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path: root/src/backend/replication/logical/logical.c
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* Don't retreat slot's confirmed_flush LSN.Amit Kapila2025-05-19
| | | | | | | | | | | | | | | | | | | | Prevent moving the confirmed_flush backwards, as this could lead to data duplication issues caused by replicating already replicated changes. This can happen when a client acknowledges an LSN it doesn't have to do anything for, and thus didn't store persistently. After a restart, the client can send the prior LSN that it stored persistently as an acknowledgement, but we need to ignore such an LSN to avoid retreating confirm_flush LSN. Diagnosed-by: Zhijie Hou <houzj.fnst@fujitsu.com> Author: shveta malik <shveta.malik@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Dilip Kumar <dilipbalaut@gmail.com> Tested-by: Nisha Moond <nisha.moond412@gmail.com> Backpatch-through: 13 Discussion: https://postgr.es/m/CAJpy0uDZ29P=BYB1JDWMCh-6wXaNqMwG1u1mB4=10Ly0x7HhwQ@mail.gmail.com Discussion: https://postgr.es/m/OS0PR01MB57164AB5716AF2E477D53F6F9489A@OS0PR01MB5716.jpnprd01.prod.outlook.com
* Use PRI?64 instead of "ll?" in format strings (continued).Peter Eisentraut2025-03-29
| | | | | | | Continuation of work started in commit 15a79c73, after initial trial. Author: Thomas Munro <thomas.munro@gmail.com> Discussion: https://postgr.es/m/b936d2fb-590d-49c3-a615-92c3a88c6c19%40eisentraut.org
* Raise an error while trying to acquire an invalid slot.Amit Kapila2025-01-31
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Once a replication slot is invalidated, it cannot be altered or used to fetch changes. However, a process could still acquire an invalid slot and fail later. For example, if a process acquires a logical slot that was invalidated due to wal_removed, it will eventually fail in CreateDecodingContext() when attempting to access the removed WAL. Similarly, for physical replication slots, even if the slot is invalidated and invalidation_reason is set to wal_removed, the walsender does not currently check for invalidation when starting physical replication. Instead, replication starts, and an error is only reported later while trying to access WAL. Similarly, we prohibit modifying slot properties for invalid slots but give the error for the same after acquiring the slot. This patch improves error handling by detecting invalid slots earlier at the time of slot acquisition which is the first step. This also helped in unifying different ERROR messages at different places and gave a consistent message for invalid slots. This means that the message for invalid slots will change to a generic message. This will also be helpful for future patches where we are planning to invalidate slots due to more reasons like idle_timeout because we don't have to modify multiple places in such cases and avoid the chances of missing out on a particular place. Author: Nisha Moond <nisha.moond412@gmail.com> Author: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Vignesh C <vignesh21@gmail.com> Reviewed-by: Peter Smith <smithpb2250@gmail.com> Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Discussion: https://postgr.es/m/CABdArM6pBL5hPnSQ+5nEVMANcF4FCH7LQmgskXyiLY75TMnKpw@mail.gmail.com
* Update copyright for 2025Bruce Momjian2025-01-01
| | | | Backpatch-through: 13
* Remove useless casts to (void *)Peter Eisentraut2024-11-28
| | | | | | | | Many of them just seem to have been copied around for no real reason. Their presence causes (small) risks of hiding actual type mismatches or silently discarding qualifiers Discussion: https://www.postgresql.org/message-id/flat/461ea37c-8b58-43b4-9736-52884e862820@eisentraut.org
* Fix a possibility of logical replication slot's restart_lsn going backwards.Masahiko Sawada2024-11-15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously LogicalIncreaseRestartDecodingForSlot() accidentally accepted any LSN as the candidate_lsn and candidate_valid after the restart_lsn of the replication slot was updated, so it potentially caused the restart_lsn to move backwards. A scenario where this could happen in logical replication is: after a logical replication restart, based on previous candidate_lsn and candidate_valid values in memory, the restart_lsn advances upon receiving a subscriber acknowledgment. Then, logical decoding restarts from an older point, setting candidate_lsn and candidate_valid based on an old RUNNING_XACTS record. Subsequent subscriber acknowledgments then update the restart_lsn to an LSN older than the current value. In the reported case, after WAL files were removed by a checkpoint, the retreated restart_lsn prevented logical replication from restarting due to missing WAL segments. This change essentially modifies the 'if' condition to 'else if' condition within the function. The previous code had an asymmetry in this regard compared to LogicalIncreaseXminForSlot(), which does almost the same thing for different fields. The WAL removal issue was reported by Hubert Depesz Lubaczewski. Backpatch to all supported versions, since the bug exists since 9.4 where logical decoding was introduced. Reviewed-by: Tomas Vondra, Ashutosh Bapat, Amit Kapila Discussion: https://postgr.es/m/Yz2hivgyjS1RfMKs%40depesz.com Discussion: https://postgr.es/m/85fff40e-148b-4e86-b921-b4b846289132%40vondra.me Backpatch-through: 13
* Message style improvementsPeter Eisentraut2024-08-29
