ScalarDB Schema Loader
ScalarDB has its own data model and schema that maps to the implementation-specific data model and schema. In addition, ScalarDB stores internal metadata, such as transaction IDs, record versions, and transaction statuses, to manage transaction logs and statuses when you use the Consensus Commit transaction manager.
Since managing the schema mapping and metadata for transactions can be difficult, you can use ScalarDB Schema Loader, which is a tool to create schemas that doesn't require you to need in-depth knowledge about schema mapping or metadata.
You have two options to specify general CLI options in Schema Loader:
- Pass the ScalarDB properties file and database-specific or storage-specific options.
- Pass database-specific or storage-specific options without the ScalarDB properties file. (Deprecated)
This tool supports only basic options to create, delete, repair, or alter a table. If you want to use the advanced features of a database, you must alter your tables with a database-specific tool after creating the tables with this tool.
Set up Schema Loader​
Select your preferred method to set up Schema Loader, and follow the instructions.
- Fat JAR
- Docker container
You can download the release versions of Schema Loader from the ScalarDB Releases page.
You can pull the Docker image from the Scalar container registry by running the following command, replacing the contents in the angle brackets as described:
$ docker run --rm -v <PATH_TO_YOUR_LOCAL_SCHEMA_FILE>:<PATH_TO_SCHEMA_FILE_DOCKER> [-v <PATH_TO_LOCAL_SCALARDB_PROPERTIES_FILE>:<PATH_TO_SCALARDB_PROPERTIES_FILE_IN_DOCKER>] ghcr.io/scalar-labs/scalardb-schema-loader:<VERSION> <COMMAND_ARGUMENTS>
You can specify the same command arguments even if you use the fat JAR or the container. In the Available commands section, the JAR is used, but you can run the commands by using the container in the same way by replacing java -jar scalardb-schema-loader-<VERSION>.jar
with docker run --rm -v <PATH_TO_YOUR_LOCAL_SCHEMA_FILE>:<PATH_TO_SCHEMA_FILE_DOCKER> [-v <PATH_TO_LOCAL_SCALARDB_PROPERTIES_FILE>:<PATH_TO_SCALARDB_PROPERTIES_FILE_IN_DOCKER>] ghcr.io/scalar-labs/scalardb-schema-loader:<VERSION>
.
Run Schema Loader​
This section explains how to run Schema Loader.
Available commands​
Select how you would like to configure Schema Loader for your database. The preferred method is to use the properties file since other, database-specific methods are deprecated.
The following commands are available when using the properties file:
Usage: java -jar scalardb-schema-loader-<VERSION>.jar [-D] [--coordinator]
[--no-backup] [--no-scaling] -c=<configPath>
[--compaction-strategy=<compactionStrategy>] [-f=<schemaFile>]
[--replication-factor=<replicaFactor>]
[--replication-strategy=<replicationStrategy>] [--ru=<ru>]
Create/Delete schemas in the storage defined in the config file
-A, --alter Alter tables : it will add new columns and create/delete
secondary index for existing tables. It compares the
provided table schema to the existing schema to decide
which columns need to be added and which indexes need
to be created or deleted
-c, --config=<configPath>
Path to the config file of ScalarDB
--compaction-strategy=<compactionStrategy>
The compaction strategy, must be LCS, STCS or TWCS
(supported in Cassandra)
--coordinator Create/delete/repair Coordinator tables
-D, --delete-all Delete tables
-f, --schema-file=<schemaFile>
Path to the schema json file
--no-backup Disable continuous backup (supported in DynamoDB)
--no-scaling Disable auto-scaling (supported in DynamoDB, Cosmos DB)
--repair-all Repair tables : it repairs the table metadata of
existing tables. When using Cosmos DB, it
additionally repairs stored procedure attached
to each table
--replication-factor=<replicaFactor>
The replication factor (supported in Cassandra)
--replication-strategy=<replicationStrategy>
The replication strategy, must be SimpleStrategy or
NetworkTopologyStrategy (supported in Cassandra)
--ru=<ru> Base resource unit (supported in DynamoDB, Cosmos DB)
For a sample properties file, see database.properties
.
The following database-specific methods have been deprecated. Please use the commands for configuring the properties file instead.
