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* Consistently test for in-use shared memory.Noah Misch2019-04-12
| | | | | | | | | | | | | | | | | | | | | | postmaster startup scrutinizes any shared memory segment recorded in postmaster.pid, exiting if that segment matches the current data directory and has an attached process. When the postmaster.pid file was missing, a starting postmaster used weaker checks. Change to use the same checks in both scenarios. This increases the chance of a startup failure, in lieu of data corruption, if the DBA does "kill -9 `head -n1 postmaster.pid` && rm postmaster.pid && pg_ctl -w start". A postmaster will no longer stop if shmat() of an old segment fails with EACCES. A postmaster will no longer recycle segments pertaining to other data directories. That's good for production, but it's bad for integration tests that crash a postmaster and immediately delete its data directory. Such a test now leaks a segment indefinitely. No "make check-world" test does that. win32_shmem.c already avoided all these problems. In 9.6 and later, enhance PostgresNode to facilitate testing. Back-patch to 9.4 (all supported versions). Reviewed (in earlier versions) by Daniel Gustafsson and Kyotaro HORIGUCHI. Discussion: https://postgr.es/m/20190408064141.GA2016666@rfd.leadboat.com
* Revert "Consistently test for in-use shared memory."Noah Misch2019-04-05
| | | | | | | | | This reverts commits 2f932f71d9f2963bbd201129d7b971c8f5f077fd, 16ee6eaf80a40007a138b60bb5661660058d0422 and 6f0e190056fe441f7cf788ff19b62b13c94f68f3. The buildfarm has revealed several bugs. Back-patch like the original commits. Discussion: https://postgr.es/m/20190404145319.GA1720877@rfd.leadboat.com
* Consistently test for in-use shared memory.Noah Misch2019-04-03
| | | | | | | | | | | | | | | | | | | | | postmaster startup scrutinizes any shared memory segment recorded in postmaster.pid, exiting if that segment matches the current data directory and has an attached process. When the postmaster.pid file was missing, a starting postmaster used weaker checks. Change to use the same checks in both scenarios. This increases the chance of a startup failure, in lieu of data corruption, if the DBA does "kill -9 `head -n1 postmaster.pid` && rm postmaster.pid && pg_ctl -w start". A postmaster will no longer recycle segments pertaining to other data directories. That's good for production, but it's bad for integration tests that crash a postmaster and immediately delete its data directory. Such a test now leaks a segment indefinitely. No "make check-world" test does that. win32_shmem.c already avoided all these problems. In 9.6 and later, enhance PostgresNode to facilitate testing. Back-patch to 9.4 (all supported versions). Reviewed by Daniel Gustafsson and Kyotaro HORIGUCHI. Discussion: https://postgr.es/m/20130911033341.GD225735@tornado.leadboat.com
* Add shared_memory_type GUC.Thomas Munro2019-02-03
| | | | | | | | | | | | | | Since 9.3 we have used anonymous shared mmap for our main shared memory region, except in EXEC_BACKEND builds. Provide a GUC so that users can opt for System V shared memory once again, like in 9.2 and earlier. A later patch proposes to add huge/large page support for AIX, which requires System V shared memory and provided the motivation to revive this possibility. It may also be useful on some BSDs. Author: Andres Freund (revived and documented by Thomas Munro) Discussion: https://postgr.es/m/HE1PR0202MB28126DB4E0B6621CC6A1A91286D90%40HE1PR0202MB2812.eurprd02.prod.outlook.com Discussion: https://postgr.es/m/2AE143D2-87D3-4AD1-AC78-CE2258230C05%40FreeBSD.org
* Update copyright for 2019Bruce Momjian2019-01-02
| | | | Backpatch-through: certain files through 9.4
* Remove configure switch --disable-strong-randomMichael Paquier2019-01-01
| | | | | | | | | | | | | | | | This removes a portion of infrastructure introduced by fe0a0b5 to allow compilation of Postgres in environments where no strong random source is available, meaning that there is no linking to OpenSSL and no /dev/urandom (Windows having its own CryptoAPI). No systems shipped this century lack /dev/urandom, and the buildfarm is actually not testing this switch at all, so just remove it. This simplifies particularly some backend code which included a fallback implementation using shared memory, and removes a set of alternate regression output files from pgcrypto. Author: Michael Paquier Reviewed-by: Tom Lane Discussion: https://postgr.es/m/20181230063219.GG608@paquier.xyz
* Revert "Allow on-line enabling and disabling of data checksums"Magnus Hagander2018-04-09
| | | | | | | | This reverts the backend sides of commit 1fde38beaa0c3e66c340efc7cc0dc272d6254bb0. I have, at least for now, left the pg_verify_checksums tool in place, as this tool can be very valuable without the rest of the patch as well, and since it's a read-only tool that only runs when the cluster is down it should be a lot safer.
