target-postgres - Meltano Hub

PostgreSQL

target-postgres (transferwise variant)🥈

PostgreSQL database loader

The target-postgres loader sends data into PostgreSQL after it was pulled from a source using an extractor

Alternate Implementations

Getting Started

Prerequisites

If you haven't already, follow the initial steps of the Getting Started guide:

Installation and configuration

Add the target-postgres loader to your project using
```
meltano add
```
:

meltano add loader target-postgres --variant transferwise

Configure the target-postgres settings using

meltano config

meltano config target-postgres set --interactive

Next steps

Follow the remaining steps of the Getting Started guide:

Run a data integration (EL) pipeline

If you run into any issues, learn how to get help.

Capabilities

This plugin currently has no capabilities defined. If you know the capabilities required by this plugin, please contribute!

Settings

The target-postgres settings that are known to Meltano are documented below. To quickly find the setting you're looking for, click on any setting name from the list:

add_metadata_columns
batch_size_rows
data_flattening_max_level
dbname
default_target_schema
default_target_schema_select_permission
flush_all_streams
hard_delete
host
parallelism
parallelism_max
password
port
primary_key_required
schema_mapping
ssl
temp_dir
user
validate_records

You can also list these settings using

meltano config

with the list subcommand:

meltano config target-postgres list

You can override these settings or specify additional ones in your meltano.yml by adding the settings key.

Please consider adding any settings you have defined locally to this definition on MeltanoHub by making a pull request to the YAML file that defines the settings for this plugin.

Add Metadata Columns (add_metadata_columns)

Environment variable: TARGET_POSTGRES_ADD_METADATA_COLUMNS
Default Value: false

Metadata columns add extra row level information about data ingestions, (i.e. when was the row read in source, when was inserted or deleted in postgres etc.) Metadata columns are creating automatically by adding extra columns to the tables with a column prefix _SDC_. The column names are following the stitch naming conventions documented in the Stitch Docs. Enabling metadata columns will flag the deleted rows by setting the _SDC_DELETED_AT metadata column. Without the add_metadata_columns option the deleted rows from singer taps will not be recognisable in Postgres. Default - False

Configure this setting directly using the following Meltano command:

meltano config target-postgres set add_metadata_columns [value]

Batch Size Rows (batch_size_rows)

Environment variable: TARGET_POSTGRES_BATCH_SIZE_ROWS
Default Value: 100000

Maximum number of rows in each batch. At the end of each batch, the rows in the batch are loaded into Postgres.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set batch_size_rows [value]

Data Flattening Max Level (data_flattening_max_level)

Environment variable: TARGET_POSTGRES_DATA_FLATTENING_MAX_LEVEL
Default Value: 0

Object type `RECORD`` items from taps can be transformed to flattened columns by creating columns automatically. When value is 0 (default) then flattening functionality is turned off.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set data_flattening_max_level [value]

Database Name (dbname)

Environment variable: TARGET_POSTGRES_DBNAME

PostgreSQL database name

Configure this setting directly using the following Meltano command:

meltano config target-postgres set dbname [value]

Default Target Schema (default_target_schema)

Environment variable: TARGET_POSTGRES_DEFAULT_TARGET_SCHEMA
Default Value: $MELTANO_EXTRACT__LOAD_SCHEMA

Note that $MELTANO_EXTRACT__LOAD_SCHEMA will expand to the value of the load_schema extra for the extractor used in the pipeline, which defaults to the extractor's namespace, e.g. tap_gitlab for tap-gitlab.

Name of the schema where the tables will be created. If schema_mapping is not defined then every stream sent by the tap is loaded into this schema.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set default_target_schema [value]

Default Target Schema Select Permission (default_target_schema_select_permission)

Environment variable: TARGET_POSTGRES_DEFAULT_TARGET_SCHEMA_SELECT_PERMISSION

Grant USAGE privilege on newly created schemas and grant SELECT privilege on newly created tables to a specific role or a list of roles. If schema_mapping is not defined then every stream sent by the tap is granted accordingly.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set default_target_schema_select_permission [value]

Flush All Streams (flush_all_streams)

Environment variable: TARGET_POSTGRES_FLUSH_ALL_STREAMS
Default Value: false

Flush and load every stream into Postgres when one batch is full. Warning: This may trigger the COPY command to use files with low number of records.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set flush_all_streams [value]

Hard Delete (hard_delete)

