gpload.py

gpload.py

Runs a load job as defined in a YAML formatted control file.

Synopsis

gpload.py -f control_file [-l log_file] [-h hostname] [-p port] 
   [-U username] [-d database] [-W] [--gpfdist_timeout seconds] 
   [--no_auto_trans] [[-v | -V] [-q]] [-D]

gpload.py -? 

gpload.py --version

Prerequisites

The client machine where gpload.py is executed must have the following:

  • Python 2.5.
  • The gpfdist.exe parallel file distribution program installed and in your PATH. This program is installed with the Greenplum loaders package.
  • Network access to and from all hosts in your Greenplum Database array (master and segments).
  • Network access to and from the hosts where the data to be loaded resides (ETL servers).

Description

gpload.py is a data loading utility that acts as an interface to Greenplum Database's external table parallel loading feature. Using a load specification defined in a YAML formatted control file, gpload.py executes a load by invoking the Greenplum parallel file server (gpfdist.exe), creating an external table definition based on the source data defined, and executing an INSERT, UPDATE or MERGE operation to load the source data into the target table in the database.

The operation, including any SQL commands specified in the SQL collection of the YAML control file (see Control File Format), are performed as a single transaction to prevent inconsistent data when performing multiple, simultaneous load operations on a target table.

Options

-f control_file
Required. A YAML file that contains the load specification details. See Control File Format.
--gpfdist_timeout seconds
Sets the timeout for the gpfdist parallel file distribution program to send a response. Enter a value from 0 to 30 seconds (entering "0" to disables timeouts). Note that you might need to increase this value when operating on high-traffic networks.
-l log_file
Specifies where to write the log file. Defaults to ~/gpAdminLogs/gpload_YYYYMMDD. For more information about the log file, see Log File Format.
--no_auto_trans
Specify --no_auto_trans to disable processing the load operation as a single transaction if you are performing a single load operation on the target table.
By default, gpload.py processes each load operation as a single transaction to prevent inconsistent data when performing multiple, simultaneous operations on a target table.
-q (no screen output)
Run in quiet mode. Command output is not displayed on the screen, but is still written to the log file.
-D (debug mode)
Check for error conditions, but do not execute the load.
-v (verbose mode)
Show verbose output of the load steps as they are executed.
-V (very verbose mode)
Shows very verbose output.
-? (show help)
Show help, then exit.
--version
Show the version of this utility, then exit.
Connection Options
-d database
The database to load into. If not specified, reads from the load control file, the environment variable $PGDATABASE or defaults to the current system user name.
-h hostname
Specifies the host name of the machine on which the Greenplum Database master database server is running. If not specified, reads from the load control file, the environment variable $PGHOST or defaults to localhost.
-p port
Specifies the TCP port on which the Greenplum Database master database server is listening for connections. If not specified, reads from the load control file, the environment variable $PGPORT or defaults to 5432.
-U username
The database role name to connect as. If not specified, reads from the load control file, the environment variable $PGUSER or defaults to the current system user name.
-W (force password prompt)
Force a password prompt. If not specified, reads the password from the environment variable $PGPASSWORD or from a password file specified by $PGPASSFILE or in ~/.pgpass. If these are not set, then gpload.py will prompt for a password even if -W is not supplied.

Control File Format

The gpload.py control file uses the YAML 1.1 document format and then implements its own schema for defining the various steps of a Greenplum Database load operation. The control file must be a valid YAML document.

The gpload.py program processes the control file document in order and uses indentation (spaces) to determine the document hierarchy and the relationships of the sections to one another. The use of white space is significant. White space should not be used simply for formatting purposes, and tabs should not be used at all.

