`snapshotReference` command

The snapshotReference command captures the current state of the referenceURL database, which is the source database.

The snapshot command has two modes:

When run without options, it gathers the current state of the database and shows a text-based version of the schema to STDOUT.
When run with the --snapshotFormat=JSON option, it creates a JSON file that represents the current state of the referenceURL database. Alternatively, you can have a YAML-based output by using the --snapshotFormat=yaml attribute.

Uses

The snapshotReference command is typically used when you want to see changes in your source database or keep a record of your current database state.

The snapshot can be used in the diff command or diffChangeLog command.

Note: It is best practice to use the --snapshotFormat=JSON option for the diff and diffChangeLog commands. Otherwise, you will get only a text report of your source database. This text report cannot be used for comparison in the future.

It can also be used to compare:

A previous database state to an online database.
A previous database state to another snapshot.

Note: Running a diff command by using at least one snapshot.json file is faster than using a diff command with two online databases. However, keep in mind that a snapshot will no longer reflect the current state of the database if the database is changed with the update command or if it is changed manually.

Running the `snapshotReference` command

To run the snapshotReference command, you can specify the driver, classpath, and URL in your liquibase.properties file. For more information, see Creating and configuring a liquibase.properties file. You can also specify these properties in your command line.

Then run the snapshotReference command:

liquibase snapshotReference

Note: To create a JSON file, add the --snapshotFormat=json attribute while running the command:

liquibase --outputFile=mySnapshot.json snapshotReference --snapshotFormat=json

Note: Enter the name of the output file that you want to use in place of mySnapshot.json. Additionally, include --snapshotFormat=json to create a file in a JSON format.

`snapshotReference` global attributes

Attributes	Definition	Requirement
`--username`	The database username	Required
`--password`	The database password	Required
`--url`	The JDBC database connection	Required
`--outputFile`*	Specifies the file path to where the snapshot JSON or YAML will be written	Optional

* If not specified, a JSON or YAML output goes to STDOUT.

Note: The username and password attributes are not required for connections and systems which use alternate means of authentication.

`snapshotReference` command attributes

Attributes	Definition	Requirement
`--snapshotFormat`	Creates a JSON or YAML file that represents the current state of the database.	Optional

Using the `snapshot` in the `diff` and `diffChangeLog` commands

You can use the JSON format snapshot file in the diff and diffChangeLog commands. One of the typical workflows is the following:

Make sure your local environment is up-to-date by getting the latest changelog from source control.
Configure your liquibase.properties file to point to a local development database and run the update command to ensure your target database matches the changelog file.
Take a snapshot of the local development database by running the snapshotReference command:

liquibase --outputFile=mySnapshot.json snapshotReference --snapshotFormat=json

Manually change the local development database if needed.
Append changes to the changelog by running the diffChangeLog command:

liquibase --url=jdbc:oracle:thin://localhost:9090/mem:test --referenceUrl=offline:mysql?snapshot=mySnapshot.json diffChangeLog

Note: If you want to see changes without appending them to the changelog file, add --changeLogFile=mydiffchangelog.xml to the diffChangeLog command:

liquibase --url=jdbc:oracle:thin://localhost:9090/mem:test --referenceUrl=offline:mysql?snapshot=mySnapshot.json --changeLogFile=mydiffchangelog.xml diffChangeLog

Note: The format for the referenceUrl is the following: offline:<db_type>?snapshot=<path/to/snapshot.json>. Use the name of your database type from the list of the supported databases in place of <db_type> and the path relative to where the command is running in place of <path/to/snapshot.json>: "offline:<db_type>?snapshot=<path/to/snapshot.json>".

Review the changelog file to ensure that it matches your expectations of the manual changes that were made.
Mark the manual changes as deployed in the local development database by running the changelogSync command:

liquibase changeLogSync

Commit the changes to the source control.

Output

When running the snapshotReference command with the --snapshotFormat attribute, the output can be as follows:

Liquibase Pro 3.8.7 by Datical licensed to Liquibase Pro Customer until Tue Sep 22 19:00:00 CDT 2020
Liquibase command 'snapshotReference' was executed successfully.

When running the snapshotReference command without indicating the --snapshotFormat, you receive the following output:

Liquibase Pro 3.8.7 by Datical licensed to Liquibase Pro Customer until Tue Sep 22 19:00:00 CDT 2020
Database snapshot for jdbc:oracle:thin:@localhost:1521:ORCL
-----------------------------------------------------------------
Database type: Oracle
Database version: Oracle Database 11g Release 11.1.0.0.0 - Production
Database user: SCHEMA2
Included types:
com.datical.liquibase.ext.appdba.synonym.Synonym
com.datical.liquibase.ext.storedlogic.checkconstraint.CheckConstraint
com.datical.liquibase.ext.storedlogic.databasepackage.DatabasePackage
com.datical.liquibase.ext.storedlogic.databasepackage.DatabasePackageBody
com.datical.liquibase.ext.storedlogic.function.Function
com.datical.liquibase.ext.storedlogic.trigger.Trigger
liquibase.structure.core.Catalog
liquibase.structure.core.Column
liquibase.structure.core.ForeignKey
liquibase.structure.core.Index
liquibase.structure.core.PrimaryKey
liquibase.structure.core.Schema
liquibase.structure.core.Sequence
liquibase.structure.core.StoredProcedure
liquibase.structure.core.Table
liquibase.structure.core.UniqueConstraint
liquibase.structure.core.View
Catalog: SCHEMA2