* Allow on-line enabling and disabling of data checksumsMagnus Hagander2018-04-05
| | | | | | | | | | | | | | | | | | | This makes it possible to turn checksums on in a live cluster, without the previous need for dump/reload or logical replication (and to turn it off). Enabling checkusm starts a background process in the form of a launcher/worker combination that goes through the entire database and recalculates checksums on each and every page. Only when all pages have been checksummed are they fully enabled in the cluster. Any failure of the process will revert to checksums off and the process has to be started. This adds a new WAL record that indicates the state of checksums, so the process works across replicated clusters. Authors: Magnus Hagander and Daniel Gustafsson Review: Tomas Vondra, Michael Banck, Heikki Linnakangas, Andrey Borodin
* Update copyright for 2018Bruce Momjian2018-01-02
| | | | Backpatch-through: certain files through 9.3
* Logical replicationPeter Eisentraut2017-01-20
| | | | | | | | | | | | | - Add PUBLICATION catalogs and DDL - Add SUBSCRIPTION catalog and DDL - Define logical replication protocol and output plugin - Add logical replication workers From: Petr Jelinek <petr@2ndquadrant.com> Reviewed-by: Steve Singer <steve@ssinger.info> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Erik Rijkers <er@xs4all.nl> Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
* Update copyright via script for 2017Bruce Momjian2017-01-03
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* Make the different Unix-y semaphore implementations ABI-compatible.Tom Lane2016-12-12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously, the "sem" field of PGPROC varied in size depending on which kernel semaphore API we were using. That was okay as long as there was only one likely choice per platform, but in the wake of commit ecb0d20a9, that assumption seems rather shaky. It doesn't seem out of the question anymore that an extension compiled against one API choice might be loaded into a postmaster built with another choice. Moreover, this prevents any possibility of selecting the semaphore API at postmaster startup, which might be something we want to do in future. Hence, change PGPROC.sem to be PGSemaphore (i.e. a pointer) for all Unix semaphore APIs, and turn the pointed-to data into an opaque struct whose contents are only known within the responsible modules. For the SysV and unnamed-POSIX APIs, the pointed-to data has to be allocated elsewhere in shared memory, which takes a little bit of rejiggering of the InitShmemAllocation code sequence. (I invented a ShmemAllocUnlocked() function to make that a little cleaner than it used to be. That function is not meant for any uses other than the ones it has now, but it beats having InitShmemAllocation() know explicitly about allocation of space for semaphores and spinlocks.) This change means an extra indirection to access the semaphore data, but since we only touch that when blocking or awakening a process, there shouldn't be any meaningful performance penalty. Moreover, at least for the unnamed-POSIX case on Linux, the sem_t type is quite a bit wider than a pointer, so this reduces sizeof(PGPROC) which seems like a good thing. For the named-POSIX API, there's effectively no change: the PGPROC.sem field was and still is a pointer to something returned by sem_open() in the postmaster's memory space. Document and check the pre-existing limitation that this case can't work in EXEC_BACKEND mode. It did not seem worth unifying the Windows semaphore ABI with the Unix cases, since there's no likelihood of needing ABI compatibility much less runtime switching across those cases. However, we can simplify the Windows code a bit if we define PGSemaphore as being directly a HANDLE, rather than pointer to HANDLE, so let's do that while we're here. (This also ends up being no change in what's physically stored in PGPROC.sem. We're just moving the HANDLE fetch from callees to callers.) It would take a bunch of additional code shuffling to get to the point of actually choosing a semaphore API at postmaster start, but the effects of that would now be localized in the port/XXX_sema.c files, so it seems like fit material for a separate patch. The need for it is unproven as yet, anyhow, whereas the ABI risk to extensions seems real enough. Discussion: https://postgr.es/m/4029.1481413370@sss.pgh.pa.us