The basic structure of a load control file is:

---
VERSION: 1.0.0.1
DATABASE: db_name
USER: db_username
HOST: master_hostname
PORT: master_port
GPLOAD:
   INPUT:
    - SOURCE:
         LOCAL_HOSTNAME:
           - hostname_or_ip
         PORT: http_port
       | PORT_RANGE: [start_port_range, end_port_range]
         FILE: 
           - /path/to/input_file
         SSL: true | false
         CERTIFICATES_PATH: /path/to/certificates
    - FULLY_QUALIFIED_DOMAIN_NAME: true | false
    - COLUMNS:
           - field_name: data_type
    - TRANSFORM: 'transformation'
    - TRANSFORM_CONFIG: 'configuration-file-path' 
    - MAX_LINE_LENGTH: integer 
    - FORMAT: text | csv
    - DELIMITER: 'delimiter_character'
    - ESCAPE: 'escape_character' | 'OFF'
    - NULL_AS: 'null_string'
    - FORCE_NOT_NULL: true | false
    - QUOTE: 'csv_quote_character'
    - HEADER: true | false
    - ENCODING: database_encoding
    - ERROR_LIMIT: integer
    - LOG_ERRORS: true | false
    - ERROR_TABLE: schema.table_name
   EXTERNAL:
      - SCHEMA: schema | '%'
   OUTPUT:
    - TABLE: schema.table_name
    - MODE: insert | update | merge
    - MATCH_COLUMNS:
           - target_column_name
    - UPDATE_COLUMNS:
           - target_column_name
    - UPDATE_CONDITION: 'boolean_condition'
    - MAPPING:
              target_column_name: source_column_name | 'expression'
   PRELOAD:
    - TRUNCATE: true | false
    - REUSE_TABLES: true | false
   SQL:
    - BEFORE: "sql_command"
    - AFTER: "sql_command"
VERSION
Optional. The version of the gpload.py control file schema. The current version is 1.0.0.1.
DATABASE
Optional. Specifies which database in the Greenplum Database system to connect to. If not specified, defaults to $PGDATABASE if set or the current system user name. You can also specify the database on the command line using the -d option.
USER
Optional. Specifies which database role to use to connect. If not specified, defaults to the current user or $PGUSER if set. You can also specify the database role on the command line using the -U option.
If the user running gpload.py is not a Greenplum Database superuser, then the server configuration parameter gp_external_grant_privileges must be set to on in order for the load to be processed. See the Greenplum Database Reference Guide for more information.
HOST
Optional. Specifies Greenplum Database master host name. If not specified, defaults to localhost or $PGHOST if set. You can also specify the master host name on the command line using the -h option.
PORT
Optional. Specifies Greenplum Database master port. If not specified, defaults to 5432 or $PGPORT if set. You can also specify the master port on the command line using the -p option.
GPLOAD
Required. Begins the load specification section. A GPLOAD specification must have an INPUT and an OUTPUT section defined.
INPUT
Required. Defines the location and the format of the input data to be loaded. gpload.py will start one or more instances of the gpfdist.exe file distribution program on the current host and create the required external table definition(s) in Greenplum Database that point to the source data. Note that the host from which you run gpload.py must be accessible over the network by all Greenplum Database hosts (master and segments).
SOURCE
Required. The SOURCE block of an INPUT specification defines the location of a source file. An INPUT section can have more than one SOURCE block defined. Each SOURCE block defined corresponds to one instance of the gpfdist.exe file distribution program that will be started on the local machine. Each SOURCE block defined must have a FILE specification. For more information about using the gpfdist parallel file server and single and multiple gpfdist instances, see "Loading and Unloading Data" in the Greenplum Database Administrator Guide.
LOCAL_HOSTNAME
Optional. Specifies the host name or IP address of the local machine on which gpload.py is running. If this machine is configured with multiple network interface cards (NICs), you can specify the host name or IP of each individual NIC to allow network traffic to use all NICs simultaneously. The default is to use the local machine's primary host name or IP only.
PORT
Optional. Specifies the specific port number that the gpfdist.exe file distribution program should use. You can also supply a PORT_RANGE to select an available port from the specified range. If both PORT and PORT_RANGE are defined, then PORT takes precedence. If neither PORT or PORT_RANGE are defined, the default is to select an available port between 8000 and 9000.

If multiple host names are declared in LOCAL_HOSTNAME, this port number is used for all hosts. This configuration is desired if you want to use all NICs to load the same file or set of files in a given directory location.

PORT_RANGE
Optional. Can be used instead of PORT to supply a range of port numbers from which gpload.py can choose an available port for this instance of the gpfdist.exe file distribution program.
FILE
Required. Specifies the location of a file, named pipe, or directory location on the local file system that contains data to be loaded. You can declare more than one file so long as the data is of the same format in all files specified.

