Specifically, permit attaching them to the error in RAISE and retrieving
them from a caught error in GET STACKED DIAGNOSTICS. RAISE enforces
nothing about the content of the fields; for its purposes, they are just
additional string fields. Consequently, clarify in the protocol and
libpq documentation that the usual relationships between error fields,
like a schema name appearing wherever a table name appears, are not
universal. This freedom has other applications; consider a FDW
propagating an error from an RDBMS having no schema support.
Back-patch to 9.3, where core support for the error fields was
introduced. This prevents the confusion of having a release where libpq
exposes the fields and PL/pgSQL does not.
Pavel Stehule, lexical revisions by Noah Misch.
Make it easier for readers of the FP docs to find out about possibly
truncated values.
Per complaint from Tom Duffey in message
F0E0F874-C86F-48D1-AA2A-0C5365BF5118@trillitech.com
Author: Albe Laurenz
Reviewed by: Abhijit Menon-Sen
SnapshotNow scans have the undesirable property that, in the face of
concurrent updates, the scan can fail to see either the old or the new
versions of the row. In many cases, we work around this by requiring
DDL operations to hold AccessExclusiveLock on the object being
modified; in some cases, the existing locking is inadequate and random
failures occur as a result. This commit doesn't change anything
related to locking, but will hopefully pave the way to allowing lock
strength reductions in the future.
The major issue has held us back from making this change in the past
is that taking an MVCC snapshot is significantly more expensive than
using a static special snapshot such as SnapshotNow. However, testing
of various worst-case scenarios reveals that this problem is not
severe except under fairly extreme workloads. To mitigate those
problems, we avoid retaking the MVCC snapshot for each new scan;
instead, we take a new snapshot only when invalidation messages have
been processed. The catcache machinery already requires that
invalidation messages be sent before releasing the related heavyweight
lock; else other backends might rely on locally-cached data rather
than scanning the catalog at all. Thus, making snapshot reuse
dependent on the same guarantees shouldn't break anything that wasn't
already subtly broken.
Patch by me. Review by Michael Paquier and Andres Freund.
On Unix, you can embed double-quotes in single-quotes, and via versa.
However, on Windows, you can only escape double-quotes in double-quotes,
so use that in the pg_dump -t/table example.
Backpatch to 9.3.
Report from Mike Toews
Add ability for to_char() to output the timezone's UTC offset (OF). We
already have the ability to return the timezone abbeviation (TZ/tz).
Per request from Andrew Dunstan
Previous code had old/new prefixes on option values, e.g.
--old-datadir=OLDDATADIR. Remove them, for simplicity; now:
--old-datadir=DATADIR. Also update docs to do the same.
On immediate shutdown, or during a restart-after-crash sequence,
postmaster used to send SIGQUIT (and then abandon ship if shutdown); but
this is not a good strategy if backends don't die because of that
signal. (This might happen, for example, if a backend gets tangled
trying to malloc() due to gettext(), as in an example illustrated by
MauMau.) This causes problems when later trying to restart the server,
because some processes are still attached to the shared memory segment.
Instead of just abandoning such backends to their fates, we now have
postmaster hang around for a little while longer, send a SIGKILL after
some reasonable waiting period, and then exit. This makes immediate
shutdown more reliable.
There is disagreement on whether it's best for postmaster to exit after
sending SIGKILL, or to stick around until all children have reported
death. If this controversy is resolved differently than what this patch
implements, it's an easy change to make.
Bug reported by MauMau in message 20DAEA8949EC4E2289C6E8E58560DEC0@maumau
MauMau and Álvaro Herrera
Change -u (user) option to -U, for consistency with other tools like
pg_dump and psql. Also expand --user to --username, again for
consistency.
BACKWARD INCOMPATIBILITY
Adjust the wording in the first para of "Sequence Manipulation Functions"
so that neither of the link phrases in it break across line boundaries,
in either A4- or US-page-size PDF output. This fixes a reported build
failure for the 9.3beta2 A4 PDF docs, and future-proofs this particular
para against causing similar problems in future. (Perhaps somebody will
fix this issue in the SGML/TeX documentation tool chain someday, but I'm
not holding my breath.)
Back-patch to all supported branches, since the same problem could rise up
to bite us in future updates if anyone changes anything earlier than this
in func.sgml.