- Cassandra
- Cosmos DB for NoSQL
- DynamoDB
- JDBC databases
Usage: java -jar scalardb-schema-loader-<VERSION>.jar --cassandra [-D]
[-c=<compactionStrategy>] -f=<schemaFile> -h=<hostIp>
[-n=<replicationStrategy>] [-p=<password>] [-P=<port>]
[-R=<replicationFactor>] [-u=<user>]
Create/Delete Cassandra schemas
-A, --alter Alter tables : it will add new columns and create/delete
secondary index for existing tables. It compares the
provided table schema to the existing schema to decide
which columns need to be added and which indexes need
to be created or deleted
-c, --compaction-strategy=<compactionStrategy>
Cassandra compaction strategy, must be LCS, STCS or TWCS
-D, --delete-all Delete tables
-f, --schema-file=<schemaFile>
Path to the schema json file
-h, --host=<hostIp> Cassandra host IP
-n, --network-strategy=<replicationStrategy>
Cassandra network strategy, must be SimpleStrategy or
NetworkTopologyStrategy
-p, --password=<password>
Cassandra password
-P, --port=<port> Cassandra Port
-R, --replication-factor=<replicationFactor>
Cassandra replication factor
--repair-all Repair tables : it repairs the table metadata of
existing tables
-u, --user=<user> Cassandra user
Usage: java -jar scalardb-schema-loader-<VERSION>.jar --cosmos [-D]
[--no-scaling] -f=<schemaFile> -h=<uri> -p=<key> [-r=<ru>]
Create/Delete Cosmos DB schemas
-A, --alter Alter tables : it will add new columns and create/delete
secondary index for existing tables. It compares the
provided table schema to the existing schema to decide
which columns need to be added and which indexes need
to be created or deleted
-D, --delete-all Delete tables
-f, --schema-file=<schemaFile>
Path to the schema json file
-h, --host=<uri> Cosmos DB account URI
--no-scaling Disable auto-scaling for Cosmos DB
-p, --password=<key> Cosmos DB key
-r, --ru=<ru> Base resource unit
--repair-all Repair tables : it repairs the table metadata of
existing tables and repairs stored procedure
attached to each table
Usage: java -jar scalardb-schema-loader-<VERSION>.jar --dynamo [-D]
[--no-backup] [--no-scaling] [--endpoint-override=<endpointOverride>]
-f=<schemaFile> -p=<awsSecKey> [-r=<ru>] --region=<awsRegion>
-u=<awsKeyId>
Create/Delete DynamoDB schemas
-A, --alter Alter tables : it will add new columns and create/delete
secondary index for existing tables. It compares the
provided table schema to the existing schema to decide
which columns need to be added and which indexes need
to be created or deleted
-D, --delete-all Delete tables
--endpoint-override=<endpointOverride>
Endpoint with which the DynamoDB SDK should
communicate
-f, --schema-file=<schemaFile>
Path to the schema json file
--no-backup Disable continuous backup for DynamoDB
--no-scaling Disable auto-scaling for DynamoDB
-p, --password=<awsSecKey> AWS access secret key
-r, --ru=<ru> Base resource unit
--region=<awsRegion> AWS region
--repair-all Repair tables : it repairs the table metadata of
existing tables
-u, --user=<awsKeyId> AWS access key ID
Usage: java -jar scalardb-schema-loader-<VERSION>.jar --jdbc [-D]
-f=<schemaFile> -j=<url> -p=<password> -u=<user>
Create/Delete JDBC schemas
-A, --alter Alter tables : it will add new columns and create/delete
secondary index for existing tables. It compares the
provided table schema to the existing schema to decide
which columns need to be added and which indexes need
to be created or deleted
-D, --delete-all Delete tables
-f, --schema-file=<schemaFile>
Path to the schema json file
-j, --jdbc-url=<url> JDBC URL
-p, --password=<password>
JDBC password
--repair-all Repair tables : it repairs the table metadata of
existing tables
-u, --user=<user> JDBC user
Create namespaces and tables​
To create namespaces and tables by using a properties file, run the following command, replacing the contents in the angle brackets as described:
$ java -jar scalardb-schema-loader-<VERSION>.jar --config <PATH_TO_SCALARDB_PROPERTIES_FILE> -f <PATH_TO_SCHEMA_FILE> [--coordinator]
If --coordinator
is specified, a Coordinator table will be created.