Environment variable: TARGET_POSTGRES_HARD_DELETE
Default Value: false

When hard_delete option is true then DELETE SQL commands will be performed in Postgres to delete rows in tables. It's achieved by continuously checking the _SDC_DELETED_AT metadata column sent by the singer tap. Due to deleting rows requires metadata columns, hard_delete option automatically enables the add_metadata_columns option as well.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set hard_delete [value]

Host (host)

Environment variable: TARGET_POSTGRES_HOST
Default Value: localhost

PostgreSQL host

Configure this setting directly using the following Meltano command:

meltano config target-postgres set host [value]

Parallelism (parallelism)

Environment variable: TARGET_POSTGRES_PARALLELISM
Default Value: 0

The number of threads used to flush tables. 0 will create a thread for each stream, up to parallelism_max. -1 will create a thread for each CPU core. Any other positive number will create that number of threads, up to parallelism_max.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set parallelism [value]

Max Parallelism (parallelism_max)

Environment variable: TARGET_POSTGRES_PARALLELISM_MAX
Default Value: 16

Max number of parallel threads to use when flushing tables.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set parallelism_max [value]

Password (password)

Environment variable: TARGET_POSTGRES_PASSWORD

PostgreSQL password

Configure this setting directly using the following Meltano command:

meltano config target-postgres set password [value]

Port (port)

Environment variable: TARGET_POSTGRES_PORT
Default Value: 5432

PostgreSQL port

Configure this setting directly using the following Meltano command:

meltano config target-postgres set port [value]

Primary Key Required (primary_key_required)

Environment variable: TARGET_POSTGRES_PRIMARY_KEY_REQUIRED
Default Value: true

Log based and Incremental replications on tables with no Primary Key cause duplicates when merging UPDATE events. When set to true, stop loading data if no Primary Key is defined.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set primary_key_required [value]

Schema Mapping (schema_mapping)

Environment variable: TARGET_POSTGRES_SCHEMA_MAPPING

Useful if you want to load multiple streams from one tap to multiple Postgres schemas.

If the tap sends the stream_id in <schema_name>-<table_name> format then this option overwrites the default_target_schema value. Note, that using schema_mapping you can overwrite the default_target_schema_select_permission value to grant SELECT permissions to different groups per schemas or optionally you can create indices automatically for the replicated tables.

This setting can hold an object mapping source schema names to objects with target_schema and (optionally) target_schema_select_permissions and indices keys.

Example structure (as YAML):

schema_mapping:
  my_tap_stream_id:
    target_schema: my_postgres_schema
    target_schema_select_permissions: [ "role_with_select_privs" ]
    indices: ["column_1", "column_2s"]

Configure this setting directly using the following Meltano command:

meltano config target-postgres set schema_mapping [value]

SSL (ssl)

Environment variable: TARGET_POSTGRES_SSL
Default Value: false

Using SSL via postgres sslmode='require' option.

If the server does not accept SSL connections or the client certificate is not recognized the connection will fail.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set ssl [value]

Temporary Directory (temp_dir)

Environment variable: TARGET_POSTGRES_TEMP_DIR

(Default: platform-dependent) Directory of temporary CSV files with RECORD messages.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set temp_dir [value]

User (user)

Environment variable: TARGET_POSTGRES_USER

PostgreSQL user

Configure this setting directly using the following Meltano command:

meltano config target-postgres set user [value]

Validate Records (validate_records)

Environment variable: TARGET_POSTGRES_VALIDATE_RECORDS
Default Value: false

Validate every single record message to the corresponding JSON schema. This option is disabled by default and invalid RECORD messages will fail only at load time by Postgres. Enabling this option will detect invalid records earlier but could cause performance degradation.

Configure this setting directly using the following Meltano command:

meltano config target-postgres set validate_records [value]

Troubleshooting

`ld`, `clang`, `lssl`, or `linker` Errors

If you have an error message like:

ld: library not found for -lssl
clang: error: linker command failed with exit code 1
error: command 'clang' failed with exit status 1

These error messages indicates that there is a problem installing OpenSSL.

This Stack Overflow answer has specific recommendations on setting the LDFLAGS and/or CPPFLAGS environment variables. Set those prior to running meltano add loader target-postgres.

Something missing?

This page is generated from a YAML file that you can contribute changes to.

Edit it on GitHub!

Looking for help?

If you're having trouble getting the target-postgres loader to work, look for an existing issue in its repository, file a new issue, or join the Meltano Slack community and ask for help in the