DBE_FILE

API Description

Table 1 lists all APIs supported by the DBE_FILE package.

• DBE_FILE.OPEN

  This function opens a file. You can specify the maximum number of characters in each line. A maximum of 50 files can be opened at a time. This function returns a handle of the INTEGER type.

  The prototype of the DBE_FILE.OPEN function is as follows:

  1 2 3 4 5 6

  DBE_FILE.OPEN ( dir IN VARCHAR2, file_name IN VARCHAR2, open_mode IN VARCHAR2, max_line_size IN INTEGER DEFAULT 1024) RETURN INTEGER;

  Table 2 DBE_FILE.OPEN API parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  dir	VARCHAR2	IN	No	Directory of a file. It is a string, indicating an object name. NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  file_name	VARCHAR2	IN	No	File name with an extension (file type), excluding the path name. A path contained in a file name is ignored in the OPEN function. In Unix, the file name cannot end with the combination of a slash and a dot (/.).
  open_mode	VARCHAR2	IN	No	File opening mode, including r (read), w (write), and a (append). NOTE: For the write operation, the system checks the file type. If the ELF file is written, an error is reported and the system exits.
  max_line_size	INTEGER	IN	Yes	Maximum number of characters in each line, including newline characters. The minimum value is 1 and the maximum is 32767. If this parameter is not specified, the default value 1024 is used.

• DBE_FILE.IS_CLOSE

  Checks whether a file handle is closed. A Boolean value is returned. If an invalid file handle is detected, the INVALID_FILEHANDLE exception is thrown.

  The prototype of the DBE_FILE.IS_CLOSE function is as follows:

  1 2 3

  DBE_FILE.IS_CLOSE ( file IN INTEGER) RETURN BOOLEAN;

  Table 3 DBE_FILE.IS_CLOSE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file IN INTEGER	INTEGER	IN	Yes	Passes a file handle to be detected.

• DBE_FILE.READ_LINE

  Reads data from an open file and stores the read result to the buffer. It reads data to the end of each line excluding the line terminator, to the end of the file, or to the size specified by the len parameter. The length of the data to be read cannot exceed the value of max_line_size specified when the file is opened.

  The prototype of the DBE_FILE.READ_LINE function is as follows:

  1 2 3 4

  DBE_FILE.READ_LINE ( file IN INTEGER, buffer OUT VARCHAR2, len IN INTEGER DEFAULT NULL)

  Table 4 DBE_FILE.READ_LINE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened by calling the OPEN function. The file must be opened in read mode. Otherwise, the INVALID_OPERATION exception is thrown.
  buffer	VARCHAR2	OUT	No	Buffer used to receive data.
  len	INTEGE	IN	Yes	Number of bytes read from a file. The default value is NULL. If the default value NULL is used, max_line_size is used to specify the line size.

• DBE_FILE.WRITE

  Writes buffer data to the buffer corresponding to a file. The file must be opened in write mode. This operation does not write a line terminator.

  The prototype of the DBE_FILE.WRITE function is as follows:

  1 2 3 4

  DBE_FILE.WRITE ( file IN INTEGER, buffer IN TEXT) RETURN BOOLEAN;;

  Table 5 DBE_FILE.WRITE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	This stored procedure writes data in the buffer to a file. The file must be opened in write mode. Line terminators are not written.
  buffer	TEXT	IN	Yes	Text data to be written to a file. The maximum buffer size is 32767 bytes. If no value is specified in the open state, the default value is 1024 bytes. Before the writing is performed, the buffer occupied by WRITE operations cannot exceed 32767 bytes. NOTE: For the write operation, the system checks the file type. If the ELF file is written, an error is reported and the system exits.

• DBE_FILE.NEW_LINE

  Writes one or more line terminators to the buffer corresponding to a file. The line terminators are related to the platform used.

  The prototype of the DBE_FILE.NEW_LINE function is as follows:

  1 2 3 4

  DBE_FILE.NEW_LINE ( file IN INTEGER, line_nums IN INTEGER := 1) RETURN BOOLEAN;

  Table 6 DBE_FILE.NEW_LINE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.
  line_nums	INTEGER	IN	Yes	Number of terminators written to a file. The default value is 1.

• DBE_FILE.WRITE_LINE

  Writes buffer data to the buffer corresponding to a file. The file must be opened in write mode. This operation automatically adds a line terminator.