The following database-specific CLI arguments have been deprecated. Please use the CLI arguments for configuring the properties file instead.
- Cassandra
- Cosmos DB for NoSQL
- DynamoDB
- JDBC databases
$ java -jar scalardb-schema-loader-<VERSION>.jar --cassandra -h <CASSANDRA_IP> [-P <CASSANDRA_PORT>] [-u <CASSANDRA_USER>] [-p <CASSANDRA_PASSWORD>] -f <PATH_TO_SCHEMA_FILE> [-n <NETWORK_STRATEGY>] [-R <REPLICATION_FACTOR>]
- If
-P <CASSANDRA_PORT>
is not supplied, it defaults to9042
. - If
-u <CASSANDRA_USER>
is not supplied, it defaults tocassandra
. - If
-p <CASSANDRA_PASSWORD>
is not supplied, it defaults tocassandra
. <NETWORK_STRATEGY>
should beSimpleStrategy
orNetworkTopologyStrategy
$ java -jar scalardb-schema-loader-<VERSION>.jar --cosmos -h <COSMOS_DB_FOR_NOSQL_ACCOUNT_URI> -p <COSMOS_DB_FOR_NOSQL_KEY> -f <PATH_TO_SCHEMA_FILE> [-r BASE_RESOURCE_UNIT]
<COSMOS_DB_FOR_NOSQL_KEY>
you can use a primary key or a secondary key.-r BASE_RESOURCE_UNIT
is an option. You can specify the RU of each database. The maximum RU in tables in the database will be set. If you don't specify RU of tables, the database RU will be set with this option. By default, it's 400.
$ java -jar scalardb-schema-loader-<VERSION>.jar --dynamo -u <AWS_ACCESS_KEY_ID> -p <AWS_ACCESS_SECRET_KEY> --region <REGION> -f <PATH_TO_SCHEMA_FILE> [-r BASE_RESOURCE_UNIT]
<REGION>
should be a string to specify an AWS region likeap-northeast-1
.-r
option is almost the same as Cosmos DB for NoSQL option. However, the unit means DynamoDB capacity unit. The read and write capacity units are set the same value.
$ java -jar scalardb-schema-loader-<VERSION>.jar --jdbc -j <JDBC_URL> -u <USER> -p <PASSWORD> -f <PATH_TO_SCHEMA_FILE>
Alter tables​
You can use a command to add new columns to and create or delete a secondary index for existing tables. This command compares the provided table schema to the existing schema to decide which columns need to be added and which indexes need to be created or deleted.
To add new columns to and create or delete a secondary index for existing tables, run the following command, replacing the contents in the angle brackets as described:
$ java -jar scalardb-schema-loader-<VERSION>.jar --config <PATH_TO_SCALARDB_PROPERTIES_FILE> -f <PATH_TO_SCHEMA_FILE> --alter
The following database-specific CLI arguments have been deprecated. Please use the CLI arguments for configuring the properties file instead.
- Cassandra
- Cosmos DB for NoSQL
- DynamoDB
- JDBC databases
$ java -jar scalardb-schema-loader-<VERSION>.jar --cassandra -h <CASSANDRA_IP> [-P <CASSANDRA_PORT>] [-u <CASSANDRA_USER>] [-p <CASSANDRA_PASSWORD>] -f <PATH_TO_SCHEMA_FILE> --alter
$ java -jar scalardb-schema-loader-<VERSION>.jar --cosmos -h <COSMOS_DB_FOR_NOSQL_ACCOUNT_URI> -p <COSMOS_DB_FOR_NOSQL_KEY> -f <PATH_TO_SCHEMA_FILE> --alter
$ java -jar scalardb-schema-loader-<VERSION>.jar --dynamo -u <AWS_ACCESS_KEY_ID> -p <AWS_ACCESS_SECRET_KEY> --region <REGION> -f <PATH_TO_SCHEMA_FILE> --alter
$ java -jar scalardb-schema-loader-<VERSION>.jar --jdbc -j <JDBC_URL> -u <USER> -p <PASSWORD> -f <PATH_TO_SCHEMA_FILE> --alter
Delete tables​
You can delete tables by using the properties file. To delete tables, run the following command, replacing the contents in the angle brackets as described:
$ java -jar scalardb-schema-loader-<VERSION>.jar --config <PATH_TO_SCALARDB_PROPERTIES_FILE> -f <PATH_TO_SCHEMA_FILE> [--coordinator] -D
If --coordinator
is specified, the Coordinator table will be deleted as well.
