiGai Kohei, slightly revised by me
In commit 4317e0246c, I accidentally broke
this behavior while rearranging code to ensure that --create wouldn't
affect whether a DATABASE entry gets put into archive-format output.
Thus, 9.2 would issue a DROP DATABASE command in --clean mode, which is
either useless or dangerous depending on the usage scenario.
It should not do that, and no longer does.
A bright spot is that this refactoring makes it easy to allow the
combination of --clean and --create to work sensibly, ie, emit DROP
DATABASE then CREATE DATABASE before reconnecting. Ordinarily we'd
consider that a feature addition and not back-patch it, but it seems
silly to not include the extra couple of lines required in the 9.2
version of the code.
Per report from Guillaume Lelarge, though this is slightly more extensive
than his proposed patch.
Rename replication_timeout to wal_sender_timeout, and add a new setting
called wal_receiver_timeout that does the same at the walreceiver side.
There was previously no timeout in walreceiver, so if the network went down,
for example, the walreceiver could take a long time to notice that the
connection was lost. Now with the two settings, both sides of a replication
connection will detect a broken connection similarly.
It is no longer necessary to manually set wal_receiver_status_interval to
a value smaller than the timeout. Both wal sender and receiver now
automatically send a "ping" message if more than 1/2 of the configured
timeout has elapsed, and it hasn't received any messages from the other end.
Amit Kapila, heavily edited by me.
dblink now has its own validator function dblink_fdw_validator(), which is
better than the core function postgresql_fdw_validator() because it gets
the list of legal options from libpq instead of having a hard-wired list.
Make the dblink extension module provide a standard foreign data wrapper
dblink_fdw that encapsulates use of this validator, and recommend use of
that wrapper instead of making up wrappers on the fly.
Unfortunately, because ad-hoc wrappers *were* recommended practice
previously, it's not clear when we can get rid of postgresql_fdw_validator
without causing upgrade problems. But this is a step in the right
direction.
Shigeru Hanada, reviewed by KaiGai Kohei
libpq defines these functions as accepting "size_t" lengths ... but the
underlying backend functions expect signed int32 length parameters, and so
will misinterpret any value exceeding INT_MAX. Fix the libpq side to throw
error rather than possibly doing something unexpected.
This is a bug of long standing, but I doubt it's worth back-patching. The
problem is really pretty academic anyway with lo_read/lo_write, since any
caller expecting sane behavior would have to have provided a multi-gigabyte
buffer. It's slightly more pressing with lo_truncate, but still we haven't
supported large objects over 2GB until now.
Copy-editing for previous patch, plus fixing some longstanding markup
issues and oversights (like not mentioning that failures will set the
PQerrorMessage string).
4TB large objects (standard 8KB BLCKSZ case). For this purpose new
libpq API lo_lseek64, lo_tell64 and lo_truncate64 are added. Also
corresponding new backend functions lo_lseek64, lo_tell64 and
lo_truncate64 are added. inv_api.c is changed to handle 64-bit
offsets.
Patch contributed by Nozomi Anzai (backend side) and Yugo Nagata
(frontend side, docs, regression tests and example program). Reviewed
by Kohei Kaigai. Committed by Tatsuo Ishii with minor editings.
Use the terms "simple bind" and "search+bind" consistently do
distinguish the two modes (better than first mode and second mode in
any case). They were already used in some places, now it's just more
prominent.
Split up the list of options into one for common options and one for
each mode, for clarity.
Add configuration examples for either mode.
These reference pages still claimed that you have to be superuser to create
a database or schema owned by a different role. That was true before 8.1,
but it was changed in commits aa1110624c and
f91370cd2f to allow assignment of ownership
to any role you are a member of. However, at the time we were thinking of
that primarily as a change to the ALTER OWNER rules, so the need to touch
these two CREATE ref pages got missed.
Per discussion, schema-element subcommands are not allowed together with
this option, since it's not very obvious what should happen to the element
objects.