If there is no <date> element, the publication date for the EPUB
manifest is taken from the copyright year. But something like
"1996-2013" is not a legal date specification. So the EPUB output
currently fails epubcheck.
Put in a separate <date> element with the current year. Put it in
legal.sgml, because copyright.pl already instructs to update that
manually, so it hopefully won't be missed.
Most of the documentation uses "single-user mode", so use that in the
code as well. Adjust the documentation to match the new error message
wording. Also add a documentation index entry for "single-user mode".
Based-on-patch-by: Jeff Janes <jeff.janes@gmail.com>
ALTER TABLE .. VALIDATE CONSTRAINT previously
gave incorrect details about lock levels and
therefore incomplete reasons to use the option.
Initial bug report and fix from Marko Tiikkaja
Reworded by me to include comments by Kevin Grittner
Extend the FDW API (which we already changed for 9.3) so that an FDW can
report whether specific foreign tables are insertable/updatable/deletable.
The default assumption continues to be that they're updatable if the
relevant executor callback function is supplied by the FDW, but finer
granularity is now possible. As a test case, add an "updatable" option to
contrib/postgres_fdw.
This patch also fixes the information_schema views, which previously did
not think that foreign tables were ever updatable, and fixes
view_is_auto_updatable() so that a view on a foreign table can be
auto-updatable.
initdb forced due to changes in information_schema views and the functions
they rely on. This is a bit unfortunate to do post-beta1, but if we don't
change this now then we'll have another API break for FDWs when we do
change it.
Dean Rasheed, somewhat editorialized on by Tom Lane
Per discussion on -hackers. We treat Unicode escapes when unescaping
them similarly to the way we treat them in PostgreSQL string literals.
Escapes in the ASCII range are always accepted, no matter what the
database encoding. Escapes for higher code points are only processed in
UTF8 databases, and attempts to process them in other databases will
result in an error. \u0000 is never unescaped, since it would result in
an impermissible null byte.
Per discussion, this restriction isn't needed for any real security reason,
and it seems to confuse people more often than it helps them. It could
also result in some database states being unrestorable. So just drop it.
Back-patch to 9.0, where ALTER DEFAULT PRIVILEGES was introduced.
In 9.2, Unicode escape sequences are not analysed at all other than
to make sure that they are in the form \uXXXX. But in 9.3 many of the
new operators and functions try to turn JSON text values into text in
the server encoding, and this includes de-escaping Unicode escape
sequences. This processing had not taken into account the possibility
that this might contain a surrogate pair to designate a character
outside the BMP. That is now handled correctly.
This also enforces correct use of surrogate pairs, something that is not
done by the type's input routines. This fact is noted in the docs.
Although the DTD technically allows this, the resulting HTML is invalid
because it puts block elements inside inline elements. DocBook 5.0 also
doesn't allow it anymore, so it's fair to assume that this was never
really intended to work. Replace <synopsis> with <literal>, which is
the markup used elsewhere in the documentation in similar cases.
The documentation for ALTER TYPE .. RENAME claimed to support a
RESTRICT/CASCADE option at the 'type' level, which wasn't implemented
and doesn't make a whole lot of sense to begin with. What is supported,
and previously undocumented, is
ALTER TYPE .. RENAME ATTRIBUTE .. RESTRICT/CASCADE.
I've updated the documentation and back-patched this to 9.1 where it was
first introduced.
The 9.2 patch that added argument name support in SQL-language functions
missed updating a parenthetical comment about that in the CREATE FUNCTION
reference page. Noted by Erwin Brandstetter.
If a standby server has a cascading standby server connected to it, it's
possible that WAL has already been sent up to the next WAL page boundary,
splitting a WAL record in the middle, when the first standby server is
promoted. Don't throw an assertion failure or error in walsender if that
happens.
Also, fix a variant of the same bug in pg_receivexlog: if it had already
received WAL on previous timeline up to a segment boundary, when the
upstream standby server is promoted so that the timeline switch record falls
on the previous segment, pg_receivexlog would miss the segment containing
the timeline switch. To fix that, have walsender send the position of the
timeline switch at end-of-streaming, in addition to the next timeline's ID.
It was previously assumed that the switch happened exactly where the
streaming stopped.
Note: this is an incompatible change in the streaming protocol. You might
get an error if you try to stream over timeline switches, if the client is
running 9.3beta1 and the server is more recent. It should be fine after a
reconnect, however.
Reported by Fujii Masao.