The snapshotReference command produces a JSON file that contains all your objects and places the file in the same directory as your changelog.

mySnapshot.json example

{
"snapshot": {
"created": "2020-07-22T08:45:07.624",
"database": {
"productVersion": "11.5",
"shortName": "postgresql",
"majorVersion": "11",
"minorVersion": "5",
"user": "daticaluser1",
"productName": "PostgreSQL",
"url": "jdbc:postgresql://localhost:5433/goku"
},
"objects": {
"liquibase.structure.core.Catalog": [
{
"catalog": {
"default": true,
"name": "goku",
"snapshotId": "bb2c100"
}
}]
,
"liquibase.structure.core.Column": [
{
"column": {
"name": "comments",
"nullable": true,
"order": "9!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c110",
"snapshotId": "bb2c119",
"type": {
"characterOctetLength": "255!{java.lang.Integer}",
"columnSize": "255!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "description",
"nullable": true,
"order": "8!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c110",
"snapshotId": "bb2c118",
"type": {
"characterOctetLength": "255!{java.lang.Integer}",
"columnSize": "255!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "exectype",
"nullable": false,
"order": "6!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c110",
"snapshotId": "bb2c116",
"type": {
"characterOctetLength": "10!{java.lang.Integer}",
"columnSize": "10!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "id",
"nullable": false,
"order": "1!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c125",
"snapshotId": "bb2c127",
"type": {
"characterOctetLength": "10!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "4!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "int4"
}
}
},
{
"column": {
"name": "id",
"nullable": true,
"order": "1!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c132",
"snapshotId": "bb2c133",
"type": {
"characterOctetLength": "10!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "4!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "int4"
}
}
},
{
"column": {
"name": "locked",
"nullable": false,
"order": "2!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c125",
"snapshotId": "bb2c128",
"type": {
"characterOctetLength": "1!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "-7!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "bool"
}
}
},
{
"column": {
"name": "lockedby",
"nullable": true,
"order": "4!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c125",
"snapshotId": "bb2c130",
"type": {
"characterOctetLength": "255!{java.lang.Integer}",
"columnSize": "255!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "lockgranted",
"nullable": true,
"order": "3!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c125",
"snapshotId": "bb2c129",
"type": {
"characterOctetLength": "29!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "93!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "timestamp"
}
}
},
{
"column": {
"name": "md5sum",
"nullable": true,
"order": "7!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c110",
"snapshotId": "bb2c117",
"type": {
"characterOctetLength": "35!{java.lang.Integer}",
"columnSize": "35!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "name",
"nullable": true,
"order": "2!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c132",
"snapshotId": "bb2c134",
"type": {
"characterOctetLength": "50!{java.lang.Integer}",
"columnSize": "50!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "supplier_id",
"nullable": true,
"order": "1!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c104",
"snapshotId": "bb2c105",
"type": {
"characterOctetLength": "4!{java.lang.Integer}",
"columnSize": "4!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "2!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "numeric"
}
}
},
{
"column": {
"name": "supplier_id",
"nullable": true,
"order": "1!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c107",
"snapshotId": "bb2c108",
"type": {
"characterOctetLength": "4!{java.lang.Integer}",
"columnSize": "4!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "2!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "numeric"
}
}
},
{
"column": {
"name": "supplier_name",
"nullable": true,
"order": "2!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c104",
"snapshotId": "bb2c106",
"type": {
"characterOctetLength": "50!{java.lang.Integer}",
"columnSize": "50!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "supplier_name",
"nullable": true,
"order": "2!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c107",
"snapshotId": "bb2c109",
"type": {
"characterOctetLength": "50!{java.lang.Integer}",
"columnSize": "50!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "supplier_name",
"nullable": true,
"order": "1!{java.lang.Integer}",
"relation": "liquibase.structure.core.View#bb2c102",
"snapshotId": "bb2c103",
"type": {
"characterOctetLength": "50!{java.lang.Integer}",
"columnSize": "50!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
},
{
"column": {
"name": "tag",
"nullable": true,
"order": "10!{java.lang.Integer}",
"relation": "liquibase.structure.core.Table#bb2c110",
"snapshotId": "bb2c120",
"type": {
"characterOctetLength": "255!{java.lang.Integer}",
"columnSize": "255!{java.lang.Integer}",
"columnSizeUnit": "BYTE!{liquibase.structure.core.DataType$ColumnSizeUnit}",
"dataTypeId": "12!{java.lang.Integer}",
"radix": "10!{java.lang.Integer}",
"typeName": "varchar"
}
}
}]
,
"liquibase.structure.core.Index": [
{
"index": {
"columns": [
"liquibase.structure.core.Column#bb2c127"]
,
"name": "databasechangeloglock_pkey",
"snapshotId": "bb2c126",
"table": "liquibase.structure.core.Table#bb2c125",
"unique": true
}
}]
,
"liquibase.structure.core.PrimaryKey": [
{
"primaryKey": {
"backingIndex": "liquibase.structure.core.Index#bb2c126",
"columns": [
"liquibase.structure.core.Column#bb2c127"]
,
"name": "databasechangeloglock_pkey",
"snapshotId": "bb2c131",
"table": "liquibase.structure.core.Table#bb2c125"
}
}]
,
"liquibase.structure.core.Schema": [
{
"schema": {
"catalog": "liquibase.structure.core.Catalog#bb2c100",
"default": true,
"name": "public",
"snapshotId": "bb2c101"
}
}]
,
"liquibase.structure.core.Table": [
{
"table": {
"columns": [
"liquibase.structure.core.Column#bb2c116",
"liquibase.structure.core.Column#bb2c117",
"liquibase.structure.core.Column#bb2c118",
"liquibase.structure.core.Column#bb2c119",
"liquibase.structure.core.Column#bb2c120",
,
"default_tablespace": false,
"name": "databasechangelog",
"schema": "liquibase.structure.core.Schema#bb2c101",
"snapshotId": "bb2c110"
}
},
{
"table": {
"columns": [
"liquibase.structure.core.Column#bb2c127",
"liquibase.structure.core.Column#bb2c128",
"liquibase.structure.core.Column#bb2c129",
"liquibase.structure.core.Column#bb2c130"]
,
"default_tablespace": false,
"indexes": [
"liquibase.structure.core.Index#bb2c126"]
,
"name": "databasechangeloglock",
"primaryKey": "liquibase.structure.core.PrimaryKey#bb2c131",
"schema": "liquibase.structure.core.Schema#bb2c101",
"snapshotId": "bb2c125"
}
},
{
"table": {
"columns": [
"liquibase.structure.core.Column#bb2c105",
"liquibase.structure.core.Column#bb2c106"]
,
"default_tablespace": false,
"name": "testcp",
"schema": "liquibase.structure.core.Schema#bb2c101",
"snapshotId": "bb2c104"
}
},
{
"table": {
"columns": [
"liquibase.structure.core.Column#bb2c108",
"liquibase.structure.core.Column#bb2c109"]
,
"default_tablespace": false,
"name": "testtable1",
"schema": "liquibase.structure.core.Schema#bb2c101",
"snapshotId": "bb2c107"
}
},
{
"table": {
"columns": [
"liquibase.structure.core.Column#bb2c133",
"liquibase.structure.core.Column#bb2c134"]
,
"default_tablespace": false,
"name": "vacuumtest",
"schema": "liquibase.structure.core.Schema#bb2c101",
"snapshotId": "bb2c132"
}
}]
,
"liquibase.structure.core.View": [
{
"view": {
"columns": [
"liquibase.structure.core.Column#bb2c103"]
,
"definition": " SELECT testtable1.supplier_name\n   FROM testtable1\n  ORDER BY testtable1.supplier_name DESC;",
"name": "testview1",
"schema": "liquibase.structure.core.Schema#bb2c101",
"snapshotId": "bb2c102"
}
}]

