Hi,
Let me ask you some questions about heap_insert().
I'm trying to insert tuples into a existing table by using intenal
functions
bypassing the query executor.
For example, let's assume that the table name is "MyTable" having a Box
type attribute.
And I want to insert a box '((1,1),(2,2))' into the table.
The following is an internal function call sequence that I think I
should
follow.
Does it make sense?
{ Relation relation; Oid oid; HeapTuple tup; Box box;
r = heap_open("MyTable", RowExclusiveLock); box.high.x = 2; box.high.y = 2; box.low.x = 1; box.low.y = 1;
.......................... oid = insert_heap(r, tup); heap_close(r, NoLock)
}
Now, what I don't know is how to set values to HeapTuple tup.
The following data structure shows the fields that I need to fill in.
I found some fields are set by heap_insert() function, and I marked
with "&". But I have still some fields needing to be set. Especilly,
I have no idea on what I need to set for a box, the actual data which is
going to be stored on PostgreSQL's database.
Does anybody know a good example concerning my question?typedef struct
HeapTupleHeaderData
{ Oid t_oid; /* & OID of this tuple -- 4
bytes */ CommandId t_cmin; /* & insert CID stamp -- 4 bytes
each */ CommandId t_cmax; /* delete CommandId stamp */ TransactionId t_xmin; /* &
insertXID stamp -- 4 bytes
each */ TransactionId t_xmax; /* & delete XID stamp */ ItemPointerData t_ctid; /*
currentTID of this or
newer tuple */ int16 t_natts; /* number of attributes */ uint16 t_infomask;
/* & various infos */ uint8 t_hoff; /* sizeof() tuple header */ bits8
t_bits[MinHeapTupleBitmapSize/ 8];
} HeapTupleHeaderData;
typedef struct HeapTupleData
{ uint32 t_len; /* length of *t_data */ ItemPointerData t_self; /*
SelfItemPointer*/ Oid t_tableOid; /* & table the tuple came from
*/ MemoryContext t_datamcxt; /* memory context of
allocation */ HeapTupleHeader t_data; /* -> tuple header and data */
} HeapTupleData;
Cheers.