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* Fix possibility of logical decoding partial transaction changes.Masahiko Sawada2024-07-11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When creating and initializing a logical slot, the restart_lsn is set to the latest WAL insertion point (or the latest replay point on standbys). Subsequently, WAL records are decoded from that point to find the start point for extracting changes in the DecodingContextFindStartpoint() function. Since the initial restart_lsn could be in the middle of a transaction, the start point must be a consistent point where we won't see the data for partial transactions. Previously, when not building a full snapshot, serialized snapshots were restored, and the SnapBuild jumps to the consistent state even while finding the start point. Consequently, the slot's restart_lsn and confirmed_flush could be set to the middle of a transaction. This could lead to various unexpected consequences. Specifically, there were reports of logical decoding decoding partial transactions, and assertion failures occurred because only subtransactions were decoded without decoding their top-level transaction until decoding the commit record. To resolve this issue, the changes prevent restoring the serialized snapshot and jumping to the consistent state while finding the start point. On v17 and HEAD, a flag indicating whether snapshot restores should be skipped has been added to the SnapBuild struct, and SNAPBUILD_VERSION has been bumpded. On backbranches, the flag is stored in the LogicalDecodingContext instead, preserving on-disk compatibility. Backpatch to all supported versions. Reported-by: Drew Callahan Reviewed-by: Amit Kapila, Hayato Kuroda Discussion: https://postgr.es/m/2444AA15-D21B-4CCE-8052-52C7C2DAFE5C%40amazon.com Backpatch-through: 12
* Revise GUC names quoting in messages againPeter Eisentraut2024-05-17
| | | | | | | | | | | | | | | After further review, we want to move in the direction of always quoting GUC names in error messages, rather than the previous (PG16) wildly mixed practice or the intermittent (mid-PG17) idea of doing this depending on how possibly confusing the GUC name is. This commit applies appropriate quotes to (almost?) all mentions of GUC names in error messages. It partially supersedes a243569bf65 and 8d9978a7176, which had moved things a bit in the opposite direction but which then were abandoned in a partial state. Author: Peter Smith <smithpb2250@gmail.com> Discussion: https://www.postgresql.org/message-id/flat/CAHut%2BPv-kSN8SkxSdoHano_wPubqcg5789ejhCDZAcLFceBR-w%40mail.gmail.com
* Ensure that the sync slots reach a consistent state after promotion without ↵Amit Kapila2024-04-03
| | | | | | | | | | | | | | | | | | | | | | | | | | losing data. We were directly copying the LSN locations while syncing the slots on the standby. Now, it is possible that at some particular restart_lsn there are some running xacts, which means if we start reading the WAL from that location after promotion, we won't reach a consistent snapshot state at that point. However, on the primary, we would have already been in a consistent snapshot state at that restart_lsn so we would have just serialized the existing snapshot. To avoid this problem we will use the advance_slot functionality unless the snapshot already exists at the synced restart_lsn location. This will help us to ensure that snapbuilder/slot statuses are updated properly without generating any changes. Note that the synced slot will remain as RS_TEMPORARY till the decoding from corresponding restart_lsn can reach a consistent snapshot state after which they will be marked as RS_PERSISTENT. Per buildfarm Author: Hou Zhijie Reviewed-by: Bertrand Drouvot, Shveta Malik, Bharath Rupireddy, Amit Kapila Discussion: https://postgr.es/m/OS0PR01MB5716B3942AE49F3F725ACA92943B2@OS0PR01MB5716.jpnprd01.prod.outlook.com
* Remove unused #include's from backend .c filesPeter Eisentraut2024-03-04
| | | | | | | | | | | | | | | | | | | | | | | | | | | | as determined by include-what-you-use (IWYU) While IWYU also suggests to *add* a bunch of #include's (which is its main purpose), this patch does not do that. In some cases, a more specific #include replaces another less specific one. Some manual adjustments of the automatic result: - IWYU currently doesn't know about includes that provide global variable declarations (like -Wmissing-variable-declarations), so those includes are being kept manually. - All includes for port(ability) headers are being kept for now, to play it safe. - No changes of catalog/pg_foo.h to catalog/pg_foo_d.h, to keep the patch from exploding in size. Note that this patch touches just *.c files, so nothing declared in header files changes in hidden ways. As a small example, in src/backend/access/transam/rmgr.c, some IWYU pragma annotations are added to handle a special case there. Discussion: https://www.postgresql.org/message-id/flat/af837490-6b2f-46df-ba05-37ea6a6653fc%40eisentraut.org
* Add a slot synchronization function.Amit Kapila2024-02-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This commit introduces a new SQL function pg_sync_replication_slots() which is used to synchronize the logical replication slots from the primary server to the physical standby so that logical replication can be resumed after a failover or planned switchover. A new 'synced' flag is introduced in pg_replication_slots view, indicating whether the slot has been synchronized from the primary server. On a standby, synced slots cannot be dropped or consumed, and any attempt to perform logical decoding on them will result in an error. The logical replication slots on the primary can be synchronized to the hot standby by using the 'failover' parameter of pg-create-logical-replication-slot(), or by using the 'failover' option of CREATE SUBSCRIPTION during slot creation, and then calling pg_sync_replication_slots() on