* Replace PostmasterRandom() with a stronger source, second attempt.Heikki Linnakangas2016-12-05
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds a new routine, pg_strong_random() for generating random bytes, for use in both frontend and backend. At the moment, it's only used in the backend, but the upcoming SCRAM authentication patches need strong random numbers in libpq as well. pg_strong_random() is based on, and replaces, the existing implementation in pgcrypto. It can acquire strong random numbers from a number of sources, depending on what's available: - OpenSSL RAND_bytes(), if built with OpenSSL - On Windows, the native cryptographic functions are used - /dev/urandom Unlike the current pgcrypto function, the source is chosen by configure. That makes it easier to test different implementations, and ensures that we don't accidentally fall back to a less secure implementation, if the primary source fails. All of those methods are quite reliable, it would be pretty surprising for them to fail, so we'd rather find out by failing hard. If no strong random source is available, we fall back to using erand48(), seeded from current timestamp, like PostmasterRandom() was. That isn't cryptographically secure, but allows us to still work on platforms that don't have any of the above stronger sources. Because it's not very secure, the built-in implementation is only used if explicitly requested with --disable-strong-random. This replaces the more complicated Fortuna algorithm we used to have in pgcrypto, which is unfortunate, but all modern platforms have /dev/urandom, so it doesn't seem worth the maintenance effort to keep that. pgcrypto functions that require strong random numbers will be disabled with --disable-strong-random. Original patch by Magnus Hagander, tons of further work by Michael Paquier and me. Discussion: https://www.postgresql.org/message-id/CAB7nPqRy3krN8quR9XujMVVHYtXJ0_60nqgVc6oUk8ygyVkZsA@mail.gmail.com Discussion: https://www.postgresql.org/message-id/CAB7nPqRWkNYRRPJA7-cF+LfroYV10pvjdz6GNvxk-Eee9FypKA@mail.gmail.com
* Add the "snapshot too old" featureKevin Grittner2016-04-08
| | | | | | | | | | | | | | | | This feature is controlled by a new old_snapshot_threshold GUC. A value of -1 disables the feature, and that is the default. The value of 0 is just intended for testing. Above that it is the number of minutes a snapshot can reach before pruning and vacuum are allowed to remove dead tuples which the snapshot would otherwise protect. The xmin associated with a transaction ID does still protect dead tuples. A connection which is using an "old" snapshot does not get an error unless it accesses a page modified recently enough that it might not be able to produce accurate results. This is similar to the Oracle feature, and we use the same SQLSTATE and error message for compatibility.
* Update copyright for 2016Bruce Momjian2016-01-02
| | | | Backpatch certain files through 9.1
* Introduce replication progress tracking infrastructure.Andres Freund2015-04-29
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When implementing a replication solution ontop of logical decoding, two related problems exist: * How to safely keep track of replication progress * How to change replication behavior, based on the origin of a row; e.g. to avoid loops in bi-directional replication setups The solution to these problems, as implemented here, consist out of three parts: 1) 'replication origins', which identify nodes in a replication setup. 2) 'replication progress tracking', which remembers, for each replication origin, how far replay has progressed in a efficient and crash safe manner. 