pg_recvlogical

Function

pg_recvlogical connects to a specified node to create and delete logical replication slots, obtains the intermediate result of logic decoding from the node continuously in real time, and outputs the result to a file or in standard mode.

Syntax

pg_recvlogical [OPTION]...

Logical replication slot behavior parameters are mandatory and must be specified. Other parameters are optional. If you do not specify them, the default values will be read.

Parameter Description

Logical replication slot behavior parameters (mandatory):

• --create

  Creates a logical replication slot. The pg_create_logical_replication_slot function is called internally. The user who calls this function must have the SYSADMIN or REPLICATION permission or inherits the permission of the built-in role gs_role_replication. This function can be called only on the primary node. For details, see the description of the pg_create_logical_replication_slot function in Developer Guide.

• --start

  Starts the flow replication of a logic replication slot.

• --drop

  Deletes a logical replication slot.

Connection parameters:

• -d, --dbname=DBNAME

  Connects to the target database.

• -h, --host=HOSTNAME

  Specifies the name or socket of the connected host.

• -p, --port=PORT

  Specifies the HA port number for connecting to the target database node.

• -U, --username=NAME

  Specifies the user name for connecting to the target database.

• -w, --no-password

  Performs connection without a password.

• -W, --password

  Performs connection with a specified password.

Replication parameters:

• -F --fsync-interval=INTERVAL

  Specifies an interval for synchronizing data to the target output file.

  The unit is s. The default value is 10.

• -o, --option=NAME[=VALUE]

  Adds parameters to the output plug-in of a logical replication slot.

  The value can be include-xids, skip-empty-xacts, include-timestamp, only-local, force-binary, white-table-list, standby-connection, parallel-decode-num, decode-style, or sending-batch.

  For details, see “SQL Reference > Functions and Operators > System Administration Functions > Logical Replication Functions > pg_logical_slot_peek_changes > options” and “Application Development Guide > Development Based on JDBC > Example: Logic Replication Code” in Developer Guide. Link: https://docs.opengauss.org/en/docs/3.1.1/docs/Developerguide/%E7%A4%BA%E4%BE%8B-%E9%80%BB%E8%BE%91%E5%A4%8D%E5%88%B6%E4%BB%A3%E7%A0%81%E7%A4%BA%E4%BE%8B.html

• -P, --plugin=PLUGIN

  Specifies the logical replication slot output plug-in.

  The default value is mppdb_decoding.

• -s, --status-interval=INTERVAL

  Specifies an interval for sending heartbeat packets.

  The unit is s. The default value is 10.

• -S, --slot=SLOT

  Specifies the name of a logical replication slot.

• -I, --startpos=PTR

  Specifies the LSN location of the initial replication when an existing logical replication slot is used.

Other parameters:

• -f, --file=FILE

  Specifies the output file.

  If - is used, data is output to stdout.

• -n, --no-loop

  Specifies that the system does not retry after the connection fails.

• -v, --verbose

  Displays detailed information.

• -V, --version

  Displays the version and exits immediately.

• -?, --help

  Displays help information and exits immediately.

• -r, --raw

  In parallel decoding scenarios, if this parameter is set, the binary format or batch sending result will not be converted to the text format. This parameter is used only by test personnel to measure the parallel decoding performance. After this parameter is set, the decoding result sent in binary mode or in batches are in unreadable format.

Examples

1. Create a logical replication slot named test_slot.

   pg_recvlogical -d postgres -S test_slot -p 26000 --create
   

2. Enable stream decoding and output the result to stdout.

   pg_recvlogical -d postgres -S test_slot -p 26000 --start -v -f -
   pg_recvlogical: starting log streaming at 0/0 (slot test_slot)
   pg_recvlogical: initiated streaming
   pg_recvlogical: confirming write up to 0/0, flush to 0/0 (slot test_slot)
   pg_recvlogical: confirming write up to 0/2A342E8, flush to 0/2A342E8 (slot test_slot)
   pg_recvlogical: confirming write up to 0/2A34320, flush to 0/2A34320 (slot test_slot)
   pg_recvlogical: confirming write up to 0/2A34320, flush to 0/2A34320 (slot test_slot)
   BEGIN 16039
   table public.t: INSERT: a[integer]:4 b[integer]:4
   COMMIT 16039
   pg_recvlogical: confirming write up to 0/2A34450, flush to 0/2A34450 (slot test_slot)
   pg_recvlogical: confirming write up to 0/2A34450, flush to 0/2A34450 (slot test_slot)
   

3. Delete the logical replication slot.

   pg_recvlogical -d postgres -S test_slot -p 26000 --drop