standby. For the synchronization to work, it is mandatory to have a physical replication slot between the primary and the standby aka 'primary_slot_name' should be configured on the standby, and 'hot_standby_feedback' must be enabled on the standby. It is also necessary to specify a valid 'dbname' in the 'primary_conninfo'. If a logical slot is invalidated on the primary, then that slot on the standby is also invalidated. If a logical slot on the primary is valid but is invalidated on the standby, then that slot is dropped but will be recreated on the standby in the next pg_sync_replication_slots() call provided the slot still exists on the primary server. It is okay to recreate such slots as long as these are not consumable on standby (which is the case currently). This situation may occur due to the following reasons: - The 'max_slot_wal_keep_size' on the standby is insufficient to retain WAL records from the restart_lsn of the slot. - 'primary_slot_name' is temporarily reset to null and the physical slot is removed. The slot synchronization status on the standby can be monitored using the 'synced' column of pg_replication_slots view. A functionality to automatically synchronize slots by a background worker and allow logical walsenders to wait for the physical will be done in subsequent commits. Author: Hou Zhijie, Shveta Malik, Ajin Cherian based on an earlier version by Peter Eisentraut Reviewed-by: Masahiko Sawada, Bertrand Drouvot, Peter Smith, Dilip Kumar, Nisha Moond, Kuroda Hayato, Amit Kapila Discussion: https://postgr.es/m/514f6f2f-6833-4539-39f1-96cd1e011f23@enterprisedb.com
* Update copyright for 2024Bruce Momjian2024-01-03
| | | | | | | | Reported-by: Michael Paquier Discussion: https://postgr.es/m/ZZKTDPxBBMt3C0J9@paquier.xyz Backpatch-through: 12
* Migrate logical slots to the new node during an upgrade.Amit Kapila2023-10-26
| | | | | | | | | | | | | | | | | | | | | | | | While reading information from the old cluster, a list of logical slots is fetched. At the later part of upgrading, pg_upgrade revisits the list and restores slots by executing pg_create_logical_replication_slot() on the new cluster. Migration of logical replication slots is only supported when the old cluster is version 17.0 or later. If the old node has invalid slots or slots with unconsumed WAL records, the pg_upgrade fails. These checks are needed to prevent data loss. The significant advantage of this commit is that it makes it easy to continue logical replication even after upgrading the publisher node. Previously, pg_upgrade allowed copying publications to a new node. With this patch, adjusting the connection string to the new publisher will cause the apply worker on the subscriber to connect to the new publisher automatically. This enables seamless continuation of logical replication, even after an upgrade. Author: Hayato Kuroda, Hou Zhijie Reviewed-by: Peter Smith, Bharath Rupireddy, Dilip Kumar, Vignesh C, Shlok Kyal Discussion: http://postgr.es/m/TYAPR01MB58664C81887B3AF2EB6B16E3F5939@TYAPR01MB5866.jpnprd01.prod.outlook.com Discussion: http://postgr.es/m/CAA4eK1+t7xYcfa0rEQw839=b2MzsfvYDPz3xbD+ZqOdP3zpKYg@mail.gmail.com
* Pre-beta mechanical code beautification.Tom Lane2023-05-19
| | | | | | | | | | | | | | | Run pgindent, pgperltidy, and reformat-dat-files. This set of diffs is a bit larger than typical. We've updated to pg_bsd_indent 2.1.2, which properly indents variable declarations that have multi-line initialization expressions (the continuation lines are now indented one tab stop). We've also updated to perltidy version 20230309 and changed some of its settings, which reduces its desire to add whitespace to lines to make assignments etc. line up. Going forward, that should make for fewer random-seeming changes to existing code. Discussion: https://postgr.es/m/20230428092545.qfb3y5wcu4cm75ur@alvherre.pgsql
* Improve error messages introduced in be87200efd9 and 0fdab27ad68Andres Freund2023-04-12
| | | | | | Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://postgr.es/m/20230411.120301.93333867350615278.horikyota.ntt@gmail.com Discussion: https://postgr.es/m/20230412174244.6njadz4uoiez3l74@awork3.anarazel.de
* Allow logical decoding on standbysAndres Freund2023-04-08
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Unsurprisingly, this requires wal_level = logical to be set on the primary and standby. The infrastructure added in 26669757b6a ensures that slots are invalidated if the primary's wal_level is lowered. Creating a slot on a standby waits for a xl_running_xact record to be processed. If the primary is idle (and thus not emitting xl_running_xact records), that can take a while. To make that faster, this commit also introduces the pg_log_standby_snapshot() function. By executing it on the primary, completion of slot creation on the standby can be accelerated. Note that logical decoding on a standby does not itself enforce that required catalog rows are not removed. The user has to use physical replication slots + hot_standby_feedback or other measures to prevent that. If catalog rows required for a slot are removed, the slot is invalidated. See 6af1793954e for an overall design of logical decoding on a standby. Bumps catversion, for the addition of the pg_log_standby_snapshot() function. Author: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com> Author: Andres Freund <andres@anarazel.de> (in an older version) Author: Amit Khandekar <amitdkhan.pg@gmail.com> (in an older version) Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: FabrÌzio de Royes Mello <fabriziomello@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-By: Robert Haas <robertmhaas@gmail.com>
