17.5. ��

����SPI��Ȥä���ϲĻ�����§���������Ƥ��ޤ���src/test/regress/regress.c��contrib/spi�ˡ������ʣ�����㤬����ޤ���

��������˴�ñ��SPI��Ȥä���Ǥ���execq�ץ����������1���ܤΰ����Ȥ���SQL�䤤��碌��2���ܤΰ����Ȥ���tcount��ȤꡢSPI_exec��Ȥä��䤤��碌��¹Ԥ����䤤��碌���оݤȤʤä����ץ�ο����֤��ޤ���

#include "executor/spi.h" /* SPI ��Ȥ�����ˤϤ��줬ɬ�פǤ� */

int execq(text *sql, int cnt);

int
execq(text *sql, int cnt)
{
    char *query;
    int ret;
    int proc;

    /* Ϳ����줿 TEXT ���֥������Ȥ� C ��ʸ������Ѵ����ޤ� */
    query = DatumGetCString(DirectFunctionCall1(textout,
                                                PointerGetDatum(sql)));

    SPI_connect();
    
    ret = SPI_exec(query, cnt);
    
    proc = SPI_processed;
    /*
     * SELECT �䤤��碌�ǡ�ʣ���Υ��ץ뤬�������줿��硢
     * elog (INFO) ��Ȥäơ����ץ��ƤӽФ������֤��ޤ���
     */
    if ( ret == SPI_OK_SELECT && SPI_processed > 0 )
    {
        TupleDesc tupdesc = SPI_tuptable->tupdesc;
        SPITupleTable *tuptable = SPI_tuptable;
        char buf[8192];
        int i,j;
        
        for (j = 0; j < proc; j++)
        {
            HeapTuple tuple = tuptable->vals[j];
            
            for (i = 1, buf[0] = 0; i <= tupdesc->natts; i++)
                snprintf(buf + strlen (buf), sizeof(buf) - strlen(buf)," %s%s",
                        SPI_getvalue(tuple, tupdesc, i),
                        (i == tupdesc->natts) ? " " : " |");
            elog (INFO, "EXECQ: %s", buf);
        }
    }

    SPI_finish();

    pfree(query);

    return (proc);
}

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CREATE FUNCTION execq (text, integer) RETURNS integer
    AS '...path_to_so'
    LANGUAGE C;

vac=> SELECT execq('CREATE TABLE a (x INTEGER)', 0);
execq
-----
    0
(1 row)

vac=> INSERT INTO a VALUES (execq('INSERT INTO a VALUES (0)',0));
INSERT 167631 1
vac=> SELECT execq('SELECT * FROM a',0);
INFO:  EXECQ:0 <<< execq �ˤ�ä��������줿���

INFO:  EXECQ:1 <<< execq �ˤ�ä��֤��줿��ΤȾ�� INSERT �ˤ�ä��������줿���

execq
-----
    2
(1 row)

vac=> SELECT execq('INSERT INTO a SELECT x + 2 FROM a',1);
execq
-----
    1
(1 row)

vac=> SELECT execq('SELECT * FROM a', 10);
INFO:  EXECQ:  0 

INFO:  EXECQ:  1 

INFO:  EXECQ:  2 <<< ���ꤵ�줿 0 + 2 �Ȥ����ͤ� 1 �ĤΥ��ץ�Τߤ���������ޤ���

execq
-----
    3            <<< 10 �Ϻ����ͤ򼨤������Ǥ��� �ºݤΥ��ץ���� 3 �Ȥʤ�ޤ���
(1 row)

vac=> DELETE FROM a;
DELETE 3
vac=> INSERT INTO a VALUES (execq('SELECT * FROM a', 0) + 1);
INSERT 167712 1
vac=> SELECT * FROM a;
x
-
1                <<<  a �ơ��֥�˥��ץ뤬¸�ߤ��ʤ�����(0) + 1 ��Ԥä����
(1 row)

vac=> INSERT INTO a VALUES (execq('SELECT * FROM a', 0) + 1);
INFO:  EXECQ:  0 
INSERT 167713 1
vac=> SELECT * FROM a;
x
-
1
2                <<< a �ơ��֥�˴�¸�� 1 �ĤΥ��ץ� + 1
(2 rows)

--   ����ϥǡ����ѹ��˴ؤ���Ļ�����§���������ޤ���

vac=> INSERT INTO a SELECT execq('SELECT * FROM a', 0) * x FROM a;
INFO:  EXECQ:  1 
INFO:  EXECQ:  2 
INFO:  EXECQ:  1 
INFO:  EXECQ:  2 
INFO:  EXECQ:  2 
INSERT 0 2
vac=> SELECT * FROM a;
x
-
1
2
2                <<< ���ץ�� 2 * 1��2 * 1 ���ܤΥ��ץ�� x ���͡�
6                <<< ���ץ�� 3 * 2��2 + �������줿 1 * 2 ���ܤΥ��ץ���͡�
(4 rows)             ^^^^^^^^^^
                     execq()�ΰۤʤ�ƤӽФ��Ǹ��뤳�Ȥ��Ǥ��륿�ץ