This online page relates to the latest released JChem PostgreSQL Cartridge. Find the version specific documentation in your installed package in
The following software versions were used at testing:
Put your valid ChemAxon license file to the
/etc/chemaxon/ folder on each node.
Create the file
pg_worker_list.conf in the master node’s PostgreSQL data directory (the directory declared in the
postgresql.conf file as
data_directory) and add the worker’s hostname and PostgreSQL port setups to this file, like:
In the example below the table is created using hash distribution, it has four shards and has one replica for each shard.
In a command line shell:
The script below cuts the original CSV file to 64 pieces and imports them to the created table parallely. This script has to be executed from command line as
The Citus 5.1 documentation states that the PostgreSQL
COPY command is also supported and inserts rows into tables parallely, but it failed in our tests.
These limitations are not invoked by JChem PostgreSQL Cartridge.
Import can be done only with a limited set of PostgreSQL methods. Only a single insert can be performed using SQL , bulk insert can be performed with a command-line tool or
COPY , described here, which has a much better performance.
No subselects are allowed in a modification statement (e.g. insert, delete, update). For example INSERT INTO table2 SELECT * FROM table1 WHERE 'C' |<| mol is not supported.
Only distributed tables can be joint in one SELECT statement. A distributed and non-distributed table join is not supported.
postgres user can have distributed tables.
Distributed tables can not be renamed.
In Citus version 5.0 explain plans are not available, but they are already available in version 5.1.
Since the ChemAxon PostgreSQL Cartridge does not contain an equality operator for
Molecule type, tables can not be distributed by hashing the
Molecule type column. Tables containing molecules have to be sharded by another column.