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postgresql/src/backend/replication/libpqwalreceiver/libpqwalreceiver.c

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Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
/*-------------------------------------------------------------------------
*
* libpqwalreceiver.c
*
* This file contains the libpq-specific parts of walreceiver. It's
* loaded as a dynamic module to avoid linking the main server binary with
* libpq.
*
Update copyright for 2015 Backpatch certain files through 9.0
2015-01-06 17:43:47 +01:00
* Portions Copyright (c) 2010-2015, PostgreSQL Global Development Group
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*
*
* IDENTIFICATION
Remove cvs keywords from all files.
2010-09-20 22:08:53 +02:00
* src/backend/replication/libpqwalreceiver/libpqwalreceiver.c
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include <unistd.h>
#include <sys/time.h>
#include "libpq-fe.h"
#include "access/xlog.h"
#include "miscadmin.h"
#include "replication/walreceiver.h"
#include "utils/builtins.h"
#ifdef HAVE_POLL_H
#include <poll.h>
#endif
#ifdef HAVE_SYS_POLL_H
#include <sys/poll.h>
#endif
#ifdef HAVE_SYS_SELECT_H
#include <sys/select.h>
#endif
PG_MODULE_MAGIC;
void _PG_init(void);
/* Current connection to the primary, if any */
static PGconn *streamConn = NULL;
/* Buffer for currently read records */
static char *recvBuf = NULL;
/* Prototypes for interface functions */
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
static void libpqrcv_connect(char *conninfo);
static void libpqrcv_identify_system(TimeLineID *primary_tli);
static void libpqrcv_readtimelinehistoryfile(TimeLineID tli, char **filename, char **content, int *len);
Introduce replication slots. 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
2014-02-01 04:45:17 +01:00
static bool libpqrcv_startstreaming(TimeLineID tli, XLogRecPtr startpoint,
pgindent run for 9.4 This includes removing tabs after periods in C comments, which was applied to back branches, so this change should not effect backpatching.
2014-05-06 18:12:18 +02:00
char *slotname);
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
static void libpqrcv_endstreaming(TimeLineID *next_tli);
pgindent run for release 9.3 This is the first run of the Perl-based pgindent script. Also update pgindent instructions.
2013-05-29 22:58:43 +02:00
static int libpqrcv_receive(int timeout, char **buffer);
Allow bidirectional copy messages in streaming replication mode. Fujii Masao. Review by Alvaro Herrera, Tom Lane, and myself.
2010-12-11 15:27:37 +01:00
static void libpqrcv_send(const char *buffer, int nbytes);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
static void libpqrcv_disconnect(void);
/* Prototypes for private functions */
static bool libpq_select(int timeout_ms);
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
static PGresult *libpqrcv_PQexec(const char *query);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
/*
* Module load callback
*/
void
_PG_init(void)
{
/* Tell walreceiver how to reach us */
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
if (walrcv_connect != NULL || walrcv_identify_system != NULL ||
walrcv_readtimelinehistoryfile != NULL ||
walrcv_startstreaming != NULL || walrcv_endstreaming != NULL ||
walrcv_receive != NULL || walrcv_send != NULL ||
walrcv_disconnect != NULL)
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
elog(ERROR, "libpqwalreceiver already loaded");
walrcv_connect = libpqrcv_connect;
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
walrcv_identify_system = libpqrcv_identify_system;
walrcv_readtimelinehistoryfile = libpqrcv_readtimelinehistoryfile;
walrcv_startstreaming = libpqrcv_startstreaming;
walrcv_endstreaming = libpqrcv_endstreaming;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
walrcv_receive = libpqrcv_receive;
Allow bidirectional copy messages in streaming replication mode. Fujii Masao. Review by Alvaro Herrera, Tom Lane, and myself.
2010-12-11 15:27:37 +01:00
walrcv_send = libpqrcv_send;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
walrcv_disconnect = libpqrcv_disconnect;
}
/*
* Establish the connection to the primary server for XLOG streaming
*/
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
static void
libpqrcv_connect(char *conninfo)
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
{
Allow using connection URI in primary_conninfo. The old method of appending options to the connection string didn't work if the primary_conninfo was a postgres:// style URI, instead of a traditional connection string. Use PQconnectdbParams instead. Alex Shulgin
2014-11-25 17:24:07 +01:00
const char *keys[5];
const char *vals[5];
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
Use "replication" as the database name when constructing a connection string for a streaming replication connection. It's ignored by the server, but allows libpq to pick up the password from .pgpass where "replication" is specified as the database name. Patch by Fujii Masao per Tom's suggestion, with some wording changes by me.
