COPY

COPY

7

SQL - Language Statements

COPY

copy data between a file and a table

COPY

table\_name

\[ (

column\_name

\[, \...\] ) \] FROM { \'

filename

\' \| PROGRAM \'

command

\' \| STDIN } \[ \[ WITH \] (

option

\[, \...\] ) \] \[ WHERE

condition

\] COPY {

table\_name

\[ (

column\_name

\[, \...\] ) \] \| (

query

) } TO { \'

filename

\' \| PROGRAM \'

command

\' \| STDOUT } \[ \[ WITH \] (

option

\[, \...\] ) \]

where

option

can be one of:

FORMAT

format\_name

FREEZE \[

boolean

\] DELIMITER \'

delimiter\_character

\' NULL \'

null\_string

\' HEADER \[

boolean

\|

match

\] QUOTE \'

quote\_character

\' ESCAPE \'

escape\_character

\' FORCE\_QUOTE { (

column\_name

\[, \...\] ) \| \* } FORCE\_NOT\_NULL (

column\_name

\[, \...\] ) FORCE\_NULL (

column\_name

\[, \...\] ) ENCODING \'

encoding\_name

\'

Description
===========

`COPY` moves data between PostgreSQL tables and standard file-system
files. `COPY TO` copies the contents of a table *to* a file, while
`COPY FROM` copies data *from* a file to a table (appending the data to
whatever is in the table already). `COPY TO` can also copy the results
of a `SELECT` query.

If a column list is specified, `COPY TO` copies only the data in the
specified columns to the file. 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. 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 `PROGRAM` is specified, the
server executes the given command and reads from the standard output of
the program, or writes to the standard input of the program. The command
must be specified from the viewpoint of the server, and be executable by
the PostgreSQL user. When `STDIN` or `STDOUT` is specified, data is
transmitted via the connection between the client and the server.

Each backend running `COPY` will report its progress in the
pg\_stat\_progress\_copy view. See [???](#copy-progress-reporting) for
details.

Parameters
==========

table\_name

:   The name (optionally schema-qualified) of an existing table.

column\_name

:   An optional list of columns to be copied. If no column list is
    specified, all columns of the table except generated columns will be
    copied.

query

:   A [`SELECT`](#sql-select), [`VALUES`](#sql-values),
    [`INSERT`](#sql-insert), [`UPDATE`](#sql-update), or
    [`DELETE`](#sql-delete) command whose results are to be copied. Note
    that parentheses are required around the query.

    For `INSERT`, `UPDATE` and `DELETE` queries a RETURNING clause must
    be provided, and the target relation must not have a conditional
    rule, nor an `ALSO` rule, nor an `INSTEAD` rule that expands to
    multiple statements.

filename

:   The path name of the input or output file. An input file name can be
    an absolute or relative path, but an output file name must be an
    absolute path. Windows users might need to use an `E''` string and
    double any backslashes used in the path name.

`PROGRAM`

:   A command to execute. In `COPY FROM`, the input is read from
    standard output of the command, and in `COPY TO`, the output is
    written to the standard input of the command.

    Note that the command is invoked by the shell, so if you need to
    pass any arguments to shell command that come from an untrusted
    source, you must be careful to strip or escape any special
    characters that might have a special meaning for the shell. For
    security reasons, it is best to use a fixed command string, or at
    least avoid passing any user input in it.

`STDIN`

:   Specifies that input comes from the client application.

`STDOUT`

:   Specifies that output goes to the client application.

boolean

:   Specifies whether the selected option should be turned on or off.
    You can write `TRUE`, `ON`, or `1` to enable the option, and
    `FALSE`, `OFF`, or `0` to disable it. The boolean value can also be
    omitted, in which case `TRUE` is assumed.

`FORMAT`

:   Selects the data format to be read or written: `text`, `csv` (Comma
    Separated Values), or `binary`. The default is `text`.

`FREEZE`

:   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. Rows will be
    frozen only if the table being loaded has been created or truncated
    in the current subtransaction, there are no cursors open and there
    are no older snapshots held by this transaction. It is currently not
    possible to perform a `COPY FREEZE` on a partitioned table.

