-------- Mensaje original --------
Asunto: Re: Problems with MemoryContextSwitchTo ()
De: Pavel Stehule
Para: Yessica Brinkmann
CC: pgsql-general
st 16. 9. 2020 v 13:32 odesílatel Yessica Brinkmann <brinkmann.yessica@xxxxxxxxx> napsal:Good Morning.I will greatly appreciate a help please on this subject. I actually did several tests already and tried a lot to fix it myself. But I am not able to. And I really need to know this in order to finish my university thesis. If someone can help me please.Best regards,Yessica Brinkmannplease, can you attach your code, and can you show the error message?It is hard to say what is the problem from your mail?RegardsPavelEl mié., 16 sept. 2020 a las 0:42, Yessica Brinkmann (<brinkmann.yessica@xxxxxxxxx>) escribió:
Hello.
I think several of you will already remember me. I'm the one with the IndexAdviser topic. Only that I changed my email address.
As you may recall, I am doing my thesis on the subject of IndexAdviser modifications.
I really appreciate the help they have given me in various Postgresql groups.
Well, I was really nearing the end of the programming part of the thesis, when I had a problem to be able to compile my program in a moment, and by accident some lines of source code were moved.
And for this reason, I think I have problems again with the context switch issue, since at some point my context switch stopped working for me, I think because of the issue that some lines of source code were moved.
Well, the fact is that I have a function called get_columnnames, which in the second foreach, is printing the values of idxcd-> varattnnames [i] the null value.
This second foreach, I only do it to test if the data is really saved well and if I can recover it properly.
And since the data is not retrieved properly, or is not saved properly, in the following functions of my program, the value of idxcd-> varattnnames [i] continues to appear as null.
I will appreciate a lot please help, if you can tell me please why the function prints null in the values of idxcd-> varattnnames [i], in the second foreach, if it is due to an error in the context switch, or why it could be .
I send my function as an attachment.
Best regards,
Yessica Brinkmann.
static List*
get_columnnames( List* candidates )
{
int proc;
int ret;
StringInfoData query; /* string for Query */
StringInfoData cols; /* string for Columns */
MemoryContext outerContext;
ListCell *cell;
IndexCandidate* idxcd;
elog( DEBUG3, "IND ADV: get_column_names: ENTER" );
initStringInfo( &query );
initStringInfo( &cols );
foreach( cell, candidates ) /* foreach cell in candidates */
{
int i;
/*elog (INFO, "Ingresando a foreach");*/
idxcd = (IndexCandidate*)lfirst( cell );
if (idxcd == NULL) {
elog( INFO, "idxcd IS NULL" );
continue; /* Or is that fatal enough to break instead? */
}
if (!idxcd->idxused)
continue;
/* pfree() the memory allocated for the previous candidate. FIXME: Avoid
* meddling with the internals of a StringInfo, and try to use an API.
*/
if( cols.len > 0 )
{
initStringInfo(&cols);
} /*IF col.len>0*/
if( query.len > 0 )
{
initStringInfo(&query);
} /*IF col.len>0*/
elog(INFO,"reloid:%d", idxcd->reloid);
appendStringInfo( &query, "select a.attname from pg_class c,pg_attribute a where c.oid=%d AND a.attrelid = c.oid AND (", idxcd->reloid);
/*elog(INFO,"QUERY:%s", query.data);*/