If the files are compressed using gzip or bzip2 (have a .gz or .bz2 file extension), the files will be uncompressed automatically (provided that gunzip or bunzip2 is in your path).

When specifying which source files to load, you can use the wildcard character (*) or other C-style pattern matching to denote multiple files. The files specified are assumed to be relative to the current directory from which gpload.py is executed (or you can declare an absolute path).

SSL
Optional. Specifies usage of SSL encryption. If SSL is set to true, gpload starts the gpfdist server with the --ssl option and uses the gpfdists:// protocol.
CERTIFICATES_PATH
Required when SSL is true; cannot be specified when SSL is false or unspecified. The location specified in CERTIFICATES_PATH must contain the following files:
  • The server certificate file, server.crt
  • The server private key file, server.key
  • The trusted certificate authorities, root.crt

The root directory (/) cannot be specified as CERTIFICATES_PATH.

FULLY_QUALIFIED_DOMAIN_NAME
Optional. Specifies whether gpload resolve hostnames to the fully qualified domain name (FQDN) or the local hostname. If the value is set to true, names are resolved to the FQDN. If the value is set to false, resolution is to the local hostname. The default is false.

A fully qualified domain name might be required in some situations. For example, if the Greenplum Database system is in a different domain than an ETL application that is being accessed by gpload.

COLUMNS
Optional. Specifies the schema of the source data file(s) in the format of field_name:data_type. The DELIMITER character in the source file is what separates two data value fields (columns). A row is determined by a line feed character (0x0a).

If the input COLUMNS are not specified, then the schema of the output TABLE is implied, meaning that the source data must have the same column order, number of columns, and data format as the target table.

The default source-to-target mapping is based on a match of column names as defined in this section and the column names in the target TABLE. This default mapping can be overridden using the MAPPING section.

