Custom reloptions for table AM

Let table AM define custom reloptions for its tables. This allows specifying
AM-specific parameters by the WITH clause when creating a table.

The reloptions, which could be used outside of table AM, are now extracted
into the CommonRdOptions data structure.  These options could be by decision
of table AM directly specified by a user or calculated in some way.

The new test module test_tam_options evaluates the ability to set up custom
reloptions and calculate fields of CommonRdOptions on their base.

The code may use some parts from prior work by Hao Wu.

Discussion: https://postgr.es/m/CAPpHfdurb9ycV8udYqM%3Do0sPS66PJ4RCBM1g-bBpvzUfogY0EA%40mail.gmail.com
Discussion: https://postgr.es/m/AMUA1wBBBxfc3tKRLLdU64rb.1.1683276279979.Hmail.wuhao%40hashdata.cn
Reviewed-by: Reviewed-by: Pavel Borisov, Matthias van de Meent, Jess Davis

1 files changed, 25 insertions, 0 deletions

diff --git a/src/backend/access/table/tableamapi.c b/src/backend/access/table/tableamapi.c
index 55b8caeadf2..d9e23ef3175 100644
--- a/src/backend/access/table/tableamapi.c
+++ b/src/backend/access/table/tableamapi.c
@@ -13,9 +13,11 @@
 
 #include "access/tableam.h"
 #include "access/xact.h"
+#include "catalog/pg_am.h"
 #include "commands/defrem.h"
 #include "miscadmin.h"
 #include "utils/guc_hooks.h"
+#include "utils/syscache.h"
 
 
 /*
@@ -98,6 +100,29 @@ GetTableAmRoutine(Oid amhandler)
 	return routine;
 }
 
+/*
+ * GetTableAmRoutineByAmOid
+ *		Given the table access method oid get its TableAmRoutine struct, which
+ *		will be palloc'd in the caller's memory context.
+ */
+const TableAmRoutine *
+GetTableAmRoutineByAmOid(Oid amoid)
+{
+	HeapTuple	ht_am;
+	Form_pg_am	amrec;
+	const TableAmRoutine *tableam = NULL;
+
+	ht_am = SearchSysCache1(AMOID, ObjectIdGetDatum(amoid));
+	if (!HeapTupleIsValid(ht_am))
+		elog(ERROR, "cache lookup failed for access method %u",
+			 amoid);
+	amrec = (Form_pg_am) GETSTRUCT(ht_am);
+
+	tableam = GetTableAmRoutine(amrec->amhandler);
+	ReleaseSysCache(ht_am);
+	return tableam;
+}
+
 /* check_hook: validate new default_table_access_method */
 bool
 check_default_table_access_method(char **newval, void **extra, GucSource source)