2010-06-11 12:13:09 +02:00
/*
Allow using connection URI in primary_conninfo. The old method of appending options to the connection string didn't work if the primary_conninfo was a postgres:// style URI, instead of a traditional connection string. Use PQconnectdbParams instead. Alex Shulgin
2014-11-25 17:24:07 +01:00
* We use the expand_dbname parameter to process the connection string
* (or URI), and pass some extra options. The deliberately undocumented
* parameter "replication=true" makes it a replication connection.
* The database name is ignored by the server in replication mode, but
* specify "replication" for .pgpass lookup.
Use "replication" as the database name when constructing a connection string for a streaming replication connection. It's ignored by the server, but allows libpq to pick up the password from .pgpass where "replication" is specified as the database name. Patch by Fujii Masao per Tom's suggestion, with some wording changes by me.
2010-06-11 12:13:09 +02:00
*/
Allow using connection URI in primary_conninfo. The old method of appending options to the connection string didn't work if the primary_conninfo was a postgres:// style URI, instead of a traditional connection string. Use PQconnectdbParams instead. Alex Shulgin
2014-11-25 17:24:07 +01:00
keys[0] = "dbname";
vals[0] = conninfo;
keys[1] = "replication";
vals[1] = "true";
keys[2] = "dbname";
vals[2] = "replication";
keys[3] = "fallback_application_name";
vals[3] = "walreceiver";
keys[4] = NULL;
vals[4] = NULL;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
Allow using connection URI in primary_conninfo. The old method of appending options to the connection string didn't work if the primary_conninfo was a postgres:// style URI, instead of a traditional connection string. Use PQconnectdbParams instead. Alex Shulgin
2014-11-25 17:24:07 +01:00
streamConn = PQconnectdbParams(keys, vals, /* expand_dbname = */ true);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
if (PQstatus(streamConn) != CONNECTION_OK)
ereport(ERROR,
Fix pg_hba.conf matching so that replication connections only match records with database = replication. The previous coding would allow them to match ordinary records too, but that seems like a recipe for security breaches. Improve the messages associated with no-such-pg_hba.conf entry to report replication connections as such, since that's now a critical aspect of whether the connection matches. Make some cursory improvements in the related documentation, too.
2010-04-21 05:32:53 +02:00
(errmsg("could not connect to the primary server: %s",
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQerrorMessage(streamConn))));
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
}
/*
* Check that primary's system identifier matches ours, and fetch the current
* timeline ID of the primary.
*/
static void
libpqrcv_identify_system(TimeLineID *primary_tli)
{
PGresult *res;
char *primary_sysid;
char standby_sysid[32];
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
/*
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
* Get the system identifier and timeline ID as a DataRow message from the
* primary server.
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*/
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
res = libpqrcv_PQexec("IDENTIFY_SYSTEM");
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
if (PQresultStatus(res) != PGRES_TUPLES_OK)
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
{
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQclear(res);
ereport(ERROR,
Message tuning
2010-03-21 01:17:59 +01:00
(errmsg("could not receive database system identifier and timeline ID from "
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
"the primary server: %s",
PQerrorMessage(streamConn))));
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
}
Revert "Fix bug in checking of IDENTIFY_SYSTEM result." This reverts commit 083d29c65b7897f90c70e6dc0a4240a5fa75c8f2. The commit changed the code so that it causes an errors when IDENTIFY_SYSTEM returns three columns. But which prevents us from using the replication-related utilities against the server with older version. This is not what we want. For that compatibility, we allow the utilities to receive three columns as the result of IDENTIFY_SYSTEM eventhough it actually returns four columns in 9.4 or later. Pointed out by Andres Freund.
2014-08-19 11:30:38 +02:00
if (PQnfields(res) < 3 || PQntuples(res) != 1)
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
{
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
int ntuples = PQntuples(res);
int nfields = PQnfields(res);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQclear(res);
ereport(ERROR,
(errmsg("invalid response from primary server"),
Misc message style and doc fixes. Euler Taveira
2014-05-15 13:49:11 +02:00
errdetail("Could not identify system: got %d rows and %d fields, expected %d rows and %d or more fields.",
Revert "Fix bug in checking of IDENTIFY_SYSTEM result." This reverts commit 083d29c65b7897f90c70e6dc0a4240a5fa75c8f2. The commit changed the code so that it causes an errors when IDENTIFY_SYSTEM returns three columns. But which prevents us from using the replication-related utilities against the server with older version. This is not what we want. For that compatibility, we allow the utilities to receive three columns as the result of IDENTIFY_SYSTEM eventhough it actually returns four columns in 9.4 or later. Pointed out by Andres Freund.
