Copies data between a file and a table.
COPY <table> [(<column> [, ...])] FROM {'<file>' | PROGRAM '<command>' | STDIN}
[ [WITH]
[ON SEGMENT]
[BINARY]
[OIDS]
[HEADER]
[DELIMITER [ AS ] '<delimiter>']
[NULL [ AS ] '<null string>']
[ESCAPE [ AS ] '<escape>' | 'OFF']
[NEWLINE [ AS ] 'LF' | 'CR' | 'CRLF']
[CSV [QUOTE [ AS ] '<quote>']
[FORCE NOT NULL <column> [, ...]]
[FILL MISSING FIELDS]
[[LOG ERRORS]
SEGMENT REJECT LIMIT <count> [ROWS | PERCENT] ]
COPY {table [(<column> [, ...])] | (<query>)} TO {'<file>' | PROGRAM '<command>' | STDOUT}
[ [WITH]
[ON SEGMENT]
[BINARY]
[OIDS]
[HEADER]
[DELIMITER [ AS ] 'delimiter']
[NULL [ AS ] 'null string']
[ESCAPE [ AS ] '<escape>' | 'OFF']
[CSV [QUOTE [ AS ] 'quote']
[FORCE QUOTE column [, ...]] ]
[IGNORE EXTERNAL PARTITIONS ]
COPY
moves data between Greenplum Database tables and standard file-system files. COPY TO
copies the contents of a table to a file (or multiple files based on the segment ID if copying ON SEGMENT
), 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 Greenplum Database master host to directly read from or write to a file. The file must be accessible to the master host and the name must be specified from the viewpoint of the master host.
When COPY
is used with the ON SEGMENT
clause, the COPY TO
causes segments to create individual segment-oriented files, which remain on the segment hosts. The file argument for ON SEGMENT
takes the string literal <SEGID>
(required) and uses either the absolute path or the <SEG_DATA_DIR>
string literal. When the COPY
operation is run, the segment IDs and the paths of the segment data directories are substituted for the string literal values.
The ON SEGMENT
clause allows you to copy table data to files on segment hosts for use in operations such as migrating data between clusters or performing a backup. Segment data created by the ON SEGMENT
clause can be restored by tools such as gpfdist
, which is useful for high speed data loading.
Warning: Use of the ON SEGMENT
clause is recommended for expert users only.
When STDIN
or STDOUT
is specified, data is transmitted via the connection between the client and the master. STDIN
and STDOUT
cannot be used with the ON SEGMENT
clause.
If SEGMENT REJECT LIMIT
is used, then a COPY FROM
operation will operate in single row error isolation mode. In this release, single row error isolation mode only applies to rows in the input file with format errors — for example, extra or missing attributes, attributes of a wrong data type, or invalid client encoding sequences. Constraint errors such as violation of a NOT NULL
, CHECK
, or UNIQUE
constraint will still be handled in 'all-or-nothing' input mode. The user can specify the number of error rows acceptable (on a per-segment basis), after which the entire COPY FROM
operation will be aborted and no rows will be loaded. The count of error rows is per-segment, not per entire load operation. If the per-segment reject limit is not reached, then all rows not containing an error will be loaded and any error rows discarded. To keep error rows for further examination, specify the LOG ERRORS
clause to capture error log information. The error information and the row is stored internally in Greenplum Database.
Outputs
On successful completion, a COPY
command returns a command tag of the form, where count is the number of rows copied:
COPY <count>
If running a COPY FROM
command in single row error isolation mode, the following notice message will be returned if any rows were not loaded due to format errors, where count is the number of rows rejected:
NOTICE: Rejected <count> badly formatted rows.
An optional list of columns to be copied. If no column list is specified, all columns of the table will be copied.
bytea
can be up to 256MB.
SELECT
or
VALUES
command whose results are to be copied. Note that parentheses are required around the query.
Specify a command to execute. The command must be specified from the viewpoint of the Greenplum Database master host system, and must be executable by the Greenplum Database administrator user (gpadmin
). The COPY FROM
command reads the input from the standard output of the command, and for the COPY TO
command, the output is written to the standard input of the command.