Fabrízio de Royes Mello
This allows logging only some fraction of transactions, greatly reducing
the amount of log generated.
Tomas Vondra, reviewed by Robert Haas and Jeff Janes.
You can now get the number of rows processed by a COPY statement in a
PL/pgSQL function with "GET DIAGNOSTICS x = ROW_COUNT".
Pavel Stehule, reviewed by Amit Kapila, with some editing by me.
Both programs got the "magic" string wrong, causing standard-conforming tar
implementations to believe the output was just legacy tar format without
any POSIX extensions. This doesn't actually matter that much, especially
since pg_dump failed to fill the POSIX fields anyway, but still there is
little point in emitting tar format if we can't be compliant with the
standard. In addition, pg_dump failed to write the EOF marker correctly
(there should be 2 blocks of zeroes not just one), pg_basebackup put the
numeric group ID in the wrong place, and both programs had a pretty
brain-dead idea of how to compute the checksum. Fix all that and improve
the comments a bit.
pg_restore is modified to accept either the correct POSIX-compliant "magic"
string or the previous value. This part of the change will need to be
back-patched to avoid an unnecessary compatibility break when a previous
version tries to read tar-format output from 9.3 pg_dump.
Brian Weaver and Tom Lane
The syntax "su -c 'command' username" is not accepted by all versions of
su, for example not OpenBSD's. More portable is "su username -c
'command'". So change runtime.sgml to recommend that syntax. Also,
add a -D switch to the OpenBSD example script, for consistency with other
examples. Per Denis Lapshin and Gábor Hidvégi.
This allows easily splitting configuration into many files, deployed in a
directory.
Magnus Hagander, Greg Smith, Selena Deckelmann, reviewed by Noah Misch.
Produce a NOTICE when the label already exists, for consistency with other
CREATE IF NOT EXISTS commands. Also, fix the code so it produces something
more user-friendly than an index violation when the label already exists.
This not incidentally enables making a regression test that the previous
patch didn't make for fear of exposing an unpredictable OID in the results.
Also some wordsmithing on the documentation.
If the label is already in the enum the statement becomes a no-op.
This will reduce the pain that comes from our not allowing this
operation inside a transaction block.
Andrew Dunstan, reviewed by Tom Lane and Magnus Hagander.
Somewhere along the line, somebody decided to remove all trace of this
notation from the documentation text. It was still in the command syntax
synopses, or at least some of them, but with no indication what it meant.
This will not do, as evidenced by the confusion apparent in bug #7543;
even if the notation is now unnecessary, people will find it in legacy
SQL code and need to know what it does.
The documentation mentioned setting autovacuum_freeze_max_age to
"its maximum allowed value of a little less than two billion".
This led to a post asking about the exact maximum allowed value,
which is precisely two billion, not "a little less".
Based on question by Radovan Jablonovsky. Backpatch to 8.3.
When starting either an old or new postmaster, force it to place its Unix
socket in the current directory. This makes it even harder for accidental
connections to occur during pg_upgrade, and also works around some
scenarios where the default socket location isn't usable. (For example,
if the default location is something other than "/tmp", it might not exist
during "make check".)
When checking an already-running old postmaster, find out its actual socket
directory location from postmaster.pid, if possible. This dodges problems
with an old postmaster having a configured location different from the
default built into pg_upgrade's libpq. We can't find that out if the old
postmaster is pre-9.1, so also document how to cope with such scenarios
manually.
In support of this, centralize handling of the connection-related command
line options passed to pg_upgrade's subsidiary programs, such as pg_dump.
This should make future changes easier.
Bruce Momjian and Tom Lane
Extend xfunc.sgml's discussion of set-returning functions to show an
example of using LATERAL, and recommend that over putting SRFs in the
targetlist.
