PostgreSQL 8.1.9ʸ��
��Υڡ��	��ᤷ	�� 33�ϥȥꥬ	��	��Υڡ��

33.3. C�ˤ��ȥꥬ�ؿ��κ��

��Ǥϥȥꥬ�ؿ��ȤΥ��󥿥ե��ˤĤ��٥�ʾܺ٤��ޤ�� ξ��C��ǥȥꥬ�ؿ��ˤΤ�ɬ�פǤ�� ٥�ʸ��Ǻ��С��ܺ٤��˰��äƤ�館�ޤ�� Ƥ��ξ�硢C�ǥȥꥬ��˼�³��Ѥ��뤳�Ȥ�Ƥ��٤��Ǥ�� Ƽ�³��ʸ��ǡ��θ��Ѥ��ȥꥬ��κ��ˡ��ޤ��

�ȥꥬ�ؿ��"version 1"�ؿ��ޥ͡��㥤�󥿥ե��Ȥ�ʤ��ƤϤ��ޤ��

�ؿ��ȥꥬ�ޥ͡��㤫��ƤӽФ��ϡ��̾�ΰ��Ϥ��ΤǤϤʤ��TriggerData��¤�Τ�ؤ�"context"�ݥ��󥿤��Ϥ��ޤ�� C�ؿ��ϡ��ȥꥬ�ޥ͡��㤫��ƤӽФ��줿�Τ��ɤ��ʲ��Υޥ��¹Ԥ��뤳�ȤǸ��뤳�Ȥ��Ǥ��ޤ��

CALLED_AS_TRIGGER(fcinfo)

��ϰʲ��Ÿ��ޤ��

((fcinfo)->context != NULL && IsA((fcinfo)->context, TriggerData))

�⤷��줬��֤��硢fcinfo->context��TriggerData *��˥��㥹�Ȥ��ؤ��줿TriggerData��¤�Τ��Ѥ��뤳�Ȥϰ��Ǥ�� δؿ��ϡ�TriggerData��¤�Τ䤽�줬�ؤ��ɤΤ褦�ʥǡ��ѹ��Ƥ���ޤ����

struct TriggerData��commands/trigger.h��Ƥ��ޤ��

typedef struct TriggerData
{
    NodeTag       type;
    TriggerEvent  tg_event;
    Relation      tg_relation;
    HeapTuple     tg_trigtuple;
    HeapTuple     tg_newtuple;
    Trigger      *tg_trigger;
    Buffer        tg_trigtuplebuf;
    Buffer        tg_newtuplebuf;
} TriggerData;

��Фϲ��Τ褦��Ƥ��ޤ��

type

��T_TriggerData�Ǥ��

tg_event

��δؿ��ƤӽФ��줿��٥�Ȥ򵭽Ҥ��ޤ�� tg_event��Ĵ�٤뤿��ˤϲ��Υޥ��Ȥ��Ȥ��Ǥ��ޤ��

TRIGGER_FIRED_BEFORE(tg_event): �ȥꥬ��BEFORE��ȯ�Ԥ��줿��翿��֤��ޤ��
TRIGGER_FIRED_AFTER(tg_event): �ȥꥬ��AFTER��ȯ�Ԥ��줿��翿��֤��ޤ��
TRIGGER_FIRED_FOR_ROW(tg_event): �ȥꥬ��ԥ�٥�Υ��٥�Ȥ�ȯ�Ԥ��줿��翿��֤��ޤ��
TRIGGER_FIRED_FOR_STATEMENT(tg_event): �ȥꥬ��ʸ��٥�Υ��٥�Ȥ�ȯ�Ԥ��줿��翿��֤��ޤ��
TRIGGER_FIRED_BY_INSERT(tg_event): �ȥꥬ��INSERT��ޥ�ɤ�ȯ�Ԥ��줿��翿��֤��ޤ��
TRIGGER_FIRED_BY_UPDATE(tg_event): �ȥꥬ��UPDATE��ޥ�ɤ�ȯ�Ԥ��줿��翿��֤��ޤ��
TRIGGER_FIRED_BY_DELETE(tg_event): �ȥꥬ��DELETE��ޥ�ɤ�ȯ�Ԥ��줿��翿��֤��ޤ��

