Parallel Backup with gpbackup and gprestore
Parallel Backup with gpbackup and gprestore
gpbackup and gprestore are Tanzu Greenplum utilities that create and restore backup sets for Greenplum Database. By default, gpbackup stores only the object metadata files and DDL files for a backup in the Greenplum Database master data directory. Greenplum Database segments use the COPY ... ON SEGMENT command to store their data for backed-up tables in compressed CSV data files, located in each segment's backups directory.
The backup metadata files contain all of the information that gprestore needs to restore a full backup set in parallel. Backup metadata also provides the framework for restoring only individual objects in the data set, along with any dependent objects, in future versions of gprestore. (See Understanding Backup Files for more information.) Storing the table data in CSV files also provides opportunities for using other restore utilities, such as gpload, to load the data either in the same cluster or another cluster. By default, one file is created for each table on the segment. You can specify the --leaf-partition-data option with gpbackup to create one data file per leaf partition of a partitioned table, instead of a single file. This option also enables you to filter backup sets by leaf partitions.
Each gpbackup task uses a single transaction in Greenplum Database. During this transaction, metadata is backed up on the master host, and data for each table on each segment host is written to CSV backup files using COPY ... ON SEGMENT commands in parallel. The backup process acquires an ACCESS SHARE lock on each table that is backed up.
Requirements and Limitations
The gpbackup and gprestore utilities are compatible with these Greenplum Database versions:
- Tanzu Greenplum 4.3.22 and later
- Tanzu Greenplum 5.5.0 and later
- Tanzu Greenplum 6.0.0 and later
- If you create an index on a parent partitioned table, gpbackup does not back up that same index on child partitioned tables of the parent, as creating the same index on a child would cause an error. However, if you exchange a partition, gpbackup does not detect that the index on the exchanged partition is inherited from the new parent table. In this case, gpbackup backs up conflicting CREATE INDEX statements, which causes an error when you restore the backup set.
- You can execute multiple instances of gpbackup, but each execution requires a distinct timestamp.
- Database object filtering is currently limited to schemas and tables.
- When backing up a partitioned table where some or all leaf partitions are in different
schemas from the root partition, the leaf partition table definitions, including the
schemas, are backed up as metadata. This occurs even if the backup operation specifies
that schemas that contain the leaf partitions should be excluded. To control data being
backed up for this type of partitioned table in this situation, use the
- If the --leaf-partition-data option is not specified, the leaf partition data is also backed up even if the backup operation specifies that the leaf partition schemas should be excluded.
- If the --leaf-partition-data option is specified, the leaf partition data will not be backed up if the backup operation specifies that the leaf partition schemas should be excluded. Only the metadata for leaf partition tables are backed up.
- If you specify a leaf partition name with --exclude-table or in a file used with --exclude-table-table, gpbackup ignores the partition name. The leaf partition is not excluded from the backup.
- If you use the gpbackup --single-data-file option to combine table backups into a single file per segment, you cannot perform a parallel restore operation with gprestore (cannot set --jobs to a value higher than 1).
- Backing up a database with gpbackup while simultaneously running DDL
commands might cause gpbackup to fail, in order to ensure consistency
within the backup set. For example, if a table is dropped after the start of the backup
operation, gpbackup exits and displays the error message ERROR:
relation <schema.table> does not
gpbackup might fail when a table is dropped during a backup operation due to table locking issues. gpbackup generates a list of tables to back up and acquires an ACCESS SHARED lock on the tables. If an EXCLUSIVE LOCK is held on a table, gpbackup acquires the ACCESS SHARED lock after the existing lock is released. If the table no longer exists when gpbackup attempts to acquire a lock on the table, gpbackup exits with the error message.
For tables that might be dropped during a backup, you can exclude the tables from a backup with a gpbackup table filtering option such as --exclude-table or --exclude-schema.
- A backup created with gpbackup can only be restored to a Greenplum Database cluster with the same number of segment instances as the source cluster. If you run gpexpand to add segments to the cluster, backups you made before starting the expand cannot be restored after the expansion has completed.
Objects Included in a Backup or Restore
The following table lists the objects that are backed up and restored with gpbackup and gprestore.
Database objects are backed up for the database you specify with the --dbname option.
|Database Objects||Global Objects|
When restoring to an existing database, gprestore assumes the public schema exists when restoring objects to the public schema. When restoring to a new database (with the --create-db option), gprestore creates the public schema automatically when creating a database with the CREATE DATABASE command. The command uses the template0 database that contains the public schema.
See also Understanding Backup Files.