2014-08-19 11:30:38 +02:00
ntuples, nfields, 3, 1)));
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
}
primary_sysid = PQgetvalue(res, 0, 0);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
*primary_tli = pg_atoi(PQgetvalue(res, 0, 1), 4, 0);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
/*
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
* Confirm that the system identifier of the primary is the same as ours.
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*/
snprintf(standby_sysid, sizeof(standby_sysid), UINT64_FORMAT,
GetSystemIdentifier());
if (strcmp(primary_sysid, standby_sysid) != 0)
{
Fix use of free in walsender error handling after a sysid mismatch. Found via valgrind. The bug exists since the introduction of the walsender, so backpatch to 9.0. Andres Freund
2014-05-06 14:14:51 +02:00
primary_sysid = pstrdup(primary_sysid);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQclear(res);
ereport(ERROR,
Message tuning
2010-03-21 01:17:59 +01:00
(errmsg("database system identifier differs between the primary and standby"),
errdetail("The primary's identifier is %s, the standby's identifier is %s.",
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
primary_sysid, standby_sysid)));
}
PQclear(res);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
}
/*
* Start streaming WAL data from given startpoint and timeline.
*
* Returns true if we switched successfully to copy-both mode. False
* means the server received the command and executed it successfully, but
* didn't switch to copy-mode. That means that there was no WAL on the
* requested timeline and starting point, because the server switched to
* another timeline at or before the requested starting point. On failure,
* throws an ERROR.
*/
static bool
Introduce replication slots. 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
2014-02-01 04:45:17 +01:00
libpqrcv_startstreaming(TimeLineID tli, XLogRecPtr startpoint, char *slotname)
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
{
Use a longer buffer in libpqrcv_startstreaming. Because of the new SLOT clause in the START_REPLICATION command, it's possible for the command to end up too long for the old maximum buffer length. Andres Freund
2014-03-03 13:24:52 +01:00
char cmd[256];
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
PGresult *res;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
/* Start streaming from the point requested by startup process */
Introduce replication slots. 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
2014-02-01 04:45:17 +01:00
if (slotname != NULL)
snprintf(cmd, sizeof(cmd),
"START_REPLICATION SLOT \"%s\" %X/%X TIMELINE %u", slotname,
(uint32) (startpoint >> 32), (uint32) startpoint, tli);
else
snprintf(cmd, sizeof(cmd),
"START_REPLICATION %X/%X TIMELINE %u",
(uint32) (startpoint >> 32), (uint32) startpoint, tli);
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
res = libpqrcv_PQexec(cmd);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
if (PQresultStatus(res) == PGRES_COMMAND_OK)
{
PQclear(res);
return false;
}
else if (PQresultStatus(res) != PGRES_COPY_BOTH)
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
{
PQclear(res);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
ereport(ERROR,
Message tuning
2010-03-21 01:17:59 +01:00
(errmsg("could not start WAL streaming: %s",
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQerrorMessage(streamConn))));
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
}
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQclear(res);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
return true;
}
/*
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
* Stop streaming WAL data. Returns the next timeline's ID in *next_tli, as
* reported by the server, or 0 if it did not report it.
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
*/
static void
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
libpqrcv_endstreaming(TimeLineID *next_tli)
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
{
PGresult *res;
if (PQputCopyEnd(streamConn, NULL) <= 0 || PQflush(streamConn))
ereport(ERROR,
pgindent run for release 9.3 This is the first run of the Perl-based pgindent script. Also update pgindent instructions.
2013-05-29 22:58:43 +02:00
(errmsg("could not send end-of-streaming message to primary: %s",
PQerrorMessage(streamConn))));
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
/*
* After COPY is finished, we should receive a result set indicating the
pgindent run for release 9.3 This is the first run of the Perl-based pgindent script. Also update pgindent instructions.
2013-05-29 22:58:43 +02:00
* next timeline's ID, or just CommandComplete if the server was shut
* down.
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
*
* If we had not yet received CopyDone from the backend, PGRES_COPY_IN
* would also be possible. However, at the moment this function is only
* called after receiving CopyDone from the backend - the walreceiver
* never terminates replication on its own initiative.
