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1.1 root 1: .th OPENR AM 9/13/77
2: .sh NAME
3: openr - open a relation
4: .sh SYNOPSIS
5: .nf
6: openr(d, mode, uniqid)
7: struct descriptor *d;
8: int mode;
9: char uniqid[MAXNAME];
10: .fi
11: .sh DESCRIPTION
12: OPENR is used to open a relation and set up a descriptor
13: for the relation.
14: The descriptor is used by all of the
15: access method functions and contains a template of the relation.
16: The parameter UNIQID is the unique relation id which is to
17: be opened.
18: OPENR will search the relation relation and find the tuple which describes
19: the desired relation.
20: OPENR will first search for a relation named by UNIQID and
21: owned by the current user.
22: If tha fails,
23: OPENR will search for a relation with the same name
24: but owned by the data base administrator.
25: The calling program may determine who the relation owner is by
26: examining D->RELOWNER in the returned descriptor.
27: OPENR will also search the attribute
28: relation and gather information necessary to create a template
29: of the relation.
30: Finally, OPENR will do the UNIX open on the
31: file which contains the relation.
32: .sp
33: If MODE equals 0, the relation will be opened as a read only file,
34: if MODE equals 1 or 2, the relation will be opened as a read/write file.
35: If MODE is specified as -1 then the relation will be looked
36: up in the relation relation and that part
37: of the descriptor will be filled in.
38: However, the relation will not
39: be opened and the attribute template will not be set in the
40: descriptor.
41: OPENR may be called with MODE set to -2,
42: which will fill in the attribute template and open the relation as read only.
43: Calling OPENR twice, first with MODE set to -1, the second time
44: with MODE set to -2,
45: is equivalent to calling OPENR once with MODE set to 0.
46: Using mode -3 is the same as mode
47: -2 except that the relation is open for writing.
48: Modes -4 and -5 both assume the relation has been
49: opened previously and the descriptor is complete.
50: Mode -4 will reopen the unix file for reading,
51: and mode -5 will reopen the unix file for writing.
52: .sh DIAGNOSTICS
53: .nf
54: AMOPNVIEW_ERR -- attempt to open a view for reading or writing.
55: AMFIND_ERR -- unidentifiable storage structure for relation or attribute
56: relations
57: AMNOATTS_ERR -- error in filling attribute template
58: AMNOFILE_ERR -- no UNIX file corresponding to relation
59: AMWRITE_ERR -- pageflush failure
60: AMREAD_ERR -- get_page failure
61: 0 -- success
62: 1 -- no such relation
63: .fi
64: .sh "TRACE FLAGS"
65: 21.0, 21.4
66: .sh "SEE ALSO"
67: closer, get_attuples, get_reltuple, inpcloser, noclose
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