* Support invalidating replication slots due to horizon and wal_levelAndres Freund2023-04-07
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | Needed for logical decoding on a standby. Slots need to be invalidated because of the horizon if rows required for logical decoding are removed. If the primary's wal_level is lowered from 'logical', logical slots on the standby need to be invalidated. The new invalidation methods will be used in a subsequent commit. Logical slots that have been invalidated can be identified via the new pg_replication_slots.conflicting column. See 6af1793954e for an overall design of logical decoding on a standby. Bumps catversion for the addition of the new pg_replication_slots column. Author: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com> Author: Andres Freund <andres@anarazel.de> Author: Amit Khandekar <amitdkhan.pg@gmail.com> (in an older version) Reviewed-by: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Robert Haas <robertmhaas@gmail.com> Reviewed-by: Fabrízio de Royes Mello <fabriziomello@gmail.com> Reviewed-by: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Amit Kapila <amit.kapila16@gmail.com> Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Reviewed-by: Alvaro Herrera <alvherre@alvh.no-ip.org> Discussion: https://postgr.es/m/20230407075009.igg7be27ha2htkbt@awork3.anarazel.de
* Prevent use of invalidated logical slot in CreateDecodingContext()Andres Freund2023-04-07
| | | | | | | | | | | | | | Previously we had checks for this in multiple places. Support for logical decoding on standbys will add other forms of invalidation, making it worth while to centralize the checks. This slightly changes the error message for both the walsender and SQL interface. Particularly the SQL interface error was inaccurate, as the "This slot has never previously reserved WAL" portion was unreachable. Reviewed-by: "Drouvot, Bertrand" <bertranddrouvot.pg@gmail.com> Reviewed-by: Melanie Plageman <melanieplageman@gmail.com> Discussion: https://postgr.es/m/20230407075009.igg7be27ha2htkbt@awork3.anarazel.de
* Fix the logical replication timeout during large DDLs.Amit Kapila2023-02-08
| | | | | | | | | | | | | | | | | | | The DDLs like Refresh Materialized views that generate lots of temporary data due to rewrite rules may not be processed by output plugins (for example pgoutput). So, we won't send keep-alive messages for a long time while processing such commands and that can lead the subscriber side to timeout. We have previously fixed a similar case for large transactions in commit f95d53eded where the output plugin filters all or most of the changes but missed to handle the DDLs. We decided not to backpatch this as this adds a new callback in the existing exposed structure and moreover, users can increase the wal_sender_timeout and wal_receiver_timeout to avoid this problem. Author: Wang wei, Hou Zhijie Reviewed-by: Peter Smith, Ashutosh Bapat, Shi yu, Amit Kapila Discussion: https://postgr.es/m/OS3PR01MB6275478E5D29E4A563302D3D9E2B9@OS3PR01MB6275.jpnprd01.prod.outlook.com Discussion: https://postgr.es/m/CAA5-nLARN7-3SLU_QUxfy510pmrYK6JJb=bk3hcgemAM_pAv+w@mail.gmail.com
* Acquire spinlock when updating 2PC slot data during logical decoding creationMichael Paquier2023-01-12
| | | | | | | | | | | | | | The creation of a logical decoding context in CreateDecodingContext() updates some data of its slot for two-phase transactions if enabled by the caller, but the code forgot to acquire a spinlock when updating these fields like any other code paths. This could lead to the read of inconsistent data. Oversight in a8fd13c. Author: Sawada Masahiko Discussion: https://postgr.es/m/CAD21AoAD8_fp47191LKuecjDd3DYhoQ4TaucFco1_TEr_jQ-Zw@mail.gmail.com Backpatch-through: 15
* Update copyright for 2023Bruce Momjian2023-01-02
| | | | Backpatch-through: 11
* Fix the logical replication timeout during large transactions.Amit Kapila2022-05-11
| | | | | | | | | | | | | | | | | | | The problem is that we don't send keep-alive messages for a long time while processing large transactions during logical replication where we don't send any data of such transactions. This can happen when the table modified in the transaction is not published or because all the changes got filtered. We do try to send the keep_alive if necessary at the end of the transaction (via WalSndWriteData()) but by that time the subscriber-side can timeout and exit. To fix this we try to send the keepalive message if required after processing certain threshold of changes. Reported-by: Fabrice Chapuis Author: Wang wei and Amit Kapila Reviewed By: Masahiko Sawada, Euler Taveira, Hou Zhijie, Hayato Kuroda Backpatch-through: 10 Discussion: https://postgr.es/m/CAA5-nLARN7-3SLU_QUxfy510pmrYK6JJb=bk3hcgemAM_pAv+w@mail.gmail.com
* Revert "Logical decoding of sequences"Tomas Vondra2022-04-07
| | | | | | | | | | | | | | | | | | | | | This reverts a sequence of commits, implementing features related to logical decoding and replication of sequences: - 0da92dc530c9251735fc70b20cd004d9630a1266 - 80901b32913ffa59bf157a4d88284b2b3a7511d9 - b779d7d8fdae088d70da5ed9fcd8205035676df3 - d5ed9da41d96988d905b49bebb273a9b2d6e2915 - a180c2b34de0989269fdb819bff241a249bf5380 - 75b1521dae1ff1fde17fda2e30e591f2e5d64b6a - 2d2232933b02d9396113662e44dca5f120d6830e - 002c9dd97a0c874fd1693a570383e2dd38cd40d5 - 05843b1aa49df2ecc9b97c693b755bd1b6f856a9 The implementation has issues, mostly due to combining transactional and non-transactional behavior of sequences. It's not clear how this could be fixed, but it'll require reworking significant part of the patch. Discussion: https://postgr.es/m/95345a19-d508-63d1-860a-f5c2f41e8d40@enterprisedb.com
