Restoring to a Different Greenplum System Configuration
- To restore a database to a different system configuration

Restoring to a Different Greenplum System Configuration

To perform a parallel restore operation using gpdbrestore, the system you are restoring to must have the same configuration as the system that was backed up. To restore your database objects and data into a different system configuration, for example, to expand into a system with more segments, restore your parallel backup files by loading them through the Greenplum master. To perform a non-parallel restore, you must have:

A full backup set created by a gpcrondump operation. The backup file of the master contains the DDL to recreate your database objects. The backup files of the segments contain the data.
A running Greenplum Database system.
The database you are restoring to exists in the system.

Segment dump files contain a COPY command for each table followed by the data in delimited text format. Collect all of the dump files for all of the segment instances and run them through the master to restore your data and redistribute it across the new system configuration.

To restore a database to a different system configuration

Ensure that you have a complete backup set, including dump files of the master (gp_dump_-1_1_timestamp, gp_dump_-1_1_timestamp_post_data) and one for each segment instance (for example, gp_dump_0_2_timestamp, gp_dump_1_3_timestamp, gp_dump_2_4_timestamp, and so on). Each dump file must have the same timestamp key. gpcrondump creates the dump files in each segment instance’s data directory. You must collect all the dump files and move them to one location on the master host. You can copy each segment dump file to the master, load it, and then delete it after it loads successfully.
Ensure that the database you are restoring to is created in the system. For example:
```
$ createdb <database_name>
```
Load the master dump file to restore the database objects. For example:
```
$ psql <database_name> -f /gpdb/backups/gp_dump_-1_1_20160714
```

Load each segment dump file to restore the data. For example:

$ psql <database_name> -f /gpdb/backups/gp_dump_0_2_20160714
$ psql <database_name> -f /gpdb/backups/gp_dump_1_3_20160714
$ psql <database_name> -f /gpdb/backups/gp_dump_2_4_20160714
$ psql <database_name> -f /gpdb/backups/gp_dump_3_5_20160714
...

Load the post data file to restore database objects such as indexes, triggers, primary key constraints, etc.
```
$ psql <database_name> -f /gpdb/backups/gp_dump_0_5_20160714_post_data
```
Update the database sequences based on the values from the original database.

You can use the system utilities gunzip and egrep to extract the sequence value information from the original Greenplum Database master dump file gp_dump_-1_1_timestamp.gz into a text file. This command extracts the information into the file schema_path_and_seq_next_val.
```
gunzip -c <path_to_master_dump_directory>/gp_dump_-1_1_<timestamp>.gz | egrep "SET search_path|SELECT pg_catalog.setval"  
   > schema_path_and_seq_next_val
```
This example command assumes the original Greenplum Database master dump file is in /data/gpdb/master/gpseg-1/db_dumps/20150112.
```
gunzip -c /data/gpdb/master/gpseg-1/db_dumps/20150112/gp_dump_-1_1_20150112140316.gz 
  | egrep "SET search_path|SELECT pg_catalog.setval" > schema_path_and_seq_next_val
```
After extracting the information, use the Greenplum Database psql utility to update the sequences in the database. This example command updates the sequence information in the database test_restore:
```
psql test_restore -f schema_path_and_seq_next_val
```

Parent topic: Parallel Backup with gpcrondump and gpdbrestore