    Note that all other sessions will immediately be able to see the
    data once it has been successfully loaded. This violates the normal
    rules of MVCC visibility and users specifying should be aware of the
    potential problems this might cause.

`DELIMITER`

:   Specifies the character that separates columns within each row
    (line) of the file. The default is a tab character in text format, a
    comma in `CSV` format. This must be a single one-byte character.
    This option is not allowed when using `binary` format.

`NULL`

:   Specifies the string that represents a null value. The default is
    `\N` (backslash-N) in text format, and an unquoted empty string in
    `CSV` format. You might prefer an empty string even in text format
    for cases where you don\'t want to distinguish nulls from empty
    strings. This option is not allowed when using `binary` format.

    > **Note**
    >
    > When using `COPY FROM`, any data item that matches this string
    > will be stored as a null value, so you should make sure that you
    > use the same string as you used with `COPY TO`.

`HEADER`

:   Specifies that the file contains a header line with the names of
    each column in the file. On output, the first line contains the
    column names from the table. On input, the first line is discarded
    when this option is set to `true` (or equivalent Boolean value). If
    this option is set to `match`, the number and names of the columns
    in the header line must match the actual column names of the table,
    otherwise an error is raised. This option is not allowed when using
    `binary` format.

`QUOTE`

:   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.

`ESCAPE`

:   Specifies the character that should appear before a data character
    that matches the `QUOTE` value. The default is the same as the
    `QUOTE` value (so that the quoting character is doubled if it
    appears in the data). This must be a single one-byte character. This
    option is allowed only when using `CSV` format.

`FORCE_QUOTE`

:   Forces quoting to be used for all non-`NULL` values in each
    specified column. `NULL` output is never quoted. If `*` is
    specified, non-`NULL` values will be quoted in all columns. This
    option is allowed only in `COPY TO`, and only when using `CSV`
    format.

`FORCE_NOT_NULL`

:   Do not match the specified columns\' values against the null string.
    In the default case where the null string is empty, this means that
    empty values will be read as zero-length strings rather than nulls,
    even when they are not quoted. This option is allowed only in
    `COPY FROM`, and only when using `CSV` format.

`FORCE_NULL`

:   Match the specified columns\' values against the null string, even
    if it has been quoted, and if a match is found set the value to
    `NULL`. In the default case where the null string is empty, this
    converts a quoted empty string into NULL. This option is allowed
    only in `COPY FROM`, and only when using `CSV` format.

`ENCODING`

:   Specifies that the file is encoded in the encoding\_name. If this
    option is omitted, the current client encoding is used. See the
    Notes below for more details.

`WHERE`

:   The optional `WHERE` clause has the general form WHERE condition
    where condition is any expression that evaluates to a result of type
    `boolean`. Any row that does not satisfy this condition will not be
    inserted to the table. A row satisfies the condition if it returns
    true when the actual row values are substituted for any variable
    references.

    Currently, subqueries are not allowed in `WHERE` expressions, and
    the evaluation does not see any changes made by the `COPY` itself
    (this matters when the expression contains calls to `VOLATILE`
    functions).

Outputs
=======

On successful completion, a `COPY` command returns a command tag of the
form

    COPY count

The count is the number of rows copied.

> **Note**
>
> psql will print this command tag only if the command was not
> `COPY ... TO STDOUT`, or the equivalent psql meta-command
> `\copy ... to stdout`. This is to prevent confusing the command tag
> with the data that was just printed.

Notes
=====

`COPY TO` can be used only with plain tables, not views, and does not
copy rows from child tables or child partitions. For example,
`COPY table TO` copies the same rows as `SELECT * FROM ONLY table`. The
syntax `COPY (SELECT * FROM table) TO ...` can be used to dump all of
the rows in an inheritance hierarchy, partitioned table, or view.

`COPY FROM` can be used with plain, foreign, or partitioned tables or
with views that have `INSTEAD OF INSERT` triggers.