* pgstat: store statistics in shared memory.Andres Freund2022-04-06
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Previously the statistics collector received statistics updates via UDP and shared statistics data by writing them out to temporary files regularly. These files can reach tens of megabytes and are written out up to twice a second. This has repeatedly prevented us from adding additional useful statistics. Now statistics are stored in shared memory. Statistics for variable-numbered objects are stored in a dshash hashtable (backed by dynamic shared memory). Fixed-numbered stats are stored in plain shared memory. The header for pgstat.c contains an overview of the architecture. The stats collector is not needed anymore, remove it. By utilizing the transactional statistics drop infrastructure introduced in a prior commit statistics entries cannot "leak" anymore. Previously leaked statistics were dropped by pgstat_vacuum_stat(), called from [auto-]vacuum. On systems with many small relations pgstat_vacuum_stat() could be quite expensive. Now that replicas drop statistics entries for dropped objects, it is not necessary anymore to reset stats when starting from a cleanly shut down replica. Subsequent commits will perform some further code cleanup, adapt docs and add tests. Bumps PGSTAT_FILE_FORMAT_ID. Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Author: Andres Freund <andres@anarazel.de> Author: Melanie Plageman <melanieplageman@gmail.com> Reviewed-By: Andres Freund <andres@anarazel.de> Reviewed-By: Thomas Munro <thomas.munro@gmail.com> Reviewed-By: Justin Pryzby <pryzby@telsasoft.com> Reviewed-By: "David G. Johnston" <david.g.johnston@gmail.com> Reviewed-By: Tomas Vondra <tomas.vondra@2ndquadrant.com> (in a much earlier version) Reviewed-By: Arthur Zakirov <a.zakirov@postgrespro.ru> (in a much earlier version) Reviewed-By: Antonin Houska <ah@cybertec.at> (in a much earlier version) Discussion: https://postgr.es/m/20220303021600.hs34ghqcw6zcokdh@alap3.anarazel.de Discussion: https://postgr.es/m/20220308205351.2xcn6k4x5yivcxyd@alap3.anarazel.de Discussion: https://postgr.es/m/20210319235115.y3wz7hpnnrshdyv6@alap3.anarazel.de
* pgstat: revise replication slot API in preparation for shared memory stats.Andres Freund2022-04-06
| | | | | | | | | | | | | | | | | | Previously the pgstat <-> replication slots API was done with on the basis of names. However, the upcoming move to storing stats in shared memory makes it more convenient to use a integer as key. Change the replication slot functions to take the slot rather than the slot name, and expose ReplicationSlotIndex() to compute the index of an replication slot. Special handling will be required for restarts, as the index is not stable across restarts. For now pgstat internally still uses names. Rename pgstat_report_replslot_{create,drop}() to pgstat_{create,drop}_replslot() to match the functions for other kinds of stats. Reviewed-By: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Discussion: https://postgr.es/m/20220404041516.cctrvpadhuriawlq@alap3.anarazel.de
* Skip empty transactions for logical replication.Amit Kapila2022-03-30
| | | | | | | | | | | | | | | | | | | | | The current logical replication behavior is to send every transaction to subscriber even if the transaction is empty. This can happen because transaction doesn't contain changes from the selected publications or all the changes got filtered. It is a waste of CPU cycles and network bandwidth to build/transmit these empty transactions. This patch addresses the above problem by postponing the BEGIN message until the first change is sent. While processing a COMMIT message, if there was no other change for that transaction, do not send the COMMIT message. This allows us to skip sending BEGIN/COMMIT messages for empty transactions. When skipping empty transactions in synchronous replication mode, we send a keepalive message to avoid delaying such transactions. Author: Ajin Cherian, Hou Zhijie, Euler Taveira Reviewed-by: Peter Smith, Takamichi Osumi, Shi Yu, Masahiko Sawada, Greg Nancarrow, Vignesh C, Amit Kapila Discussion: https://postgr.es/m/CAMkU=1yohp9-dv48FLoSPrMqYEyyS5ZWkaZGD41RJr10xiNo_Q@mail.gmail.com
* Logical decoding of sequencesTomas Vondra2022-02-10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This extends the logical decoding to also decode sequence increments. We differentiate between sequences created in the current (in-progress) transaction, and sequences created earlier. This mixed behavior is necessary because while sequences are not transactional (increments are not subject to ROLLBACK), relfilenode changes are. So we do this: * Changes for sequences created in the same top-level transaction are treated as transactional, i.e. just like any other change from that transaction, and discarded in case of a rollback. * Changes for sequences created earlier are applied immediately, as if performed outside any transaction. This applies also after ALTER SEQUENCE, which may create a new relfilenode. Moreover, if we ever get support for DDL replication, the sequence won't exist until the transaction gets applied. Sequences created in the current transaction are tracked in a simple hash table, identified by a relfilenode. That means a sequence may already exist, but if a transaction does ALTER SEQUENCE then the increments for the new relfilenode will be treated as transactional. For each relfilenode we track the XID of (sub)transaction that created it, which is needed for cleanup at transaction end. We don't need to check the XID to decide if an increment is transactional - if we find a match in the hash table, it has to be the