Re: [PATCH] postgres_fdw extension support

Hi,

On 2015-07-21 07:28:22 -0700, Paul Ramsey wrote:
> /*
> @@ -229,6 +236,9 @@ foreign_expr_walker(Node *node,
> Oid collation;
> FDWCollateState state;
>
> + /* Access extension metadata from fpinfo on baserel */
> + PgFdwRelationInfo *fpinfo = (PgFdwRelationInfo *)(glob_cxt->foreignrel->fdw_private);
> +
> /* Need do nothing for empty subexpressions */
> if (node == NULL)
> return true;
> @@ -361,7 +371,7 @@ foreign_expr_walker(Node *node,
> * can't be sent to remote because it might have incompatible
> * semantics on remote side.
> */
> - if (!is_builtin(fe->funcid))
> + if (!is_builtin(fe->funcid) && !is_in_extension(fe->funcid, fpinfo))
> return false;

...

> /*
> + * Returns true if given operator/function is part of an extension declared in the
> + * server options.
> + */
> +static bool
> +is_in_extension(Oid procnumber, PgFdwRelationInfo *fpinfo)
> +{
> + static int nkeys = 1;
> + ScanKeyData key[nkeys];
> + HeapTuple tup;
> + Relation depRel;
> + SysScanDesc scan;
> + int nresults = 0;
> +
> + /* Always return false if we don't have any declared extensions */
> + if ( ! fpinfo->extensions )
> + return false;
> +
> + /* We need this relation to scan */
> + depRel = heap_open(DependRelationId, RowExclusiveLock);
> +
> + /* Scan the system dependency table for a all entries this operator */
> + /* depends on, then iterate through and see if one of them */
> + /* is a registered extension */
> + ScanKeyInit(&key[0],
> + Anum_pg_depend_objid,
> + BTEqualStrategyNumber, F_OIDEQ,
> + ObjectIdGetDatum(procnumber));
> +
> + scan = systable_beginscan(depRel, DependDependerIndexId, true,
> + GetCatalogSnapshot(depRel->rd_id), nkeys, key);
> +
> + while (HeapTupleIsValid(tup = systable_getnext(scan)))
> + {
> + Form_pg_depend foundDep = (Form_pg_depend) GETSTRUCT(tup);
> +
> + if ( foundDep->deptype == DEPENDENCY_EXTENSION )
> + {
> + List *extlist = fpinfo->extensions;
> + ListCell *ext;
> +
> + foreach(ext, extlist)
> + {
> + Oid extension_oid = (Oid) lfirst(ext);
> + if ( foundDep->refobjid == extension_oid )
> + {
> + nresults++;
> + }
> + }
> + }
> + if ( nresults > 0 ) break;
> + }
> +
> + systable_endscan(scan);
> + relation_close(depRel, RowExclusiveLock);
> +
> + return nresults > 0;
> +}

Phew. That's mighty expensive to do at frequency.

I guess it'll be more practical to expand this list once and then do a
binary search on the result for the individual functions

Greetings,

Andres Freund