current/doc/DbFiles.txt

order of opening database files


*       checking options

-       try to read an options file .opt or .OPT
        if found, merge options with those passed,
        and use the successful case for extensions
-       else, if the last path component contains an uppercase ascii
        and no lowercase ascii, use uppercase extensions
-       Options may select to open only index or only data.
-       For both index and data, either traditional or new files are used
        during normal operation, with new files preferred.
        However, both sets may be open during copying.
-       if no read/write mode is explicitly selected,
        readonly is used if a TXT or MST file exists and is readonly.
        (By index file permissions in index-only mode).


*       checking data

-       if TXT exists, use it, done
-       if traditional MST/XRF exist,
        and they are writable or writing was not explicitly selected,
        use them as is, done
-       create TXT and copy any available readonly data

If for a TXT no valid PTR exists, create one.


*       checking index

-       if OXI exits, use it, done
-       if traditional index files exist, open readonly
-       else, OR if writing is wanted
        create OXI for writing, copy old index

1	dpavlin	237	order of opening database files
2
3
4			* checking options
5
6			- try to read an options file .opt or .OPT
7			if found, merge options with those passed,
8			and use the successful case for extensions
9			- else, if the last path component contains an uppercase ascii
10			and no lowercase ascii, use uppercase extensions
11			- Options may select to open only index or only data.
12			- For both index and data, either traditional or new files are used
13			during normal operation, with new files preferred.
14			However, both sets may be open during copying.
15			- if no read/write mode is explicitly selected,
16			readonly is used if a TXT or MST file exists and is readonly.
17			(By index file permissions in index-only mode).
18
19
20			* checking data
21
22			- if TXT exists, use it, done
23			- if traditional MST/XRF exist,
24			and they are writable or writing was not explicitly selected,
25			use them as is, done
26			- create TXT and copy any available readonly data
27
28			If for a TXT no valid PTR exists, create one.
29
30
31			* checking index
32
33			- if OXI exits, use it, done
34			- if traditional index files exist, open readonly
35			- else, OR if writing is wanted
36			create OXI for writing, copy old index
37