Databases
Introduction
Neo4j supports the management of multiple databases within the same DBMS.
The metadata for these databases, including the associated security model, is maintained in a special database called the system database.
All multi-database administrative commands must be run against the system database.
These administrative commands are automatically routed to the system database when connected to the DBMS over Bolt.
Listing databases
There are three different commands for listing databases. Listing all databases, listing a particular database or listing the default database.
SHOW { DATABASE name | DATABASES | DEFAULT DATABASE }
[YIELD field[, ...] [ORDER BY field[, ...]] [SKIP n] [LIMIT n]]
[WHERE expression]All available databases can be seen using the command SHOW DATABASES.
SHOW DATABASES| name | address | role | requestedStatus | currentStatus | error | default |
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Rows: 4 |
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Note that the results of this command are filtered according to the |
A particular database can be seen using the command SHOW DATABASE name.
SHOW DATABASE system| name | address | role | requestedStatus | currentStatus | error | default |
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Rows: 1 |
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The default database can be seen using the command SHOW DEFAULT DATABASE.
SHOW DEFAULT DATABASE| name | address | role | requestedStatus | currentStatus | error |
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Rows: 1 |
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It is also possible to filter and sort the results by using YIELD, ORDER BY and WHERE.
SHOW DATABASES YIELD name, currentStatus, requestedStatus ORDER BY currentStatus WHERE name CONTAINS 'e'In this example:
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The number of columns returned has been reduced with the
YIELDclause. -
The order of the returned columns has been changed.
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The results have been filtered to only show database names containing 'e'.
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The results are ordered by the 'currentStatus' column using
ORDER BY.
It is also possible to use SKIP and LIMIT to paginate the results.
| name | currentStatus | requestedStatus |
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Rows: 3 |
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Note that for failed databases, the |
Creating databases
Databases can be created using CREATE DATABASE.
CREATE DATABASE customers0 rows, System updates: 1
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Database names are subject to the standard Cypher® restrictions on valid identifiers. The following naming rules apply:
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When a database has been created, it will show up in the listing provided by the command SHOW DATABASES.
SHOW DATABASES| name | address | role | requestedStatus | currentStatus | error | default |
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Rows: 5 |
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This command is optionally idempotent, with the default behavior to throw an exception if the database already exists. Appending IF NOT EXISTS to the command will ensure that no exception is thrown and nothing happens should the database already exist. Adding OR REPLACE to the command will result in any existing database being deleted and a new one created.
CREATE DATABASE customers IF NOT EXISTSCREATE OR REPLACE DATABASE customersThis is equivalent to running DROP DATABASE customers IF EXISTS followed by CREATE DATABASE customers.
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The |
Stopping databases
Databases can be stopped using the command STOP DATABASE.
STOP DATABASE customers0 rows, System updates: 1
The status of the stopped database can be seen using the command SHOW DATABASE name.
SHOW DATABASE customers| name | address | role | requestedStatus | currentStatus | error | default |
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Rows: 1 |
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Starting databases
Databases can be started using the command START DATABASE.
START DATABASE customers0 rows, System updates: 1
The status of the started database can be seen using the command SHOW DATABASE name.
SHOW DATABASE customers| name | address | role | requestedStatus | currentStatus | error | default |
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Rows: 1 |
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Deleting databases
Databases can be deleted using the command DROP DATABASE.
DROP DATABASE customers0 rows, System updates: 1
When a database has been deleted, it will no longer show up in the listing provided by the command SHOW DATABASES.
SHOW DATABASES| name | address | role | requestedStatus | currentStatus | error | default |
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Rows: 4 |
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This command is optionally idempotent, with the default behavior to throw an exception if the database does not exists. Appending IF EXISTS to the command will ensure that no exception is thrown and nothing happens should the database not exist.
DROP DATABASE customers IF EXISTSThe DROP DATABASE command will remove a database entirely. However, you can request that a dump of the store files is produced first, and stored in the path configured using the dbms.directories.dumps.root setting (by default <neo4j-home>/data/dumps). This can be achieved by appending DUMP DATA to the command (or DESTROY DATA to explicitly request the default behaviour). These dumps are equivalent to those produced by neo4j-admin dump and can be similarly restored using neo4j-admin load.
DROP DATABASE customers DUMP DATAThe options IF EXISTS and DUMP DATA/ DESTROY DATA can also be combined. An example could look like this:
DROP DATABASE customers IF EXISTS DUMP DATA