---
name: "PQregisterResult"
section: "3"
platform: "linux"
package: "libpqtypes-dev"
version: "1.5.1-9"
release: "Debian 12 (Bookworm)"
platforms: ["linux"]
url: "https://new.carta.tech/PQregisterResult"
---

# PQregisterResult(3)

Registers sub-classes, composites and user-defined types found within a PGresult.

## NAME

PQregisterResult - Registers sub-classes, composites and user-defined types found within a PGresult.

## SYNOPSIS

**#include \<libpqtypes.h\>**\
 **int PQregisterResult(PGconn \****conn***, int** *which***, PGregisterType \****types***,**\
\
                     **int** *count***, PGresult \****res***);**

## DESCRIPTION

*The PQregisterResult() function registers the types found within* *a given PGresult, thus this function makes no calls to a PostgreSQL server* *since the result data is already available.*

*The which argument can be PQT\_COMPOSITE or PQT\_USERDEFINED,* *but not PQT\_SUBCLASS.  The only reason being sub-classes don't talk to* *the server so they have no result set.*

*The types argument is an array containing count types* *to register.  This array must be identical to what was provided to* *the originating PQregisterTypes call.*

*The res argument is a PGresult normally created by calling* *PQregisterTypes followed by PQgetResult.  However, it is possible to* *create your own result via PQmakeEmptyPGresult, PQsetResultAttrs,* *PQsetvalue and call this function.  This approach is a bit risky being* *how the result set generated by type lookup queries are internal and* *subject to change.*

## EXAMPLES

### Using PQregisterResult

*The example registers two composite types asynchronously.  It is worth* *noting that the PGresult obtained via PQgetResult can be cached by an* *application and used when creating new connections, as a way to avoid* *repeatedly performing type lookups with the server.*

```

```

**PGregisterType comp\_types\[\] = {**\
 	**{"myschema.simple", NULL, NULL},**\
 	**{"complex", NULL, NULL}** **};**

**/\* asynchronous registration \*/** **if (PQregisterTypes(conn, PQT\_COMPOSITE, comp\_types, 2, 1))** **{**\
 	**/\* example of a typical event loop \*/**\
 	**for(;;)**\
 	**{**\
 		**int n;**\
 		**fd\_set set;**\
 		**int fd = PQsocket(conn);**\
 		**struct timeval tv = {0, 500000};**

		**FD\_ZERO(&set);**\
 		**FD\_SET(fd, &set);**\
 		**n = select(fd + 1, &set, NULL, NULL, &tv); //or kqueue,epoll,poll,etc..**

		**if (n == -1)**\
 		**{**\
 			**//error**\
 		**}**\
 		**else if (n == 0)**\
 		**{**\
 			**//timeout, do other work ....**\
 		**}**\
 		**else**\
 		**{**\
 			**PGresult \*res;**

			**PQconsumeInput(conn);**\
 			**if(!PQisBusy(conn))**\
 			**{**\
 				**/\* done \*/**\
 				**if(!(res = PQgetResult(conn)))**\
 					**break;**

				**n = PQregisterResult(conn, PQT\_COMPOSITE, comp\_types, 2, res);**

				**/\* This could also be cached and reused with PQregisterResult \*/**\
 				**PQclear(res);**

				**if (!n)**\
 					**//error, consult PQgeterror()**\
 			**}**\
 		**}**\
 	**}** **}**

## RETURN VALUE

*On success, a non-zero value is returned.  On error, zero is* *returned and [PQgeterror(3)](/PQgeterror/3.md) will contain an error message.*

## EXAMPLES

*None.*

## AUTHOR

*A contribution of eSilo, LLC. for the PostgreSQL Database Management System.* *Written by Andrew Chernow.*

## REPORTING BUGS

*Report bugs to \<libpqtypes@esilo.com\>.*

## COPYRIGHT

*Copyright (c) 2011 eSilo, LLC. All rights reserved.*\
 *This is free software; see the source for copying conditions.* *There is NO warranty; not even for MERCHANTABILITY or  FITNESS* *FOR A PARTICULAR PURPOSE.*

## SEE ALSO

*[PQregisterTypes(3)](/PQregisterTypes/3.md), [pqt-handlers(3)](/pqt-handlers/3.md), [PQputf(3)](/PQputf/3.md), [PQgetf(3)](/PQgetf/3.md)*