3) The ability to filter out changes performed on the behest of a replication origin during logical decoding; this allows complex replication topologies. E.g. by filtering all replayed changes out. Most of this could also be implemented in "userspace", e.g. by inserting additional rows contain origin information, but that ends up being much less efficient and more complicated. We don't want to require various replication solutions to reimplement logic for this independently. The infrastructure is intended to be generic enough to be reusable. This infrastructure also replaces the 'nodeid' infrastructure of commit timestamps. It is intended to provide all the former capabilities, except that there's only 2^16 different origins; but now they integrate with logical decoding. Additionally more functionality is accessible via SQL. Since the commit timestamp infrastructure has also been introduced in 9.5 (commit 73c986add) changing the API is not a problem. For now the number of origins for which the replication progress can be tracked simultaneously is determined by the max_replication_slots GUC. That GUC is not a perfect match to configure this, but there doesn't seem to be sufficient reason to introduce a separate new one. Bumps both catversion and wal page magic. Author: Andres Freund, with contributions from Petr Jelinek and Craig Ringer Reviewed-By: Heikki Linnakangas, Petr Jelinek, Robert Haas, Steve Singer Discussion: 20150216002155.GI15326@awork2.anarazel.de, 20140923182422.GA15776@alap3.anarazel.de, 20131114172632.GE7522@alap2.anarazel.de
* Update copyright for 2015Bruce Momjian2015-01-06
| | | | Backpatch certain files through 9.0
* Keep track of transaction commit timestampsAlvaro Herrera2014-12-03
| | | | | | | | | | | | | | | | | | | | | Transactions can now set their commit timestamp directly as they commit, or an external transaction commit timestamp can be fed from an outside system using the new function TransactionTreeSetCommitTsData(). This data is crash-safe, and truncated at Xid freeze point, same as pg_clog. This module is disabled by default because it causes a performance hit, but can be enabled in postgresql.conf requiring only a server restart. A new test in src/test/modules is included. Catalog version bumped due to the new subdirectory within PGDATA and a couple of new SQL functions. Authors: Álvaro Herrera and Petr Jelínek Reviewed to varying degrees by Michael Paquier, Andres Freund, Robert Haas, Amit Kapila, Fujii Masao, Jaime Casanova, Simon Riggs, Steven Singer, Peter Eisentraut
* pgindent run for 9.4Bruce Momjian2014-05-06
| | | | | This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
* Get rid of the dynamic shared memory state file.Robert Haas2014-04-08
| | | | | | | | | | | | | Instead of storing the ID of the dynamic shared memory control segment in a file within the data directory, store it in the main control segment. This avoids a number of nasty corner cases, most seriously that doing an online backup and then using it on the same machine (e.g. to fire up a standby) would result in the standby clobbering all of the master's dynamic shared memory segments. Per complaints from Heikki Linnakangas, Fujii Masao, and Tom Lane.
* Introduce replication slots.Robert Haas2014-01-31
| | | | | | | | | | | | | | | | Replication slots are a crash-safe data structure which can be created on either a master or a standby to prevent premature removal of write-ahead log segments needed by a standby, as well as (with hot_standby_feedback=on) pruning of tuples whose removal would cause replication conflicts. Slots have some advantages over existing techniques, as explained in the documentation. In a few places, we refer to the type of replication slots introduced by this patch as "physical" slots, because forthcoming patches for logical decoding will also have slots, but with somewhat different properties. Andres Freund and Robert Haas
* Relax the requirement that all lwlocks be stored in a single array.Robert Haas2014-01-27
| | | | | | | | | | | | | | This makes it possible to store lwlocks as part of some other data structure in the main shared memory segment, or in a dynamic shared memory segment. There is still a main LWLock array and this patch does not move anything out of it, but it provides necessary infrastructure for doing that in the future. This change is likely to increase the size of LWLockPadded on some platforms, especially 32-bit platforms where it was previously only 16 bytes. Patch by me. Review by Andres Freund and KaiGai Kohei.