tg_relation

�ȥꥬ��ȯ�Ը��Υ�졼��򵭽Ҥ��빽¤�ΤؤΥݥ��󥿤Ǥ�� ι�¤�ΤˤĤ��Ƥξܺ٤ϡ�utils/rel.h�򻲾Ȥ��Ƥ�� Ǥⶽ̣��Τϡ�tg_relation->rd_att�ʥ�졼��󥿥ץ�ε��һҡˤ�tg_relation->rd_rel->relname�Ǥ��ʥ�졼��̾��char*�ǤϤʤ�NameData�Ǥ�� ̾��Υ��ԡ��ɬ�פʾ��ϡ�char*��뤿��SPI_getrelname(tg_relation)��Ѥ��Ƥ��ˡ�

tg_trigtuple

�ȥꥬ��ȯ�Ԥ��줿�ԤؤΥݥ��󥿤Ǥ�� 롢��롢��뤤�Ϲ��ԤǤ�� ⤷INSERT/DELETE�Ǥ��Υȥꥬ��ȯ�Ԥ��줿��ιԤ��̤Τ�Τ��֤��ʤ��INSERT�ξ��˾��䡢��Ф��ʤ��ϡ��򤳤δؿ��֤��Ƥ��

tg_newtuple

�ȥꥬ��UPDATE��ȯ�Ԥ��줿��ϡ��Ԥο��С��ؤΥݥ��󥿤Ǥ�� INSERT�⤷��DELETE�ξ��ϡ�NULL�Ǥ�� UPDATE��٥�Ȥλ��ιԤ��̤Τ�Τ��֤��ʤ��Ф��ʤ��ϡ��򤳤δؿ��֤��Ƥ��

tg_trigger

�ʲ��Τ褦��utils/rel.h��줿��Trigger��¤�ΤؤΥݥ��󥿤Ǥ��

typedef struct Trigger
{
    Oid         tgoid;
    char       *tgname;
    Oid         tgfoid;
    int16       tgtype;
    bool        tgenabled;
    bool        tgisconstraint;
    Oid         tgconstrrelid;
    bool        tgdeferrable;
    bool        tginitdeferred;
    int16       tgnargs;
    int16       tgnattr;
    int16      *tgattr;
    char      **tgargs;
} Trigger;

��ǡ�tgname��ȥꥬ��̾��tgnargs��tgargs��ΰ��ο��tgargs��CREATE TRIGGERʸ�ǻ��ꤵ�줿��ؤΥݥ��󥿤��Ǥ�� ¾�Υ��Ф��ǤΤ߻��Ѥ��ޤ��

tg_trigtuplebuf

tg_trigtuple��ޤ�Хåե��Ǥ�� ץ뤬¸�ߤ��ʤ��ǥ��Хåե��˳�Ǽ��Ƥ��ʤ��InvalidBuffer�Ǥ��

tg_newtuplebuf

tg_newtuple��ޤ�Хåե��Ǥ�� ץ뤬¸�ߤ��ʤ��ǥ��Хåե��˳�Ǽ��Ƥ��ʤ��InvalidBuffer�Ǥ��

�ȥꥬ�ؿ��HeapTuple�ݥ��󥿤⤷��NULL�ݥ��󥿡�SQL��NULL�Ǥ���ޤ���� äơ�isNull�Ͽ��ˤϤʤ�ޤ��ˤΤɤ��餫��֤��ʤ��Фʤ�ޤ�� оݤιԤ��ѹ��ʤ��ϡ��դ��ơ�tg_trigtuple��tg_newtuple��Ŭ�ڤ��֤��Ƥ��

��Υڡ��	�ۡ��	��Υڡ��
�ǡ��ѹ��βĻ��	��	��

33.3. C�ˤ��ȥꥬ�ؿ��κ���

33.3. C�ˤ��ȥꥬ�ؿ��κ��