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/*
* logutriga.c - Smart trigger that logs urlencoded changes.
*
* Copyright (c) 2007 Marko Kreen, Skype Technologies OÜ
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <postgres.h>
#include <executor/spi.h>
#include <commands/trigger.h>
#include <catalog/pg_operator.h>
#include <lib/stringinfo.h>
#include <utils/typcache.h>
#include <utils/rel.h>
#include "common.h"
#include "stringutil.h"
PG_FUNCTION_INFO_V1(pgq_logutriga);
Datum pgq_logutriga(PG_FUNCTION_ARGS);
/* need to ignore UPDATE where only ignored columns change */
static int is_interesting_change(PgqTriggerEvent *ev, TriggerData *tg)
{
HeapTuple old_row = tg->tg_trigtuple;
HeapTuple new_row = tg->tg_newtuple;
TupleDesc tupdesc = tg->tg_relation->rd_att;
Datum old_value;
Datum new_value;
bool old_isnull;
bool new_isnull;
bool is_pk;
int i, attkind_idx = -1;
int ignore_count = 0;
/* only UPDATE may need to be ignored */
if (!TRIGGER_FIRED_BY_UPDATE(tg->tg_event))
return 1;
for (i = 0; i < tupdesc->natts; i++) {
/*
* Ignore dropped columns
*/
if (tupdesc->attrs[i]->attisdropped)
continue;
attkind_idx++;
is_pk = pgqtriga_is_pkey(ev, i, attkind_idx);
if (!is_pk && ev->tgargs->ignore_list == NULL)
continue;
old_value = SPI_getbinval(old_row, tupdesc, i + 1, &old_isnull);
new_value = SPI_getbinval(new_row, tupdesc, i + 1, &new_isnull);
/*
* If old and new value are NULL, the column is unchanged
*/
if (old_isnull && new_isnull)
continue;
/*
* If both are NOT NULL, we need to compare the values and skip
* setting the column if equal
*/
if (!old_isnull && !new_isnull) {
Oid opr_oid;
FmgrInfo *opr_finfo_p;
/*
* Lookup the equal operators function call info using the
* typecache if available
*/
TypeCacheEntry *type_cache;
type_cache = lookup_type_cache(SPI_gettypeid(tupdesc, i + 1),
TYPECACHE_EQ_OPR | TYPECACHE_EQ_OPR_FINFO);
opr_oid = type_cache->eq_opr;
if (opr_oid == ARRAY_EQ_OP)
opr_oid = InvalidOid;
else
opr_finfo_p = &(type_cache->eq_opr_finfo);
/*
* If we have an equal operator, use that to do binary
* comparision. Else get the string representation of both
* attributes and do string comparision.
*/
if (OidIsValid(opr_oid)) {
if (DatumGetBool(FunctionCall2(opr_finfo_p, old_value, new_value)))
continue;
} else {
char *old_strval = SPI_getvalue(old_row, tupdesc, i + 1);
char *new_strval = SPI_getvalue(new_row, tupdesc, i + 1);
if (strcmp(old_strval, new_strval) == 0)
continue;
}
}
if (is_pk)
elog(ERROR, "primary key update not allowed");
if (pgqtriga_skip_col(ev, i, attkind_idx)) {
/* this change should be ignored */
ignore_count++;
continue;
}
/* a non-ignored column has changed */
return 1;
}
/* skip if only ignored column had changed */
if (ignore_count)
return 0;
/* do show NOP updates */
return 1;
}
void pgq_urlenc_row(PgqTriggerEvent *ev, HeapTuple row, StringInfo buf)
{
TriggerData *tg = ev->tgdata;
TupleDesc tupdesc = tg->tg_relation->rd_att;
bool first = true;
int i;
const char *col_ident, *col_value;
int attkind_idx = -1;
if (ev->op_type == 'R')
return;
for (i = 0; i < tg->tg_relation->rd_att->natts; i++) {
/* Skip dropped columns */
if (tupdesc->attrs[i]->attisdropped)
continue;
attkind_idx++;
if (pgqtriga_skip_col(ev, i, attkind_idx))
continue;
if (first)
first = false;
else
appendStringInfoChar(buf, '&');
/* quote column name */
col_ident = SPI_fname(tupdesc, i + 1);
pgq_encode_cstring(buf, col_ident, TBUF_QUOTE_URLENC);
/* quote column value */
col_value = SPI_getvalue(row, tupdesc, i + 1);
if (col_value != NULL) {
appendStringInfoChar(buf, '=');
pgq_encode_cstring(buf, col_value, TBUF_QUOTE_URLENC);
}
}
}
/*
* PgQ log trigger, takes 2 arguments:
* 1. queue name to be inserted to.
*
* Queue events will be in format:
* ev_type - operation type, I/U/D
* ev_data - urlencoded column values
* ev_extra1 - table name
* ev_extra2 - optional urlencoded backup
*/
Datum pgq_logutriga(PG_FUNCTION_ARGS)
{
TriggerData *tg;
struct PgqTriggerEvent ev;
HeapTuple row;
/*
* Get the trigger call context
*/
if (!CALLED_AS_TRIGGER(fcinfo))
elog(ERROR, "pgq.logutriga not called as trigger");
tg = (TriggerData *)(fcinfo->context);
if (TRIGGER_FIRED_BY_UPDATE(tg->tg_event))
row = tg->tg_newtuple;
else
row = tg->tg_trigtuple;
if (pgq_is_logging_disabled())
goto skip_it;
/*
* Connect to the SPI manager
*/
if (SPI_connect() < 0)
elog(ERROR, "logutriga: SPI_connect() failed");
pgq_prepare_event(&ev, tg, true);
appendStringInfoString(ev.field[EV_EXTRA1], ev.info->table_name);
appendStringInfoChar(ev.field[EV_TYPE], ev.op_type);
if (ev.op_type != 'R') {
appendStringInfoChar(ev.field[EV_TYPE], ':');
appendStringInfoString(ev.field[EV_TYPE], ev.pkey_list);
}
if (is_interesting_change(&ev, tg)) {
/*
* create type, data
*/
pgq_urlenc_row(&ev, row, ev.field[EV_DATA]);
/*
* Construct the parameter array and insert the log row.
*/
pgq_insert_tg_event(&ev);
}
if (SPI_finish() < 0)
elog(ERROR, "SPI_finish failed");
/*
* After trigger ignores result,
* before trigger skips event if NULL.
*/
skip_it:
if (TRIGGER_FIRED_AFTER(tg->tg_event) || ev.tgargs->skip)
return PointerGetDatum(NULL);
else
return PointerGetDatum(row);
}
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