In passing, reword func.sgml's section on set-returning functions so
that it doesn't claim that the functions listed therein are all the
built-in set-returning functions. That hasn't been true for a long
time, and trying to make it so doesn't seem like it would be an
improvement. (Perhaps we should rename that section?)
Both per suggestions from Merlin Moncure.
Only warn when connecting to a newer server, since connecting to older
servers works pretty well nowadays. Also update the documentation a
little about current psql/server compatibility expectations.
The existing documentation in Linux Memory Overcommit seemed to
assume that PostgreSQL itself could never be the problem, or at
least it didn't tell you what to do about it.
Per discussion with Craig Ringer and Kevin Grittner.
This is so that these sections will have stable HTML tags that one can
link to, rather than things like "AEN1902". Perhaps we should mount a
campaign to do this everywhere, but I've found myself pointing at
syntax.sgml subsections often enough to be sure it's useful here.
As of 9.2, constraint exclusion should work okay with prepared statements:
the planner will try custom plans with actual values of the parameters,
and observe that they are a lot cheaper than the generic plan, and thus
never fall back to using the generic plan. Noted by Tatsuhito Kasahara.
The docs claimed that this mode only waits for the standby to receive WAL
data, but actually it waits for the data to be written out to the standby's
OS; which is a pretty significant difference because it removes the risk of
crash of the walreceiver process.
libxslt offers the ability to read and write both files and URLs through
stylesheet commands, thus allowing unprivileged database users to both read
and write data with the privileges of the database server. Disable that
through proper use of libxslt's security options.
Also, remove xslt_process()'s ability to fetch documents and stylesheets
from external files/URLs. While this was a documented "feature", it was
long regarded as a terrible idea. The fix for CVE-2012-3489 broke that
capability, and rather than expend effort on trying to fix it, we're just
going to summarily remove it.
While the ability to write as well as read makes this security hole
considerably worse than CVE-2012-3489, the problem is mitigated by the fact
that xslt_process() is not available unless contrib/xml2 is installed,
and the longstanding warnings about security risks from that should have
discouraged prudent DBAs from installing it in security-exposed databases.
Reported and fixed by Peter Eisentraut.
Security: CVE-2012-3488
Replace unix_socket_directory with unix_socket_directories, which is a list
of socket directories, and adjust postmaster's code to allow zero or more
Unix-domain sockets to be created.
This is mostly a straightforward change, but since the Unix sockets ought
to be created after the TCP/IP sockets for safety reasons (better chance
of detecting a port number conflict), AddToDataDirLockFile needs to be
fixed to support out-of-order updates of data directory lockfile lines.
That's a change that had been foreseen to be necessary someday anyway.
Honza Horak, reviewed and revised by Tom Lane
Should be limited to the maximum number of connections excluding
autovacuum workers, not including.
Add similar check for max_wal_senders, which should never be higher than
max_connections.
Previously, the -1 option was silently ignored.
Also, emit an error if -1 is used in a context where it won't be
respected, to avoid user confusion.
Original patch by Fabien COELHO, but this version is quite different
from the original submission.
This patch implements the standard syntax of LATERAL attached to a
sub-SELECT in FROM, and also allows LATERAL attached to a function in FROM,
since set-returning function calls are expected to be one of the principal
use-cases.
The main change here is a rewrite of the mechanism for keeping track of
which relations are visible for column references while the FROM clause is
being scanned. The parser "namespace" lists are no longer lists of bare
RTEs, but are lists of ParseNamespaceItem structs, which carry an RTE
pointer as well as some visibility-controlling flags. Aside from
supporting LATERAL correctly, this lets us get rid of the ancient hacks
that required rechecking subqueries and JOIN/ON and function-in-FROM
expressions for invalid references after they were initially parsed.
Invalid column references are now always correctly detected on sight.
In passing, remove assorted parser error checks that are now dead code by
virtue of our having gotten rid of add_missing_from, as well as some
comments that are obsolete for the same reason. (It was mainly
add_missing_from that caused so much fudging here in the first place.)
