Age Owner TLA Line data Source code
1 : /*-------------------------------------------------------------------------
2 : *
3 : * trigfuncs.c
4 : * Builtin functions for useful trigger support.
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
8 : * Portions Copyright (c) 1994, Regents of the University of California
9 : *
10 : * src/backend/utils/adt/trigfuncs.c
11 : *
12 : *-------------------------------------------------------------------------
13 : */
14 : #include "postgres.h"
15 :
16 : #include "access/htup_details.h"
17 : #include "commands/trigger.h"
18 : #include "utils/builtins.h"
19 : #include "utils/rel.h"
20 :
21 :
22 : /*
23 : * suppress_redundant_updates_trigger
24 : *
25 : * This trigger function will inhibit an update from being done
26 : * if the OLD and NEW records are identical.
27 : */
28 : Datum
5270 andrew 29 CBC 15 : suppress_redundant_updates_trigger(PG_FUNCTION_ARGS)
30 : {
5050 bruce 31 15 : TriggerData *trigdata = (TriggerData *) fcinfo->context;
32 : HeapTuple newtuple,
33 : oldtuple,
34 : rettuple;
35 : HeapTupleHeader newheader,
36 : oldheader;
37 :
38 : /* make sure it's called as a trigger */
39 15 : if (!CALLED_AS_TRIGGER(fcinfo))
5050 bruce 40 UBC 0 : ereport(ERROR,
41 : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
42 : errmsg("suppress_redundant_updates_trigger: must be called as trigger")));
43 :
44 : /* and that it's called on update */
5050 bruce 45 CBC 15 : if (!TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event))
5050 bruce 46 UBC 0 : ereport(ERROR,
47 : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
48 : errmsg("suppress_redundant_updates_trigger: must be called on update")));
49 :
50 : /* and that it's called before update */
5050 bruce 51 CBC 15 : if (!TRIGGER_FIRED_BEFORE(trigdata->tg_event))
5050 bruce 52 UBC 0 : ereport(ERROR,
53 : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
54 : errmsg("suppress_redundant_updates_trigger: must be called before update")));
55 :
56 : /* and that it's called for each row */
5050 bruce 57 CBC 15 : if (!TRIGGER_FIRED_FOR_ROW(trigdata->tg_event))
5050 bruce 58 UBC 0 : ereport(ERROR,
59 : (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED),
60 : errmsg("suppress_redundant_updates_trigger: must be called for each row")));
61 :
62 : /* get tuple data, set default result */
5050 bruce 63 CBC 15 : rettuple = newtuple = trigdata->tg_newtuple;
5270 andrew 64 15 : oldtuple = trigdata->tg_trigtuple;
65 :
66 15 : newheader = newtuple->t_data;
67 15 : oldheader = oldtuple->t_data;
68 :
69 : /* if the tuple payload is the same ... */
5050 bruce 70 15 : if (newtuple->t_len == oldtuple->t_len &&
5270 andrew 71 12 : newheader->t_hoff == oldheader->t_hoff &&
5050 bruce 72 12 : (HeapTupleHeaderGetNatts(newheader) ==
5269 tgl 73 12 : HeapTupleHeaderGetNatts(oldheader)) &&
5050 bruce 74 12 : ((newheader->t_infomask & ~HEAP_XACT_MASK) ==
5269 tgl 75 12 : (oldheader->t_infomask & ~HEAP_XACT_MASK)) &&
2969 76 12 : memcmp(((char *) newheader) + SizeofHeapTupleHeader,
77 : ((char *) oldheader) + SizeofHeapTupleHeader,
78 12 : newtuple->t_len - SizeofHeapTupleHeader) == 0)
79 : {
80 : /* ... then suppress the update */
5270 andrew 81 6 : rettuple = NULL;
82 : }
83 :
5268 tgl 84 15 : return PointerGetDatum(rettuple);
85 : }
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