The following database-specific CLI arguments have been deprecated. Please use the CLI arguments for configuring the properties file instead.
- Cassandra
- Cosmos DB for NoSQL
- DynamoDB
- JDBC databases
$ java -jar scalardb-schema-loader-<VERSION>.jar --cassandra -h <CASSANDRA_IP> [-P <CASSANDRA_PORT>] [-u <CASSANDRA_USER>] [-p <CASSANDRA_PASSWORD>] -f <PATH_TO_SCHEMA_FILE> -D
$ java -jar scalardb-schema-loader-<VERSION>.jar --cosmos -h <COSMOS_DB_FOR_NOSQL_ACCOUNT_URI> -p <COSMOS_DB_FOR_NOSQL_KEY> -f <PATH_TO_SCHEMA_FILE> -D
$ java -jar scalardb-schema-loader-<VERSION>.jar --dynamo -u <AWS_ACCESS_KEY_ID> -p <AWS_ACCESS_SECRET_KEY> --region <REGION> -f <PATH_TO_SCHEMA_FILE> -D
$ java -jar scalardb-schema-loader-<VERSION>.jar --jdbc -j <JDBC_URL> -u <USER> -p <PASSWORD> -f <PATH_TO_SCHEMA_FILE> -D
Repair tables​
You can repair the table metadata of existing tables by using the properties file. To repair table metadata of existing tables, run the following command, replacing the contents in the angle brackets as described:
$ java -jar scalardb-schema-loader-<VERSION>.jar --config <PATH_TO_SCALARDB_PROPERTIES_FILE> -f <PATH_TO_SCHEMA_FILE> [--coordinator] --repair-all
If --coordinator
is specified, the Coordinator table will be repaired as well. In addition, if you're using Cosmos DB for NoSQL, running this command will also repair stored procedures attached to each table.
The following database-specific CLI arguments have been deprecated. Please use the CLI arguments for configuring the properties file instead.
- Cassandra
- Cosmos DB for NoSQL
- DynamoDB
- JDBC databases
$ java -jar scalardb-schema-loader-<VERSION>.jar --cassandra -h <CASSANDRA_IP> [-P <CASSANDRA_PORT>] [-u <CASSANDRA_USER>] [-p <CASSANDRA_PASSWORD>] -f <PATH_TO_SCHEMA_FILE> --repair-all
$ java -jar scalardb-schema-loader-<VERSION>.jar --cosmos -h <COSMOS_DB_FOR_NOSQL_ACCOUNT_URI> -p <COSMOS_DB_FOR_NOSQL_KEY> -f <PATH_TO_SCHEMA_FILE> --repair-all
$ java -jar scalardb-schema-loader-<VERSION>.jar --dynamo -u <AWS_ACCESS_KEY_ID> -p <AWS_ACCESS_SECRET_KEY> --region <REGION> [--no-backup] -f <PATH_TO_SCHEMA_FILE> --repair-all
$ java -jar scalardb-schema-loader-<VERSION>.jar --jdbc -j <JDBC_URL> -u <USER> -p <PASSWORD> -f <PATH_TO_SCHEMA_FILE> --repair-all
Sample schema file​
The following is a sample schema. For a sample schema file, see schema_sample.json
.
{
"sample_db.sample_table": {
"transaction": false,
"partition-key": [
"c1"
],
"clustering-key": [
"c4 ASC",
"c6 DESC"
],
"columns": {
"c1": "INT",
"c2": "TEXT",
"c3": "BLOB",
"c4": "INT",
"c5": "BOOLEAN",
"c6": "INT"
},
"secondary-index": [
"c2",
"c4"
]
},
"sample_db.sample_table1": {
"transaction": true,
"partition-key": [
"c1"
],
"clustering-key": [
"c4"
],
"columns": {
"c1": "INT",
"c2": "TEXT",
"c3": "INT",
"c4": "INT",
"c5": "BOOLEAN"
}
},
"sample_db.sample_table2": {
"transaction": false,
"partition-key": [
"c1"
],
"clustering-key": [
"c4",
"c3"
],
"columns": {
"c1": "INT",
"c2": "TEXT",
"c3": "INT",
"c4": "INT",
"c5": "BOOLEAN"
}
}
}
The schema has table definitions that include columns
, partition-key
, clustering-key
, secondary-index
, and transaction
fields.