* Allow use of "z" flag in our printf calls, and use it where appropriate.Tom Lane2014-01-23
| | | | | | | | | | | | | | | | | | | | | | | | | Since C99, it's been standard for printf and friends to accept a "z" size modifier, meaning "whatever size size_t has". Up to now we've generally dealt with printing size_t values by explicitly casting them to unsigned long and using the "l" modifier; but this is really the wrong thing on platforms where pointers are wider than longs (such as Win64). So let's start using "z" instead. To ensure we can do that on all platforms, teach src/port/snprintf.c to understand "z", and add a configure test to force use of that implementation when the platform's version doesn't handle "z". Having done that, modify a bunch of places that were using the unsigned-long hack to use "z" instead. This patch doesn't pretend to have gotten everyplace that could benefit, but it catches many of them. I made an effort in particular to ensure that all uses of the same error message text were updated together, so as not to increase the number of translatable strings. It's possible that this change will result in format-string warnings from pre-C99 compilers. We might have to reconsider if there are any popular compilers that will warn about this; but let's start by seeing what the buildfarm thinks. Andres Freund, with a little additional work by me
* Reduce the number of semaphores used under --disable-spinlocks.Robert Haas2014-01-08
| | | | | | | | | | | | | | | | | | | | | | | Instead of allocating a semaphore from the operating system for every spinlock, allocate a fixed number of semaphores (by default, 1024) from the operating system and multiplex all the spinlocks that get created onto them. This could self-deadlock if a process attempted to acquire more than one spinlock at a time, but since processes aren't supposed to execute anything other than short stretches of straight-line code while holding a spinlock, that shouldn't happen. One motivation for this change is that, with the introduction of dynamic shared memory, it may be desirable to create spinlocks that last for less than the lifetime of the server. Without this change, attempting to use such facilities under --disable-spinlocks would quickly exhaust any supply of available semaphores. Quite apart from that, it's desirable to contain the quantity of semaphores needed to run the server simply on convenience grounds, since using too many may make it harder to get PostgreSQL running on a new platform, which is mostly the point of --disable-spinlocks in the first place. Patch by me; review by Tom Lane.
* Update copyright for 2014Bruce Momjian2014-01-07
| | | | | Update all files in head, and files COPYRIGHT and legal.sgml in all back branches.
* Allow dynamic allocation of shared memory segments.Robert Haas2013-10-09
| | | | | Patch by myself and Amit Kapila. Design help from Noah Misch. Review by Andres Freund.
* Allow background workers to be started dynamically.Robert Haas2013-07-16
| | | | | | | | | | | | | | | | | | | | | | | | There is a new API, RegisterDynamicBackgroundWorker, which allows an ordinary user backend to register a new background writer during normal running. This means that it's no longer necessary for all background workers to be registered during processing of shared_preload_libraries, although the option of registering workers at that time remains available. When a background worker exits and will not be restarted, the slot previously used by that background worker is automatically released and becomes available for reuse. Slots used by background workers that are configured for automatic restart can't (yet) be released without shutting down the system. This commit adds a new source file, bgworker.c, and moves some of the existing control logic for background workers there. Previously, there was little enough logic that it made sense to keep everything in postmaster.c, but not any more. This commit also makes the worker_spi contrib module into an extension and adds a new function, worker_spi_launch, which can be used to demonstrate the new facility.
* Update copyrights for 2013Bruce Momjian2013-01-01
| | | | | Fully update git head, and update back branches in ./COPYRIGHT and legal.sgml files.
* Tighten up includes in sinvaladt.h, twophase.h, proc.hAlvaro Herrera2012-06-25
| | | | | Remove proc.h from sinvaladt.h and twophase.h; also replace xlog.h in proc.h with xlogdefs.h.
* Rename BgWriterShmem/Request to CheckpointerShmem/RequestSimon Riggs2012-05-09
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* Update copyright notices for year 2012.Bruce Momjian2012-01-01
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* Move "hot" members of PGPROC into a separate PGXACT array.Robert Haas2011-11-25