same transaction. This requires two minor changes to WAL-logging. Firstly, we need to ensure the sequence record has a valid XID - until now the the increment might have XID 0 if it was the first change in a subxact. But the sequence might have been created in the same top-level transaction. So we ensure the XID is assigned when WAL-logging increments. The other change is addition of "created" flag, marking increments for newly created relfilenodes. This makes it easier to maintain the hash table of sequences that need transactional handling. Note: This is needed because of subxacts. A XID 0 might still have the sequence created in a different subxact of the same top-level xact. This does not include any changes to test_decoding and/or the built-in replication - those will be committed in separate patches. A patch adding decoding of sequences was originally submitted by Cary Huang. This commit reworks various important aspects (e.g. the WAL logging and transactional/non-transactional handling). However, the original patch and reviews were very useful. Author: Tomas Vondra, Cary Huang Reviewed-by: Peter Eisentraut, Hannu Krosing, Andres Freund Discussion: https://postgr.es/m/d045f3c2-6cfb-06d3-5540-e63c320df8bc@enterprisedb.com Discussion: https://postgr.es/m/1710ed7e13b.cd7177461430746.3372264562543607781@highgo.ca
* Update copyright for 2022Bruce Momjian2022-01-07
| | | | Backpatch-through: 10
* Be more specific about OOM in XLogReaderAllocateAlvaro Herrera2021-11-22
| | | | | | | | | | | A couple of spots can benefit from an added errdetail(), which matches what we were already doing in other places; and those that cannot withstand errdetail() can get a more descriptive primary message. Author: Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com> Reviewed-by: Daniel Gustafsson <daniel@yesql.se> Reviewed-by: Julien Rouhaud <rjuju123@gmail.com> Discussion: https://postgr.es/m/CALj2ACV+cX1eM03GfcA=ZMLXh5fSn1X1auJLz3yuS1duPSb9QA@mail.gmail.com
* Improve error messages for some callers of XLogReadRecord()Michael Paquier2021-11-10
| | | | | | | | | | | | A couple of code paths related to logical decoding (WAL sender, slot advancing, etc.) use XLogReadRecord(), feeding on error messages generated by walreader.c on a failure. All those messages have no context, making it harder to spot from where an error could come even if these should not happen. All the other callers of XLogReadRecord() do that already. Reviewed-by: Kyotaro Horiguchi Discussion: https://postgr.es/m/YYnTH6OyOwQcAdkw@paquier.xyz
* Log new catalog xmin candidate in LogicalIncreaseXminForSlot().Amit Kapila2021-09-07
| | | | | | | | | | | | Similar to LogicalIncreaseRestartDecodingForSlot() add a debug message to LogicalIncreaseXminForSlot() reporting a new catalog_xmin candidate. This just adds additional diagnostic information during logical decoding that can aid debugging. Author: Ashutosh Bapat Reviewed-by: Masahiko Sawada, Amit Kapila Discussion: https://postgr.es/m/CAExHW5usQWbiUz0hHOCu5twS1O9DvpcPojf6sor=8q--VUuMbA@mail.gmail.com
* Improve documentation for START_REPLICATION ... LOGICAL.Jeff Davis2021-07-30
| | | | | | | | | | The starting point may not be exactly what the client requested; it may be at the slot's confirmed_flush_lsn. Also, upgrade the message from DEBUG1 to LOG when this happens. Reviewed-by: Amit Kapila Discussion: https://postgr.es/m/c5c861d576f2511732f8002c76245da587110b1c.camel%40j-davis.com
* Clarify some comments making use of leetspeak term "up2date"Michael Paquier2021-07-28
| | | | | | | | Most of these are new, as of a8fd13c, and "up-to-date" is much easier to parse for the average reader. Author: Peter Smith Discussion: https://postgr.es/m/CAHut+PtHbHvgOjs_R9LyDF21j-Wn8SxoTtWMQNP2ifXN6t2cSg@mail.gmail.com
* Add support for prepared transactions to built-in logical replication.Amit Kapila2021-07-14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | To add support for streaming transactions at prepare time into the built-in logical replication, we need to do the following things: * Modify the output plugin (pgoutput) to implement the new two-phase API callbacks, by leveraging the extended replication protocol. * Modify the replication apply worker, to properly handle two-phase transactions by replaying them on prepare. * Add a new SUBSCRIPTION option "two_phase" to allow users to enable two-phase transactions. We enable the two_phase once the initial data sync is over. We however must explicitly disable replication of two-phase transactions during replication slot creation, even if the plugin supports it. We don't need to replicate the changes accumulated during this phase, and moreover, we don't have a replication connection open so we don't know where to send the data anyway. The streaming option is not allowed with this new two_phase option. This can be done as a separate patch. We don't allow to toggle two_phase option of a subscription because it can lead to an inconsistent replica. For the same reason, we don't allow to refresh the publication once the two_phase is enabled for a subscription unless copy_data option is false. Author: Peter Smith, Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich Reviewed-by: Amit Kapila, Sawada Masahiko, Vignesh C, Dilip Kumar, Takamichi Osumi, Greg Nancarrow Tested-By: Haiying Tang Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru Discussion: https://postgr.es/m/CAA4eK1+opiV4aFTmWWUF9h_32=HfPOW9vZASHarT0UA5oBrtGw@mail.gmail.com
* Error message refactoringPeter Eisentraut2021-06-27
| | | | | | Take some untranslatable things out of the message and replace by format placeholders, to reduce translatable strings and reduce translation mistakes.