- The
columns
field defines columns of the table and their data types. - The
partition-key
field defines which columns the partition key is composed of. - The
clustering-key
field defines which columns the clustering key is composed of. - The
secondary-index
field defines which columns are indexed. - The
transaction
field indicates whether the table is for transactions or not.- If you set the
transaction
field totrue
or don't specify thetransaction
field, this tool creates a table with transaction metadata if needed. - If you set the
transaction
field tofalse
, this tool creates a table without any transaction metadata (that is, for a table with Storage API).
- If you set the
You can also specify database or storage-specific options in the table definition as follows:
{
"sample_db.sample_table3": {
"partition-key": [
"c1"
],
"columns": {
"c1": "INT",
"c2": "TEXT",
"c3": "BLOB"
},
"compaction-strategy": "LCS",
"ru": 5000
}
}
The database or storage-specific options you can specify are as follows:
- Cassandra
- Cosmos DB for NoSQL
- DynamoDB
- JDBC databases
The compaction-strategy
option is the compaction strategy used. This option should be STCS
(SizeTieredCompaction), LCS
(LeveledCompactionStrategy), or TWCS
(TimeWindowCompactionStrategy).
The ru
option stands for Request Units. For details, see RUs.
The ru
option stands for Request Units. For details, see RUs.
No options are available for JDBC databases.
Scale for performance when using Cosmos DB for NoSQL or DynamoDB​
When using Cosmos DB for NoSQL or DynamoDB, you can scale by using Request Units (RUs) or auto-scaling.
RUs​
You can scale the throughput of Cosmos DB for NoSQL and DynamoDB by specifying the --ru
option. When specifying this option, scaling applies to all tables or the ru
parameter for each table.
If the --ru
option is not set, the default values will be 400
for Cosmos DB for NoSQL and 10
for DynamoDB.
- Schema Loader abstracts Request Units for Cosmos DB for NoSQL and Capacity Units for DynamoDB with
RU
. Therefore, be sure to set an appropriate value depending on the database implementation. - Be aware that Schema Loader sets the same value to both read capacity unit and write capacity unit for DynamoDB.
Auto-scaling​
By default, Schema Loader enables auto-scaling of RUs for all tables: RUs scale between 10 percent and 100 percent of a specified RU depending on the workload. For example, if you specify -r 10000
, the RUs of each table auto-scales between 1000
and 10000
.
Auto-scaling for Cosmos DB for NoSQL is enabled only when this option is set to 4000
or more.
Data-type mapping between ScalarDB and other databases​
The following table shows the supported data types in ScalarDB and their mapping to the data types of other databases.
ScalarDB | Cassandra | Cosmos DB for NoSQL | DynamoDB | MySQL | PostgreSQL | Oracle | SQL Server |
---|---|---|---|---|---|---|---|
BOOLEAN | boolean | boolean (JSON) | BOOL | boolean | boolean | number(1) | bit |
INT | int | number (JSON) | N | int | int | int | int |
BIGINT | bigint | number (JSON) | N | bigint | bigint | number(19) | bigint |
FLOAT | float | number (JSON) | N | double | float | binary_float | float(24) |
DOUBLE | double | number (JSON) | N | double | double precision | binary_double | float |
TEXT | text | string (JSON) | S | longtext | text | varchar2(4000) | varchar(8000) |
BLOB | blob | string (JSON) | B | longblob | bytea | RAW(2000) | varbinary(8000) |
However, the following data types in JDBC databases are converted differently when they are used as a primary key or a secondary index key. This is due to the limitations of RDB data types.
ScalarDB | MySQL | PostgreSQL | Oracle |
---|---|---|---|
TEXT | VARCHAR(64) | VARCHAR(10485760) | VARCHAR2(64) |
BLOB | VARBINARY(64) | RAW(64) |
The value range of BIGINT
in ScalarDB is from -2^53 to 2^53, regardless of the underlying database.
If this data-type mapping doesn't match your application, please alter the tables to change the data types after creating them by using this tool.