You must have select privilege on the table whose values are read by
`COPY TO`, and insert privilege on the table into which values are
inserted by `COPY FROM`. It is sufficient to have column privileges on
the column(s) listed in the command.

If row-level security is enabled for the table, the relevant `SELECT`
policies will apply to `COPY
    table TO` statements. Currently, `COPY FROM` is not supported for
tables with row-level security. Use equivalent `INSERT` statements
instead.

Files named in a `COPY` command are read or written directly by the
server, not by the client application. Therefore, they must reside on or
be accessible to the database server machine, not the client. They must
be accessible to and readable or writable by the PostgreSQL user (the
user ID the server runs as), not the client. Similarly, the command
specified with `PROGRAM` is executed directly by the server, not by the
client application, must be executable by the PostgreSQL user. `COPY`
naming a file or command is only allowed to database superusers or users
who are granted one of the roles `pg_read_server_files`,
`pg_write_server_files`, or `pg_execute_server_program`, since it allows
reading or writing any file or running a program that the server has
privileges to access.

Do not confuse `COPY` with the psql instruction `\copy`. `\copy` invokes
`COPY FROM STDIN` or `COPY TO
    STDOUT`, and then fetches/stores the data in a file accessible to
the psql client. Thus, file accessibility and access rights depend on
the client rather than the server when `\copy` is used.

It is recommended that the file name used in `COPY` always be specified
as an absolute path. This is enforced by the server in the case of
`COPY TO`, but for `COPY FROM` you do have the option of reading from a
file specified by a relative path. The path will be interpreted relative
to the working directory of the server process (normally the cluster\'s
data directory), not the client\'s working directory.

Executing a command with `PROGRAM` might be restricted by the operating
system\'s access control mechanisms, such as SELinux.

`COPY FROM` will invoke any triggers and check constraints on the
destination table. However, it will not invoke rules.

For identity columns, the `COPY FROM` command will always write the
column values provided in the input data, like the `INSERT` option
`OVERRIDING SYSTEM
    VALUE`.

`COPY` input and output is affected by `DateStyle`. To ensure
portability to other PostgreSQL installations that might use non-default
`DateStyle` settings, `DateStyle` should be set to `ISO` before using
`COPY TO`. It is also a good idea to avoid dumping data with
`IntervalStyle` set to `sql_standard`, because negative interval values
might be misinterpreted by a server that has a different setting for
`IntervalStyle`.

Input data is interpreted according to `ENCODING` option or the current
client encoding, and output data is encoded in `ENCODING` or the current
client encoding, even if the data does not pass through the client but
is read from or written to a file directly by the server.

`COPY` stops operation at the first error. This should not lead to
problems in the event of a `COPY
    TO`, but the target table will already have received earlier rows in
a `COPY FROM`. These rows will not be visible or accessible, but they
still occupy disk space. This might amount to a considerable amount of
wasted disk space if the failure happened well into a large copy
operation. You might wish to invoke `VACUUM` to recover the wasted
space.

`FORCE_NULL` and `FORCE_NOT_NULL` can be used simultaneously on the same
column. This results in converting quoted null strings to null values
and unquoted null strings to empty strings.

File Formats
============

Text Format
-----------

When the `text` format is used, the data read or written is a text file
with one line per table row. Columns in a row are separated by the
delimiter character. The column values themselves are strings generated
by the output function, or acceptable to the input function, of each
attribute\'s data type. The specified null string is used in place of
columns that are null. `COPY FROM` will raise an error if any line of
the input file contains more or fewer columns than are expected.

End of data can be represented by a single line containing just
backslash-period (`\.`). An end-of-data marker is not necessary when
reading from a file, since the end of file serves perfectly well; it is
needed only when copying data to or from client applications using
pre-3.0 client protocol.

Backslash characters (`\`) can be used in the `COPY` data to quote data
characters that might otherwise be taken as row or column delimiters. In
particular, the following characters *must* be preceded by a backslash
if they appear as part of a column value: backslash itself, newline,
carriage return, and the current delimiter character.