*/
res = PQgetResult(streamConn);
if (PQresultStatus(res) == PGRES_TUPLES_OK)
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
{
Fix walsender failure at promotion. 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.
2013-05-08 19:10:17 +02:00
/*
* Read the next timeline's ID. The server also sends the timeline's
* starting point, but it is ignored.
*/
if (PQnfields(res) < 2 || PQntuples(res) != 1)
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
ereport(ERROR,
(errmsg("unexpected result set after end-of-streaming")));
*next_tli = pg_atoi(PQgetvalue(res, 0, 0), sizeof(uint32), 0);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
PQclear(res);
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
/* the result set should be followed by CommandComplete */
res = PQgetResult(streamConn);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
}
Now that START_REPLICATION returns the next timeline's ID after reaching end of timeline, take advantage of that in walreceiver. Startup process is still in control of choosign the target timeline, by scanning the timeline history files present in pg_xlog, but walreceiver now uses the next timeline's ID to fetch its history file immediately after it has finished streaming the old timeline. Before, the standby would first try to restart streaming on the old timeline, which fetches the missing timeline history file as a side-effect, and only then restart from the new timeline. This patch eliminates the extra iteration, which speeds up the timeline switch and reduces the noise in the log caused by the extra restart on the old timeline.
2013-01-18 10:48:29 +01:00
else
*next_tli = 0;
if (PQresultStatus(res) != PGRES_COMMAND_OK)
ereport(ERROR,
(errmsg("error reading result of streaming command: %s",
PQerrorMessage(streamConn))));
/* Verify that there are no more results */
res = PQgetResult(streamConn);
if (res != NULL)
ereport(ERROR,
(errmsg("unexpected result after CommandComplete: %s",
PQerrorMessage(streamConn))));
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
}
/*
* Fetch the timeline history file for 'tli' from primary.
*/
static void
libpqrcv_readtimelinehistoryfile(TimeLineID tli,
char **filename, char **content, int *len)
{
PGresult *res;
char cmd[64];
/*
* Request the primary to send over the history file for given timeline.
*/
snprintf(cmd, sizeof(cmd), "TIMELINE_HISTORY %u", tli);
res = libpqrcv_PQexec(cmd);
if (PQresultStatus(res) != PGRES_TUPLES_OK)
{
PQclear(res);
ereport(ERROR,
(errmsg("could not receive timeline history file from "
"the primary server: %s",
PQerrorMessage(streamConn))));
}
if (PQnfields(res) != 2 || PQntuples(res) != 1)
{
int ntuples = PQntuples(res);
int nfields = PQnfields(res);
PQclear(res);
ereport(ERROR,
(errmsg("invalid response from primary server"),
errdetail("Expected 1 tuple with 2 fields, got %d tuples with %d fields.",
ntuples, nfields)));
}
*filename = pstrdup(PQgetvalue(res, 0, 0));
*len = PQgetlength(res, 0, 1);
*content = palloc(*len);
memcpy(*content, PQgetvalue(res, 0, 1), *len);
PQclear(res);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
}
/*
* Wait until we can read WAL stream, or timeout.
*
* Returns true if data has become available for reading, false if timed out
* or interrupted by signal.
*
* This is based on pqSocketCheck.
*/
static bool
libpq_select(int timeout_ms)
{
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
int ret;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
Assert(streamConn != NULL);
if (PQsocket(streamConn) < 0)
ereport(ERROR,
(errcode_for_socket_access(),
errmsg("socket not open")));
/* We use poll(2) if available, otherwise select(2) */
{
#ifdef HAVE_POLL
struct pollfd input_fd;
input_fd.fd = PQsocket(streamConn);
input_fd.events = POLLIN | POLLERR;
input_fd.revents = 0;
ret = poll(&input_fd, 1, timeout_ms);
#else /* !HAVE_POLL */
fd_set input_mask;
struct timeval timeout;
struct timeval *ptr_timeout;
FD_ZERO(&input_mask);
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
FD_SET(PQsocket(streamConn), &input_mask);
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
if (timeout_ms < 0)
ptr_timeout = NULL;
else
{
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
timeout.tv_sec = timeout_ms / 1000;
timeout.tv_usec = (timeout_ms % 1000) * 1000;
ptr_timeout = &timeout;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
}
ret = select(PQsocket(streamConn) + 1, &input_mask,
NULL, NULL, ptr_timeout);
#endif /* HAVE_POLL */
}
if (ret == 0 || (ret < 0 && errno == EINTR))
return false;
if (ret < 0)
ereport(ERROR,
(errcode_for_socket_access(),
errmsg("select() failed: %m")));
return true;
}
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
/*
* Send a query and wait for the results by using the asynchronous libpq
* functions and the backend version of select().