Performing Basic Backup and Restore Operations
$ gpbackup --dbname <database_name>
$ gpbackup --dbname demo 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Starting backup of database demo 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Backup Timestamp = 20180105112754 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Backup Database = demo 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Backup Type = Unfiltered Compressed Full Backup 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Gathering list of tables for backup 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Acquiring ACCESS SHARE locks on tables Locks acquired: 6 / 6 [================================================================] 100.00% 0s 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Gathering additional table metadata 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Writing global database metadata 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Global database metadata backup complete 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Writing pre-data metadata 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Pre-data metadata backup complete 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Writing post-data metadata 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Post-data metadata backup complete 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Writing data to file Tables backed up: 3 / 3 [==============================================================] 100.00% 0s 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Data backup complete 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Found neither /usr/local/greenplum-db/./bin/gp_email_contacts.yaml nor /home/gpadmin/gp_email_contacts.yaml 20180105:11:27:54 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Email containing gpbackup report /gpmaster/seg-1/backups/20180105/20180105112754/gpbackup_20180105112754_report will not be sent 20180105:11:27:55 gpbackup:gpadmin:centos6.localdomain:002182-[INFO]:-Backup completed successfully
$ ls /gpmaster/gpsne-1/backups/20180105/20180105112754 gpbackup_20180105112754_config.yaml gpbackup_20180105112754_report gpbackup_20180105112754_metadata.sql gpbackup_20180105112754_toc.yaml
$ ls /gpdata1/gpsne0/backups/20180105/20180105112754/ gpbackup_0_20180105112754_17166.gz gpbackup_0_20180105112754_26303.gz gpbackup_0_20180105112754_21816.gz
$ gpbackup --dbname demo --backup-dir /home/gpadmin/backups 20171103:15:31:56 gpbackup:gpadmin:0ee2f5fb02c9:017586-[INFO]:-Starting backup of database demo ... 20171103:15:31:58 gpbackup:gpadmin:0ee2f5fb02c9:017586-[INFO]:-Backup completed successfully $ find /home/gpadmin/backups/ -type f /home/gpadmin/backups/gpseg0/backups/20171103/20171103153156/gpbackup_0_20171103153156_16543.gz /home/gpadmin/backups/gpseg0/backups/20171103/20171103153156/gpbackup_0_20171103153156_16524.gz /home/gpadmin/backups/gpseg1/backups/20171103/20171103153156/gpbackup_1_20171103153156_16543.gz /home/gpadmin/backups/gpseg1/backups/20171103/20171103153156/gpbackup_1_20171103153156_16524.gz /home/gpadmin/backups/gpseg-1/backups/20171103/20171103153156/gpbackup_20171103153156_config.yaml /home/gpadmin/backups/gpseg-1/backups/20171103/20171103153156/gpbackup_20171103153156_predata.sql /home/gpadmin/backups/gpseg-1/backups/20171103/20171103153156/gpbackup_20171103153156_global.sql /home/gpadmin/backups/gpseg-1/backups/20171103/20171103153156/gpbackup_20171103153156_postdata.sql /home/gpadmin/backups/gpseg-1/backups/20171103/20171103153156/gpbackup_20171103153156_report /home/gpadmin/backups/gpseg-1/backups/20171103/20171103153156/gpbackup_20171103153156_toc.yaml
When performing a backup operation, you can use the --single-data-file in situations where the additional overhead of multiple files might be prohibitive. For example, if you use a third party storage solution such as Data Domain with back ups.
Restoring from Backup
$ dropdb demo $ gprestore --timestamp 20171103152558 --create-db 20171103:15:45:30 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Restore Key = 20171103152558 20171103:15:45:31 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Creating database 20171103:15:45:44 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Database creation complete 20171103:15:45:44 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Restoring pre-data metadata from /gpmaster/gpsne-1/backups/20171103/20171103152558/gpbackup_20171103152558_predata.sql 20171103:15:45:45 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Pre-data metadata restore complete 20171103:15:45:45 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Restoring data 20171103:15:45:45 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Data restore complete 20171103:15:45:45 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Restoring post-data metadata from /gpmaster/gpsne-1/backups/20171103/20171103152558/gpbackup_20171103152558_postdata.sql 20171103:15:45:45 gprestore:gpadmin:0ee2f5fb02c9:017714-[INFO]:-Post-data metadata restore complete
$ dropdb demo $ gprestore --backup-dir /home/gpadmin/backups/ --timestamp 20171103153156 --create-db 20171103:15:51:02 gprestore:gpadmin:0ee2f5fb02c9:017819-[INFO]:-Restore Key = 20171103153156 ... 20171103:15:51:17 gprestore:gpadmin:0ee2f5fb02c9:017819-[INFO]:-Post-data metadata restore complete
gprestore does not attempt to restore global metadata for the Greenplum System by default. If this is required, include the --with-globals argument.
