The pg_dump utility program makes a consistent database copy, which is an image of the database when it has been started the pg_dump program. We can perform the following steps, The pg_dump utility program is used to back up a single part or all parts of the PostgreSQL database.
Now consider if the database file is larger and the connection between the server is slow. PostgreSQL COPY DATABASE operation from a server to another Consider the following example where we will get an error or exception, as template ‘educba’ does not exist.Ģ. Step 3: If the given template does not exist in PostgreSQL, then it will throw an exception on error. Illustrate the database list to verify the copy of the ‘eduCBA’ database is created with a new database named ‘NewEduCBA’ using the ‘\ l’ command and the snapshot. Step 2: Consider the following example, where we will copy the ‘eduCBA’ database, which has been created with templates, to the ‘NewEduCBA’ by using the following statement: In order to make an empty database, we can use the template0 to avoid local additions, otherwise, we can use the templates. If the given template does not exist in PostgreSQL, then it will throw an exception on error. COPY should be used to create a csv on the server’s side.Explanation This above statement will copy the source_database database to the target_database database.\copy should be used for a copy to local systems.To copy a table or query to a csv file, use either the \copy command or the COPY command.In order to do this with COPY, ‘/Users//Desktop/.csv’ would need to be used as shown below: In order to save to the desktop using \copy ‘Desktop/.csv’ would be used. The \! pwd is very useful for finding the absolute path if you do not know where to save the file. This is because COPY is for copying a database from a server to another location on the same server not to a client computer. Unlike \copy however, the COPY command requires an absolute path. The COPY command also requires the user to specify a Table/Query to copy. The ‘header’ specifies that, when the data is copied to a csv file, the names of each column should be saved on the first line as shown here: Other possible formats are ‘text’ and ‘Binary.’ The ‘csv’ specifies that the data should be stored in the CSV format. For example, if ‘/Desktop/.csv’ is entered as the path, the file will be saved to the desktop.įollowing the Relative Path in the command is the text ‘csv header ’ This text does two things.
The file can also be saved elsewhere by entering a specific relative path. This means that if the file name “myTools.csv” is used as the, it will be saved in /Users/matt/ as can be seen below: The meta-command \! pwd and \! ls are shown being used below: The pwd command prints the current working directory. Note: The \! meta-command takes whatever arguments it is given and runs them as a bash command within psql. The location that psql is currently saving can be found by using the \! pwd command. The is the path from where psql is currently saving files to where you want to save the file. To copy all entries that contain “saw” in their names from the table of tools to a csv, the following commands could be run: For example to copy all entries from a table, the table name can be put here. The section can be filled with a table or query. The format of a \copy to csv is as follows: \copy to csv header For example, a user may want to generate a csv so that they can analyse financial data in excel. It is useful for copying a database that may have somewhat restricted access and for creating a personal copy of the data. The \copy meta-command is used for exporting to a client computer. The second command, COPY, generates a CSV file on the server where the database is running. This command takes the specified table or query results and writes them to the client’s computer. The first is the \copy meta-command which is used to generate a client CSV file. In psql there are two commands that can do this, both slightly different. Many tools support importing data from CSV files because it is an easy to read format that is plain text and not metadata dependent.
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