*
* We must not use the regular blocking libpq functions like PQexec()
* since they are uninterruptible by signals on some platforms, such as
* Windows.
*
* We must also not use vanilla select() here since it cannot handle the
* signal emulation layer on Windows.
*
* The function is modeled on PQexec() in libpq, but only implements
* those parts that are in use in the walreceiver.
*
* Queries are always executed on the connection in streamConn.
*/
static PGresult *
libpqrcv_PQexec(const char *query)
{
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
PGresult *result = NULL;
PGresult *lastResult = NULL;
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
/*
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
* PQexec() silently discards any prior query results on the connection.
* This is not required for walreceiver since it's expected that walsender
* won't generate any such junk results.
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
*/
/*
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
* Submit a query. Since we don't use non-blocking mode, this also can
* block. But its risk is relatively small, so we ignore that for now.
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
*/
if (!PQsendQuery(streamConn, query))
return NULL;
for (;;)
{
/*
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
* Receive data until PQgetResult is ready to get the result without
* blocking.
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
*/
while (PQisBusy(streamConn))
{
/*
* We don't need to break down the sleep into smaller increments,
* and check for interrupts after each nap, since we can just
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
* elog(FATAL) within SIGTERM signal handler if the signal arrives
* in the middle of establishment of replication connection.
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
*/
if (!libpq_select(-1))
continue; /* interrupted */
if (PQconsumeInput(streamConn) == 0)
return NULL; /* trouble */
}
/*
pgindent run for 9.0, second run
2010-07-06 21:19:02 +02:00
* Emulate the PQexec()'s behavior of returning the last result when
* there are many. Since walsender will never generate multiple
* results, we skip the concatenation of error messages.
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
*/
result = PQgetResult(streamConn);
if (result == NULL)
break; /* query is complete */
PQclear(lastResult);
lastResult = result;
if (PQresultStatus(lastResult) == PGRES_COPY_IN ||
PQresultStatus(lastResult) == PGRES_COPY_OUT ||
Allow bidirectional copy messages in streaming replication mode. Fujii Masao. Review by Alvaro Herrera, Tom Lane, and myself.
2010-12-11 15:27:37 +01:00
PQresultStatus(lastResult) == PGRES_COPY_BOTH ||
Add wrapper function libpqrcv_PQexec() in the walreceiver that uses async libpq to send queries, making the waiting for responses interruptible on platforms where PQexec() can't normally be interrupted by signals, such as win32. Fujii Masao and Magnus Hagander
2010-04-19 16:10:45 +02:00
PQstatus(streamConn) == CONNECTION_BAD)
break;
}
return lastResult;
}
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
/*
* Disconnect connection to primary, if any.
*/
static void
libpqrcv_disconnect(void)
{
PQfinish(streamConn);
streamConn = NULL;
}
/*
Add a message type header to the CopyData messages sent from primary to standby in streaming replication. While we only have one message type at the moment, adding a message type header makes this easier to extend.
2010-02-03 10:47:19 +01:00
* Receive a message available from XLOG stream, blocking for
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
* maximum of 'timeout' ms.
*
* Returns:
*
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
* If data was received, returns the length of the data. *buffer is set to
* point to a buffer holding the received message. The buffer is only valid
* until the next libpqrcv_* call.
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
* 0 if no data was available within timeout, or wait was interrupted
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
* by signal.
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*
pgindent run for release 9.3 This is the first run of the Perl-based pgindent script. Also update pgindent instructions.
2013-05-29 22:58:43 +02:00
* -1 if the server ended the COPY.
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
*
* ereports on error.
*/
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
static int
libpqrcv_receive(int timeout, char **buffer)
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
{
int rawlen;
if (recvBuf != NULL)
PQfreemem(recvBuf);
recvBuf = NULL;
Fix the logic in libpqrcv_receive() to determine if there's any incoming data that can be read without blocking. It used to conclude that there isn't, even though there was data in the socket receive buffer. That lead walreceiver to flush the WAL after every received chunk, potentially causing big performance issues. Backpatch to 9.0, because the performance impact can be very significant.
