Update user guide regarding BucketFS paths

[ckunki]

Current Situation

PGVS User Guide says

ExaLoader expects the driver in BucketFS folder default/drivers/jdbc.

The Section Installing the Adapter Script later on only mentions "upload" and links to docs.exasol.com.

General Requirements

Uploading files to the BucketFS requires specifying

• Protocol (http or https)
• the Port (default 2580)
• bucket (default: default)

The following BucketFS paths are independent

• JDBC driver
• Jar file implementing the Virtual Schema dialect

Problems

Proposals and comments

• I propose to be as concrete and precise as possible in the user guide.
• Maybe linking the following URL is better? https://docs.exasol.com/db/latest/database_concepts/virtual_schema/user_guide.htm#Install

Unfortunately the page

• Does not give dedicated instructions for downloading and installing the Jar file implementing the Virtual Schema dialect.
• Doesn't clearly separate the paths in the BucketFS to the VS Jar vs. the driver, which are independent (see above)

Concrete proposal

1. Choose BucketFS, bucket, and path for uploading

File(s)	BucketFS	Bucket	Path
(B1) The JDBC driver and file settings.cfg	bfsdefault	default	drivers/jdbc
(B2) The Jar file implementing the Virtual Schema dialect	bfsdefault	default	(root)

For B1, we recommend using the same location as used by the ExaLoader.

2. Upload the files to the selected locations

3. Create the Adapter script

In the following template, <BFS service x> refers to the BucketFS service, <bucket x> to the Bucket and <path x> to the respective path.

--/
CREATE OR REPLACE JAVA ADAPTER SCRIPT ADAPTER.JDBC_ADAPTER AS
  %scriptclass com.exasol.adapter.RequestDispatcher;
  %jar /buckets/<BFS service 1>/<bucket 1>/<path 1>/postgresql-<postgresql-driver-version>.jar;
  %jar /buckets/<BFS service 2>/<bucket 2>/<path 2>virtual-schema-dist-13.0.0-postgresql-3.1.1.jar;
/

In our example, the complete paths would be

• /buckets/bfsdefault/default/drivers/jdbc/postgresql-<postgresql-driver-version>.jar:
• /buckets/bfsdefault/default/virtual-schema-dist-13.0.0-postgresql-3.1.1.jar;