$ gprestore --backup-dir /home/gpadmin/backups/ --timestamp 20171103153156 --create-db --jobs 8
Test the number of parallel connections with your backup set to determine the ideal number for fast data recovery.
Restoring a materialized view does not restore materialized view data. Only the materialized view definition is restored. To populate the materialized view with data, use REFRESH MATERIALIZED VIEW. The tables that are referenced by the materialized view definition must be available when you refresh the materialized view. The gprestore log file lists the materialized views that were restored and the REFRESH MATERIALIZED VIEW commands that are used to populate the materialized views with data.
When performing a backup or restore operation, gpbackup and gprestore generate a report file. When email notification is configured, the email sent contains the contents of the report file. For information about email notification, see Configuring Email Notifications.
The report file is placed in the Greenplum Database master backup directory. The report file name contains the timestamp of the operation. These are the formats of the gpbackup and gprestore report file names.
gpbackup_<backup_timestamp>_report gprestore_<backup_timestamp>_<restore_timesamp>_reportFor these example report file names, 20180213114446 is the timestamp of the backup and 20180213115426 is the timestamp of the restore operation.
This backup directory on a Greenplum Database master host contains both a gpbackup and gprestore report file.
$ ls -l /gpmaster/seg-1/backups/20180213/20180213114446 total 36 -r--r--r--. 1 gpadmin gpadmin 295 Feb 13 11:44 gpbackup_20180213114446_config.yaml -r--r--r--. 1 gpadmin gpadmin 1855 Feb 13 11:44 gpbackup_20180213114446_metadata.sql -r--r--r--. 1 gpadmin gpadmin 1402 Feb 13 11:44 gpbackup_20180213114446_report -r--r--r--. 1 gpadmin gpadmin 2199 Feb 13 11:44 gpbackup_20180213114446_toc.yaml -r--r--r--. 1 gpadmin gpadmin 404 Feb 13 11:54 gprestore_20180213114446_20180213115426_report
The contents of the report files are similar. This is an example of the contents of a gprestore report file.
Greenplum Database Restore Report Timestamp Key: 20180213114446 GPDB Version: 5.4.1+dev.8.g9f83645 build commit:9f836456b00f855959d52749d5790ed1c6efc042 gprestore Version: 1.0.0-alpha.3+dev.73.g0406681 Database Name: test Command Line: gprestore --timestamp 20180213114446 --with-globals --createdb Start Time: 2018-02-13 11:54:26 End Time: 2018-02-13 11:54:31 Duration: 0:00:05 Restore Status: Success
When performing a backup operation, gpbackup appends backup information in the gpbackup history file, gpbackup_history.yaml, in the Greenplum Database master data directory. The file contains the backup timestamp, information about the backup options, and backup set information for incremental backups. From gpbackup v1.19.0, this file also records failed backup operations. This file is not backed up by gpbackup.
gpbackup uses the information in the file to find a matching backup for an incremental backup when you run gpbackup with the --incremental option and do not specify the --from-timesamp option to indicate the backup that you want to use as the latest backup in the incremental backup set. For information about incremental backups, see Creating and Using Incremental Backups with gpbackup and gprestore.
- 0 – Backup or restore completed with no problems
- 1 – Backup or restore completed with non-fatal errors. See log file for more information.
- 2 – Backup or restore failed with a fatal error. See log file for more information.
Filtering the Contents of a Backup or Restore
gpbackup backs up all schemas and tables in the specified database, unless you exclude or include individual schema or table objects with schema level or table level filter options.
$ gpbackup --dbname demo --include-schema wikipedia $ gpbackup --dbname demo --exclude-schema twitter
$ gpbackup --dbname demo --include-schema wikipedia --include-schema twitter
gpbackup --dbname demo --include-schema-file /users/home/gpadmin/backup-schemas
To filter the individual tables that are included in a backup set, or excluded from a backup set, specify individual tables with the --include-table option or the --exclude-table option. The table must be schema qualified, <schema-name>.<table-name>. The individual table filtering options can be specified multiple times. However, --include-table and --exclude-table cannot both be used in the same command.
beer."IPA" "Wine".riesling "Wine"."sauvignon blanc" water.tonic
$ gpbackup --dbname demo --include-table-file /home/gpadmin/table-list.txt
You can combine -include schema with --exclude-table or --exclude-table-file for a backup. This example uses --include-schema with --exclude-table to back up a schema except for a single table.