The command is invoked by a shell. When passing arguments to the shell, strip or escape any special characters that 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 the string.
When ON SEGMENT
is specified, the command must be executable on all Greenplum Database primary segment hosts by the Greenplum Database administrator user (gpadmin
). The command is executed by each Greenplum segment instance. The <SEGID>
is required in the command.
ON SEGMENT
clause for information about command syntax requirements and the data that is copied when the clause is specified.
ON SEGMENT
clause is not supported with
STDIN
.
ON SEGMENT
clause is not supported with
STDOUT
.
Specify individual, segment data files on the segment hosts. Each file contains the table data that is managed by the primary segment instance. For example, when copying data to files from a table with a COPY TO...ON SEGMENT
command, the command creates a file on the segment host for each segment instance on the host. Each file contains the table data that is managed by the segment instance.
The COPY
command does not copy data from or to mirror segment instances and segment data files.
The keywords STDIN
and STDOUT
are not supported with ON SEGMENT
.
The <SEG_DATA_DIR>
and <SEGID>
string literals are used to specify an absolute path and file name with the following syntax:
COPY <table> [TO|FROM] '<SEG_DATA_DIR>/<gpdumpname><SEGID>_<suffix>' ON SEGMENT;
ON SEGMENT
copying. The angle brackets (
<
and
>
) are part of the string literal used to specify the path.
COPY
replaces the string literal with the segment path(s) when
COPY
is run. An absolute path can be used in place of the
<SEG_DATA_DIR>
string literal.
ON SEGMENT
.
<SEGID>
is a required part of the file name when
ON SEGMENT
is specified. The angle brackets are part of the string literal used to specify the file name.
: With COPY TO
, the string literal is replaced by the content ID of the segment instance when the COPY
command is run.
: With COPY FROM
, specify the segment instance content ID in the name of the file and place that file on the segment instance host. There must be a file for each primary segment instance on each host. When the COPY FROM
command is run, the data is copied from the file to the segment instance.
When the PROGRAM command
clause is specified, the <SEGID>
string literal is required in the command, the <SEG_DATA_DIR>
string literal is optional. See Examples.
COPY FROM...ON SEGMENT
command, the table distribution policy is checked when data is copied into the table. By default, an error is returned if a data row violates the table distribution policy. You can deactivate the distribution policy check with the server configuration parameter
gp_enable_segment_copy_checking
. See
Notes.
Causes all data to be stored or read in binary format rather than as text. You cannot specify the DELIMITER
, NULL
, or CSV
options in binary mode. See Binary Format.
CSV
mode.
\N
(backslash-N) in text mode, and a empty value with no quotes in
CSV
mode. You might prefer an empty string even in text mode for cases where you don't want to distinguish nulls from empty strings. 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
.
\n
,
\t
,
\100
, and so on) and for quoting data characters that might otherwise be taken as row or column delimiters. Make sure to choose an escape character that is not used anywhere in your actual column data. The default escape character is
\
(backslash) for text files or
"
(double quote) for CSV files, however it is possible to specify any other character to represent an escape. It is also possible to deactivate escaping on text-formatted files by specifying the value '
OFF'
as the escape value. This is very useful for data such as web log data that has many embedded backslashes that are not intended to be escapes.
LF
(Line feed, 0x0A),
CR
(Carriage return, 0x0D), or
CRLF
(Carriage return plus line feed, 0x0D 0x0A). If not specified, a Greenplum Database segment will detect the newline type by looking at the first row of data it receives and using the first newline type encountered.
CSV COPY TO
mode, forces quoting to be used for all non-
NULL
values in each specified column.
NULL
output is never quoted.
CSV COPY FROM
mode, process each specified column as though it were quoted and hence not a
NULL
value. For the default null string in
CSV
mode (nothing between two delimiters), this causes missing values to be evaluated as zero-length strings.
COPY FROM
more for both
TEXT
and
CSV
, specifying
FILL MISSING FIELDS
will set missing trailing field values to
NULL
(instead of reporting an error) when a row of data has missing data fields at the end of a line or row. Blank rows, fields with a
NOT NULL
constraint, and trailing delimiters on a line will still report an error.