  The prototype of the DBE_FILE.WRITE_LINE function is as follows:

  1 2 3 4 5

  DBE_FILE.WRITE_LINE( file IN INTEGER, buffer IN TEXT, flush IN BOOLEAN DEFAULT FALSE) RETURN BOOLEAN;

  Table 7 DBE_FILE.WRITE_LINE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.
  buffer	TEXT	IN	Yes	Text data to be written to a file. The maximum buffer size is 32767 bytes. If no value is specified during the open state, the default value is 1024 bytes. Before the writing is performed, the buffer occupied by PUT operations cannot exceed 32767 bytes. NOTE: For the write operation, the system checks the file type. If the ELF file is written, an error is reported and the system exits.
  flush	BOOLEAN	IN	Yes	Specifies whether to flush data to the disk after the writing.

• DBE_FILE.FORMAT_WRITE

  Writes formatted data to the buffer corresponding to an open file. It is a DBE_FILE.WRITE API that allows formatting.

  The prototype of the DBE_FILE.FORMAT_WRITE function is as follows:

  1 2 3 4 5 6 7

  DBE_FILE.FORMAT_WRITE ( file IN INTEGER, format IN VARCHAR2, arg1 IN VARCHAR2 DEFAULT NULL, . . . arg6 IN VARCHAR2 DEFAULT NULL]) RETURN BOOLEAN;

  Table 8 DBE_FILE.FORMAT_WRITE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.
  format	VARCHAR2	IN	Yes	A string to be formatted, containing the text and format characters \n and %s.
  [arg1. . .arg6]	VARCHAR2	IN	Yes	Six optional parameters. The parameters and the positions of characters to be formatted are in one-to-one correspondence. If the parameter corresponding to a character to be formatted is not provided, an empty string is used to replace %s.

• DBE_FILE.GET_RAW

  Reads RAW data from an open file, stores the read result in the buffer, and returns the result from r.

  The prototype of the DBE_FILE.GET_RAW function is as follows:

  1 2 3 4

  DBE_FILE.GET_RAW ( file IN INTEGER, r OUT RAW, length IN INTEGER DEFAULT NULL);

  Table 9 DBE_FILE.GET_RAW parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.
  r	RAW	OUT	No	Output binary data.
  length	INTEGER	IN	Yes	Length of the file to be read. The default value is NULL. All data in the file is read. The maximum length is 1 GB.

• DBE_FILE.PUT_RAW

  Writes raw data to the buffer corresponding to a file.

  The prototype of the DBE_FILE.PUT_RAW function is as follows:

  1 2 3 4 5

  DBE_FILE.PUT_RAW ( file IN INTEGER, r IN RAW, flush IN BOOLEAN DEFAULT FALSE) RETURN BOOLEAN;

  Table 10 DBE_FILE.PUT_RAW parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.
  r	RAW	IN	No	Output binary data. NOTE: For the write operation, the system checks the file type. If the ELF file is written, an error is reported and the system exits.
  flush	BOOLEAN	IN	Yes	Specifies whether to flush data to a file. The default value is false.

• DBE_FILE.FLUSH

  Writes cached data to a physical file. The cached data must have a line terminator.

  The prototype of the DBE_FILE.FLUSH function is as follows:

  1 2 3

  DBE_FILE.FLUSH ( file IN INTEGER) RETURN VOID;

  Table 11 DBE_FILE.FLUSH parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.

• DBE_FILE.CLOSE

  Closes an open file. When this function is called, if there is cached data to be written, exception information may be received.

  The prototype of the DBE_FILE.CLOSE function is as follows:

  1 2 3

  DBE_FILE.CLOSE ( file IN INTEGER )RETURN INTEGER;

  Table 12 DBE_FILE.CLOSE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.

• DBE_FILE.CLOSE_ALL

  Closes all file handles opened in a session. This function can be used for emergency cleanup.

  The prototype of the DBE_FILE.CLOSE_ALL function is as follows:

  1 2	DBE_FILE.CLOSE_ALL() RETRUN VOID;

  Table 13 DBE_FILE.CLOSE_ALL API parameters

  Parameter	Description
  None.	None.

• DBE_FILE.REMOVE

  Deletes a disk file. To use this function, you must have the required permission.