| | | | | | | | | | | | This speeds up snapshot-taking and reduces ProcArrayLock contention. Also, the PGPROC (and PGXACT) structures used by two-phase commit are now allocated as part of the main array, rather than in a separate array, and we keep ProcArray sorted in pointer order. These changes are intended to minimize the number of cache lines that must be pulled in to take a snapshot, and testing shows a substantial increase in performance on both read and write workloads at high concurrencies. Pavan Deolasee, Heikki Linnakangas, Robert Haas
* Implement genuine serializable isolation level.Heikki Linnakangas2011-02-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Until now, our Serializable mode has in fact been what's called Snapshot Isolation, which allows some anomalies that could not occur in any serialized ordering of the transactions. This patch fixes that using a method called Serializable Snapshot Isolation, based on research papers by Michael J. Cahill (see README-SSI for full references). In Serializable Snapshot Isolation, transactions run like they do in Snapshot Isolation, but a predicate lock manager observes the reads and writes performed and aborts transactions if it detects that an anomaly might occur. This method produces some false positives, ie. it sometimes aborts transactions even though there is no anomaly. To track reads we implement predicate locking, see storage/lmgr/predicate.c. Whenever a tuple is read, a predicate lock is acquired on the tuple. Shared memory is finite, so when a transaction takes many tuple-level locks on a page, the locks are promoted to a single page-level lock, and further to a single relation level lock if necessary. To lock key values with no matching tuple, a sequential scan always takes a relation-level lock, and an index scan acquires a page-level lock that covers the search key, whether or not there are any matching keys at the moment. A predicate lock doesn't conflict with any regular locks or with another predicate locks in the normal sense. They're only used by the predicate lock manager to detect the danger of anomalies. Only serializable transactions participate in predicate locking, so there should be no extra overhead for for other transactions. Predicate locks can't be released at commit, but must be remembered until all the transactions that overlapped with it have completed. That means that we need to remember an unbounded amount of predicate locks, so we apply a lossy but conservative method of tracking locks for committed transactions. If we run short of shared memory, we overflow to a new "pg_serial" SLRU pool. We don't currently allow Serializable transactions in Hot Standby mode. That would be hard, because even read-only transactions can cause anomalies that wouldn't otherwise occur. Serializable isolation mode now means the new fully serializable level. Repeatable Read gives you the old Snapshot Isolation level that we have always had. Kevin Grittner and Dan Ports, reviewed by Jeff Davis, Heikki Linnakangas and Anssi Kääriäinen
* Stamp copyrights for year 2011.Bruce Momjian2011-01-01
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* Remove cvs keywords from all files.Magnus Hagander2010-09-20
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* Simplify Windows implementation of latches. There's no need to keep aHeikki Linnakangas2010-09-15
| | | | | | | | dynamic pool of event handles, we can permanently assign one for each shared latch. Thanks to that, we no longer need a separate shared memory block for latches, and we don't need to know in advance how many shared latches there is, so you no longer need to remember to update NumSharedLatches when you introduce a new latch to the system.
* Introduce latches. A latch is a boolean variable, with the capability toHeikki Linnakangas2010-09-11
| | | | | | | | | | | | | | | | | | wait until it is set. Latches can be used to reliably wait until a signal arrives, which is hard otherwise because signals don't interrupt select() on some platforms, and even when they do, there's race conditions. On Unix, latches use the so called self-pipe trick under the covers to implement the sleep until the latch is set, without race conditions. On Windows, Windows events are used. Use the new latch abstraction to sleep in walsender, so that as soon as a transaction finishes, walsender is woken up to immediately send the WAL to the standby. This reduces the latency between master and standby, which is good. Preliminary work by Fujii Masao. The latch implementation is by me, with helpful comments from many people.
* Replace the pg_listener-based LISTEN/NOTIFY mechanism with an in-memory queue.Tom Lane2010-02-16
| | | | | | | | | | | | In addition, add support for a "payload" string to be passed along with each notify event. This implementation should be significantly more efficient than the old one, and is also more compatible with Hot Standby usage. There is not yet any facility for HS slaves to receive notifications generated on the master, although such a thing is possible in future. Joachim Wieland, reviewed by Jeff Davis; also hacked on by me.