What we have implemented is a radix tree (or a radix trie or a patricia
trie), but the docs and code comments incorrectly called it a "suffix tree".
Alexander Korotkov
It is surprisingly common mistake to leave out backup_label file from a base
backup. Say more explicitly that it must be included.
Jeff Janes, with minor rewording by me.
Previously this state was represented by whether the view's disk file had
zero or nonzero size, which is problematic for numerous reasons, since it's
breaking a fundamental assumption about heap storage. This was done to
allow unlogged matviews to revert to unpopulated status after a crash
despite our lack of any ability to update catalog entries post-crash.
However, this poses enough risk of future problems that it seems better to
not support unlogged matviews until we can find another way. Accordingly,
revert that choice as well as a number of existing kluges forced by it
in favor of creating a pg_class.relispopulated flag column.
The initial implementation of this feature was really unsupportable,
because it's relying on the physical size of an on-disk file to carry the
relation's populated/unpopulated state, which is at least a modularity
violation and could have serious long-term consequences. We could say that
an unlogged matview goes to empty on crash, but not everybody likes that
definition, so let's just remove the feature for 9.3. We can add it back
when we have a less klugy implementation.
I left the grammar and tab-completion support for CREATE UNLOGGED
MATERIALIZED VIEW in place, since it's harmless and allows delivering a
more specific error message about the unsupported feature.
I'm committing this separately to ease identification of what should be
reverted when/if we are able to re-enable the feature.
Restore 4-byte designation for docs. Fix 9.3 doc query to properly pad
to four digits.
Backpatch to all active branches
Per suggestions from Ian Lawrence Barwick
Previously, libpq and the backend had opposite ideas about whether
it was necessary for the client to send a CopyDone message after
receiving an ErrorResponse, making it impossible to cleanly exit
COPY BOTH mode. Fix libpq so that works correctly, adopting the
backend's notion that an ErrorResponse kills the copy in both
directions.
Adjust receivelog.c to avoid a degradation in the quality of the
resulting error messages. libpqwalreceiver.c is already doing
the right thing, so no adjustment needed there.
Add an explicit statement to the documentation explaining how
this part of the protocol is supposed to work, in the hopes of
avoiding future confusion in this area.
Since the consequences of all this confusion are very limited,
especially in the back-branches where no client ever attempts
to exit COPY BOTH mode without closing the connection entirely,
no back-patch.
This changes the behavior of the start and stop actions to exit
successfully if the server was already started or stopped.
This changes the default behavior of the start action: Before, if the
server was already running, it would print a message and succeed. Now,
that situation will result in an error. When running in idempotent
mode, no message is printed and pg_ctl exits successfully.
It was considered to just make the idempotent behavior the default and
only option, but pg_upgrade needs the old behavior.
This wasn't addressed in the original patch, but it doesn't take very
much additional code to cover the case, so let's get it done.
Since pg_trgm 1.1 hasn't been released yet, I just changed the definition
of what's in it, rather than inventing a 1.2.
This works by extracting trigrams from the given regular expression,
in generally the same spirit as the previously-existing support for
LIKE searches, though of course the details are far more complicated.
Currently, only GIN indexes are supported. We might be able to make
it work with GiST indexes later.
The implementation includes adding API functions to backend/regex/
to provide a view of the search NFA created from a regular expression.
These functions are meant to be generic enough to be supportable in
a standalone version of the regex library, should that ever happen.
Alexander Korotkov, reviewed by Heikki Linnakangas and Tom Lane
This will hopefully be easier to use than pg_config for users who are
already used to the pkg-config interface. It also works better for
multi-arch installations.
reviewed by Tom Lane
The JSON parser is converted into a recursive descent parser, and
exposed for use by other modules such as extensions. The API provides
hooks for all the significant parser event such as the beginning and end
of objects and arrays, and providing functions to handle these hooks
allows for fairly simple construction of a wide variety of JSON
processing functions. A set of new basic processing functions and
operators is also added, which use this API, including operations to
extract array elements, object fields, get the length of arrays and the
set of keys of a field, deconstruct an object into a set of key/value
pairs, and create records from JSON objects and arrays of objects.
Catalog version bumped.
Andrew Dunstan, with some documentation assistance from Merlin Moncure.