/*elog(INFO,"ncols:%d", idxcd->ncols);*/
for (i = 0; i < idxcd->ncols; ++i)
{
/*elog(INFO,"i:%d", i);*/
/*elog(INFO,"var attno i:%d", idxcd->varattno[i]);*/
/*elog(INFO,"cols:%s", cols.data);*/
appendStringInfo( &cols, "%s a.attnum=%d", (i>0 ? " OR" : ""), idxcd->varattno[i]);
/*elog(INFO,"cols:%s", cols.data);*/
/*elog(INFO,"i:%d", i);*/
elog(INFO,"varattno i:%d", idxcd->varattno[i]);
}/* foreach col in varattno*/
/*elog(INFO,"PASA EL FOR");*/
appendStringInfo( &cols, "%s", ")");
/* FIXME: Mention the column names explicitly after the table name. */
appendStringInfo( &query, "%s;", cols.data);
elog(INFO,"QUERY:%s", query.data);
/*elog(INFO,"LONGITUD:%d", query.len);*/
if( query.len > 0 ) /* if we generated any SQL */
{
outerContext = CurrentMemoryContext;
if( SPI_connect() == SPI_OK_CONNECT )
{
/*elog(INFO,"CONECTADO:%d", query.len);*/
ret=SPI_exec(query.data, 0);
proc=SPI_processed;
TupleDesc tupdesc=SPI_tuptable->tupdesc;
SPITupleTable *tuptable=SPI_tuptable;
char buf[8192];
if( ret>0 )
{
/*elog(INFO,"EJECUTA:%d", query.len);*/
if( SPI_tuptable != NULL)
{
//TupleDesc tupdesc;
//SPITupleTable *tuptable = SPI_tuptable;
//tupdesc = tuptable->tupdesc;
elog(INFO,"procantesciclo:%d", proc);
int i,j;
for(j=0;j<proc;j++)
{
HeapTuple tuple;
elog(INFO,"procdespuesciclo:%d", proc);
/*cada fila*/
int cont=0;
tuple=tuptable->vals[j];
if (tuple!=NULL)
{
for (i=1,buf[0]=0;i<=tupdesc->natts;i++)
{
char *data;
/* cada columna de cada fila*/
data=SPI_getvalue(tuple,tupdesc,i);
elog(INFO,"data:%s", data);
idxcd->varattnombres[i]=MemoryContextStrdup(outerContext, data);
elog(INFO,"valorgc:%s", idxcd->varattnombres[i]);
elog(INFO,"indice:%d", cont);
cont++;
snprintf(buf + strlen (buf), sizeof(buf) - strlen(buf), " %s%s", SPI_getvalue(tuple, tupdesc, i),(i == tupdesc->natts) ? " " : " |");
} /* (i=0,buf[0]=0;i<tupdesc->natts;i++)*/
elog (INFO, "EXECQ: %s", buf);
} /* if (tuple!=null)*/
else
elog( WARNING, "IND ADV: tuple is null." );
} /* (j=0;j<proc;j++)*/
} /*if( SPI_tuptable != NULL)*/
else
elog( WARNING, "IND ADV: SPI_tuptable is null." );
}
else
elog( WARNING, "IND ADV: SPI_execute failed while select." );
if( SPI_finish() != SPI_OK_FINISH )
elog( WARNING, "IND ADV: SPI_finish failed while select." );
} /*if( SPI_connect() == SPI_OK_CONNECT )*/
else
elog( WARNING, "IND ADV: SPI_connect failed while select." );
} /*if( query.len > 0 )*/
elog (INFO, "if( query.len > 0");
/*if( query.len > 0 )*/
} /* foreach cell in candidates */
elog (INFO, "/* foreach cell in candidates */");
foreach( cell, candidates ) /* foreach cell in candidates */
{
MemoryContext oldContext = MemoryContextSwitchTo( outerContext );
MemoryContextSwitchTo( oldContext );
/*elog (INFO, "Ingresando a foreach");*/
idxcd = (IndexCandidate*)lfirst( cell );
if (idxcd == NULL) {
elog( INFO, "idxcd IS NULL" );
continue; /* Or is that fatal enough to break instead? */
}
if (!idxcd->idxused)
continue;
int i;
for (i = 0; i < idxcd->ncols; ++i)
{
/*elog(INFO,"cols:%s", cols.data);*/
elog(INFO,"i:%d", i);
elog(INFO,"varattnombres i:%s", idxcd->varattnombres[i]);
elog(INFO,"varattno i:%d", idxcd->varattno[i]);
}/* foreach col in varattno*/
}
/* TODO: Propose to -hackers to introduce API to free a StringInfoData . */
if ( query.len > 0 )
pfree( query.data );
elog( DEBUG3, "IND ADV: select: EXIT" );
elog (INFO, "retornando get_columnnames");
return candidates;
}