2011-01-13 16:51:28 +01:00
/* Try to receive a CopyData message */
rawlen = PQgetCopyData(streamConn, &recvBuf, 1);
if (rawlen == 0)
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
{
Fix the logic in libpqrcv_receive() to determine if there's any incoming data that can be read without blocking. It used to conclude that there isn't, even though there was data in the socket receive buffer. That lead walreceiver to flush the WAL after every received chunk, potentially causing big performance issues. Backpatch to 9.0, because the performance impact can be very significant.
2011-01-13 16:51:28 +01:00
/*
* No data available yet. If the caller requested to block, wait for
* more data to arrive.
*/
if (timeout > 0)
{
if (!libpq_select(timeout))
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
return 0;
Fix the logic in libpqrcv_receive() to determine if there's any incoming data that can be read without blocking. It used to conclude that there isn't, even though there was data in the socket receive buffer. That lead walreceiver to flush the WAL after every received chunk, potentially causing big performance issues. Backpatch to 9.0, because the performance impact can be very significant.
2011-01-13 16:51:28 +01:00
}
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
if (PQconsumeInput(streamConn) == 0)
ereport(ERROR,
Message tuning
2010-03-21 01:17:59 +01:00
(errmsg("could not receive data from WAL stream: %s",
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQerrorMessage(streamConn))));
Fix the logic in libpqrcv_receive() to determine if there's any incoming data that can be read without blocking. It used to conclude that there isn't, even though there was data in the socket receive buffer. That lead walreceiver to flush the WAL after every received chunk, potentially causing big performance issues. Backpatch to 9.0, because the performance impact can be very significant.
2011-01-13 16:51:28 +01:00
/* Now that we've consumed some input, try again */
rawlen = PQgetCopyData(streamConn, &recvBuf, 1);
if (rawlen == 0)
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
return 0;
Fix the logic in libpqrcv_receive() to determine if there's any incoming data that can be read without blocking. It used to conclude that there isn't, even though there was data in the socket receive buffer. That lead walreceiver to flush the WAL after every received chunk, potentially causing big performance issues. Backpatch to 9.0, because the performance impact can be very significant.
2011-01-13 16:51:28 +01:00
}
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
if (rawlen == -1) /* end-of-streaming or error */
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
{
pgindent run for 9.0
2010-02-26 03:01:40 +01:00
PGresult *res;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
res = PQgetResult(streamConn);
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
if (PQresultStatus(res) == PGRES_COMMAND_OK ||
PQresultStatus(res) == PGRES_COPY_IN)
{
PQclear(res);
return -1;
}
else
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
{
PQclear(res);
ereport(ERROR,
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
(errmsg("could not receive data from WAL stream: %s",
PQerrorMessage(streamConn))));
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
}
}
if (rawlen < -1)
ereport(ERROR,
Message tuning
2010-03-21 01:17:59 +01:00
(errmsg("could not receive data from WAL stream: %s",
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
PQerrorMessage(streamConn))));
Add a message type header to the CopyData messages sent from primary to standby in streaming replication. While we only have one message type at the moment, adding a message type header makes this easier to extend.
2010-02-03 10:47:19 +01:00
/* Return received messages to caller */
Allow a streaming replication standby to follow a timeline switch. 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.
2012-12-13 18:00:00 +01:00
*buffer = recvBuf;
return rawlen;
Rethink the way walreceiver is linked into the backend. Instead than shoving walreceiver as whole into a dynamically loaded module, split the libpq-specific parts of it into dynamically loaded module and keep the rest in the main backend binary. Although Tom fixed the Windows compilation problems with the old walreceiver module already, this is a cleaner division of labour and makes the code more readable. There's also the prospect of adding new transport methods as pluggable modules in the future, which this patch makes easier, though for now the API between libpqwalreceiver and walreceiver process should be considered private. The libpq-specific module is now in src/backend/replication/libpqwalreceiver, and the part linked with postgres binary is in src/backend/replication/walreceiver.c.
2010-01-20 10:16:24 +01:00
}
Allow bidirectional copy messages in streaming replication mode. Fujii Masao. Review by Alvaro Herrera, Tom Lane, and myself.
2010-12-11 15:27:37 +01:00
/*
* Send a message to XLOG stream.
*
* ereports on error.
*/
static void
libpqrcv_send(const char *buffer, int nbytes)
{
if (PQputCopyData(streamConn, buffer, nbytes) <= 0 ||
PQflush(streamConn))
ereport(ERROR,
(errmsg("could not send data to WAL stream: %s",
PQerrorMessage(streamConn))));
}