  The prototype of the DBE_FILE.REMOVE function is as follows:

  1 2 3 4

  DBE_FILE.REMOVE ( dir IN VARCHAR2, file_name IN VARCHAR2) RETURN VOID;

  Table 14 DBE_FILE.REMOVE parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  dir	VARCHAR2	IN	No	Directory of a file. It is a string, indicating an object name. NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  file_name	VARCHAR2	IN	No	File name.

• DBE_FILE.RENAME

  Renames a disk file. This function is similar to the mv command of Unix.

  The prototype of the DBE_FILE.RENAME function is as follows:

  1 2 3 4 5 6 7

  DBE_FILE.RENAME ( src_dir IN VARCHAR2, src_file_name IN VARCHAR2, dest_dir IN VARCHAR2, dest_file_name IN VARCHAR2, overwrite IN BOOLEAN DEFAULT FALSE) RETURN VOID;

  Table 15 DBE_FILE.RENAME parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  src_dir	VARCHAR2	IN	No	Directory of the original file (case-sensitive) NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  src_file_name	VARCHAR2	IN	No	Original file to be renamed
  dest_dir	VARCHAR2	IN	No	Target directory (case-sensitive). NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  dest_file_name	VARCHAR2	IN	No	New file name
  overwrite	BOOLEAN	IN	Yes	Specifies whether to overwrite the file. If the parameter is left empty or not specified, the parameter is not overwritten. If a file with the same name exists in the target directory, the file will not be overwritten.

• DBE_FILE.COPY

  Copies data in a continuous area to a new file. If start_line and end_line are omitted, the entire file is copied.

  The prototype of the DBE_FILE.COPY function is as follows:

  1 2 3 4 5 6 7 8

  DBE_FILE.COPY ( src_dir IN VARCHAR2, src_file_name IN VARCHAR2, dest_dir IN VARCHAR2, dest_file_name IN VARCHAR2, start_line IN INTEGER DEFAULT 1, end_line IN INTEGER DEFAULT NULL) RETURN VOID;

  Table 16 DBE_FILE.COPY parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  src_dir	VARCHAR2	IN	No	Directory of the original file NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  src_file_name	VARCHAR2	IN	No	File to be copied.
  dest_dir	VARCHAR2	IN	No	Directory of the destination file NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  dest_file_name	VARCHAR2	IN	No	Target file NOTE: For the write operation, the system checks the file type. If the ELF file is written, an error is reported and the system exits.
  start_line	INTEGER	IN	No	Number of the line where the copy starts. The default value is 1.
  end_line	INTEGER	IN	Yes	Number of the line where the copy ends. The default value is NULL, indicating the end of the file.

• DBE_FILE.GET_ATTR

  Reads and returns the attributes of a disk file.

  The prototype of the DBE_FILE.GET_ATTR stored procedure is as follows:

  1 2 3 4 5 6

  DBE_FILE.GET_ATTR( location IN text, filename IN text, OUT fexists boolean, OUT file_length bigint, OUT block_size integer);

  Table 17 DBE_FILE.GET_ATTR parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  location	TEXT	IN	No	File directory NOTE: File directories need to be added to the system catalog PG_DIRECTORY. If the input path does not match the path in PG_DIRECTORY, an error indicating that the path does not exist will be reported. Functions that involve location as parameters also comply with this rule. When the GUC parameter safe_data_path is enabled, you can only use an advanced package to read and write files in the file path specified by safe_data_path.
  filename	TEXT	IN	No	File name.
  fexists	BOOLEAN	OUT	No	Specifies whether the file exists.
  file_length	BIGINT	OUT	No	File length (unit: byte). If the file does not exist, NULL is returned.
  block_size	INTEGER	OUT	No	Block size of the file system (unit: byte). If the file does not exist, NULL is returned.

• DBE_FILE.SEEK

  Adjusts the position of a file pointer forward or backward based on the specified number of bytes.

  The prototype of the DBE_FILE.SEEK function is as follows:

  1 2 3 4 5

  DBE_FILE.SEEK ( file IN INTEGER, absolute_start IN BIGINT DEFAULT NULL, relative_start IN BIGINT DEFAULT NULL) RETURN VOID;

  Table 18 DBE_FILE.SEEK parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.
  absolute_start	BIGINT	IN	Yes	Absolute offset of a file. The default value is NULL.
  relative_start	BIGINT	IN	Yes	Relative offset of a file. A positive number indicates forward offset and a negative number indicates backward offset. The default value is NULL. If both absolute_start and this parameter are specified, the absolute_start parameter is used.

