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Problems with MemoryContextSwitchTo ()

Started byYessica Brinkmann <brinkmann.yessica@gmail.com>
First post2020-09-15 20:14 -0700
Last post2020-09-15 21:28 -0700
Articles 2 — 1 participant

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  Problems with MemoryContextSwitchTo () Yessica Brinkmann <brinkmann.yessica@gmail.com> - 2020-09-15 20:14 -0700
    Re: Problems with MemoryContextSwitchTo () Yessica Brinkmann <brinkmann.yessica@gmail.com> - 2020-09-15 21:28 -0700

#95 — Problems with MemoryContextSwitchTo ()

FromYessica Brinkmann <brinkmann.yessica@gmail.com>
Date2020-09-15 20:14 -0700
SubjectProblems with MemoryContextSwitchTo ()
Message-ID<edea5da9-897e-45ee-979b-3f8cd28067c2n@googlegroups.com>
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 .
Best regards,
Yessica Brinkmann.
Below I write my function:
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;
}

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#96

FromYessica Brinkmann <brinkmann.yessica@gmail.com>
Date2020-09-15 21:28 -0700
Message-ID<594a9ad1-f7ef-43f1-aae7-86eb420e8cc9n@googlegroups.com>
In reply to#95
El martes, 15 de septiembre de 2020 a las 23:14:22 UTC-4, Yessica Brinkmann 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 . 
> Best regards, 
> Yessica Brinkmann. 
> Below I write my function: 
> 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; 
> }
I wanted to send my function as a separate source code file, but I am not allowed to send emails from the mail, I get a warning that messages can only be sent from Google Groups, and it does not allow sending messages with attachments.

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