Couchbase Query

Couchbase Query

This component retrieves data on a Couchbase server and loads it into a table. This stages the data, so the table is reloaded each time. You may then use transformations to enrich and manage the data in permanent tables.

Warning: This component is destructive as it truncates or recreates its target table on each run. Do not modify the target table structure manually.


Properties

Property Setting Description
Name Text The descriptive name for the component.
Basic/Advanced Mode Choice Basic - This mode will build a Query for you using settings from Data Source, Data Selection and Data Source Filter parameters. In most cases, this will be sufficient.
Advanced - This mode will require you to write an SQL-like query to call data from Couchbase. The available fields and their descriptions are documented in the data model.
Server Choice Address of the Couchbase server from which data is to be sourced.
User Text Login name for the Couchbase server.
Password Text Login password for the Couchbase server.
Data Source Choice Select a data source from the server.
Data Selection Choice Select one or more columns to return from the query.
Data Source Filter Input Column The available input columns vary depending upon the Data Source.
Qualifier Is - Compares the column to the value using the comparator.
Not - Reverses the effect of the comparison, so "equals" becomes "not equals", "less than" becomes "greater than or equal to", etc.
Comparator Choose a method of comparing the column to the value. Possible comparators include: 'Equal To', 'Greater than', 'Less than', 'Greater than or equal to', 'Less than or equal to', 'Like', 'Null'.
'Equal To' can match exact strings and numeric values while other comparators such as 'Greater than' will work only with numerics. The 'Like' operator allows the wildcard character (%) to be used at the start and end of a string value to match a column. The Null operator matches only Null values, ignoring whatever the value is set to.
Not all data sources support all comparators, thus it is likely only a subset of the above comparators will be available to choose from.
Value The value to be compared.
SQL Text Custom SQL-like query only available during 'Advanced' mode.
Limit Number Limits the number of rows that are loaded from file.
Connection Options Parameter A JDBC parameter supported by the Database Driver. The available parameters are determined automatically from the driver, and may change from version to version.
They are usually not required as sensible defaults are assumed.
Value A value for the given Parameter.
S3 Staging Area Text The name of an S3 bucket for temporary storage. Ensure your access credentials have S3 access and permission to write to the bucket. See this document for details on setting up access. The temporary objects created in this bucket will be removed again after the load completes, they are not kept.
Warehouse Select Choose a Snowflake warehouse that will run the load.
Database Select Choose a database to create the new table in.
Type Select Choose between using a standard table or an external table.
Standard: The data will be staged on an S3 bucket before being loaded into a table.
External: The data will be put into an S3 Bucket and referenced by an external table.
Schema Select Select the table schema. The special value, [Environment Default] will use the schema defined in the environment. For more information on using multiple schemas, see this article.
Note: An external schema is required if the 'Type' property is set to 'External'.
Target Table Text Provide a new table name.
Warning: This table will be recreated and will drop any existing table of the same name.
Location Text/Select When using an 'External' type table, Provide an S3 Bucket path that will be used to store the data. Once on an S3 bucket, the data can be referenced by the external table.
Distribution Style Select Even - the default option, distribute rows around the Redshift Cluster evenly.
All - copy rows to all nodes in the Redshift Cluster.
Key - distribute rows around the Redshift cluster according to the value of a key column.
Table-distribution is critical to good performance - see the Amazon Redshift documentation for more information.
Sort Key Select This is optional, and specifies the columns from the input that should be set as the table's sort-key.
Sort-keys are critical to good performance - see the Amazon Redshift documentation for more information.
Load Options Multiple Selection Comp Update: Apply automatic compression to the target table (if ON). Default is ON.
Stat Update: Automatically update statistics when filling a table (if ON). Default is ON. In this case, it is updating the statistics of the target table.
Clean S3 Objects: Automatically remove UUID-based objects on the S3 Bucket (if ON). Default is ON. Effectively decides whether to keep the staged data in the S3 Bucket or not.
String Null is Null: Converts any strings equal to "null" into a null value. This is case sensitive and only works with entirely lower-case strings. Default is ON.
Recreate Target Table:Choose whether the component recreates its target table before the data load. If OFF, the existing table will be used. Default is ON.
Project Text The target BigQuery project to load data into.
Dataset Text The target BigQuery dataset to load data into.
Cloud Storage Staging Area Text The URL and path of the target Google Storage bucket to be used for staging the queried data.
Sort Key Options Select Decide whether the sort key is of a compound or interleaved variety - see the Amazon Redshift documentation for more information.
Encryption Select Decide on how the files are encrypted inside the S3 Bucket.
None: No encryption.
SSE KMS: Encrypt the data according to a key stored on KMS.
SSE S3: Encrypt the data according to a key stored on an S3 bucket
KMS Key ID Select The ID of the KMS encryption key you have chosen to use in the 'Encryption' property.


Variable Exports

This component makes the following values available to export into variables:

Source Description
Time Taken To Stage The amount of time (in seconds) taken to fetch the data from the data source and upload it to storage.
Time Taken To Load The amount of time (in seconds) taken to execute the COPY statement to load the data into the target table from storage.


Strategy

Connect to the target database and issue the query. Stream the results into objects on S3. Then create or truncate the target table and issue a COPY command to load the S3 objects into the table. Finally, clean up the temporary S3 objects.


Example

In this example we will load flight data from Couchbase into a table where the data can be later transformed. The layout for this job is shown below.

The job is quite straight forward. We are using the table 'docs_tbl' to load data into - the Couchbase Query component will automatically create this table, dropping it first should it already exist.

The Couchbase server, with matching username and password, are entered which allows the component to generate a list of Data Sources available. Picking one will then allow us to import to all columns in the 'Data Selection' property. The rest of the component will configure itself with default values that can be used in our job. Details of the Couchbase Query component are shown below.

Now by right-clicking the job or job canvas, 'Run Job' can be selected to run the job as it currently stands. When this run has completed, we can sample the table using a Table Input component in a transformation job to ensure the data has been loaded correctly.