$ gpbackup --dbname demo --include-schema mydata --exclude-table mydata.addresses
You cannot combine --include-schema with --include-table or --include-table-file, and you cannot combine --exclude-schema with any table filtering option such as --exclude-table or --include-table.
When you use --include-table or --include-table-file dependent objects are not automatically backed up or restored, you must explicitly specify the dependent objects that are required. For example, if you back up or restore a view or materialized view, you must also specify the tables that the view or the materialized view uses. If you backup or restore a table that uses a sequence, you must also specify the sequence.
Filtering by Leaf Partition
demo=# CREATE TABLE sales (id int, date date, amt decimal(10,2)) DISTRIBUTED BY (id) PARTITION BY RANGE (date) ( PARTITION Jan17 START (date '2017-01-01') INCLUSIVE , PARTITION Feb17 START (date '2017-02-01') INCLUSIVE , PARTITION Mar17 START (date '2017-03-01') INCLUSIVE , PARTITION Apr17 START (date '2017-04-01') INCLUSIVE , PARTITION May17 START (date '2017-05-01') INCLUSIVE , PARTITION Jun17 START (date '2017-06-01') INCLUSIVE , PARTITION Jul17 START (date '2017-07-01') INCLUSIVE , PARTITION Aug17 START (date '2017-08-01') INCLUSIVE , PARTITION Sep17 START (date '2017-09-01') INCLUSIVE , PARTITION Oct17 START (date '2017-10-01') INCLUSIVE , PARTITION Nov17 START (date '2017-11-01') INCLUSIVE , PARTITION Dec17 START (date '2017-12-01') INCLUSIVE END (date '2018-01-01') EXCLUSIVE ); NOTICE: CREATE TABLE will create partition "sales_1_prt_jan17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_feb17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_mar17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_apr17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_may17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_jun17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_jul17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_aug17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_sep17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_oct17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_nov17" for table "sales" NOTICE: CREATE TABLE will create partition "sales_1_prt_dec17" for table "sales" CREATE TABLE
public.sales_1_prt_oct17 public.sales_1_prt_nov17 public.sales_1_prt_dec17
$ gpbackup --dbname demo --include-table-file last-quarter.txt --leaf-partition-data
$ gpbackup --dbname demo --include-table public.sales --leaf-partition-data
When leaf partitions are backed up, the leaf partition data is backed up along with the metadata for the entire partitioned table.
Filtering with gprestore
- The tables that you attempt to restore must not already exist in the database.
- If you attempt to restore a schema or table that does not exist in the backup set, the gprestore does not execute.
- If you use the --include-schema option, gprestore cannot restore objects that have dependencies on multiple schemas.
- If you use the --include-table-file option, gprestore does not create roles or set the owner of the tables. The utility restores table indexes and rules. Triggers are also restored but are not supported in Greenplum Database.
- The file that you specify with --include-table-file cannot include
a leaf partition name, as it can when you specify this option with
gpbackup. If you specified leaf partitions in the backup set,
specify the partitioned table to restore the leaf partition data.
When restoring a backup set that contains data from some leaf partitions of a partitioned table, the partitioned table is restored along with the data for the leaf partitions. For example, you create a backup with the gpbackup option --include-table-file and the text file lists some leaf partitions of a partitioned table. Restoring the backup creates the partitioned table and restores the data only for the leaf partitions listed in the file.
gprestore performs a special filtered restore operation with a storage plugin that supports this functionality when all of the following conditions hold:
- You specify the --plugin-config config.yml option when you invoke both the gpbackup and gprestore commands and the configuration file includes the restore_subset: "on" setting.
- The backup is an uncompressed, single-data-file backup (you invoked the gpbackup command with the --no-compression and --single-data-file flags).
- You specify filtering options (--include-table, --exclude-table, --include-table-file, or ‑‑exclude-table-file) on the gprestore command line.
The storage plugin reads and restores only the relations that you specify from the backup file, improving restore performance.
Configuring Email Notifications
gpbackup and gprestore can send email notifications after a back up or restore operation completes.
To have gpbackup or gprestore send out status email notifications, you must place a file named gp_email_contacts.yaml in the home directory of the user running gpbackup or gprestore in the same directory as the utilities ($GPHOME/bin). A utility issues a message if it cannot locate a gp_email_contacts.yaml file in either location. If both locations contain a .yaml file, the utility uses the file in user $HOME.