TRANSFORM
Optional. Specifies the name of the input XML transformation passed to gploadl.py. For more information about XML transformations, see "Loading and Unloading Data" in the Greenplum Database Administrator Guide.
TRANSFORM_CONFIG
Optional. Specifies the location of the XML transformation configuration file that is specified in the TRANSFORM parameter, above.
MAX_LINE_LENGTH
Optional. An integer that specifies the maximum length of a line in the XML transformation data passed to gpload.py.
FORMAT
Optional. Specifies the format of the source data file(s) - either plain text (TEXT) or comma separated values (CSV) format. Defaults to TEXT if not specified. For more information about the format of the source data, see "Loading and Unloading Data" in the Greenplum Database Administrator Guide.
DELIMITER
Optional. Specifies a single ASCII character that separates columns within each row (line) of data. The default is a tab character in TEXT mode, a comma in CSV mode. You can also specify a non- printable ASCII character or a non-printable unicode character, for example: "\x1B" or "\u001B". The escape string syntax, E'character-code', is also supported for non-printable characters. The ASCII or unicode character must be enclosed in single quotes. For example: E'\x1B' or E'\u001B'.
ESCAPE
Specifies the single character that is used for C escape sequences (such as \n, \t, \100, and so on) and for escaping 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 a \ (backslash) for text-formatted files and a " (double quote) for csv-formatted files, however it is possible to specify another character to represent an escape. It is also possible to disable escaping in text-formatted files by specifying the value 'OFF' as the escape value. This is very useful for data such as text-formatted web log data that has many embedded backslashes that are not intended to be escapes.
NULL_AS
Optional. Specifies the string that represents a null value. The default is \N (backslash-N) in TEXT mode, and an empty value with no quotations in CSV mode. You might prefer an empty string even in TEXT mode for cases where you do not want to distinguish nulls from empty strings. Any source data item that matches this string will be considered a null value.
FORCE_NOT_NULL
Optional. In CSV mode, processes 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.
QUOTE
Required when FORMAT is CSV. Specifies the quotation character for CSV mode. The default is double-quote (").
HEADER
Optional. Specifies that the first line in the data file(s) is a header row (contains the names of the columns) and should not be included as data to be loaded. If using multiple data source files, all files must have a header row. The default is to assume that the input files do not have a header row.
ENCODING
Optional. Character set encoding of the source data. Specify a string constant (such as 'SQL_ASCII'), an integer encoding number, or 'DEFAULT' to use the default client encoding. If not specified, the default client encoding is used. For information about supported character sets, see the Greenplum Database Reference Guide.
ERROR_LIMIT
Optional. Enables single row error isolation mode for this load operation. When enabled, input rows that have format errors will be discarded provided that the error limit count is not reached on any Greenplum Database segment instance during input processing. If the error limit is not reached, all good rows will be loaded and any error rows will either be discarded or logged to the table specified in ERROR_TABLE. The default is to abort the load operation on the first error encountered. Note that single row error isolation only applies to data rows with format errors; for example, extra or missing attributes, attributes of a wrong data type, or invalid client encoding sequences. Constraint errors, such as primary key violations, will still cause the load operation to abort if encountered. For information about handling load errors, see "Loading and Unloading Data" in the Greenplum Database Administrator Guide.
LOG_ERRORS
Optional when ERROR_LIMIT is declared. Value is either true or false. The default value is false. If the value is true, rows with formatting errors are logged internally when running in single row error isolation mode. You can examine formatting errors with the Greenplum Database built-in SQL function gp_read_error_log('table_name'). If formatting errors are detected when loading data, gpload.py generates a warning message with the name of the table that contains the error information similar to this message.
timestamp|WARN|1 bad row, please use GPDB built-in function gp_read_error_log('table-name') 
   to access the detailed error row
If LOG_ERRORS: true is specified, REUSE TABLES: true must be specified to retain the formatting errors in Greenplum Database error logs. If REUSE TABLES: true is not specified, the error information is deleted after the gpload operation. You can delete the formatting errors from the error logs with the Greenplum Database function gp_truncate_error_log().
Only LOG_ERRORS or ERROR_TABLE can be specified. If both are specified, an error message is returned.
For more information about handling load errors, see "Loading and Unloading Data" in the Greenplum Database Administrator Guide. For information about the gp_read_error_log() function, see the CREATE EXTERNAL TABLE command in the Greenplum Database Reference Guide
ERROR_TABLE
Optional when ERROR_LIMIT is declared. Specifies an error table where rows with formatting errors will be logged when running in single row error isolation mode. You can then examine this error table to see error rows that were not loaded (if any). If the ERROR_TABLE specified already exists, it will be used. If it does not exist, it will be automatically generated.
Only LOG_ERRORS or ERROR_TABLE can be specified. If both are specified, an error message is returned. Use LOG_ERRORS to capture formatting errors.
For more information about handling load errors, see "Loading and Unloading Data" in the Greenplum Database Administrator Guide.
EXTERNAL
Optional. Defines the schema of the external table database objects created by gpload.py.
The default is to use the Greenplum Database search_path.
SCHEMA
Required when EXTERNAL is declared. The name of the schema of the external table. If the schema does not exist, an error is returned.
If % (percent character) is specified, the schema of the table name specified by TABLE in the OUTPUT section is used. If the table name does not specify a schema, the default schema is used.
OUTPUT
Required. Defines the target table and final data column values that are to be loaded into the database.
TABLE
Required. The name of the target table to load into.
MODE
Optional. Defaults to INSERT if not specified. There are three available load modes:
INSERT - Loads data into the target table using the following method:
INSERT INTO target_table SELECT * FROM input_data;
UPDATE - Updates the UPDATE_COLUMNS of the target table where the rows have MATCH_COLUMNS attribute values equal to those of the input data, and the optional UPDATE_CONDITION is true.
MERGE - Inserts new rows and updates the UPDATE_COLUMNS of existing rows where FOOBAR attribute values are equal to those of the input data, and the optional MATCH_COLUMNS is true. New rows are identified when the MATCH_COLUMNS value in the source data does not have a corresponding value in the existing data of the target table. In those cases, the entire row from the source file is inserted, not only the MATCH and UPDATE columns. If there are multiple new MATCH_COLUMNS values that are the same, only one new row for that value will be inserted. Use UPDATE_CONDITION to filter out the rows to discard.
MATCH_COLUMNS
Required if MODE is UPDATE or MERGE. Specifies the column(s) to use as the join condition for the update. The attribute value in the specified target column(s) must be equal to that of the corresponding source data column(s) in order for the row to be updated in the target table.
UPDATE_COLUMNS
Required if MODE is UPDATE or MERGE. Specifies the column(s) to update for the rows that meet the MATCH_COLUMNS criteria and the optional UPDATE_CONDITION.
UPDATE_CONDITION
Optional. Specifies a Boolean condition (similar to what you would declare in a WHERE clause) that must be met in order for a row in the target table to be updated (or inserted in the case of a MERGE).
MAPPING
Optional. If a mapping is specified, it overrides the default source-to-target column mapping. The default source-to-target mapping is based on a match of column names as defined in the source COLUMNS section and the column names of the target TABLE. A mapping is specified as either:
target_column_name: source_column_name
or
target_column_name: 'expression'
Where expression is any expression that you would specify in the SELECT list of a query, such as a constant value, a column reference, an operator invocation, a function call, and so on.
PRELOAD
Optional. Specifies operations to run prior to the load operation. Right now the only preload operation is TRUNCATE.
TRUNCATE
Optional. If set to true, gpload.py will remove all rows in the target table prior to loading it.
REUSE_TABLES
Optional. If set to true, gpload.py will not drop the external table objects and staging table objects it creates. These objects will be reused for future load operations that use the same load specifications. This improves performance of trickle loads (ongoing small loads to the same target table).
If LOG_ERRORS: true is specified, REUSE TABLES: true must be specified to retain the formatting errors in Greenplum Database error logs. If REUSE TABLES: true is not specified, formatting error information is deleted after the gpload operation.
SQL
Optional. Defines SQL commands to run before and/or after the load operation. You can specify multiple BEFORE and/or AFTER commands. List commands in the order of desired execution.
BEFORE
Optional. An SQL command to run before the load operation starts. Enclose commands in quotes.
AFTER
Optional. An SQL command to run after the load operation completes. Enclose commands in quotes.