The specified null string is sent by `COPY TO` without adding any
backslashes; conversely, `COPY FROM` matches the input against the null
string before removing backslashes. Therefore, a null string such as
`\N` cannot be confused with the actual data value `\N` (which would be
represented as `\\N`).

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)
  `\t`         Tab (ASCII 9)
  `\v`         Vertical tab (ASCII 11)
  `\`digits    Backslash followed by one to three octal digits specifies the byte with that numeric code
  `\x`digits   Backslash `x` followed by one or two hex digits specifies the byte with that numeric code

Presently, `COPY TO` will never emit an octal or hex-digits backslash
sequence, but it does use the other sequences listed above for those
control characters.

Any other backslashed character that is not mentioned in the above table
will be taken to represent itself. However, beware of adding backslashes
unnecessarily, since that might accidentally produce a string matching
the end-of-data marker (`\.`) or the null string (`\N` by default).
These strings will be recognized before any other backslash processing
is done.

It is strongly recommended that applications generating `COPY` data
convert data newlines and carriage returns to the `\n` and `\r`
sequences respectively. At present it is possible to represent a data
carriage return by a backslash and carriage return, and to represent a
data newline by a backslash and newline. However, these representations
might not be accepted in future releases. They are also highly
vulnerable to corruption if the `COPY` file is transferred across
different machines (for example, from Unix to Windows or vice versa).

All backslash sequences are interpreted after encoding conversion. The
bytes specified with the octal and hex-digit backslash sequences must
form valid characters in the database encoding.

`COPY TO` will terminate each row with a Unix-style newline ("`\n`").
Servers running on Microsoft Windows instead output carriage
return/newline ("`\r\n`"), but only for `COPY` to a server file; for
consistency across platforms, `COPY TO STDOUT` always sends "`\n`"
regardless of server platform. `COPY FROM` can handle lines ending with
newlines, carriage returns, or carriage return/newlines. To reduce the
risk of error due to un-backslashed newlines or carriage returns that
were meant as data, `COPY FROM` will complain if the line endings in the
input are not all alike.

CSV Format
----------

This format option is used for importing and exporting the Comma
Separated Value (`CSV`) file format used by many other programs, such as
spreadsheets. Instead of the escaping rules used by PostgreSQL\'s
standard text format, it produces and recognizes the common CSV escaping
mechanism.

The values in each record are separated by the `DELIMITER` character. If
the value contains the delimiter character, the `QUOTE` character, the
`NULL` string, a carriage return, or line feed character, then the whole
value is prefixed and suffixed by the `QUOTE` character, and any
occurrence within the value of a `QUOTE` character or the `ESCAPE`
character is preceded by the escape character. You can also use
`FORCE_QUOTE` to force quotes when outputting non-`NULL` values in
specific columns.

The `CSV` format has no standard way to distinguish a `NULL` value from
an empty string. PostgreSQL\'s `COPY` handles this by quoting. A `NULL`
is output as the `NULL` parameter string and is not quoted, while a
non-`NULL` value matching the `NULL` parameter string is quoted. For
example, with the default settings, a `NULL` is written as an unquoted
empty string, while an empty string data value is written with double
quotes (`""`). Reading values follows similar rules. You can use
`FORCE_NOT_NULL` to prevent `NULL` input comparisons for specific
columns. You can also use `FORCE_NULL` to convert quoted null string
data values to `NULL`.

Because backslash is not a special character in the `CSV` format, `\.`,
the end-of-data marker, could also appear as a data value. To avoid any
misinterpretation, a `\.` data value appearing as a lone entry on a line
is automatically quoted on output, and on input, if quoted, is not
interpreted as the end-of-data marker. If you are loading a file created
by another application that has a single unquoted column and might have
a value of `\.`, you might need to quote that value in the input file.

> **Note**
>
> In `CSV` format, all characters are significant. A quoted value
> surrounded by white space, or any characters other than `DELIMITER`,
> will include those characters. This can cause errors if you import
> data from a system that pads `CSV` lines with white space out to some
> fixed width. If such a situation arises you might need to preprocess
> the `CSV` file to remove the trailing white space, before importing
> the data into PostgreSQL.

