Minor rewordings + formatting fixes.

This commit is contained in:
Michael Kerrisk 2007-12-16 13:21:15 +00:00
parent 9091595d88
commit fe4d4c41ab
1 changed files with 20 additions and 19 deletions

View File

@ -73,46 +73,41 @@ typedef struct {
.in
.PP
The elements of this structure are as follows:
.TP
bsize
.I Bsize
.TP 10
.I bsize
defines the hash table bucket size, and is, by default, 256 bytes.
It may be preferable to increase the page size for disk-resident tables
and tables with large data items.
.TP
ffactor
.I Ffactor
.I ffactor
indicates a desired density within the hash table.
It is an approximation of the number of keys allowed to accumulate in any
one bucket, determining when the hash table grows or shrinks.
The default value is 8.
.TP
nelem
.I Nelem
.I nelem
is an estimate of the final size of the hash table.
If not set or set too low, hash tables will expand gracefully as keys
are entered, although a slight performance degradation may be noticed.
The default value is 1.
.TP
cachesize
A suggested maximum size, in bytes, of the memory cache.
.I cachesize
is the suggested maximum size, in bytes, of the memory cache.
This value is
.B only
advisory, and the access method will allocate more memory rather
than fail.
.IR "only advisory" ,
and the access method will allocate more memory rather than fail.
.TP
hash
.I Hash
.I hash
is a user defined hash function.
Since no hash function performs equally well on all possible data, the
user may find that the built-in hash function does poorly on a particular
data set.
User specified hash functions must take two arguments (a pointer to a byte
A user-specified hash functions must take two arguments (a pointer to a byte
string and a length) and return a 32-bit quantity to be used as the hash
value.
.TP
lorder
The byte order for integers in the stored database metadata.
.I lorder
is the byte order for integers in the stored database metadata.
The number should represent the order as an integer; for example,
big endian order would be the number 4,321.
If
@ -124,7 +119,13 @@ value specified when the tree was created is used.
If the file already exists (and the
.B O_TRUNC
flag is not specified), the
values specified for the parameters bsize, ffactor, lorder and nelem are
values specified for the parameters
.IR bsize ,
.IR ffactor ,
.IR lorder ,
and
.I nelem
are
ignored and the values specified when the tree was created are used.
.PP
If a hash function is specified,
@ -146,7 +147,7 @@ access method routines may fail and set
for any of the errors specified for the library routine
.BR dbopen (3).
.SH BUGS
Only big and little endian byte order is supported.
Only big and little endian byte order are supported.
.SH "SEE ALSO"
.BR btree (3),
.BR dbopen (3),