},
"snapshotControl": {
"snapshotControl": {
"includedType": [
"com.datical.liquibase.ext.appdba.synonym.Synonym",
"com.datical.liquibase.ext.storedlogic.checkconstraint.CheckConstraint",
"com.datical.liquibase.ext.storedlogic.databasepackage.DatabasePackage",
"com.datical.liquibase.ext.storedlogic.databasepackage.DatabasePackageBody",
"com.datical.liquibase.ext.storedlogic.function.Function",
"com.datical.liquibase.ext.storedlogic.trigger.Trigger",
"liquibase.structure.core.Catalog",
"liquibase.structure.core.Column",
"liquibase.structure.core.ForeignKey",
"liquibase.structure.core.Index",
"liquibase.structure.core.PrimaryKey",
"liquibase.structure.core.Schema",
"liquibase.structure.core.Sequence",
"liquibase.structure.core.StoredProcedure",
"liquibase.structure.core.Table",
"liquibase.structure.core.UniqueConstraint",
"liquibase.structure.core.View"]

}
}
}
}

Liquibase Community snapshotReference categories:

Catalog
Column
Foreign Key
Index
Primary Key
Schema
Sequence
Unique Constraints
View

Liquibase Pro snapshotReference categories:

Package
Package Body
Procedures
Function
Trigger
Synonyms
Check Constraints

snapshotReference command

Uses

Running the snapshotReference command

snapshotReference global attributes

snapshotReference command attributes

Using the snapshot in the diff and diffChangeLog commands

`snapshotReference` command

Running the `snapshotReference` command

`snapshotReference` global attributes

`snapshotReference` command attributes

Using the `snapshot` in the `diff` and `diffChangeLog` commands