This is an optional clause that can precede a SEGMENT REJECT LIMIT
clause to capture error log information about rows with formatting errors.
Error log information is stored internally and is accessed with the Greenplum Database built-in SQL function gp_read_error_log()
.
Runs a COPY FROM
operation in single row error isolation mode. If the input rows have format errors they will be discarded provided that the reject limit count is not reached on any Greenplum Database segment instance during the load operation. The reject limit count can be specified as number of rows (the default) or percentage of total rows (1-100). If PERCENT
is used, each segment starts calculating the bad row percentage only after the number of rows specified by the parameter gp_reject_percent_threshold
has been processed. The default for gp_reject_percent_threshold
is 300 rows. Constraint errors such as violation of a NOT NULL
, CHECK
, or UNIQUE
constraint will still be handled in 'all-or-nothing' input mode. If the limit is not reached, all good rows will be loaded and any error rows discarded.
SEGMENT REJECT LIMIT
is not triggered first or is not specified. If the first 1000 rows are rejected, the
COPY
operation is stopped and rolled back.
The limit for the number of initial rejected rows can be changed with the Greenplum Database server configuration parameter gp_initial_bad_row_limit
. See Server Configuration Parameters for information about the parameter.
When copying data from partitioned tables, data are not copied from leaf child partitions that are external tables. A message is added to the log file when data are not copied.
If this clause is not specified and Greenplum Database attempts to copy data from a leaf child partition that is an external table, an error is returned.
COPY
can only be used with tables, not with external tables or 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.
Similarly, to copy data from a partitioned table with a leaf child partition that is an external table, use an SQL query to select the data to copy. For example, if the table my_sales
contains a leaf child partition that is an external table, this command COPY my_sales TO stdout
returns an error. This command sends the data to stdout
:
COPY (SELECT * from my_sales ) TO stdout
The BINARY
keyword causes all data to be stored/read as binary format rather than as text. It is somewhat faster than the normal text mode, but a binary-format file is less portable across machine architectures and Greenplum Database versions. Also, you cannot run COPY FROM
in single row error isolation mode if the data is in binary format.
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 columns listed in the command.
Files named in a COPY
command are read or written directly by the database server, not by the client application. Therefore, they must reside on or be accessible to the Greenplum Database master host machine, not the client. They must be accessible to and readable or writable by the Greenplum Database system user (the user ID the server runs as), not the client. Only database superusers are permitted to name files with COPY
, because this allows reading or writing any file that the server has privileges to access.
COPY FROM
will invoke any triggers and check constraints on the destination table. However, it will not invoke rewrite rules. Note that in this release, violations of constraints are not evaluated for single row error isolation mode.
COPY
input and output is affected by DateStyle
. To ensure portability to other Greenplum Database 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.
When copying XML data from a file in text mode, the server configuration parameter xmloption affects the validation of the XML data that is copied. If the value is content
(the default), XML data is validated as an XML content fragment. If the parameter value is document
, XML data is validated as an XML document. If the XML data is not valid, COPY
returns an error.
By default, 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 may amount to a considerable amount of wasted disk space if the failure happened well into a large COPY FROM
operation. You may wish to invoke VACUUM
to recover the wasted space. Another option would be to use single row error isolation mode to filter out error rows while still loading good rows.
When a COPY FROM...ON SEGMENT
command is run, the server configuration parameter gp_enable_segment_copy_checking
controls whether the table distribution policy (from the table DISTRIBUTED
clause) is checked when data is copied into the table. The default is to check the distribution policy. An error is returned if the row of data violates the distribution policy for the segment instance. For information about the parameter, see Server Configuration Parameters.
Data from a table that is generated by a COPY TO...ON SEGMENT
command can be used to restore table data with COPY FROM...ON SEGMENT
. However, data restored to the segments is distributed according to the table distribution policy at the time the files were generated with the COPY TO
command. The COPY
command might return table distribution policy errors, if you attempt to restore table data and the table distribution policy was changed after the COPY FROM...ON SEGMENT
was run.