* Revert recovery prefetching feature.Thomas Munro2021-05-10
| | | | | | | | | | | | | | | | | | This set of commits has some bugs with known fixes, but at this late stage in the release cycle it seems best to revert and resubmit next time, along with some new automated test coverage for this whole area. Commits reverted: dc88460c: Doc: Review for "Optionally prefetch referenced data in recovery." 1d257577: Optionally prefetch referenced data in recovery. f003d9f8: Add circular WAL decoding buffer. 323cbe7c: Remove read_page callback from XLogReader. Remove the new GUC group WAL_RECOVERY recently added by a55a9847, as the corresponding section of config.sgml is now reverted. Discussion: https://postgr.es/m/CAOuzzgrn7iKnFRsB4MHp3UisEQAGgZMbk_ViTN4HV4-Ksq8zCg%40mail.gmail.com
* Use HTAB for replication slot statistics.Amit Kapila2021-04-27
| | | | | | | | | | | | | | | | | | | | | | | Previously, we used to use the array of size max_replication_slots to store stats for replication slots. But that had two problems in the cases where a message for dropping a slot gets lost: 1) the stats for the new slot are not recorded if the array is full and 2) writing beyond the end of the array if the user reduces the max_replication_slots. This commit uses HTAB for replication slot statistics, resolving both problems. Now, pgstat_vacuum_stat() search for all the dead replication slots in stats hashtable and tell the collector to remove them. To avoid showing the stats for the already-dropped slots, pg_stat_replication_slots view searches slot stats by the slot name taken from pg_replication_slots. Also, we send a message for creating a slot at slot creation, initializing the stats. This reduces the possibility that the stats are accumulated into the old slot stats when a message for dropping a slot gets lost. Reported-by: Andres Freund Author: Sawada Masahiko, test case by Vignesh C Reviewed-by: Amit Kapila, Vignesh C, Dilip Kumar Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
* Add information of total data processed to replication slot stats.Amit Kapila2021-04-16
| | | | | | | | | | | | This adds the statistics about total transactions count and total transaction data logically sent to the decoding output plugin from ReorderBuffer. Users can query the pg_stat_replication_slots view to check these stats. Suggested-by: Andres Freund Author: Vignesh C and Amit Kapila Reviewed-by: Sawada Masahiko, Amit Kapila Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
* Use NameData datatype for slotname in stats.Amit Kapila2021-04-14
| | | | | | | | | | | This will make it consistent with the other usage of slotname in the code. In the passing, change pgstat_report_replslot signature to use a structure rather than multiple parameters. Reported-by: Andres Freund Author: Vignesh C Reviewed-by: Sawada Masahiko, Amit Kapila Discussion: https://postgr.es/m/20210319185247.ldebgpdaxsowiflw@alap3.anarazel.de
* Remove read_page callback from XLogReader.Thomas Munro2021-04-08
| | | | | | | | | | | | | | | | | | | | | Previously, the XLogReader module would fetch new input data using a callback function. Redesign the interface so that it tells the caller to insert more data with a special return value instead. This API suits later patches for prefetching, encryption and maybe other future projects that would otherwise require continually extending the callback interface. As incidental cleanup work, move global variables readOff, readLen and readSegNo inside XlogReaderState. Author: Kyotaro HORIGUCHI <horiguchi.kyotaro@lab.ntt.co.jp> Author: Heikki Linnakangas <hlinnaka@iki.fi> (parts of earlier version) Reviewed-by: Antonin Houska <ah@cybertec.at> Reviewed-by: Alvaro Herrera <alvherre@2ndquadrant.com> Reviewed-by: Takashi Menjo <takashi.menjo@gmail.com> Reviewed-by: Andres Freund <andres@anarazel.de> Reviewed-by: Thomas Munro <thomas.munro@gmail.com> Discussion: https://postgr.es/m/20190418.210257.43726183.horiguchi.kyotaro%40lab.ntt.co.jp
* Add a xid argument to the filter_prepare callback for output plugins.Amit Kapila2021-03-30
| | | | | | | | | | | | Along with gid, this provides a different way to identify the transaction. The users that use xid in some way to prepare the transactions can use it to filter prepare transactions. The later commands COMMIT PREPARED or ROLLBACK PREPARED carries both identifiers, providing an output plugin the choice of what to use. Author: Markus Wanner Reviewed-by: Vignesh C, Amit Kapila Discussion: https://postgr.es/m/ee280000-7355-c4dc-e47b-2436e7be959c@enterprisedb.com
* Add option to enable two_phase commits via pg_create_logical_replication_slot.Amit Kapila2021-03-03
| | | | | | | | | | | | | | | | | | | | Commit 0aa8a01d04 extends the output plugin API to allow decoding of prepared xacts and allowed the user to enable/disable the two-phase option via pg_logical_slot_get_changes(). This can lead to a problem such that the first time when it gets changes via pg_logical_slot_get_changes() without two_phase option enabled it will not get the prepared even though prepare is after consistent snapshot. Now next time during getting changes, if the two_phase option is enabled it can skip prepare because by that time start decoding point has been moved. So the user will only get commit prepared. Allow to enable/disable this option at the create slot time and default will be false. It will break the existing slots which is fine in a major release. Author: Ajin Cherian Reviewed-by: Amit Kapila and Vignesh C Discussion: https://postgr.es/m/d0f60d60-133d-bf8d-bd70-47784d8fabf3@enterprisedb.com