Log File Format

Log files output by gpload.py have the following format:

timestamp|level|message

Where timestamp takes the form: YYYY-MM-DD HH:MM:SS, level is one of DEBUG, LOG, INFO, ERROR, and message is a normal text message.

Some INFO messages that may be of interest in the log files are (where # corresponds to the actual number of seconds, units of data, or failed rows):

INFO|running time: #.## seconds
INFO|transferred #.# kB of #.# kB.
INFO|gpload succeeded
INFO|gpload succeeded with warnings
INFO|gpload failed
INFO|1 bad row
INFO|# bad rows

Notes

If your database object names were created using a double-quoted identifier (delimited identifier), you must specify the delimited name within single quotes in the gpload.py control file. For example, if you create a table as follows:

CREATE TABLE "MyTable" ("MyColumn" text);

Your YAML-formatted gpload.py control file would refer to the above table and column names as follows:

- COLUMNS:
   - '"MyColumn"': text
OUTPUT:
   - TABLE: public.'"MyTable"'

Examples

Run a load job as defined in my_load.yml:

gpload.py -f my_load.yml

Example load control file:

---
VERSION: 1.0.0.1
DATABASE: ops
USER: gpadmin
HOST: mdw-1
PORT: 5432
GPLOAD:
   INPUT:
    - SOURCE:
         LOCAL_HOSTNAME:
           - etl1-1
           - etl1-2
           - etl1-3
           - etl1-4
         PORT: 8081
         FILE: 
           - /var/load/data/*
    - COLUMNS:
           - name: text
           - amount: float4
           - category: text
           - desc: text
           - date: date
    - FORMAT: text
    - DELIMITER: '|'
    - ERROR_LIMIT: 25
    - ERROR_TABLE: payables.err_expenses
   OUTPUT:
    - TABLE: payables.expenses
    - MODE: INSERT
   SQL:
   - BEFORE: "INSERT INTO audit VALUES('start', 
current_timestamp)"
   - AFTER: "INSERT INTO audit VALUES('end', 
current_timestamp)"

See Also

gpfdist.exe, CREATE EXTERNAL TABLE in the Greenplum Database Reference Guide