I changed this in commit fd15dba543, but
missed the fact that the SGML documentation of the function specified
exactly what it did. Well, one of the two places where it's specified
documented that --- probably I looked at the other place and thought
nothing needed to be done. Sync the two places where encode() and
decode() are described.
The main change here is to call security_compute_create_name_raw()
rather than security_compute_create_raw(). This ups the minimum
requirement for libselinux from 2.0.99 to 2.1.10, but it looks
like most distributions will have picked that up before 9.3 is out.
KaiGai Kohei
This event takes place just before ddl_command_end, and is fired if and
only if at least one object has been dropped by the command. (For
instance, DROP TABLE IF EXISTS of a table that does not in fact exist
will not lead to such a trigger firing). Commands that drop multiple
objects (such as DROP SCHEMA or DROP OWNED BY) will cause a single event
to fire. Some firings might be surprising, such as
ALTER TABLE DROP COLUMN.
The trigger is fired after the drop has taken place, because that has
been deemed the safest design, to avoid exposing possibly-inconsistent
internal state (system catalogs as well as current transaction) to the
user function code. This means that careful tracking of object
identification is required during the object removal phase.
Like other currently existing events, there is support for tag
filtering.
To support the new event, add a new pg_event_trigger_dropped_objects()
set-returning function, which returns a set of rows comprising the
objects affected by the command. This is to be used within the user
function code, and is mostly modelled after the recently introduced
pg_identify_object() function.
Catalog version bumped due to the new function.
Dimitri Fontaine and Álvaro Herrera
Review by Robert Haas, Tom Lane
A new 'starttli' field was added to the response of BASE_BACKUP command.
Make pg_basebackup tolerate the case that it's missing, so that it still
works with older servers.
Add an explicit check for the server version, so that you get a nicer error
message if you try to use it with a pre-9.1 server.
The streaming protocol message format changed in 9.3, so -X stream still won't
work with pre-9.3 servers. I added a version check to ReceiveXLogStream()
earlier, but write that slightly differently, so that in 9.4, it will still
work with a 9.3 server. (In 9.4, the error message needs to be adjusted to
"9.3 or above", though). Also, if the version check fails, don't retry.
New infrastructure is added which creates a set number of workers
(threads on Windows, forked processes on Unix). Jobs are then
handed out to these workers by the master process as needed.
pg_restore is adjusted to use this new infrastructure in place of the
old setup which created a new worker for each step on the fly. Parallel
dumps acquire a snapshot clone in order to stay consistent, if
available.
The parallel option is selected by the -j / --jobs command line
parameter of pg_dump.
Joachim Wieland, lightly editorialized by Andrew Dunstan.
Doing that results in a broken index entry in PDF output. We had only
a few like that, which is probably why nobody noticed before.
Standardize on putting the <term> first.
Josh Kupershmidt
One of the use-cases for postgres_fdw is extracting data from older PG
servers, so cross-version compatibility is important. Document what we
can do here, and further annotate some of the coding choices that create
compatibility constraints. In passing, remove one unnecessary
incompatibility with old servers, namely assuming that we didn't need to
quote the timezone name 'UTC'.
Commit 13fe298ca0 changed this GUC to be
PGC_SUSET, but neglected to update the documentation to match.
While at it, edit and rearrange the text a little for clarity.
Checksums are set immediately prior to flush out of shared buffers
and checked when pages are read in again. Hint bit setting will
require full page write when block is dirtied, which causes various
infrastructure changes. Extensive comments, docs and README.
WARNING message thrown if checksum fails on non-all zeroes page;
ERROR thrown but can be disabled with ignore_checksum_failure = on.
Feature enabled by an initdb option, since transition from option off
to option on is long and complex and has not yet been implemented.
Default is not to use checksums.
Checksum used is WAL CRC-32 truncated to 16-bits.
Simon Riggs, Jeff Davis, Greg Smith
Wide input and assistance from many community members. Thank you.
Introduce pg_identify_object(oid,oid,int4), which is similar in spirit
to pg_describe_object but instead produces a row of machine-readable
information to uniquely identify the given object, without resorting to
OIDs or other internal representation. This is intended to be used in
the event trigger implementation, to report objects being operated on;
but it has usefulness of its own.
Catalog version bumped because of the new function.
Add section to the Reliability section about what is and is not protected for
various file types.
Further edits welcome.
Designed to allow 1-2 line change when/if checksums are committed.
Inspired by docs written by Jeff Davis, though completely different from his
patch.
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