* Introduce Streaming Replication.Heikki Linnakangas2010-01-15
| | | | | | | | | | | | | | | | | | | | This includes two new kinds of postmaster processes, walsenders and walreceiver. Walreceiver is responsible for connecting to the primary server and streaming WAL to disk, while walsender runs in the primary server and streams WAL from disk to the client. Documentation still needs work, but the basics are there. We will probably pull the replication section to a new chapter later on, as well as the sections describing file-based replication. But let's do that as a separate patch, so that it's easier to see what has been added/changed. This patch also adds a new section to the chapter about FE/BE protocol, documenting the protocol used by walsender/walreceivxer. Bump catalog version because of two new functions, pg_last_xlog_receive_location() and pg_last_xlog_replay_location(), for monitoring the progress of replication. Fujii Masao, with additional hacking by me
* Update copyright for the year 2010.Bruce Momjian2010-01-02
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* Create a multiplexing structure for signals to Postgres child processes.Tom Lane2009-07-31
| | | | | | | | | | | | | | | This patch gets us out from under the Unix limitation of two user-defined signal types. We already had done something similar for signals directed to the postmaster process; this adds multiplexing for signals directed to backends and auxiliary processes (so long as they're connected to shared memory). As proof of concept, replace the former usage of SIGUSR1 and SIGUSR2 for backends with use of the multiplexing mechanism. There are still some hard-wired definitions of SIGUSR1 and SIGUSR2 for other process types, but getting rid of those doesn't seem interesting at the moment. Fujii Masao
* Install a "dead man switch" to allow the postmaster to detect cases whereTom Lane2009-05-05
| | | | | | | | | | | | | | | | | | | | | | | | | | a backend has done exit(0) or exit(1) without having disengaged itself from shared memory. We are at risk for this whenever third-party code is loaded into a backend, since such code might not know it's supposed to go through proc_exit() instead. Also, it is reported that under Windows there are ways to externally kill a process that cause the status code returned to the postmaster to be indistinguishable from a voluntary exit (thank you, Microsoft). If this does happen then the system is probably hosed --- for instance, the dead session might still be holding locks. So the best recovery method is to treat this like a backend crash. The dead man switch is armed for a particular child process when it acquires a regular PGPROC, and disarmed when the PGPROC is released; these should be the first and last touches of shared memory resources in a backend, or close enough anyway. This choice means there is no coverage for auxiliary processes, but I doubt we need that, since they shouldn't be executing any user-provided code anyway. This patch also improves the management of the EXEC_BACKEND ShmemBackendArray array a bit, by reducing search costs. Although this problem is of long standing, the lack of field complaints seems to mean it's not critical enough to risk back-patching; at least not till we get some more testing of this mechanism.
* Create a "shmem_startup_hook" to be called at the end of shared memoryTom Lane2009-01-03
| | | | | | | | | | | | | initialization, to give loadable modules a reasonable place to perform creation of any shared memory areas they need. This is the logical conclusion of our previous creation of RequestAddinShmemSpace() and RequestAddinLWLocks(). We don't need an explicit shmem_shutdown_hook, because the existing on_shmem_exit and on_proc_exit mechanisms serve that need. Also, adjust SubPostmasterMain so that libraries that got loaded into the postmaster will be loaded into all child processes, not only regular backends. This improves consistency with the non-EXEC_BACKEND behavior, and might be necessary for functionality for some types of add-ons.
* Update copyright for 2009.Bruce Momjian2009-01-01
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* Rewrite the FSM. Instead of relying on a fixed-size shared memory segment, theHeikki Linnakangas2008-09-30
| | | | | | | | | | | | | free space information is stored in a dedicated FSM relation fork, with each relation (except for hash indexes; they don't use FSM). This eliminates the max_fsm_relations and max_fsm_pages GUC options; remove any trace of them from the backend, initdb, and documentation. Rewrite contrib/pg_freespacemap to match the new FSM implementation. Also introduce a new variant of the get_raw_page(regclass, int4, int4) function in contrib/pageinspect that let's you to return pages from any relation fork, and a new fsm_page_contents() function to inspect the new FSM pages.
* Restructure some header files a bit, in particular heapam.h, by removing someAlvaro Herrera2008-05-12
| | | | | | | | | | | | unnecessary #include lines in it. Also, move some tuple routine prototypes and macros to htup.h, which allows removal of heapam.h inclusion from some .c files. For this to work, a new header file access/sysattr.h needed to be created, initially containing attribute numbers of system columns, for pg_dump usage. While at it, make contrib ltree, intarray and hstore header files more consistent with our header style.
* Modify interactions between sinval.c and sinvaladt.c. The code that actuallyAlvaro Herrera2008-03-16
| | | | | | | | deals with the queue, including locking etc, is all in sinvaladt.c. This means that the struct definition of the queue, and the queue pointer, are now internal "implementation details" inside sinvaladt.c. Per my proposal dated 25-Jun-2007 and followup discussion.
* Update copyrights in source tree to 2008.Bruce Momjian2008-01-01
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* pgindent run for 8.3.Bruce Momjian2007-11-15
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* Arrange for large sequential scans to synchronize with each other, so thatTom Lane2007-06-08
| | | | | | | when multiple backends are scanning the same relation concurrently, each page is (ideally) read only once. Jeff Davis, with review by Heikki and Tom.
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