copyapi.h

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/*-------------------------------------------------------------------------
 *
 * copyapi.h
 *    API for COPY TO/FROM handlers
 *
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/commands/copyapi.h
 *
 *-------------------------------------------------------------------------
 */
#ifndef COPYAPI_H
#define COPYAPI_H
 
#include "commands/copy.h"
 
/*
 * API structure for a COPY TO format implementation. Note this must be
 * allocated in a server-lifetime manner, typically as a static const struct.
 */
typedef struct CopyToRoutine
{
    /*
     * Set output function information. This callback is called once at the
     * beginning of COPY TO.
     *
     * 'finfo' can be optionally filled to provide the catalog information of
     * the output function.
     *
     * 'atttypid' is the OID of data type used by the relation's attribute.
     */
    void        (*CopyToOutFunc) (CopyToState cstate, Oid atttypid,
                                  FmgrInfo *finfo);
 
    /*
     * Start a COPY TO. This callback is called once at the beginning of COPY
     * TO.
     *
     * 'tupDesc' is the tuple descriptor of the relation from where the data
     * is read.
     */
    void        (*CopyToStart) (CopyToState cstate, TupleDesc tupDesc);
 
    /*
     * Write one row stored in 'slot' to the destination.
     */
    void        (*CopyToOneRow) (CopyToState cstate, TupleTableSlot *slot);
 
    /*
     * End a COPY TO. This callback is called once at the end of COPY TO.
     */
    void        (*CopyToEnd) (CopyToState cstate);
} CopyToRoutine;
 
/*
 * API structure for a COPY FROM format implementation. Note this must be
 * allocated in a server-lifetime manner, typically as a static const struct.
 */
typedef struct CopyFromRoutine
{
    /*
     * Set input function information. This callback is called once at the
     * beginning of COPY FROM.
     *
     * 'finfo' can be optionally filled to provide the catalog information of
     * the input function.
     *
     * 'typioparam' can be optionally filled to define the OID of the type to
     * pass to the input function.'atttypid' is the OID of data type used by
     * the relation's attribute.
     */
    void        (*CopyFromInFunc) (CopyFromState cstate, Oid atttypid,
                                   FmgrInfo *finfo, Oid *typioparam);
 
    /*
     * Start a COPY FROM. This callback is called once at the beginning of
     * COPY FROM.
     *
     * 'tupDesc' is the tuple descriptor of the relation where the data needs
     * to be copied. This can be used for any initialization steps required by
     * a format.
     */
    void        (*CopyFromStart) (CopyFromState cstate, TupleDesc tupDesc);
 
    /*
     * Read one row from the source and fill *values and *nulls.
     *
     * 'econtext' is used to evaluate default expression for each column that
     * is either not read from the file or is using the DEFAULT option of COPY
     * FROM. It is NULL if no default values are used.
     *
     * Returns false if there are no more tuples to read.
     */
    bool        (*CopyFromOneRow) (CopyFromState cstate, ExprContext *econtext,
                                   Datum *values, bool *nulls);
 
    /*
     * End a COPY FROM. This callback is called once at the end of COPY FROM.
     */
    void        (*CopyFromEnd) (CopyFromState cstate);
} CopyFromRoutine;
 
#endif                          /* COPYAPI_H */