> **Note**
>
> CSV format will both recognize and produce CSV files with quoted
> values containing embedded carriage returns and line feeds. Thus the
> files are not strictly one line per table row like text-format files.

> **Note**
>
> Many programs produce strange and occasionally perverse CSV files, so
> the file format is more a convention than a standard. Thus you might
> encounter some files that cannot be imported using this mechanism, and
> `COPY` might produce files that other programs cannot process.

Binary Format
-------------

The `binary` format option causes all data to be stored/read as binary
format rather than as text. It is somewhat faster than the text and
`CSV` formats, but a binary-format file is less portable across machine
architectures and PostgreSQL versions. Also, the binary format is very
data type specific; for example it will not work to output binary data
from a `smallint` column and read it into an `integer` column, even
though that would work fine in text format.

The `binary` file format consists of a file header, zero or more tuples
containing the row data, and a file trailer. Headers and data are in
network byte order.

> **Note**
>
> PostgreSQL releases before 7.4 used a different binary file format.

### File Header

The file header consists of 15 bytes of fixed fields, followed by a
variable-length header extension area. The fixed fields are:

Signature

:   11-byte sequence `PGCOPY\n\377\r\n\0` MDASH note that the zero byte
    is a required part of the signature. (The signature is designed to
    allow easy identification of files that have been munged by a
    non-8-bit-clean transfer. This signature will be changed by
    end-of-line-translation filters, dropped zero bytes, dropped high
    bits, or parity changes.)

Flags field

:   32-bit integer bit mask to denote important aspects of the file
    format. Bits are numbered from 0 (LSB) to 31 (MSB). Note that this
    field is stored in network byte order (most significant byte first),
    as are all the integer fields used in the file format. Bits
    16NDASH31 are reserved to denote critical file format issues; a
    reader should abort if it finds an unexpected bit set in this range.
    Bits 0NDASH15 are reserved to signal backwards-compatible format
    issues; a reader should simply ignore any unexpected bits set in
    this range. Currently only one flag bit is defined, and the rest
    must be zero:

    Bit 16

    :   If 1, OIDs are included in the data; if 0, not. Oid system
        columns are not supported in PostgreSQL anymore, but the format
        still contains the indicator.

Header extension area length

:   32-bit integer, length in bytes of remainder of header, not
    including self. Currently, this is zero, and the first tuple follows
    immediately. Future changes to the format might allow additional
    data to be present in the header. A reader should silently skip over
    any header extension data it does not know what to do with.

The header extension area is envisioned to contain a sequence of
self-identifying chunks. The flags field is not intended to tell readers
what is in the extension area. Specific design of header extension
contents is left for a later release.

This design allows for both backwards-compatible header additions (add
header extension chunks, or set low-order flag bits) and
non-backwards-compatible changes (set high-order flag bits to signal
such changes, and add supporting data to the extension area if needed).

### Tuples

Each tuple begins with a 16-bit integer count of the number of fields in
the tuple. (Presently, all tuples in a table will have the same count,
but that might not always be true.) Then, repeated for each field in the
tuple, there is a 32-bit length word followed by that many bytes of
field data. (The length word does not include itself, and can be zero.)
As a special case, -1 indicates a NULL field value. No value bytes
follow in the NULL case.

There is no alignment padding or any other extra data between fields.

Presently, all data values in a binary-format file are assumed to be in
binary format (format code one). It is anticipated that a future
extension might add a header field that allows per-column format codes
to be specified.

To determine the appropriate binary format for the actual tuple data you
should consult the PostgreSQL source, in particular the `*send` and
`*recv` functions for each column\'s data type (typically these
functions are found in the `src/backend/utils/adt/` directory of the
source distribution).

If OIDs are included in the file, the OID field immediately follows the
field-count word. It is a normal field except that it\'s not included in
the field-count. Note that oid system columns are not supported in
current versions of PostgreSQL.

### File Trailer

The file trailer consists of a 16-bit integer word containing -1. This
is easily distinguished from a tuple\'s field-count word.

A reader should report an error if a field-count word is neither -1 nor
the expected number of columns. This provides an extra check against
somehow getting out of sync with the data.