The planner support for this feature is very minimal, and will be improved
in future patches. It works well enough for testing purposes, though.
catversion bump forced due to new field in RangeTblEntry.
century specifications just like positive/AD centuries. Previously the
behavior was either wrong or inconsistent with positive/AD handling.
Centuries without years now always assume the first year of the century,
which is now documented.
After taking awhile to digest the row-processor feature that was added to
libpq in commit 92785dac2e, we've concluded
it is over-complicated and too hard to use. Leave the core infrastructure
changes in place (that is, there's still a row processor function inside
libpq), but remove the exposed API pieces, and instead provide a "single
row" mode switch that causes PQgetResult to return one row at a time in
separate PGresult objects.
This approach incurs more overhead than proper use of a row processor
callback would, since construction of a PGresult per row adds extra cycles.
However, it is far easier to use and harder to break. The single-row mode
still affords applications the primary benefit that the row processor API
was meant to provide, namely not having to accumulate large result sets in
memory before processing them. Preliminary testing suggests that we can
probably buy back most of the extra cycles by micro-optimizing construction
of the extra results, but that task will be left for another day.
Marko Kreen
The most user-visible part of this is to change the long options
--statusint and --noloop to --status-interval and --no-loop,
respectively, per discussion.
Also, consistently enclose file names in double quotes, per our
conventions; and consistently use the term "transaction log file" to
talk about WAL segments. (Someday we may need to go over this
terminology and make it consistent across the whole source code.)
Finally, reflow the code to better fit in 80 columns, and have pgindent
fix it up some more.
The initially implemented syntax, "CHECK NO INHERIT (expr)" was not
deemed very good, so switch to "CHECK (expr) NO INHERIT" instead. This
way it looks similar to SQL-standards compliant constraint attribute.
Backport to 9.2 where the new syntax and feature was introduced.
Per discussion.
This is apparently faster than doing things the other way around when
the scale factor is large.
Along the way, adjust -n to suppress vacuuming during initialization
as well as during test runs.
Jeff Janes, with some small changes by me.
Commit 3855968f32 added syntax, pg_dump,
psql support, and documentation, but the triggers didn't actually fire.
With this commit, they now do. This is still a pretty basic facility
overall because event triggers do not get a whole lot of information
about what the user is trying to do unless you write them in C; and
there's still no option to fire them anywhere except at the very
beginning of the execution sequence, but it's better than nothing,
and a good building block for future work.
Along the way, add a regression test for ALTER LARGE OBJECT, since
testing of event triggers reveals that we haven't got one.
Dimitri Fontaine and Robert Haas
They don't actually do anything yet; that will get fixed in a
follow-on commit. But this gets the basic infrastructure in place,
including CREATE/ALTER/DROP EVENT TRIGGER; support for COMMENT,
SECURITY LABEL, and ALTER EXTENSION .. ADD/DROP EVENT TRIGGER;
pg_dump and psql support; and documentation for the anticipated
initial feature set.
Dimitri Fontaine, with review and a bunch of additional hacking by me.
Thom Brown extensively reviewed earlier versions of this patch set,
but there's not a whole lot of that code left in this commit, as it
turns out.
Historically we have not worried about fsync'ing anything during initdb
(in fact, initdb intentionally passes -F to each backend launch to prevent
it from fsync'ing). But with filesystems getting more aggressive about
caching data, that's not such a good plan anymore. Make initdb do a pass
over the finished data directory tree to fsync everything. For testing
purposes, the -N/--nosync flag can be used to restore the old behavior.
Also, testing shows that on Linux, sync_file_range() is much faster than
posix_fadvise() for hinting to the kernel that an fsync is coming,
apparently because the latter blocks on a rather small request queue while
the former doesn't. So use this function if available in initdb, and also
in the backend's pg_flush_data() (where it currently will affect only the
speed of CREATE DATABASE's cloning step).