• DBE_FILE.GET_POS

  Returns the current offset of the file in bytes.

  The prototype of the DBE_FILE.FGETPOS function is as follows:

  1 2 3

  DBE_FILE.GET_POS ( file IN INTEGER) RETURN BIGINT;

  Table 19 DBE_FILE.GET_POS parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.

• DBE_FILE.IS_OPEN

  Returns the current offset of the file in bytes.

  The prototype of the DBE_FILE.IS_OPEN function is as follows:

  1 2 3

  DBE_FILE.IS_OPEN ( file IN INTEGER) RETURN BOOLEAN;

  Table 20 DBE_FILE.IS_OPEN parameters

  Parameter	Type	Input/Output Parameter	Can Be Empty	Description
  file	INTEGER	IN	No	File handle opened using OPEN.

Examples

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-- Add the /temp/ directory to the PG_DIRECTORY system catalog as a SYSADMIN.
CREATE OR REPLACE DIRECTORY dir AS '/tmp/';
-- The expected result is as follows:
CREATE DIRECTORY

-- Open a file and write data into the file.
DECLARE
  f integer;
  dir text := 'dir';
BEGIN
  f := dbe_file.open(dir, 'sample.txt', 'w');
  PERFORM dbe_file.write_line(f, 'ABC');
  PERFORM dbe_file.write_line(f, '123'::numeric);
  PERFORM dbe_file.write_line(f, '-----');
  PERFORM dbe_file.new_line(f);
  PERFORM dbe_file.write_line(f, '*******');
  PERFORM dbe_file.new_line(f, 0);
  PERFORM dbe_file.write_line(f, '++++++++');
  PERFORM dbe_file.new_line(f, 2);
  PERFORM dbe_file.write_line(f, '#######');
  PERFORM dbe_file.write(f, 'A');
  PERFORM dbe_file.write(f, 'B');
  PERFORM dbe_file.new_line(f);
  PERFORM dbe_file.format_write(f, '[1 -> %s, 2 -> %s, 3 -> %s, 4 -> %s, 5 -> %s]', 'gaussdb', 'dbe', 'file', 'get', 'line');
  PERFORM dbe_file.new_line(f);
  PERFORM dbe_file.write_line(f, '1234567890');
  f := dbe_file.close(f);
END;
/
-- The expected result is as follows:
ANONYMOUS BLOCK EXECUTE

-- Read data from the file mentioned above.
DECLARE
  f integer;
  dir text := 'dir';
BEGIN
  f := dbe_file.open(dir, 'sample.txt', 'r');
  FOR i IN 1..11 LOOP
       RAISE INFO '[%] : %', i, dbe_file.read_line(f);
  END LOOP;
END;
/
-- The expected result is as follows:
INFO:  [1] : ABC
INFO:  [2] : 123
INFO:  [3] : -----
INFO:  [4] : 
INFO:  [5] : *******
INFO:  [6] : ++++++++
INFO:  [7] : 
INFO:  [8] : 
INFO:  [9] : #######
INFO:  [10] : AB
INFO:  [11] : [1 -> gaussdb, 2 -> dbe, 3 -> file, 4 -> get, 5 -> line]
ANONYMOUS BLOCK EXECUTE

-- Offset the file handle and obtain the current file location.
DECLARE
      l_file   integer;
      l_buffer VARCHAR2(32767);
      dir text := 'dir';
      abs_offset number := 100;
      rel_offset number := NULL;
BEGIN
      l_file := dbe_file.open(dir  => dir,  file_name  => 'sample.txt',open_mode => 'R');
      dbe_output.print_line('before seek: current position is ' || dbe_file.get_pos(file => l_file)); -- before seek: current position is 0
      dbe_file.seek(file => l_file, absolute_start=>abs_offset, relative_start=>rel_offset);
      dbe_output.print_line('fseek: current position is ' || dbe_file.get_pos(file => l_file)); -- seek: current position is 100
      l_file := dbe_file.close(file => l_file);
END;
/
-- The expected result is as follows:
before seek: current position is 0
fseek: current position is 100
ANONYMOUS BLOCK EXECUTE