Examples
========

The following example copies a table to the client using the vertical
bar (`|`) as the field delimiter:

    COPY country TO STDOUT (DELIMITER '|');

To copy data from a file into the `country` table:

    COPY country FROM '/usr1/proj/bray/sql/country_data';

To copy into a file just the countries whose names start with \'A\':

    COPY (SELECT * FROM country WHERE country_name LIKE 'A%') TO '/usr1/proj/bray/sql/a_list_countries.copy';

To copy into a compressed file, you can pipe the output through an
external compression program:

    COPY country TO PROGRAM 'gzip > /usr1/proj/bray/sql/country_data.gz';

Here is a sample of data suitable for copying into a table from `STDIN`:

    AF      AFGHANISTAN
    AL      ALBANIA
    DZ      ALGERIA
    ZM      ZAMBIA
    ZW      ZIMBABWE

Note that the white space on each line is actually a tab character.

The following is the same data, output in binary format. The data is
shown after filtering through the Unix utility `od -c`. The table has
three columns; the first has type `char(2)`, the second has type `text`,
and the third has type `integer`. All the rows have a null value in the
third column.

    0000000   P   G   C   O   P   Y  \n 377  \r  \n  \0  \0  \0  \0  \0  \0
    0000020  \0  \0  \0  \0 003  \0  \0  \0 002   A   F  \0  \0  \0 013   A
    0000040   F   G   H   A   N   I   S   T   A   N 377 377 377 377  \0 003
    0000060  \0  \0  \0 002   A   L  \0  \0  \0 007   A   L   B   A   N   I
    0000100   A 377 377 377 377  \0 003  \0  \0  \0 002   D   Z  \0  \0  \0
    0000120 007   A   L   G   E   R   I   A 377 377 377 377  \0 003  \0  \0
    0000140  \0 002   Z   M  \0  \0  \0 006   Z   A   M   B   I   A 377 377
    0000160 377 377  \0 003  \0  \0  \0 002   Z   W  \0  \0  \0  \b   Z   I
    0000200   M   B   A   B   W   E 377 377 377 377 377 377

Compatibility
=============

There is no `COPY` statement in the SQL standard.

The following syntax was used before PostgreSQL version 9.0 and is still
supported: COPY table\_name \[ ( column\_name \[, \...\] ) \] FROM {
\'filename\' \| STDIN } \[ \[ WITH \] \[ BINARY \] \[ DELIMITER \[ AS \]
\'delimiter\_character\' \] \[ NULL \[ AS \] \'null\_string\' \] \[ CSV
\[ HEADER \] \[ QUOTE \[ AS \] \'quote\_character\' \] \[ ESCAPE \[ AS
\] \'escape\_character\' \] \[ FORCE NOT NULL column\_name \[, \...\] \]
\] \] COPY { table\_name \[ ( column\_name \[, \...\] ) \] \| ( query )
} TO { \'filename\' \| STDOUT } \[ \[ WITH \] \[ BINARY \] \[ DELIMITER
\[ AS \] \'delimiter\_character\' \] \[ NULL \[ AS \] \'null\_string\'
\] \[ CSV \[ HEADER \] \[ QUOTE \[ AS \] \'quote\_character\' \] \[
ESCAPE \[ AS \] \'escape\_character\' \] \[ FORCE QUOTE { column\_name
\[, \...\] \| \* } \] \] \] Note that in this syntax, `BINARY` and `CSV`
are treated as independent keywords, not as arguments of a `FORMAT`
option.

The following syntax was used before PostgreSQL version 7.3 and is still
supported: COPY \[ BINARY \] table\_name FROM { \'filename\' \| STDIN }
\[ \[USING\] DELIMITERS \'delimiter\_character\' \] \[ WITH NULL AS
\'null\_string\' \] COPY \[ BINARY \] table\_name TO { \'filename\' \|
STDOUT } \[ \[USING\] DELIMITERS \'delimiter\_character\' \] \[ WITH
NULL AS \'null\_string\' \]

See Also
========
