[![License](https://img.shields.io/badge/license-MIT-brightgreen.svg?maxAge=2592000)](https://opensource.org/licenses/MIT) [![Version](https://img.shields.io/badge/version-0.1.0-brightgreen.svg?maxAge=2592000)]() [![User chat](https://img.shields.io/badge/chat-users-brightgreen.svg)](https://gitter.im/debezium/user) [![Developer chat](https://img.shields.io/badge/chat-devs-brightgreen.svg)](https://gitter.im/debezium/dev) [![Google Group](https://img.shields.io/:mailing%20list-debezium-brightgreen.svg)](https://groups.google.com/forum/#!forum/debezium) [![Stack Overflow](http://img.shields.io/:stack%20overflow-debezium-brightgreen.svg)](http://stackoverflow.com/questions/tagged/debezium) # Postgres Decoderbufs A PostgreSQL logical decoder output plugin to deliver data as [Protocol Buffers](https://developers.google.com/protocol-buffers), adapted for Debezium ## Thanks to - The original [Decoderbufs Project](https://github.com/xstevens/decoderbufs) on which this is based - [The PostgreSQL Team](https://postgresql.org) for adding [logical decoding](http://www.postgresql.org/docs/9.4/static/logicaldecoding.html) support ## Dependencies This code depends on the following libraries and requires them for compilation: - [PostgreSQL](http://www.postgresql.org) 9.6+ - [Protobuf-c](https://github.com/protobuf-c/protobuf-c) 1.2+ - used for data serialization - [PostGIS](http://www.postgis.net/) 2.1+ - used for Postgres geometric types support ## Building `postgres-decoderbufs` has to be built from source after installing required dependencies. The required dependencies are first PostgreSQL (for pg_config), PostgreSQL server development packages, protobuf-c for the Protocol Buffer support and some PostGIS development packages. ### Installing Dependencies #### Debian ```bash # Core build utilities apt-get update && apt-get install -f -y software-properties-common build-essential pkg-config git postgresql-server-dev-9.6 # PostGIS dependency apt-get install -f -y libproj-dev liblwgeom-dev # Protobuf-c dependency (requires a non-stable Debian repo) add-apt-repository "deb http://ftp.debian.org/debian testing main contrib" && apt-get update apt-get install -y libprotobuf-c-dev=1.2.1-1+b1 ``` When updating the ProtoBuf definition, also install the ProtoBuf C compiler: ```bash apt-get install -y protobuf-c-compiler=1.2.* ``` The above are taken from the Debezium [container images](https://github.com/debezium/docker-images). #### Other Linux distributions You just need to make sure the above software packages (_or some flavour thereof_) are installed for your distro. Note that the last step from the above sequence is only required for Debian to be able to install `libprotobuf-c-dev:1.2.1` ### Getting the source code If you have all of the above prerequisites installed, clone this git repo to build from source: ```bash git clone https://github.com/debezium/postgres-decoderbufs.git cd postgres-decoderbufs ``` ### Optional: Re-generating ProtoBuf code This is only needed after changes to the ProtoBuf definition (_proto/pg_logicaldec.proto): ```bash cd proto protoc-c --c_out=../src/proto pg_logicaldec.proto cd .. ``` Commit the generated files to git then. ### Building and installing decoderbufs If you have multiple Postgres versions installed, you can select which version to install decoderbufs into by altering your `$PATH` to point to the right version. Then `make` and `make install` for each version. Here is an example: ```bash # Install for Postgres 9.6 if I have multiple local versions export PATH=/usr/lib/postgresql/9.6/bin:$PATH make make install ``` Once the extension has been installed you just need to enable it and logical replication in postgresql.conf: ```bash # MODULES shared_preload_libraries = 'decoderbufs' # REPLICATION wal_level = logical # minimal, archive, hot_standby, or logical (change requires restart) max_wal_senders = 8 # max number of walsender processes (change requires restart) wal_keep_segments = 4 # in logfile segments, 16MB each; 0 disables #wal_sender_timeout = 60s # in milliseconds; 0 disables max_replication_slots = 4 # max number of replication slots (change requires restart) ``` In addition, permissions will have to be added for the user that connects to the DB to be able to replicate. This can be modified in _pg\_hba.conf_ like so: ```make local replication trust host replication 127.0.0.1/32 trust host replication ::1/128 trust ``` And restart PostgreSQL. ## Usage ```sql -- can use SQL for demo purposes select * from pg_create_logical_replication_slot('decoderbufs_demo', 'decoderbufs'); -- DO SOME TABLE MODIFICATIONS (see below about UPDATE/DELETE) -- peek at WAL changes using decoderbufs debug mode for SQL console select data from pg_logical_slot_peek_changes('decoderbufs_demo', NULL, NULL, 'debug-mode', '1'); -- get WAL changes using decoderbufs to update the WAL position select data from pg_logical_slot_get_changes('decoderbufs_demo', NULL, NULL, 'debug-mode', '1'); -- check the WAL position of logical replicators select * from pg_replication_slots where slot_type = 'logical'; ``` If you're performing an UPDATE/DELETE on your table and you don't see results for those operations from logical decoding, make sure you have set [REPLICA IDENTITY](http://www.postgresql.org/docs/9.4/static/sql-altertable.html#SQL-CREATETABLE-REPLICA-IDENTITY) appropriately for your use case. The binary format will be consumed by the Debezium Postgres Connector. ## Type Mappings The following table shows how current PostgreSQL type OIDs are mapped to which decoderbuf fields: | PostgreSQL Type OID | Decoderbuf Field | |---------------------|---------------| | BOOLOID | datum_boolean | | INT2OID | datum_int32 | | INT4OID | datum_int32 | | INT8OID | datum_int64 | | OIDOID | datum_int64 | | FLOAT4OID | datum_float | | FLOAT8OID | datum_double | | NUMERICOID | datum_double | | CHAROID | datum_string | | VARCHAROID | datum_string | | BPCHAROID | datum_string | | TEXTOID | datum_string | | JSONOID | datum_string | | XMLOID | datum_string | | UUIDOID | datum_string | | TIMESTAMPOID | datum_string | | TIMESTAMPTZOID | datum_string | | BYTEAOID | datum_bytes | | POINTOID | datum_point | | PostGIS geometry | datum_point | | PostGIS geography | datum_point | ## Support File bug reports and feature requests using [Debezium's JIRA](https://issues.jboss.org/browse/DBZ) and the [postgresql-connector](https://issues.jboss.org/browse/DBZ/component/12323543) component