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1.1 root 1: #
2: /*
3: ** ACCESS.H -- definitions relating to the access methods.
4: **
5: ** Version:
6: ** @(#)access.h 8.2 2/8/85
7: */
8:
9: # ifndef PGSIZE
10:
11:
12: /*
13: ** PGSIZE is the physical size of a page.
14: ** MAXTUP is the maximum size of a tuple, assuming only one
15: ** tuple on the page. This is PGSIZE-hdrsize, where
16: ** hdrsize is the size of the page header (12 bytes).
17: ** MAXLINENO is the maximum number of tuples on a page
18: ** assuming minimum size tuples (1 byte). This is
19: ** constrained by the size of the lineid field of
20: ** the tid.
21: */
22:
23: # define PGSIZE 1024 /* size of page */
24: # define MAXTUP 1010 /* max size of a tuple */
25: # define MAXLINENO 254 /* max tuples per page */
26: # define PGPTRSIZ 4 /* size of a tid */
27: # define MAXTUPS 100 /* maximum number of tups */
28:
29: /* storage structure flags; < 0 means compressed */
30: # define M_HEAP 5 /* paged heap */
31: # define M_ISAM 11 /* indexed sequential */
32: # define M_HASH 21 /* random hash */
33: # define M_BTREE 31 /* BTREES */
34: # define M_ORDER 41 /* ordered */
35: # define M_TRUNC 99 /* internal pseudo-mode: truncated */
36:
37: # define NACCBUFS 3 /* number of access method buffers */
38:
39: /* error flags */
40: # define AMREAD_ERR -1
41: # define AMWRITE_ERR -2
42: # define AMNOFILE_ERR -3 /* can't open file for a relation */
43: # define AMREL_ERR -4 /* can't open relation relation */
44: # define AMATTR_ERR -5 /* can't open attribute relation */
45: # define AMNOATTS_ERR -6 /* attribute missing or xtra in att-rel */
46: # define AMCLOSE_ERR -7 /* can't close relation */
47: # define AMFIND_ERR -8 /* unidentifiable stora Petructure in find */
48: # define AMINVL_ERR -9 /* invalid TID */
49: # define AMOPNVIEW_ERR -10 /* attempt to open a view for rd or wr */
50:
51: /* the following is the access methods buffer */
52: struct accbuf
53: {
54: /* this stuff is actually stored in the relation */
55: long mainpg; /* next main page (0 - eof) */
56: long ovflopg; /* next ovflo page (0 - none) */
57: short nxtlino; /* next avail line no for this page */
58: char firstup[PGSIZE - 12]; /* tuple space */
59: short linetab[1]; /* line table at end of buffer - grows down */
60: /* linetab[lineno] is offset into
61: ** the buffer for that line; linetab[nxtlino]
62: ** is free space pointer */
63:
64: /* this stuff is not stored in the relation */
65: long rel_tupid; /* unique relation id */
66: long thispage; /* page number of the current page */
67: int filedesc; /* file descriptor for this reln */
68: struct accbuf *modf; /* use time link list forward pointer */
69: struct accbuf *modb; /* back pointer */
70: int bufstatus; /* various bits defined below */
71: };
72:
73: /* The following assignments are status bits for accbuf.bufstatus */
74: # define BUF_DIRTY 001 /* page has been changed */
75: # define BUF_LOCKED 002 /* page has a page lock on it */
76: # define BUF_DIRECT 004 /* this is a page from isam direct */
77:
78: /* access method buffer typed differently for various internal operations */
79: struct
80: {
81: char acc_buf[NACCBUFS];
82: };
83:
84: /* pointers to maintain the buffer */
85: extern struct accbuf *Acc_head; /* head of the LRU list */
86: extern struct accbuf *Acc_tail; /* tail of the LRU list */
87: extern struct accbuf Acc_buf[NACCBUFS]; /* the buffers themselves */
88:
89:
90: /*
91: ** ADMIN file struct
92: **
93: ** The ADMIN struct describes the initial part of the ADMIN file
94: ** which exists in each database. This file is used to initially
95: ** create the database, to maintain some information about the
96: ** database, and to access the RELATION and ATTRIBUTE relations
97: ** on OPENR calls.
98: */
99:
100: struct adminhdr
101: {
102: char adowner[2]; /* user code of data base owner */
103: short adflags; /* database flags */
104: short adlength; /* length of adminhdr */
105: short adversion; /* database format stamp */
106: short adreldsz; /* length of relation descriptor */
107: short adattdsz; /* length of attribute descriptor */
108: };
109:
110: struct admin
111: {
112: struct adminhdr adhdr;
113: struct descriptor adreld;
114: struct descriptor adattd;
115: };
116:
117: /*
118: ** Admin status bits
119: **
120: ** These bits define the status of the database. They are
121: ** contained in the adflags field of the admin struct.
122: */
123:
124: # define A_DBCONCUR 0000001 /* set database concurrency */
125: # define A_QRYMOD 0000002 /* database uses query modification */
126: # define A_NEWFMT 0000004 /* database is post-6.2 */
127:
128:
129: /* following is buffer space for data from admin file */
130: extern struct admin Admin;
131:
132: /*
133: ** PGTUPLE -- btree index key (a tid and an index key)
134: */
135:
136: struct pgtuple
137: {
138: struct tup_id childtid; /* the pointer comes before */
139: char childtup[MAXTUP];
140: };
141:
142: /*
143: ** global counters for the number of UNIX read and write
144: ** requests issued by the access methods.
145: */
146:
147: extern long Accuread, Accuwrite;
148:
149: /*
150: ** Global values used by everything
151: */
152:
153: extern char *Acctuple; /* pointer to canonical tuple */
154: extern Accerror; /* error no for fatal errors */
155: extern char Accanon[MAXTUP]; /* canonical tuple buffer */
156:
157:
158: /* Macros for the return values of iutil/add_ovflo.c */
159: # define NOBUFFER -1 /* can't get buffer for overflow page */
160: # define NOSETUP -2 /* can't set up overflow page */
161: # define NOGETCURRENT -3 /* can't get the current page */
162: # define NORMVMAIN -4 /* can't remove the main page */
163: # define NOGETOVFLO -5 /* can't get the overflow page */
164: # endif PGSIZE
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