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How does a copy from function work in PostgreSQL?
For COPY FROM, each field in the file is inserted, in order, into the specified column. Table columns not specified in the COPY FROM column list will receive their default values. COPY with a file name instructs the PostgreSQL server to directly read from or write to a file.
How to recognize backslash sequences in PostgreSQL 9.2?
The following special backslash sequences are recognized by COPY FROM: Sequence Represents b Backspace (ASCII 8) f Form feed (ASCII 12) n Newline (ASCII 10) r Carriage return (ASCII 13)
Which is the default format for copy in PostgreSQL?
Selects the data format to be read or written: text, csv (Comma Separated Values), or binary. The default is text. Requests copying the data with rows already frozen, just as they would be after running the VACUUM FREEZE command. This is intended as a performance option for initial data loading.
When do you use double quote in PostgreSQL?
Specifies the quoting character to be used when a data value is quoted. The default is double-quote. This must be a single one-byte character. This option is allowed only when using CSV format. Specifies the character that should appear before a data character that matches the QUOTE value.
What does copy with file name mean in PostgreSQL?
COPY with a file name instructs the PostgreSQL server to directly read from or write to a file. The file must be accessible by the PostgreSQL user (the user ID the server runs as) and the name must be specified from the viewpoint of the server.
When to use update statement in PostgreSQL?
In other words: Use UPDATE RETURNING, either directly to produce the calculated rows, or in a writeable CTE for more complex cases. Generally the answer to this question depends on the type of the driver used.
How to create a trigger function in pgSQL?
Trigger Functions. PL/pgSQL can be used to define trigger functions on data changes or database events. A trigger function is created with the CREATE FUNCTION command, declaring it as a function with no arguments and a return type of trigger (for data change triggers) or event_trigger (for database event triggers).