Internal metadata for Consensus Commit​
The Consensus Commit transaction manager manages metadata (for example, transaction ID, record version, and transaction status) stored along with the actual records to handle transactions properly.
Thus, along with any columns that the application requires, additional columns for the metadata need to be defined in the schema. Additionally, this tool creates a table with the metadata if you use the Consensus Commit transaction manager.
Use Schema Loader in your application​
You can check the version of Schema Loader from the Maven Central Repository. For example in Gradle, you can add the following dependency to your build.gradle
file, replacing <VERSION>
with the version of Schema Loader that you want to use:
dependencies {
implementation 'com.scalar-labs:scalardb-schema-loader:<VERSION>'
}
Create, alter, repair, or delete tables​
You can create, alter, delete, or repair tables that are defined in the schema by using Schema Loader. To do this, you can pass a ScalarDB properties file, schema, and additional options, if needed, as shown below:
public class SchemaLoaderSample {
public static int main(String... args) throws SchemaLoaderException {
Path configFilePath = Paths.get("database.properties");
// "sample_schema.json" and "altered_sample_schema.json" can be found in the "/sample" directory.
Path schemaFilePath = Paths.get("sample_schema.json");
Path alteredSchemaFilePath = Paths.get("altered_sample_schema.json");
boolean createCoordinatorTables = true; // whether to create the Coordinator table or not
boolean deleteCoordinatorTables = true; // whether to delete the Coordinator table or not
boolean repairCoordinatorTables = true; // whether to repair the Coordinator table or not
Map<String, String> tableCreationOptions = new HashMap<>();
tableCreationOptions.put(
CassandraAdmin.REPLICATION_STRATEGY, ReplicationStrategy.SIMPLE_STRATEGY.toString());
tableCreationOptions.put(CassandraAdmin.COMPACTION_STRATEGY, CompactionStrategy.LCS.toString());
tableCreationOptions.put(CassandraAdmin.REPLICATION_FACTOR, "1");
tableCreationOptions.put(DynamoAdmin.REQUEST_UNIT, "1");
tableCreationOptions.put(DynamoAdmin.NO_SCALING, "true");
tableCreationOptions.put(DynamoAdmin.NO_BACKUP, "true");
Map<String, String> indexCreationOptions = new HashMap<>();
indexCreationOptions.put(DynamoAdmin.NO_SCALING, "true");
Map<String, String> tableReparationOptions = new HashMap<>();
indexCreationOptions.put(DynamoAdmin.NO_BACKUP, "true");
// Create tables.
SchemaLoader.load(configFilePath, schemaFilePath, tableCreationOptions, createCoordinatorTables);
// Alter tables.
SchemaLoader.alterTables(configFilePath, alteredSchemaFilePath, indexCreationOptions);
// Repair tables.
SchemaLoader.repairTables(configFilePath, schemaFilePath, tableReparationOptions, repairCoordinatorTables);
// Delete tables.
SchemaLoader.unload(configFilePath, schemaFilePath, deleteCoordinatorTables);
return 0;
}
}
You can also create, delete, or repair a schema by passing a serialized-schema JSON string (the raw text of a schema file) as shown below:
// Create tables.
SchemaLoader.load(configFilePath, serializedSchemaJson, tableCreationOptions, createCoordinatorTables);
// Alter tables.
SchemaLoader.alterTables(configFilePath, serializedAlteredSchemaFilePath, indexCreationOptions);
// Repair tables.
SchemaLoader.repairTables(configFilePath, serializedSchemaJson, tableReparationOptions, repairCoordinatorTables);
// Delete tables.
SchemaLoader.unload(configFilePath, serializedSchemaJson, deleteCoordinatorTables);
When configuring ScalarDB, you can use a Properties
object as well, as shown below:
// Create tables.
SchemaLoader.load(properties, serializedSchemaJson, tableCreationOptions, createCoordinatorTables);
// Alter tables.
SchemaLoader.alterTables(properties, serializedAlteredSchemaFilePath, indexCreationOptions);
// Repair tables.
SchemaLoader.repairTables(properties, serializedSchemaJson, tableReparationOptions, repairCoordinatorTables);
// Delete tables.
SchemaLoader.unload(properties, serializedSchemaJson, deleteCoordinatorTables);