Export and import features

This topic provides reference information on data export and import capabilities in Microsoft SQL Server and PostgreSQL, with a focus on migration scenarios. You can use various tools and utilities to export data from SQL Server and import it into PostgreSQL, which is particularly useful when migrating to Amazon Aurora PostgreSQL.

SQL Server Usage

SQL Server provides many options for exporting and importing text files. These operations are commonly used for data migration, scripting, and backup.

All of the options described before required additional tools to export data. Most of the tools are open source and provide support for a variety of databases.

SQLCMD is a command line utility for running T-SQL statements, system procedures, and script files. It uses ODBC to run T-SQL batches. For example:

SQLCMD -i C:\sql\myquery.sql -o C:\sql\output.txt

SQLCMD utility syntax:

sqlcmd
    -a packet_size
    -A (dedicated administrator connection)
    -b (terminate batch job if there is an error)
    -c batch_terminator
    -C (trust the server certificate)
    -d db_name
    -e (echo input)
    -E (use trusted connection)
    -f codepage | i:codepage[,o:codepage] | o:codepage[,i:codepage]
    -g (enable column encryption)
    -G (use Azure Active Directory for authentication)
    -h rows_per_header
    -H workstation_name
    -i input_file
    -I (enable quoted identifiers)
    -j (Print raw error messages)
    -k[1 | 2] (remove or replace control characters)
    -K application_intent
    -l login_timeout
    -L[c] (list servers, optional clean output)
    -m error_level
    -M multisubnet_failover
    -N (encrypt connection)
    -o output_file
    -p[1] (print statistics, optional colon format)
    -P password
    -q "cmdline query"
    -Q "cmdline query" (and exit)
    -r[0 | 1] (msgs to stderr)
    -R (use client regional settings)
    -s col_separator
    -S [protocol:]server[instance_name][,port]
    -t query_timeout
    -u (unicode output file)
    -U login_id
    -v var = "value"
    -V error_severity_level
    -w column_width
    -W (remove trailing spaces)
    -x (disable variable substitution)
    -X[1] (disable commands, startup script, environment variables, optional exit)
    -y variable_length_type_display_width
    -Y fixed_length_type_display_width
    -z new_password
    -Z new_password (and exit)
    -? (usage)

Examples

Connect to a named instance using Windows Authentication and specify input and output files.

sqlcmd -S MyMSSQLServer\MyMSSQLInstance -i query.sql -o outputfile.txt

If the file is needed for import to another database, query the data as INSERT commands and CREATE for the object.

You can export data with SQLCMD and import with the Export/Import wizard.

For more information, see sqlcmd Utility in the SQL Server documentation.

PostgreSQL Usage

PostgreSQL provides the native utilities pg_dump and pg_restore to perform logical database exports and imports with comparable functionality to the SQl Server SQLCMD utility. For example, moving data between two databases and creating logical database backups.

The binaries for both utilities must be installed on your local workstation or on an Amazon EC2 server as part of the PostgreSQL client binaries.

You can export and copy PostgreSQL dump files created using pg_dump to an Amazon S3 bucket as cloud backup storage or for maintaining the desired backup retention policy. Later, when you need the dump files for database restore, you can copy them copied back to a desktop or server that has a PostgreSQL client, such as your workstation or an Amazon EC2 server. Then you can issue the pg_restore command.

Starting with PostgreSQL 10, these capabilities were added:

Starting with PostgreSQL 11, the following capabilities were added: * pg_dump and pg_restore now export or import relationships between extensions and database objects established with ALTER …​ DEPENDS ON EXTENSION, which allows these objects to be dropped when extension is dropped with CASCADE option.

Notes

Another option to export and import data from PostgreSQL database is to use COPY TO/COPY FROM commands. Starting with PostgreSQL 12, you can use the COPY FROM command to load data into DB. This command has support for filtering incoming rows with the WHERE condition.

CREATE TABLE tst_copy(v TEXT);

COPY tst_copy FROM '/home/postgres/file.csv' WITH (FORMAT CSV) WHERE v LIKE '%apple%';

Examples

Export data using pg_dump. Use a workstation or server with the PostgreSQL client installed to connect to the Amazon Aurora PostgreSQL-Compatible Edition (Aurora PostgreSQL) instance. Issue the pg_dump command providing the hostname (-h), database user name (-U), and database name (-d).

$ pg_dump -h hostname.rds.amazonaws.com -U username -d db_name -f dump_file_name.sql

The output dump_file_name.sql file is stored on the server where the pg_dump command runs. You can copy the output file to an Amazon S3 bucket if needed.

Run pg_dump and copy the backup file to an Amazon S3 bucket using a pipe and the AWS CLI.

$ pg_dump -h hostname.rds.amazonaws.com -U username -d db_name -f dump_file_name.sql | aws s3 cp - s3://pg-backup/pg_bck-$(date"+%Y-%m-%d-%H-%M-%S")

Restore data using pg_restore. Use a workstation or server with the PostgreSQL client installed to connect to the Aurora PostgreSQL instance. Issue the pg_restore command providing the hostname (-h), database user name (-U), database name (-d), and the dump file.

$ pg_restore -h hostname.rds.amazonaws.com -U username -d dbname_restore dump_file_name.sql

Copy the output file from the local server to an Amazon S3 Bucket using the AWS CLI. Upload the dump file to an Amazon S3 bucket.

$ aws s3 cp /usr/Exports/hr.dmp s3://my-bucket/backup-$(date "+%Y-%m-%d-%H-%M-%S")

Download the output file from the Amazon S3 bucket.

$ aws s3 cp s3://my-bucket/backup-2017-09-10-01-10-10 /usr/Exports/hr.dmp

CREATE DATABASE mydb_copy TEPLATE mydb;

Summary

SQLCMD -i C:\sql\myquery.sql -o C:\sql\output.txt

pg_dump -F c -h hostname.rds.amazonaws.com
    -U username -d hr -p 5432 > c:\Export\hr.dmp

SQLCMD -i C:\sql\myquery.sql

For more information, see SQL Dump and pg_restore in the PostgreSQL documentation.