Note: If you run COPY FROM...ON SEGMENT
and the server configuration parameter gp_enable_segment_copy_checking
is false
, manual redistribution of table data might be required. See the ALTER TABLE
clause WITH REORGANIZE
.
When you specify the LOG ERRORS
clause, Greenplum Database captures errors that occur while reading the external table data. You can view and manage the captured error log data.
Use the built-in SQL function gp_read_error_log('table\_name')
. It requires SELECT
privilege on table_name. This example displays the error log information for data loaded into table ext_expenses
with a COPY
command:
SELECT * from gp_read_error_log('ext_expenses');
For information about the error log format, see Viewing Bad Rows in the Error Log in the Greenplum Database Administrator Guide.
The function returns FALSE
if table_name does not exist.
If error log data exists for the specified table, the new error log data is appended to existing error log data. The error log information is not replicated to mirror segments.
Use the built-in SQL function gp_truncate_error_log('table\_name')
to delete the error log data for table_name. It requires the table owner privilege This example deletes the error log information captured when moving data into the table ext_expenses
:
SELECT gp_truncate_error_log('ext_expenses');
The function returns FALSE
if table_name does not exist.
Specify the *
wildcard character to delete error log information for existing tables in the current database. Specify the string *.*
to delete all database error log information, including error log information that was not deleted due to previous database issues. If * is specified, database owner privilege is required. If *.*
is specified, operating system super-user privilege is required.
When a Greenplum Database user who is not a superuser runs a COPY
command, the command can be controlled by a resource queue. The resource queue must be configured with the ACTIVE_STATEMENTS
parameter that specifies a maximum limit on the number of queries that can be executed by roles assigned to that queue. Greenplum Database does not apply a cost value or memory value to a COPY
command, resource queues with only cost or memory limits do not affect the running of COPY
commands.
A non-superuser can run only these types of COPY
commands:
COPY FROM
command where the source is stdin
COPY TO
command where the destination is stdout
For information about resource queues, see "Resource Management with Resource Queues" in the Greenplum Database Administrator Guide.
File formats supported by COPY
.
Text Format
When COPY
is used without the BINARY
or CSV
options, 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 (tab by default). 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.
The data file has two reserved characters that have special meaning to COPY
:
\n
or 0x0a
), which is used to designate a new row in the data file. It is strongly recommended that applications generating COPY
data convert data line feeds to UNIX-style line feeds rather than Microsoft Windows style carriage return line feeds (\r\n
or 0x0a 0x0d
).If your data contains either of these characters, you must escape the character so COPY
treats it as data and not as a field separator or new row.
By default, the escape character is a \ (backslash) for text-formatted files and a "
(double quote) for csv-formatted files. If you want to use a different escape character, you can do so using the ESCAPE AS
clause. Make sure to choose an escape character that is not used anywhere in your data file as an actual data value. You can also deactivate escaping in text-formatted files by using ESCAPE 'OFF'
.
For example, suppose you have a table with three columns and you want to load the following three fields using COPY
.
Your designated delimiter character is |
(pipe character), and your designated escape character is *
(asterisk). The formatted row in your data file would look like this:
percentage sign = % | vertical bar = *| | backslash = \
Notice how the pipe character that is part of the data has been escaped using the asterisk character (*). Also notice that we do not need to escape the backslash since we are using an alternative escape character.
The following characters must be preceded by the escape character if they appear as part of a column value: the escape character itself, newline, carriage return, and the current delimiter character. You can specify a different escape character using the ESCAPE AS
clause.
CSV Format
This format 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 used by Greenplum Database standard text mode, 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 ESCAPE
character (which is double quote by default), the NULL
string, a carriage return, or line feed character, then the whole value is prefixed and suffixed by the QUOTE
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. Greenplum Database COPY
handles this by quoting. A NULL
is output as the NULL
string and is not quoted, while a data value matching the NULL
string is quoted. Therefore, using the default settings, a NULL
is written as an unquoted empty string, while an empty string 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
mode, 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 Greenplum Database.
CSV
mode 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-mode 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 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:
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 COPY BINARY
file are assumed to be in binary format (format code one). It is anticipated that a future extension may add a header field that allows per-column format codes to be specified.