* Avoid repeated decoding of prepared transactions after a restart.Amit Kapila2021-03-01
| | | | | | | | | | | | | | | | | | | | In commit a271a1b50e, we allowed decoding at prepare time and the prepare was decoded again if there is a restart after decoding it. It was done that way because we can't distinguish between the cases where we have not decoded the prepare because it was prior to consistent snapshot or we have decoded it earlier but restarted. To distinguish between these two cases, we have introduced an initial_consistent_point at the slot level which is an LSN at which we found a consistent point at the time of slot creation. This is also the point where we have exported a snapshot for the initial copy. So, prepare transaction prior to this point are sent along with commit prepared. This commit bumps SNAPBUILD_VERSION because of change in SnapBuild. It will break existing slots which is fine in a major release. Author: Ajin Cherian, based on idea by Andres Freund Reviewed-by: Amit Kapila and Vignesh C Discussion: https://postgr.es/m/d0f60d60-133d-bf8d-bd70-47784d8fabf3@enterprisedb.com
* Simplify printing of LSNsPeter Eisentraut2021-02-23
| | | | | | | | | | Add a macro LSN_FORMAT_ARGS for use in printf-style printing of LSNs. Convert all applicable code to use it. Reviewed-by: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com> Reviewed-by: Kyotaro Horiguchi <horikyota.ntt@gmail.com> Reviewed-by: Michael Paquier <michael@paquier.xyz> Discussion: https://www.postgresql.org/message-id/flat/CAExHW5ub5NaTELZ3hJUCE6amuvqAtsSxc7O+uK7y4t9Rrk23cw@mail.gmail.com
* Fix typos in decode.c and logical.c.Amit Kapila2021-01-06
| | | | | Per report by Ajin Cherian in email: https://postgr.es/m/CAFPTHDYnRKDvzgDxoMn_CKqXA-D0MtrbyJvfvjBsO4G=UHDXkg@mail.gmail.com
* Allow decoding at prepare time in ReorderBuffer.Amit Kapila2021-01-04
| | | | | | | | | | | | | | | | | | | | | | | This patch allows PREPARE-time decoding of two-phase transactions (if the output plugin supports this capability), in which case the transactions are replayed at PREPARE and then committed later when COMMIT PREPARED arrives. Now that we decode the changes before the commit, the concurrent aborts may cause failures when the output plugin consults catalogs (both system and user-defined). We detect such failures with a special sqlerrcode ERRCODE_TRANSACTION_ROLLBACK introduced by commit 7259736a6e and stop decoding the remaining changes. Then we rollback the changes when rollback prepared is encountered. Author: Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich Reviewed-by: Amit Kapila, Peter Smith, Sawada Masahiko, Arseny Sher, and Dilip Kumar Tested-by: Takamichi Osumi Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru https://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com
* Update copyright for 2021Bruce Momjian2021-01-02
| | | | Backpatch-through: 9.5
* Extend the output plugin API to allow decoding of prepared xacts.Amit Kapila2020-12-30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds six methods to the output plugin API, adding support for streaming changes of two-phase transactions at prepare time. * begin_prepare * filter_prepare * prepare * commit_prepared * rollback_prepared * stream_prepare Most of this is a simple extension of the existing methods, with the semantic difference that the transaction is not yet committed and maybe aborted later. Until now two-phase transactions were translated into regular transactions on the subscriber, and the GID was not forwarded to it. None of the two-phase commands were communicated to the subscriber. This patch provides the infrastructure for logical decoding plugins to be informed of two-phase commands Like PREPARE TRANSACTION, COMMIT PREPARED and ROLLBACK PREPARED commands with the corresponding GID. This also extends the 'test_decoding' plugin, implementing these new methods. This commit simply adds these new APIs and the upcoming patch to "allow the decoding at prepare time in ReorderBuffer" will use these APIs. Author: Ajin Cherian and Amit Kapila based on previous work by Nikhil Sontakke and Stas Kelvich Reviewed-by: Amit Kapila, Peter Smith, Sawada Masahiko, and Dilip Kumar Discussion: https://postgr.es/m/02DA5F5E-CECE-4D9C-8B4B-418077E2C010@postgrespro.ru https://postgr.es/m/CAMGcDxeqEpWj3fTXwqhSwBdXd2RS9jzwWscO-XbeCfso6ts3+Q@mail.gmail.com
* Restore lock level to update statusFlagsAlvaro Herrera2020-11-26
| | | | | | | | | | | | | | Reverts 27838981be9d (some comments are kept). Per discussion, it does not seem safe to relax the lock level used for this; in order for it to be safe, there would have to be memory barriers between the point we set the flag and the point we set the trasaction Xid, which perhaps would not be so bad; but there would also have to be barriers at the readers' side, which from a performance perspective might be bad. Now maybe this analysis is wrong and it *is* safe for some reason, but proof of that is not trivial. Discussion: https://postgr.es/m/20201118190928.vnztes7c2sldu43a@alap3.anarazel.de