postgresql/src/include/commands/copyfrom_internal.h

/*-------------------------------------------------------------------------
 *
 * copyfrom_internal.h
 *	  Internal definitions for COPY FROM command.
 *
 *
 * Portions Copyright (c) 1996-2021, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/commands/copyfrom_internal.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef COPYFROM_INTERNAL_H
#define COPYFROM_INTERNAL_H

#include "commands/copy.h"
#include "commands/trigger.h"

/*
 * Represents the different source cases we need to worry about at
 * the bottom level
 */
typedef enum CopySource
{
	COPY_FILE,					/* from file (or a piped program) */
	COPY_OLD_FE,				/* from frontend (2.0 protocol) */
	COPY_NEW_FE,				/* from frontend (3.0 protocol) */
	COPY_CALLBACK				/* from callback function */
} CopySource;

/*
 *	Represents the end-of-line terminator type of the input
 */
typedef enum EolType
{
	EOL_UNKNOWN,
	EOL_NL,
	EOL_CR,
	EOL_CRNL
} EolType;

/*
 * Represents the heap insert method to be used during COPY FROM.
 */
typedef enum CopyInsertMethod
{
	CIM_SINGLE,					/* use table_tuple_insert or fdw routine */
	CIM_MULTI,					/* always use table_multi_insert */
	CIM_MULTI_CONDITIONAL		/* use table_multi_insert only if valid */
} CopyInsertMethod;

/*
 * This struct contains all the state variables used throughout a COPY FROM
 * operation.
 *
 * Multi-byte encodings: all supported client-side encodings encode multi-byte
 * characters by having the first byte's high bit set. Subsequent bytes of the
 * character can have the high bit not set. When scanning data in such an
 * encoding to look for a match to a single-byte (ie ASCII) character, we must
 * use the full pg_encoding_mblen() machinery to skip over multibyte
 * characters, else we might find a false match to a trailing byte. In
 * supported server encodings, there is no possibility of a false match, and
 * it's faster to make useless comparisons to trailing bytes than it is to
 * invoke pg_encoding_mblen() to skip over them. encoding_embeds_ascii is true
 * when we have to do it the hard way.
 */
typedef struct CopyFromStateData
{
	/* low-level state data */
	CopySource	copy_src;		/* type of copy source */
	FILE	   *copy_file;		/* used if copy_src == COPY_FILE */
	StringInfo	fe_msgbuf;		/* used if copy_src == COPY_NEW_FE */
	bool		reached_eof;	/* true if we read to end of copy data (not
								 * all copy_src types maintain this) */

	EolType		eol_type;		/* EOL type of input */
	int			file_encoding;	/* file or remote side's character encoding */
	bool		need_transcoding;	/* file encoding diff from server? */
	bool		encoding_embeds_ascii;	/* ASCII can be non-first byte? */

	/* parameters from the COPY command */
	Relation	rel;			/* relation to copy from */
	List	   *attnumlist;		/* integer list of attnums to copy */
	char	   *filename;		/* filename, or NULL for STDIN */
	bool		is_program;		/* is 'filename' a program to popen? */
	copy_data_source_cb data_source_cb; /* function for reading data */

	CopyFormatOptions opts;
	bool	   *convert_select_flags;	/* per-column CSV/TEXT CS flags */
	Node	   *whereClause;	/* WHERE condition (or NULL) */

	/* these are just for error messages, see CopyFromErrorCallback */
	const char *cur_relname;	/* table name for error messages */
	uint64		cur_lineno;		/* line number for error messages */
	const char *cur_attname;	/* current att for error messages */
	const char *cur_attval;		/* current att value for error messages */

	/*
	 * Working state
	 */
	MemoryContext copycontext;	/* per-copy execution context */

	AttrNumber	num_defaults;
	FmgrInfo   *in_functions;	/* array of input functions for each attrs */
	Oid		   *typioparams;	/* array of element types for in_functions */
	int		   *defmap;			/* array of default att numbers */
	ExprState **defexprs;		/* array of default att expressions */
	bool		volatile_defexprs;	/* is any of defexprs volatile? */
	List	   *range_table;
	ExprState  *qualexpr;

	TransitionCaptureState *transition_capture;

	/*
	 * These variables are used to reduce overhead in COPY FROM.
	 *
	 * attribute_buf holds the separated, de-escaped text for each field of
	 * the current line.  The CopyReadAttributes functions return arrays of
	 * pointers into this buffer.  We avoid palloc/pfree overhead by re-using
	 * the buffer on each cycle.
	 *
	 * In binary COPY FROM, attribute_buf holds the binary data for the
	 * current field, but the usage is otherwise similar.
	 */
	StringInfoData attribute_buf;

	/* field raw data pointers found by COPY FROM */

	int			max_fields;
	char	  **raw_fields;

	/*
	 * Similarly, line_buf holds the whole input line being processed. The
	 * input cycle is first to read the whole line into line_buf, convert it
	 * to server encoding there, and then extract the individual attribute
	 * fields into attribute_buf.  line_buf is preserved unmodified so that we
	 * can display it in error messages if appropriate.  (In binary mode,
	 * line_buf is not used.)
	 */
	StringInfoData line_buf;
	bool		line_buf_converted; /* converted to server encoding? */
	bool		line_buf_valid; /* contains the row being processed? */

	/*
	 * Finally, raw_buf holds raw data read from the data source (file or
	 * client connection).  In text mode, CopyReadLine parses this data
	 * sufficiently to locate line boundaries, then transfers the data to
	 * line_buf and converts it.  In binary mode, CopyReadBinaryData fetches
	 * appropriate amounts of data from this buffer.  In both modes, we
	 * guarantee that there is a \0 at raw_buf[raw_buf_len].
	 */
#define RAW_BUF_SIZE 65536		/* we palloc RAW_BUF_SIZE+1 bytes */
	char	   *raw_buf;
	int			raw_buf_index;	/* next byte to process */
	int			raw_buf_len;	/* total # of bytes stored */
	uint64		bytes_processed;/* number of bytes processed so far */
	/* Shorthand for number of unconsumed bytes available in raw_buf */
#define RAW_BUF_BYTES(cstate) ((cstate)->raw_buf_len - (cstate)->raw_buf_index)
} CopyFromStateData;

extern void ReceiveCopyBegin(CopyFromState cstate);
extern void ReceiveCopyBinaryHeader(CopyFromState cstate);

#endif							/* COPYFROM_INTERNAL_H */