The email subject line includes the utility name, timestamp, job status (Success or Failure), and the name of the Greenplum Database host gpbackup or gprestore is called from. These are example subject lines for gpbackup emails.
gpbackup 20180202133601 on gp-master completed: Success
gpbackup 20200925140738 on mdw completed: Failure
The email contains summary information about the operation including options, duration, and number of objects backed up or restored. For information about the contents of a notification email, see Report Files.
gpbackup and gprestore Email File Format
The gpbackup and gprestore email notification YAML file gp_email_contacts.yaml uses indentation (spaces) to determine the document hierarchy and the relationships of the sections to one another. The use of white space is significant. White space should not be used simply for formatting purposes, and tabs should not be used at all.
This is the format of the gp_email_contacts.yaml YAML file for gpbackup email notifications:
contacts: gpbackup: - address: user@domain status: success: [true | false] success_with_errors: [true | false] failure: [true | false] gprestore: - address: user@domain status: success: [true | false] success_with_errors: [true | false] failure: [true | false]
Email YAML File Sections
- Required. The section that contains the gpbackup and gprestore sections. The YAML file can contain a gpbackup section, a gprestore section, or one of each.
- Optional. Begins the gpbackup email section.
- Required. At least one email address must be specified. Multiple email address parameters can be specified. Each address requires a status section.
- user@domain is a single, valid email address.
- Required. Specify when the utility sends an email to the specified email address. The default is to not send email notification.
- You specify sending email notifications based on the completion status of a
backup or restore operation. At least one of these parameters must be
specified and each parameter can appear at most once.
- Optional. Specify if an email is sent if the operation completes without errors. If the value is true, an email is sent if the operation completes without errors. If the value is false (the default), an email is not sent.
- Optional. Specify if an email is sent if the operation completes with errors. If the value is true, an email is sent if the operation completes with errors. If the value is false (the default), an email is not sent.
- Optional. Specify if an email is sent if the operation fails. If the value is true, an email is sent if the operation fails. If the value is false (the default), an email is not sent.
- Optional. Begins the gprestore email section. This section contains the address and status parameters that are used to send an email notification after a gprestore operation. The syntax is the same as the gpbackup section.
contacts: gpbackup: - address: firstname.lastname@example.org status: success:true - address: email@example.com status: success_with_errors: true failure: true gprestore: - address: firstname.lastname@example.org status: success: true success_with_errors: true
Understanding Backup Files
A complete backup set for gpbackup includes multiple metadata files, supporting files, and CSV data files, each designated with the timestamp at which the backup was created.
|gpbackup_<YYYYMMDDHHMMSS>_metadata.sql||Contains global and database-specific metadata:
Note: Global metadata is not restored by default. You must include the --with-globals option to the gprestore command to restore global metadata.Database-specific objects that must be created before to restoring the actual data include:
|gpbackup_<YYYYMMDDHHMMSS>_toc.yaml||Contains metadata for locating object DDL in the _predata.sql and _postdata.sql files. This file also contains the table names and OIDs used for locating the corresponding table data in CSV data files that are created on each segment. See Segment Data Files.|
|gpbackup_<YYYYMMDDHHMMSS>_report||Contains information about the backup operation that is used to populate the
email notice (if configured) that is sent after the backup completes. This file
contains information such as:
|gpbackup_<YYYYMMDDHHMMSS>_config.yaml||Contains metadata about the execution of the particular backup task,
|gpbackup_<YYYYMMDDHHMMSS>_statistics.sql||Contains table statistics.
Created when the gpbackup option --with-stats is specified. Statistics are restored when the gprestore option --with-stats is specified.
|gpbackup_history.yaml||Contains information about options that were used when creating a backup with
gpbackup, information about incremental backups, and
information about failed backup operations.
Stored on the Greenplum Database master host in the Greenplum Database master data directory.
This file is not backed up by gpbackup.
For information about incremental backups, see Creating and Using Incremental Backups with gpbackup and gprestore.
Segment Data Files
By default, each segment creates one compressed CSV file for each table that is backed up on the segment. You can optionally specify the --single-data-file option to create a single data file on each segment. The files are stored in <seg_dir>/backups/YYYYMMDD/YYYYMMDDHHMMSS/.
If you specify a custom backup directory, segment data files are copied to this same file path as a subdirectory of the backup directory. If you include the --leaf-partition-data option, gpbackup creates one data file for each leaf partition of a partitioned table, instead of just one table for file.
- <content_id> is the content ID of the segment.
- <YYYYMMDDHHMMSS> is the timestamp of the gpbackup operation.
- <oid> is the object ID of the table. The metadata file gpbackup_<YYYYMMDDHHMMSS>_toc.yaml references this <oid> to locate the data for a specific table in a schema.
You can optionally specify the compression level (from 1-9) using the --compression-level option, or disable compression entirely with --no-compression. If you do not specify a compression level, gpbackup uses compression level 1 by default.