Provided by: postgres-xc-client_1.1-2ubuntu2_amd64 
NAME
COPY - copy data between a file and a table
SYNOPSIS
COPY table_name [ ( column_name [, ...] ) ]
FROM { 'filename' | STDIN }
[ [ WITH ] ( option [, ...] ) ]
COPY { table_name [ ( column_name [, ...] ) ] | ( query ) }
TO { 'filename' | STDOUT }
[ [ WITH ] ( option [, ...] ) ]
where option can be one of:
FORMAT format_name
OIDS [ boolean ]
DELIMITER 'delimiter_character'
NULL 'null_string'
HEADER [ boolean ]
QUOTE 'quote_character'
ESCAPE 'escape_character'
FORCE_QUOTE { ( column_name [, ...] ) | * }
FORCE_NOT_NULL ( column_name [, ...] ) |
ENCODING 'encoding_name'
DESCRIPTION
Note
The following description applies both to Postgres-XC and PostgreSQL if not described explicitly.
COPY moves data between Postgres-XC 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 list of columns is specified, COPY will only copy the data in the specified columns to or from the
file. If there are any columns in the table that are not in the column list, COPY FROM will insert the
default values for those columns.
COPY with a file name instructs the Postgres-XC server to directly read from or write to a file. The file
must be accessible to the server and the name must be specified from the viewpoint of the server. When
STDIN or STDOUT is specified, data is transmitted via the connection between the client and the server.
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
will be copied.
query
A SELECT(7) or VALUES(7) command whose results are to be copied. Note that parentheses are required
around the query.
filename
The absolute path name of the input or output file. Windows users might need to use an E'' string and
double any backslashes used in the path name.
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.
OIDS
Specifies copying the OID for each row. (An error is raised if OIDS is specified for a table that
does not have OIDs, or in the case of copying a query.)
Note
The following description applies only to Postgres-XC
In Postgres-XC, OIDs are only maintained locally in Coordinators and Datanodes. The value of OIDs may
conflict if you copy this value to another table.
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, and on input, the first line is ignored.
This option is allowed only when using CSV 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.
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.
OUTPUTS
On successful completion, a COPY command returns a command tag of the form
COPY count
The count is the number of rows copied.
NOTES
COPY can only be used with plain tables, not with views. However, you can write COPY (SELECT * FROM
viewname) TO ....
COPY only deals with the specific table named; it does not copy data to or from child tables. Thus for
example COPY table TO shows the same data as SELECT * FROM ONLY table. But COPY (SELECT * FROM table) TO
... can be used to dump all of the data in an inheritance hierarchy.
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.
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 Postgres-XC user (the user ID the server runs as), not
the client. COPY naming a file is only allowed to database superusers, since it allows reading or
writing any file that the server has privileges to access.
Do not confuse COPY with the psql instruction \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.
COPY FROM will invoke any triggers and check constraints on the destination table. However, it will not
invoke rules.
Note
The following description applies only to Postgres-XC
Postgres-XC does not support COPY FROM with ROW triggers. COPY FROM will abort with an error if there are
ROW INSERT triggers defined for the table.
COPY input and output is affected by DateStyle. To ensure portability to other Postgres-XC 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.
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. If OIDS is specified, the OID is
read or written as the first column, preceding the user data columns.
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 character with that │
│ │ numeric code │
├─────────┼────────────────────────────────────┤
│\xdigits │ Backslash x followed by one or two │
│ │ hex digits specifies │
│ │ the character 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).
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 Postgres-XC'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. Postgres-XC'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.
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 Postgres-XC.
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 Postgres-XC 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.
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\0note 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 16-31 are reserved to denote
critical file format issues; a reader should abort if it finds an unexpected bit set in this
range. Bits 0-15 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
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
Postgres-XC 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. In particular it has a length wordthis
will allow handling of 4-byte vs. 8-byte OIDs without too much pain, and will allow OIDs to be shown
as null if that ever proves desirable.
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';
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 ]
[ OIDS ]
[ DELIMITER [ AS ] 'delimiter' ]
[ NULL [ AS ] 'null string' ]
[ CSV [ HEADER ]
[ QUOTE [ AS ] 'quote' ]
[ ESCAPE [ AS ] 'escape' ]
[ FORCE NOT NULL column_name [, ...] ] ] ]
COPY { table_name [ ( column_name [, ...] ) ] | ( query ) }
TO { 'filename' | STDOUT }
[ [ WITH ]
[ BINARY ]
[ OIDS ]
[ DELIMITER [ AS ] 'delimiter' ]
[ NULL [ AS ] 'null string' ]
[ CSV [ HEADER ]
[ QUOTE [ AS ] 'quote' ]
[ ESCAPE [ AS ] 'escape' ]
[ 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 [ WITH OIDS ]
FROM { 'filename' | STDIN }
[ [USING] DELIMITERS 'delimiter' ]
[ WITH NULL AS 'null string' ]
COPY [ BINARY ] table_name [ WITH OIDS ]
TO { 'filename' | STDOUT }
[ [USING] DELIMITERS 'delimiter' ]
[ WITH NULL AS 'null string' ]