We will later make pg_regress invoke initdb with the --nosync flag
to avoid slowing down cases such as "make check" in contrib. But
let's not do so until we've shaken out any portability issues in this
patch.
Jeff Davis, reviewed by Andres Freund
These functions support removing or replacing array element value(s)
matching a given search value. Although intended mainly to support a
future array-foreign-key feature, they seem useful in their own right.
Marco Nenciarini and Gabriele Bartolini, reviewed by Alex Hunsaker
This hasn't been true since 9.1, when the default was changed to -1.
Remove the reference completely, keeping the discussion of the parameter
and it's shared memory effects on the config page.
Instead of letting every backend participating in a group commit wait
independently, have the first one that becomes ready to flush WAL wait
for the configured delay, and let all the others wait just long enough
for that first process to complete its flush. This greatly increases
the chances of being able to configure a commit_delay setting that
actually improves performance.
As a side consequence of this change, commit_delay now affects all WAL
flushes, rather than just commits. There was some discussion on
pgsql-hackers about whether to rename the GUC to, say, wal_flush_delay,
but in the absence of consensus I am leaving it alone for now.
Peter Geoghegan, with some changes, mostly to the documentation, by me.
A similar change was made previously for pg_cancel_backend, so now it
all matches again.
Dan Farina, reviewed by Fujii Masao, Noah Misch, and Jeff Davis,
with slight kibitzing on the doc changes by me.
The xlogid + segno representation of a particular WAL segment doesn't make
much sense in pg_resetxlog anymore, now that we don't use that anywhere
else. Use the WAL filename instead, since that's a convenient way to name a
particular WAL segment.
I did this partially for pg_resetxlog in the original xlogid/segno -> uint64
patch, but I neglected pg_upgrade and the docs. This should now be more
complete.
The latter was already the dominant use, and it's preferable because
in C the convention is that intXX means XX bits. Therefore, allowing
mixed use of int2, int4, int8, int16, int32 is obviously confusing.
Remove the typedefs for int2 and int4 for now. They don't seem to be
widely used outside of the PostgreSQL source tree, and the few uses
can probably be cleaned up by the time this ships.
Also, add some cross-links to the indexing documentation, so it's easier
to notice that && and other array operators have index support.
Ryan Kelly, edited by me.
The option --foreign-keys, used at initialization time, will create foreign
key constraints for the columns that represent references to other tables'
primary keys. This can help in benchmarking FK performance.
Jeff Janes
Previously, when executing an ON UPDATE SET NULL or SET DEFAULT action for
a multicolumn MATCH SIMPLE foreign key constraint, we would set only those
referencing columns corresponding to referenced columns that were changed.
This is what the SQL92 standard said to do --- but more recent versions
of the standard say that all referencing columns should be set to null or
their default values, no matter exactly which referenced columns changed.
At least for SET DEFAULT, that is clearly saner behavior. It's somewhat
debatable whether it's an improvement for SET NULL, but it appears that
other RDBMS systems read the spec this way. So let's do it like that.
This is a release-notable behavioral change, although considering that
our documentation already implied it was done this way, the lack of
complaints suggests few people use such cases.
Previously we followed the SQL92 wording, "MATCH <unspecified>", but since
SQL99 there's been a less awkward way to refer to the default style.
In addition to the code changes, pg_constraint.confmatchtype now stores
this match style as 's' (SIMPLE) rather than 'u' (UNSPECIFIED). This
doesn't affect pg_dump or psql because they use pg_get_constraintdef()
to reconstruct foreign key definitions. But other client-side code might
examine that column directly, so this change will have to be marked as
an incompatibility in the 9.3 release notes.
Before, some places didn't document the short options (-? and -V),
some documented both, some documented nothing, and they were listed in
various orders. Now this is hopefully more consistent and complete.
Since this is the easy way of doing it, it should be listed first. All
the old information is retained for those who want the more advanced way.
Also adds a subheading for compressing logs, that seems to have been missing