If OIDs are included in the file, the OID field immediately follows the field-count word. It is a normal field except that it is not included in the field-count. In particular it has a length word — this 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.
Copy a table to the client using the vertical bar (|) as the field delimiter:
COPY country TO STDOUT WITH DELIMITER '|';
Copy data from a file into the country
table:
COPY country FROM '/home/usr1/sql/country_data';
Copy into a file just the countries whose names start with 'A':
COPY (SELECT * FROM country WHERE country_name LIKE 'A%') TO
'/home/usr1/sql/a_list_countries.copy';
Copy data from a file into the sales
table using single row error isolation mode and log errors:
COPY sales FROM '/home/usr1/sql/sales_data' LOG ERRORS
SEGMENT REJECT LIMIT 10 ROWS;
To copy segment data for later use, use the ON SEGMENT
clause. Use of the COPY TO ON SEGMENT
command takes the form:
COPY <table> TO '<SEG_DATA_DIR>/<gpdumpname><SEGID>_<suffix>' ON SEGMENT;
The <SEGID>
is required. However, you can substitute an absolute path for the <SEG_DATA_DIR>
string literal in the path.
When you pass in the string literal <SEG_DATA_DIR>
and <SEGID>
to COPY
, COPY
will fill in the appropriate values when the operation is run.
For example, if you have mytable
with the segments and mirror segments like this:
contentid | dbid | file segment location
0 | 1 | /home/usr1/data1/gpsegdir0
0 | 3 | /home/usr1/data_mirror1/gpsegdir0
1 | 4 | /home/usr1/data2/gpsegdir1
1 | 2 | /home/usr1/data_mirror2/gpsegdir1
running the command:
COPY mytable TO '<SEG_DATA_DIR>/gpbackup<SEGID>.txt' ON SEGMENT;
would result in the following files:
/home/usr1/data1/gpsegdir0/gpbackup0.txt
/home/usr1/data2/gpsegdir1/gpbackup1.txt
The content ID in the first column is the identifier inserted into the file path (for example, gpsegdir0/gpbackup0.txt
above) Files are created on the segment hosts, rather than on the master, as they would be in a standard COPY
operation. No data files are created for the mirror segments when using ON SEGMENT
copying.
If an absolute path is specified, instead of <SEG_DATA_DIR>
, such as in the statement
COPY mytable TO '/tmp/gpdir/gpbackup_<SEGID>.txt' ON SEGMENT;
files would be placed in /tmp/gpdir
on every segment. The gpfdist
tool can also be used to restore data files generated with COPY TO
with the ON SEGMENT
option if redistribution is necessary.
Note: Tools such as gpfdist
can be used to restore data. The backup/restore tools will not work with files that were manually generated with COPY TO ON SEGMENT
.
This example uses a SELECT
statement to copy data to files on each segment:
COPY (SELECT * FROM testtbl) TO '/tmp/mytst<SEGID>' ON SEGMENT;
This example copies the data from the lineitem
table and uses the PROGRAM
clause to add the data to the /tmp/lineitem_program.csv
file with cat
utility. The file is placed on the Greenplum Database master.
COPY LINEITEM TO PROGRAM 'cat > /tmp/lineitem.csv' CSV;
This example uses the PROGRAM
and ON SEGMENT
clauses to copy data to files on the segment hosts. On the segment hosts, the COPY
command replaces <SEGID>
with the segment content ID to create a file for each segment instance on the segment host.
COPY LINEITEM TO PROGRAM 'cat > /tmp/lineitem_program<SEGID>.csv' ON SEGMENT CSV;
This example uses the PROGRAM
and ON SEGMENT
clauses to copy data from files on the segment hosts. The COPY
command replaces <SEGID>
with the segment content ID when copying data from the files. On the segment hosts, there must be a file for each segment instance where the file name contains the segment content ID on the segment host.
COPY LINEITEM_4 FROM PROGRAM 'cat /tmp/lineitem_program<SEGID>.csv' ON SEGMENT CSV;
There is no COPY
statement in the SQL standard.
Parent topic: SQL Command Reference