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c219d9b0a5
This reduces unnecessary exposure of other headers through htup.h, which is very widely included by many files. I have chosen to move the function prototypes to the new file as well, because that means htup.h no longer needs to include tupdesc.h. In itself this doesn't have much effect in indirect inclusion of tupdesc.h throughout the tree, because it's also required by execnodes.h; but it's something to explore in the future, and it seemed best to do the htup.h change now while I'm busy with it.
97 lines
3.1 KiB
C
97 lines
3.1 KiB
C
/*-------------------------------------------------------------------------
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*
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* trigfuncs.c
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* Builtin functions for useful trigger support.
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*
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*
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* Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
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* Portions Copyright (c) 1994, Regents of the University of California
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*
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* src/backend/utils/adt/trigfuncs.c
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*
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*-------------------------------------------------------------------------
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*/
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#include "postgres.h"
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#include "access/htup_details.h"
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#include "commands/trigger.h"
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#include "utils/builtins.h"
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#include "utils/rel.h"
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/*
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* suppress_redundant_updates_trigger
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*
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* This trigger function will inhibit an update from being done
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* if the OLD and NEW records are identical.
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*/
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Datum
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suppress_redundant_updates_trigger(PG_FUNCTION_ARGS)
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{
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TriggerData *trigdata = (TriggerData *) fcinfo->context;
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HeapTuple newtuple,
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oldtuple,
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rettuple;
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HeapTupleHeader newheader,
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oldheader;
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/* make sure it's called as a trigger */
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if (!CALLED_AS_TRIGGER(fcinfo))
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ereport(ERROR,
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(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
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errmsg("suppress_redundant_updates_trigger: must be called as trigger")));
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/* and that it's called on update */
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if (!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
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ereport(ERROR,
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(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
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errmsg("suppress_redundant_updates_trigger: must be called on update")));
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/* and that it's called before update */
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if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
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ereport(ERROR,
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(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
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errmsg("suppress_redundant_updates_trigger: must be called before update")));
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/* and that it's called for each row */
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if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
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ereport(ERROR,
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(errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
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errmsg("suppress_redundant_updates_trigger: must be called for each row")));
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/* get tuple data, set default result */
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rettuple = newtuple = trigdata->tg_newtuple;
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oldtuple = trigdata->tg_trigtuple;
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newheader = newtuple->t_data;
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oldheader = oldtuple->t_data;
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/*
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* We are called before the OID, if any, has been transcribed from the old
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* tuple to the new (in heap_update). To avoid a bogus compare failure,
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* copy the OID now. But check that someone didn't already put another
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* OID value into newtuple. (That's not actually possible at present, but
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* maybe someday.)
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*/
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if (trigdata->tg_relation->rd_rel->relhasoids &&
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!OidIsValid(HeapTupleHeaderGetOid(newheader)))
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HeapTupleHeaderSetOid(newheader, HeapTupleHeaderGetOid(oldheader));
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/* if the tuple payload is the same ... */
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if (newtuple->t_len == oldtuple->t_len &&
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newheader->t_hoff == oldheader->t_hoff &&
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(HeapTupleHeaderGetNatts(newheader) ==
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HeapTupleHeaderGetNatts(oldheader)) &&
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((newheader->t_infomask & ~HEAP_XACT_MASK) ==
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(oldheader->t_infomask & ~HEAP_XACT_MASK)) &&
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memcmp(((char *) newheader) + offsetof(HeapTupleHeaderData, t_bits),
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((char *) oldheader) + offsetof(HeapTupleHeaderData, t_bits),
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newtuple->t_len - offsetof(HeapTupleHeaderData, t_bits)) == 0)
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{
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/* ... then suppress the update */
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rettuple = NULL;
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}
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return PointerGetDatum(rettuple);
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}
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